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Endpoint:
dermal absorption in vitro / ex vivo
Type of information:
read-across from supporting substance (structural analogue or surrogate)
Adequacy of study:
key study
Justification for type of information:
See the RAAF document.
Reason / purpose for cross-reference:
read-across: supporting information
Reason / purpose for cross-reference:
read-across source
Absorption in different matrices:
See table in "Remarks on results..."
Total recovery:
See table in "Remarks on results..."

The distribution of sodium chlorate in human and rat skin is summarised below.

Dose level

 

High (5 mg/cm2)

Low (150 µg/cm2)

Skin type

Unit

Human

Rat

Human

Rat

Total non-absorbed

 

 

 

 

 

Skin surface(skin swabs + surface strips)

 

%

98.40

93.19

99.36

78.66

µg

4772.5

4451.0

144.64

114.36

Remaining on cell (Donor chamber)

 

%

0.07

0.29

0.15

0.68

µg

3.23

13.97

0.22

0.98

Total

%

98.47

93.48

99.49

79.32

Stratum corneum

%

0.22

1.20

0.81

3.67

µg

10.60

57.77

1.17

5.33

Total abosorbed

 

 

 

 

 

Receptor fluid

%

0.20

0.21

0.83

10.82

µg

9.81

10.54

1.21

15.73

skin

%

0.09

1.94

0.22

3.58

µg

4.26

93.36

0.31

5.20

Remaining on cell (receptor chamber)

 

%

0.009

0.009

<0.03

0.05

µg

0.43

0.42

<0.05

0.08

Total

%

0.30

2.17

1.05

14.42

Stratum corneum

%

0.22

1.20

0.81

3.67

µg

10.60

57.77

1.17

5.33

Total absorbable (absorbed + stratum corneum)

%

0.51

3.37

1.85

18.09

Total recovery

%

98.98

96.84

101.35

97.41

Absorption rate (µg/cm2/hr)

 

0.446

0.467

0.166

4.875

Results are expressed as mean applied dose and are calculated from the mean of the individual recoveries and not the sum of the mean components

 

Conclusions:
Rat skin was considerably more permeable than human skin following application at the low dose level. At the high dose level, the permeability of human and rat skin was similar.
The surface swab at 8 hours was intended to reflect a simple washing regimen at the end of the working day and, as such, this material is not regarded as available for absorption. For human skin, 98.31% and 98.92% of the applied dose was recovered in the skin swabs at high and low dose levels, respectively. For rat skin, 92.98% and 77.72% of the applied dose was recovered in the skin swabs at high and low dose levels, respectively. The material recovered on the surface tape strips at 24 hours was considered to be associated with surface residues following incomplete removal at 8 hours, and/or material from the superficial stratum corneum and so was considered to be non-absorbed.
The material present in the receptor fluid, together with that located in the skin sample remaining after tape-stripping and that remaining on the receptor chamber, accounted for 0.30% and 2.17% of the high dose and 1.05% and 14.42% of the low dose for the human and rat skin respectively and this is considered to be directly absorbed.
It was evident that there was some affinity of sodium chlorate for the stratum corneum, with means of 0.22% and 1.20% of the applied dose detected in this compartment for human and rat skin at the high dose, and 0.81% and 3.67% for human and rat skin at the low dose. In vivo, material associated with the stratum corneum may be ultimately absorbed, or lost externally as a result of desquamation of the stratum corneum. In the case of sodium chlorate it was shown that material remaining in the stratum corneum should be considered as available for absorption. Thus, the total absorbable was 0.51% and 3.37% for human and rat skin for the high dose, and 1.85% and 18.09% for human and rat skin for the low dose.
The steady-state absorption rates for sodium chlorate were low, with values of 0.446 µg/cm2/hr (human) and 0.467 µg/cm2/hr (rat) at the high dose level and 0.166 µg/cm2/hr (human) and 4.875 µg/cm2/hr (rat) at the low dose level, showing that sodium chlorate does not rapidly penetrate the skin.
Executive summary:

According to OECD428 and under GLP a comparative in vitro dermal penetration study using human and rat skin was performed.The rate and extent of absorption of sodium chlorate was investigated following dermal application to excised human and rat skin at two dose concentrations. The sodium chlorate was applied as the commercially available undiluted formulation (high level, 5 mg/cm2) and after dilution into water to simulate practical use (low level of 15 g/l). Seven static diffusion cells were prepared for each skin type at each dose level. Dermatomed membranes (200 - 400 µm thickness) were maintained in the cells at approximately 32°C. The integrity of the membranes was first tested using tritiated water (3H2O). After removal of the residual 3H2O, the test formulation was applied to the unoccluded skin samples as a solution at 9.5 µl per cell (10 µl/cm2) (low dose level) and as a granular solid at approximately 5 mg/cm2 (high dose level. To assist skin contact and to mimic perspiration, a saline solution (0.9% w/v) was applied to the skin-membrane (9.5 µl per 0.95 cm2) prior to high dose administration). The skin samples were exposed to the test material for 8 hours, after which time the remaining dose was washed off the skin with a mild detergent solution. Receptor fluid was collected at 0, 2, 4, 6, 8 and 24 hours after dosing. The solubility of sodium chlorate in the receptor fluid was demonstrated to be sufficient for the study and was not rate limiting to the absorption process. At the end of the study, the skin samples were tape stripped to remove residual surface dose and the stratum corneum. The group mean distributions of sodium chlorate are summarised below:


 




















































Dose levelHigh (5 mg/cm2)Low (150 µg/cm2)
 HumanRatHumanRat
Total % non-absorbed98.47 93.4899.4979.32
Total % absorbed0.30 2.171.0514.42
Total % in stratum corneum0.22 1.200.813.67
Total % absorbable0.513.371.8518.09
Absorption rate (µg/cm2/hr)0.446 0.4670.1664.875

Total % absorbable = Total % absorbed + Total % in stratum corneum


 


Results are expressed as mean % applied dose and are calculated from the mean of the individual recoveries and not the sum of the mean components. Rat skin was considerably more permeable than human skin following application at the low dose level. At the high dose level, the permeability of human and rat skin was similar. The directly absorbed material (that in the receptor fluid and remaining in the skin after tape stripping) at 24 hours were 0.30% and 2.17% for the high dose level, and 1.05% and 14.42% for the low dose level, in human and rat skin respectively. There was some affinity of sodium chlorate for the stratum corneum (means of 0.22% and 1.20% of the high dose for human and rat skin respectively, and 0.81% and 3.67% of the low dose for human and rat skin respectively). In vivo, material associated with the stratum corneum may be ultimately absorbed, or lost externally as a result of desquamation of the stratum corneum, and in the case of sodium chlorate the material in this skin layer should be considered as available for absorption. Thus, the total absorbable was 0.51% and 3.37% for human and rat skin at the high dose level, and 1.85% and 18.09% for human and rat skin at the low dose level. The steady-state absorption rates for sodium chlorate applied at the high dose level were 0.446 µg/cm2/hr and 0.467 µg/cm2/hr in human and rat skin, respectively. The steady-state absorption rates for sodium chlorate applied as the aqueous diluted formulation (15 g/l) were 0.166 µg/cm2/hr and 4.875 µg/cm2/hr in human and rat skin, respectively.

Endpoint:
dermal absorption in vitro / ex vivo
Type of information:
experimental study
Adequacy of study:
key study
Study period:
August 2006 - December 2006.
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
other: The study is performed according to internationally accepted guidelines and under GLP.
Qualifier:
according to guideline
Guideline:
OECD Guideline 428 (Skin Absorption: In Vitro Method)
GLP compliance:
yes (incl. QA statement)
Radiolabelling:
no
Remarks:
The test substance was not radiolabelled, 3H2O was used to assess integrity of the skin membranes.
Species:
rat
Strain:
Sprague-Dawley
Sex:
male
Details on test animals or test system and environmental conditions:
TEST ANIMALS
Rat skin:
- Source: Charles River UK Ltd, Margate, Kent, UK.
- Age at study initiation: 28 - 32 days
- Weight at study initiation: 119-134g
- Fasting period before study: not applicable
- Housing: stainless-steel cages with suspended mesh floors in groups of up to a maximum of six rats per cage
- Individual metabolism cages: not applicable
- Diet (e.g. ad libitum): VRF1 diet (Special Diet Services, Witham, UK), ad libitum
- Water (e.g. ad libitum): potable water (Anglian Water), ad libitum
- Acclimation period: at least 5 days


ENVIRONMENTAL CONDITIONS
- Temperature (°C): 21 ± 2
- Humidity (%): 55 ± 15
- Air changes (per hr): 15
- Photoperiod (hrs dark / hrs light): 12/12

IN-LIFE DATES: no data

Human skin:
The skin samples were obtained from human donors post-mortem and were supplied by International Institute for the Advancement of Medicine and Asterand Inc. They were stored at ca -20ºC.

The provenance of each skin sample were as follows:
Skin number Sex Anatomical region Age Receipt at Huntingdon Life Sciences
H1 Female Abdominal 73 22 September 2005
H2 Male Abdominal 47 13 September 2006
H3 Female Abdominal 64 9 March 2005
H4 Female Back 47 14 December 2005
Type of coverage:
other: The skin was placed in static glass diffusion cells
Vehicle:
other: High dose: Unchanged, no vehicle. Low dose: water.
Duration of exposure:
24 hours
Doses:
- Nominal doses:
High dose (Group 1)
Solid granular sodium chlorate was supplied ready for use by the Study Sponsor and therefore no dose preparation was necessary.
Low dose (Group 2)
An aqueous dilution of the sodium chlorate at a concentration of sodium chlorate of 15 g/l was prepared. Solid granular sodium chlorate (0.1502 g) was weighed into a pre-weighed vial. Water was added to a final volume of 10 ml. The diluted dose formulation was magnetically stirred throughout the dosing procedure.
- Actual doses calculated as follows: To accurately determine the quantity of test substance administered to each cell, quality control (QC) doses (9.5 µl) of the test substance were dispensed into vials at intervals throughout the dosing procedure. The QC samples were retained for analysis using the validated analytical method.
- Actual doses: At the low dose level, the achieved dose levels of sodium chlorate applied to the skin were determined by analysis of QC samples taken before, during and after dosing the cells. The achieved doses of sodium chlorate were 145.4 µg per cell, equivalent to 153.1 µg/cm2. At the high dose level, the achieved dose levels of sodium chlorate applied to the skin were determined by direct weighing of each dose. The mean achieved doses of sodium chlorate were 4870 µg per cell (range 4680 - 5220 µg per cell), equivalent to 5130 µg/cm2. The achieved dose levels were considered acceptable to fulfil the objectives of the study.
- Dose volume: 9.5 µl
- Rationale for dose selection: The sodium chlorate was applied as the commercially available undiluted formulation (high level, 5 mg/cm2) and after dilution into water to simulate practical use (low level of 15 g/l).
No. of animals per group:
7 skins were used per dose group per human or rat, in total 14 skins per dose.
Control animals:
yes
Remarks:
one untreated control skin was taken along for the high dose and one for the low dose.
Details on study design:
DOSE PREPARATION
- Method for preparation of dose suspensions: Solid granular sodium chlorate (0.1502 g) was weighed into a pre-weighed vial. Water was added to a final volume of 10 ml. The diluted dose formulation was magnetically stirred throughout the dosing procedure.
- Method of storage: no data

APPLICATION OF DOSE: The low dose formulation was applied to the skin membrane with a calibrated positive displacement pipette at approximately 10 µl/cm2 exposed skin area (9.5 µl of dose, unoccluded). The actual amount of sodium chlorate applied to the skin was determined from aliquots (9.5 Al) of each dose formulation (QC checks) taken at the time of dosing each group of cells. The high dose formulation was evenly applied to the skinmembrane as a granular solid at approximately 5 mg/cm2 exposed skin area (4.75 mg of dose, unoccluded). To assist skin contact and to mimic perspiration, a saline solution (0.9% w/v) was applied to the skin-membrane (9.5 µl per 0.95 cm2) prior to high dose level administration.

VEHICLE
- Justification for use and choice of vehicle (if other than water): water
- Amount(s) applied (volume or weight with unit): 9.5 µl
- Concentration (if solution): 15 mg/L
- Lot/batch no. (if required): no applicable
- Purity: not applicable

ANALYSIS

Measurement of radioactivity
Radioactivity (3H) was measured by liquid scintillation counting (LSC) using LKB-Rackbeta Spectral Rackbeta Spectral (Wallac Oy, Turku, Finland) liquid scintillation counter with automatic quench correction. Generally radioactivity in gross amounts of less than twice background (4 minute counts) was considered to be below the limit of detection.

Receptor fluid (membrane integrity test samples only)
Ultima Gold scintillator (10 ml) was directly added to the receptor fluid samples and the radioactivity measured for tritium (3H) by LSC (Appendix 3). The receptor cell chamber components were soaked in Elga water and sonicated for 30 minutes. The extraction procedure was repeated for the donor cells.

SAMPLE ANALYSIS
Measurement of the amounts of sodium chlorate in the test samples was performed using validated analytical methodology described in Appendix 2. In outline, sodium chlorate was extracted from diffusion cell components, skin, tape-strips and swab samples with water; receptor fluid samples were diluted with water. The quantification of sodium chlorate was performed using liquid chromatography with mass spectrometric detection (LC-MS).
Details on in vitro test system (if applicable):
SKIN PREPARATION
- Source of skin: from rats, details see above or from humans supplied by International Institute for the Advancement of Medicine and Asterand Inc.
- Ethical approval if human skin: no data
- Type of skin: rat and human skin frozen at -15ºC or -20ºC, respectively
- Preparative technique:
Full thickness human skin preparation
Prior to use, skin samples were thawed to room temperature. Each full thickness skin membrane was then swabbed with 70% v/v ethanol/water to remove residual fat and blood, wiped dry and re-hydrated with distilled water prior to dermatoming.
Full thickness rat skin preparation
Six rats weighing 119 - 134 g (28 - 32 days old) were used. Each rat was sacrificed by cervical dislocation. After sacrifice, the body was shaved with
electric clippers and the skin removed and stored at. <-15ºC. Prior to use, skin samples were thawed to room temperature. The skin was then prepared in the same manner as human skin.
Dermatomed skin
The full thickness skin sample was pinned out on a dermatome board (cork board with raised rubber cutting surface) and a mini-dermatome used to cut slices of skin which contained epidermis and some dermis.
- Thickness of skin (in mm): dermatomed skin thickness 200 - 400 µm, measured using a digital calliper
- Membrane integrity check: tritiated water (3H2O) through each membrane prior to the application of the test formulations. Distilled water (3 ml) was added to the receptor chamber of each diffusion cell. An aliquot (250 µl) of 3H2O was applied to the surface of the skin membrane and the cells then occluded. The water in the receptor chambers was removed after 1 hour into scintillation vials and the receptor chamber replenished with 3 ml distilled water. After a further 3 hours, the receptor chamber contents were removed to scintillation vials.
- Storage conditions: rat and human skin frozen at -15ºC or -20ºC, respectively
- Justification of species, anatomical site and preparative technique: no data

PRINCIPLES OF ASSAY
- Diffusion cell: Static glass diffusion cells providing an exposure area of approximately 0.95 cm2 were used. Skin samples were cut from the dermatomed slice and placed onto the receptor chamber of the diffusion cell. The donor chamber was then fixed in place. The receptor fluid used following application of the test substance was 50% v/v ethanol : water. The receptor chamber was filled so that the underside of the skin membrane was in full contact with the receptor fluid. A stirrer bar was inserted into the receptor chamber and the receptor fluid continuously stirred and maintained at 32ºC by placing the diffusion cells onto a multi-plate magnetic stirrer in a water bath.
- Receptor fluid: distilled water
- Solubility od test substance in receptor fluid: The solubility of sodium chlorate in the receptor fluid 50% v/v ethanol : water was shown to be 0.288 mg/ml (range 0.273 - 0.312 mg/ml) after incubation for approximately 24 hours at 32ºC. The solubility of sodium chlorate in the receptor fluid was demonstrated to be adequate and not rate limiting to the absorption process.
- Static system: no
- Flow-through system: no, semi static. The receptor fluid (approximately 3 ml) was taken from each diffusion cell and replenished with fresh receptor fluid (3 ml) at 2, 4, 6 and 8 hours after dose application.
- Test temperature: 32ºC
- Humidity: 44.5 - 48.6%
- Occlusion: no
- Reference substance(s): none
- Other:
Administration and sampling
Following the membrane integrity test, the receptor chamber of the diffusion cell was rinsed out to remove residual 3H2O and filled with 3 ml of receptor (50% v/v ethanol : water). The diffusion cells were returned to the multi-plate magnetic stirrer in the temperature controlled water bath (maintained at 32°C). The low dose formulation was applied to the skin membrane with a calibrated positive displacement pipette at approximately 10 µl/cm2 exposed skin area (9.5 µl of dose, unoccluded). The actual amount of sodium chlorate applied to the skin was determined from aliquots (9.5 µl) of each dose formulation (QC checks) taken at the time of dosing each group of cells. The high dose formulation was evenly applied to the skin membrane
as a granular solid at approximately 5 mg/cm2 exposed skin area (4.75 mg of dose, unoccluded). To assist skin contact and to mimic perspiration, a saline solution (0.9% w/v) was applied to the skin-membrane (9.5 µl per 0.95 cm2) prior to high dose level administration.

Assessment of the skin absorption and distribution of sodium chlorate
The receptor fluid (approximately 3 ml) was taken from each diffusion cell and replenished with fresh receptor fluid (3 ml) at 2, 4, 6 and 8 hours after dose application. The receptor fluid taken at these times and that removed at the end of the experiment (24 hours) were retained for analysis. A sample of fresh 50% v/v ethanol : water was analysed as the zero-hour receptor fluid. Untreated diffusion cells containing skin membranes were also set up to assess background levels of sodium chlorate and (control cells) and to provide samples of matrices for the determination of procedural recoveries through the analytical method (procedural recovery cells).
Each skin sample was swabbed at 8 hours after dosing using 1% Tween 80 in distilled water on three cotton wool buds. A dry cotton wool bud was then used to remove residual 1% Tween 80 solution. At the end of the experimental phase (24 hours after application) the skin membranes were tape-stripped using 3M Scotch ‘Magic’ tape. The initial tape strips (1 - 2) were collected into a glass vial separately and represented residual surface (non-absorbed) dose. Subsequent tape strips containing the stratum corneum were pooled as one batch and collected into sample pots. The remaining skin was retained separately. The diffusion cell components were also retained and analysed for mass balance purposes.
All samples that were not analysed immediately after collection were stored at approximately <-15ºC as soon as possible after collection.
Absorption in different matrices:
See table in "Remarks on results..."
Total recovery:
See table in "Remarks on results..."

The distribution of sodium chlorate in human and rat skin is summarised below.

Dose level

 

High (5 mg/cm2)

Low (150 µg/cm2)

Skin type

Unit

Human

Rat

Human

Rat

Total non-absorbed

 

 

 

 

 

Skin surface(skin swabs + surface strips)

 

%

98.40

93.19

99.36

78.66

µg

4772.5

4451.0

144.64

114.36

Remaining on cell (Donor chamber)

 

%

0.07

0.29

0.15

0.68

µg

3.23

13.97

0.22

0.98

Total

%

98.47

93.48

99.49

79.32

Stratum corneum

%

0.22

1.20

0.81

3.67

µg

10.60

57.77

1.17

5.33

Total abosorbed

 

 

 

 

 

Receptor fluid

%

0.20

0.21

0.83

10.82

µg

9.81

10.54

1.21

15.73

skin

%

0.09

1.94

0.22

3.58

µg

4.26

93.36

0.31

5.20

Remaining on cell (receptor chamber)

 

%

0.009

0.009

<0.03

0.05

µg

0.43

0.42

<0.05

0.08

Total

%

0.30

2.17

1.05

14.42

Stratum corneum

%

0.22

1.20

0.81

3.67

µg

10.60

57.77

1.17

5.33

Total absorbable (absorbed + stratum corneum)

%

0.51

3.37

1.85

18.09

Total recovery

%

98.98

96.84

101.35

97.41

Absorption rate (µg/cm2/hr)

 

0.446

0.467

0.166

4.875

Results are expressed as mean applied dose and are calculated from the mean of the individual recoveries and not the sum of the mean components

 

Conclusions:
Rat skin was considerably more permeable than human skin following application at the low dose level. At the high dose level, the permeability of human and rat skin was similar.
The surface swab at 8 hours was intended to reflect a simple washing regimen at the end of the working day and, as such, this material is not regarded as available for absorption. For human skin, 98.31% and 98.92% of the applied dose was recovered in the skin swabs at high and low dose levels, respectively. For rat skin, 92.98% and 77.72% of the applied dose was recovered in the skin swabs at high and low dose levels, respectively. The material recovered on the surface tape strips at 24 hours was considered to be associated with surface residues following incomplete removal at 8 hours, and/or material from the superficial stratum corneum and so was considered to be non-absorbed.
The material present in the receptor fluid, together with that located in the skin sample remaining after tape-stripping and that remaining on the receptor chamber, accounted for 0.30% and 2.17% of the high dose and 1.05% and 14.42% of the low dose for the human and rat skin respectively and this is considered to be directly absorbed.
It was evident that there was some affinity of sodium chlorate for the stratum corneum, with means of 0.22% and 1.20% of the applied dose detected in this compartment for human and rat skin at the high dose, and 0.81% and 3.67% for human and rat skin at the low dose. In vivo, material associated with the stratum corneum may be ultimately absorbed, or lost externally as a result of desquamation of the stratum corneum. In the case of sodium chlorate it was shown that material remaining in the stratum corneum should be considered as available for absorption. Thus, the total absorbable was 0.51% and 3.37% for human and rat skin for the high dose, and 1.85% and 18.09% for human and rat skin for the low dose.
The steady-state absorption rates for sodium chlorate were low, with values of 0.446 µg/cm2/hr (human) and 0.467 µg/cm2/hr (rat) at the high dose level and 0.166 µg/cm2/hr (human) and 4.875 µg/cm2/hr (rat) at the low dose level, showing that sodium chlorate does not rapidly penetrate the skin.
Executive summary:

According to OECD428 and under GLP a comparative in vitro dermal penetration study using human and rat skin was performed.The rate and extent of absorption of sodium chlorate was investigated following dermal application to excised human and rat skin at two dose concentrations. The sodium chlorate was applied as the commercially available undiluted formulation (high level, 5 mg/cm2) and after dilution into water to simulate practical use (low level of 15 g/l). Seven static diffusion cells were prepared for each skin type at each dose level. Dermatomed membranes (200 - 400 µm thickness) were maintained in the cells at approximately 32°C. The integrity of the membranes was first tested using tritiated water (3H2O). After removal of the residual 3H2O, the test formulation was applied to the unoccluded skin samples as a solution at 9.5 µl per cell (10 µl/cm2) (low dose level) and as a granular solid at approximately 5 mg/cm2 (high dose level. To assist skin contact and to mimic perspiration, a saline solution (0.9% w/v) was applied to the skin-membrane (9.5 µl per 0.95 cm2) prior to high dose administration). The skin samples were exposed to the test material for 8 hours, after which time the remaining dose was washed off the skin with a mild detergent solution. Receptor fluid was collected at 0, 2, 4, 6, 8 and 24 hours after dosing. The solubility of sodium chlorate in the receptor fluid was demonstrated to be sufficient for the study and was not rate limiting to the absorption process. At the end of the study, the skin samples were tape stripped to remove residual surface dose and the stratum corneum. The group mean distributions of sodium chlorate are summarised below:


 




















































Dose levelHigh (5 mg/cm2)Low (150 µg/cm2)
 HumanRatHumanRat
Total % non-absorbed98.47 93.4899.4979.32
Total % absorbed0.30 2.171.0514.42
Total % in stratum corneum0.22 1.200.813.67
Total % absorbable0.513.371.8518.09
Absorption rate (µg/cm2/hr)0.446 0.4670.1664.875

Total % absorbable = Total % absorbed + Total % in stratum corneum


 


Results are expressed as mean % applied dose and are calculated from the mean of the individual recoveries and not the sum of the mean components. Rat skin was considerably more permeable than human skin following application at the low dose level. At the high dose level, the permeability of human and rat skin was similar. The directly absorbed material (that in the receptor fluid and remaining in the skin after tape stripping) at 24 hours were 0.30% and 2.17% for the high dose level, and 1.05% and 14.42% for the low dose level, in human and rat skin respectively. There was some affinity of sodium chlorate for the stratum corneum (means of 0.22% and 1.20% of the high dose for human and rat skin respectively, and 0.81% and 3.67% of the low dose for human and rat skin respectively). In vivo, material associated with the stratum corneum may be ultimately absorbed, or lost externally as a result of desquamation of the stratum corneum, and in the case of sodium chlorate the material in this skin layer should be considered as available for absorption. Thus, the total absorbable was 0.51% and 3.37% for human and rat skin at the high dose level, and 1.85% and 18.09% for human and rat skin at the low dose level. The steady-state absorption rates for sodium chlorate applied at the high dose level were 0.446 µg/cm2/hr and 0.467 µg/cm2/hr in human and rat skin, respectively. The steady-state absorption rates for sodium chlorate applied as the aqueous diluted formulation (15 g/l) were 0.166 µg/cm2/hr and 4.875 µg/cm2/hr in human and rat skin, respectively.

Endpoint:
basic toxicokinetics in vivo
Type of information:
experimental study
Adequacy of study:
weight of evidence
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
other: see 'Remark'
Remarks:
The study is reliable with some restrictions. It is not performed under GLP or according to a standard guideline. The purity of the test substance or vehicle of the chemical. Potassium chlorate is used in stead of sodium chlorate, this does not influence the test results (see Details on test material).
Objective of study:
toxicokinetics
Principles of method if other than guideline:
No guideline followed.

Only males were on test. It was not specified whether Cl- was the only metabolite of ClO2- and Cl- and ClO2- the only metabolites of ClO3- (there was no listing of metabolites). There was no description of methods used to identify the reactive compounds. The unit of the radioactivity in tissues was not an international unit (ng/gm, assumed to be ng/g) and there were no tabulated data (only a histogram was available). The batches used for the study and their purity were not mentioned.
GLP compliance:
no
Radiolabelling:
yes
Species:
rat
Strain:
Sprague-Dawley
Sex:
male
Route of administration:
oral: gavage
Vehicle:
not specified
Duration and frequency of treatment / exposure:
A single dose was given and animals were investigated for 72 hour(s)
Remarks:
Doses / Concentrations:
Males: 0.06 to 0.07 mg/kg bw
No. of animals per sex per dose / concentration:
Males: 8
Females: 0
Control animals:
no
Details on distribution in tissues:
The concentration of labelled Cl was highest in the in plasma (a peak 36Cl plasma level (185 ng/mL) was reached at 30 min) followed by whole blood, stomach, testes, lung, kidney, skin, duodenum, spleen, brain, packed cells, ileum, carcass, liver and bone marrow.
Details on excretion:
The excretion was about 43% in 72h, via the urinary (40%) and faecal (3%) routes. Most of the labelled Cl (39%) was recovered during the first 24h. No radioactivity was detected in the expired air.
Toxicokinetic parameters:
half-life 1st: Elimination of 36Cl radioactivity from plasma was 35 hours after oral administration. After oral treatment with 36ClO3- there was a biphasic decline of 36Cl plasma residue levels, with successive t1/2 of 6.0 hours and 36.7 hours.
Metabolites identified:
yes
Details on metabolites:
Deg. product:
The chlorate ion is eliminated as chloride (55%) and chlorite (10%).

• A peak36Cl-equivalent plasma level (470 ng/mL) was reached 2 hours after administration of36ClO2-. The half-life for the elimination36Cl from plasma was 35 hours.

 

A peak36Cl-equivalent plasma level (185 ng/mL) was reached 30 minutes after administration of36ClO3-. There was a biphasic decline of plasma residue levels, with successive t1/2of 6.0 hours and 36.7 hours.

 

• It was not possible to determine the total recovery (combining both sub-studies) as the unit of radioactivity in organs was not an international unit (ng/gm) and no percentages of the dose were given (Table B.6.1.1-1).

 

Table B.6.1.1-1: Total radioactive residues and total recovery at 72 hours

 

 

 

Total radioactive residues (percent of administered dose)

Treatment schedule

36ClO2-

36ClO3-

Dose-level ranges (mg/kg) RMS

0.12-0.14

0.06-0.07

Sub-study 2

Urine

34.51

40.13

Faeces

4.75

3.14

Cage wash

Not performed

Exhaled air14CO2

0

0

 

Total excreted

39.26

43.27

Sub-study 1

Total retained in tissues, organs and carcass

ND

ND

 

Total recovery

-

-

ND: not expressed as percent of the dose.

-: the total recovery could not be calculated.

 

Cumulated excretions of radioactivity in urine and faeces are summarized in table B.6.1-2.

 

Table B.6.1.1-2: Excretion of radioactivity (expressed as % of the administered dose) in urine and faeces after oral administration of36ClO2-or36ClO3-to male rats

 

Total radioactive residues (percent of administered dose)

Treatment schedule

36ClO2-

36ClO3-

Dose-level ranges (mg/kg) RMS

0.12-0.14

0.06-0.07

Time of collection

urine

faeces

total

urine

faeces

total

0-8 h

3.00

 

3.00

21.57

 

21.57

8-16 h

6.38

6.38

6.23

6.23

16-24h

4.45

4.45

8.63

8.63

0-24 h

13.83

0.87

14.7

36.43

2.47

38.90

24-48 h

8.46

2.42

10.88

0.98

0.30

1.28

48-72 h

12.23

1.46

13.69

2.73

0.37

3.10

0-72 h (total)

34.51

4.75

39.26

40.14

3.14

43.28

 

• The actual absorbed fraction could not be determined as total recovery was unknown (radioactivity in tissues, organs and carcass was not expressed as percent of the administered dose, and radioactivity in cage washes was not measured).

 

Distribution:

 

• After oral administration of36ClO2-, the highest concentration was measured (in decreased order) in whole blood, packed cells, plasma, stomach, testes, skin , lungs, kidney, duodenum, carcass ileum brain, bone marrow and liver.

After oral administration of36ClO3-, the highest concentration was measured (in decreased order) in plasma, whole blood, stomach, testes, lung, kidney, skin , duodenum, spleen, brain, packed cells, carcass, liver and bone marrow, with a 4 order magnitude factor between the smallest and the highest concentrations in tissues.

NB: unit provided in the report was an unknown unit (ng/gm, assumed by the RMS to be ng/g). There were no tabulated data, only a diagram.

 

• After36ClO2-treatment,36Cl radioactivity was detected in urines and faeces. However, it was not possible to state if36Cl radioactivity found in faeces was unchanged36ClO2-or metabolites. In urine,36ClO2-was excreted unchanged and as36Cl-(Table B.6.1.1-3).

After36ClO3-treatment,36Cl radioactivity was detected in urines and faeces. However, it was not possible to state if36Cl radioactivity found in faeces was unchanged36ClO3-or metabolites. In urine,36ClO3-was excreted unchanged and as36ClO2-and36Cl-(B.6.1.1-3).

No radioactivity was detected in the expired air over 72 hours, after36ClO2-and36ClO3-treatments.

The total radioactivity found in urine was slightly different from the sum of radioactivity as unchanged parent and metabolites in urine: 34.51vs. 37.60% after36ClO2-treatment, and 40.14vs. 37.60 after36ClO3-treatment.

 

Table B.6.1.1-3: Distribution of urinary radioactivity expressed as % of the administered dose over 72 hours

 

Total radioactive residues

(percent of administered dose)

Treatment schedule

36ClO2-

36ClO3-

Dose-level ranges (mg/kg) RMS

0.12-0.14

0.06-0.07

36Cl-

31.55

20.49

36ClO2-

6.05#

3.905

36ClO3-

-

13.2#

Total

37.60

37.60

#: parent compound.

Conclusions:
No bioaccumulation potential based on study results
Oral absorption of chlorates is fast since a peak is reached in 30 minutes. The total recovery and the actual oral absorption could not be determined because of inadequate data reporting (organs, tissues and carcass) and absence of measure of radioactivity in cage wash. An estimate of oral absorption could be the percent of administered dose found in urine (34.51% for 36ClO2- treatment and 40.13% for 36ClO3- treatment).
The half-life for the elimination of 36Cl radioactivity from plasma was 35 hours after oral administration of 36ClO2-. After oral treatment with 36ClO3- there was a biphasic decline of 36Cl plasma residue levels, with successive t1/2 of 6.0 hours and 36.7 hours. For both test items, the routes of excretion were faeces and urine (no excretion by expired air).
In urine, 36ClO2- was mainly excreted as Cl- (32% of the dose) and to a lesser extent in unchanged form (6% of the dose). In urine, 36ClO3- was mainly excreted as Cl- (20% of the dose), followed by unchanged parent (13% of the dose) and 36ClO2- (4% of the dose).
Executive summary:

Abdel-Rahman et al. (1985) determined the kinetics of chlorate (and chlorite) in rats. The test material was labelled potassium chlorate K36ClO3. No information was supplied on batch No., purity or vehicle of the chemical. Two groups of four male Sprague Dawley rats received an oral dose of 3 mL of a 5 mg/L36ClO3-(0.85 µCi) (0.06 -0.07 mg/kg bw) preparation. Heparinized blood samples were taken from the first group at 5, 10, 20, 30 and 60 min and 2, 4, 8, 24 and 48 h by orbital sinus puncture and at 72 h when the rats were sacrificed by decapitation. Tissue specimens were taken from the stomach, testes, lung, kidney, duodenum, ileum, spleen, liver, brain, bone marrow, carcass and skin. Faecal, urine and expired air samples were taken from the second group of rats after 8, 16, 24, 48 and 72 h. Radioactivity was measured in all the samples taken.

After administrating of 3 mL of 5 mg/L36ClO3-to the rats, a peak36Cl plasma level (185 ng/mL) was reached at 30 min, showing that absorption is rapid. The half-life for the elimination of36Cl radioactivity from plasma was 35 hours after oral administration of36ClO2-. After oral treatment with36ClO3-there was a biphasic decline of36Cl plasma residue levels, with successive t1/2of 6.0 hours and 36.7 hours. For both test items, the routes of excretion were faeces and urine (no excretion by expired air). T

he distribution of36Cl-compounds 72 h after administration was highest in plasma followed by whole blood, stomach, testes, lung, kidney, skin, duodenum, spleen, brain, packed cells, ileum, carcass, liver and bone marrow. The excretion after chlorate administration was about 43% of administered dose in the 72-hour period, via urinary (40%) and faecal (3%) routes. Most of the36Cl-(39% of administered dose) was recovered during the first 24 hours.

In urine,36ClO2-was mainly excreted as Cl-(32% of the dose) and to a lesser extent in unchanged form (6% of the dose). In urine,36ClO3-was mainly excreted as Cl-(20% of the dose), followed by unchanged parent (13% of the dose) and36ClO2-(4% of the dose).

Endpoint:
basic toxicokinetics in vivo
Type of information:
read-across from supporting substance (structural analogue or surrogate)
Adequacy of study:
weight of evidence
Justification for type of information:
See the RAAF document.
Reason / purpose for cross-reference:
read-across: supporting information
Reason / purpose for cross-reference:
read-across source
Preliminary studies:
Results:
- Adsorption:
62.1-67.9% of the dose was absorbed. Results suggest that chlorate and/or metabolites are rapidly absorbed.
- Distribution;
Recoveries for all tissues were between 91-121% together. The small and large intestine contained 8.2 and 5.2% for the low and the high dose steer, respectively. A significant fraction the radiolabelled chlorine was recovered from edible tissues. These residues were composed of chloride and chlorate. The liver and the kidney contained high concentrations suggesting that total residue is eliminated rapidly. Chlorate represented 28-57% of the total radioactive residues in skeletal muscle, and a smaller percentage of total residue in liver, kidney and adipose tissue. In total 88.8 and 89.9% radioactivity was recovered from the low and the high dose steer, respectively.
- Excretion:
Urine was the major excretion route of radiochlorine with approximately 39-47% eliminated in urine by slaughter. In total 56.9-75.5%. Parent chlorate was 65-100% of the urinary radiochlorine; chloride is one of the other radiochlorine species present. 1.7 and 0.4% of the total dose was excreted in the faeces for the low dose and the high dose steer, respectively. 10% is not accounted for. Excretion via respiration is ruled out. it is assumed that this 10% is present on those parts of the hide of the animals that were not sampled (contaminated with saliva, urine and faeces).
- Tox. behaviour:
During the live phase of the test the high dosage steer stopped consuming food on day 2. faecal output stopped entirely during 36-48 h (12-24 h after a capsule broke, see Overall remarks).
Toxicokinetic parameters:
half-life 2nd:
Toxicokinetic parameters:
half-life 1st:
Toxicokinetic parameters:
half-life 3rd:

Absorption & Distribution

Edible tissues contained a significant fraction of the dosed radiochlorine at slaughter. By virtue of its large proportion of the carcass, skeletal muscle contained the largest fraction of the radiochlorine retained in the body. However, tissues with excretory function such as the liver (bile) and kidney (urine) contained higher concentrations of total residues, also suggesting that the total residue is eliminated rapidly.

Summation of the total amount of radiochlorine recovered in nongastrointestinal tissues and in the urine of the steers indicates that 62.1-67.9% of the dosed chlorate was absorbed by steers 172 and 171, respectively. For edible tissues, total radioactive residues were greatest in kidney (226-236 ppm), followed by liver (70-81 ppm), skeletal muscle (53-47 ppm), and adipose tissue (29-38 ppm).

 

Table 1. Concentrations of radiochlorine, recoveries of radiochlorine in tissues, and total recoveries of radiochlorine in steers 171 and 172. 

 

Steer 171

Steer 172

Fraction

ppm

μCi

%

ppm

μCi

%

Urine

 

796.4

38.6

 

1864.7

46.9

Feces

 

34.8

1.7

 

14.

0.4

 

Edible tissuesa

 

 

 

Liver

69.6

9.7

0.5

80.7

10.0

0.3

Kidney

226.0

5.6

0.3

235.5

6.2

0.2

Skeletal muscle

52.9

285.2

9.3

46.9

163.3

4.1

Adipose tissue

37.8

NA

NA

29.2

NA

NA

 

Inedible tissuesb

 

Totals

200.5

10.1

 

179.5

4.6

Brain

76.4

1.4

0.1

59.3

1.2

0.0

Lung

171.8

12.0

0.6

163.4

10.0

0.3

Spleen

129.4

2.5

0.1

125.6

2.3

0.1

Skin

140.7

121.3

6.1

149.2

141.7

3.6

Heart

93.0

4.3

0.2

102.7

4.7

0.1

Diaphragm

73.5

2.0

0.1

74.8

2.0

0.1

Remains of C solidc

73.0

24.7

0.7

116.2

57.8

1.5

Remains of C liquidc

99.2

14.9

6.6

 

0.0

0.0

Bone

71.1

130.7

6.6

65.5

128.2

3.2

Stomach complexd

140.1

215.8

10.8

460.4

836.9

21.0

Small intestine

269.0

98.5

4.9

320.7

118.0

3.0

Large intestine

245.0

65.5

3.3

312.3

87.5

2.2

Blood

187.9

68.5

3.4

244.1

67.7

1.7

Bile

190.6

0.3

0

240.3

1.9

0.0

 

totals

762.4

38.2

 

1459.9

36.8

Cage wash

 

4.6

0.2

 

49.4

1.2

 

totals

1771.7

88.8

 

2567.9

89.9

a traditionally edible tissues in the

b traditionally non-edible tissues in the

c remains of C, remains of carcass; a liquid portion was collected for animal 171 only

d the stomach complex consisted of the rumen, reticulum, omasum, and abomasum

Excretion

Urine was the major excretory route of radiochlorine with approximately 39-47% of the total administered dose being eliminated in urine by slaughter. In contrast, fecal elimination of radiochlorine was minimal with steers 171 and 172 excreting only 1.7 and 0.4% of the total dose, respectively.

 

Metabolism

The speciation of radioactive residues present in edible tissues of cattle is shown in Table 2. For steer 171 (low dose), parent chlorate represented from 1.3 to 28.4% of the total radioactive residue, depending on the tissue. Total radioactive residues in liver were comprised almost entirely of chloride, with the concentration of chlorate residue being 0.7 ppm. Chlorate residue concentrations in skeletal muscle, kidney, and adipose tissue were 14.2, 25.9, and 2.0 ppm, respectively. For steer 172, chlorate concentrations ranged from 1.3 ppm in liver to 67.0 ppm in kidney. Skeletal muscle and adipose tissue had intermediate concentrations of chlorate at 21.1 and 11.7 ppm, respectively.

Table2. Speciation of total radioactive residues in edible tissues of cattlea

 

 

Steer 171

Steer 172

 

TRRb

extractabilityc

Chloride

 

Chlorate

 

TRRb

extractabilityc

Chloride

 

Chlorate

 

Tissue

(ppmd)

(%)

%

ppmd

%

ppmd

(ppmd)

(%)

%

ppmd

%

ppmd

Adipose tissue

37.8

99.4

94.9

35.9

5.2

2.0

29.2

74.6

59.8

17.5

40.2

11.7

Skeletal muscle

52.9

110.4

73.3

38.8

26.7

14.1

46.9

100.7

56.0

26.3

44.9

21.1

Liver

69.6

98.2

98.8

52.3

1.3

0.7

80.7

95.4

98.5

46.2

1.6

1.3

kidney

226

96.4

88.6

200

11.5

25.9

236

97.1

71.6

169

28.4

67.0

a reported values are means from duplicate analysis

b TRR, total radioactive residues

c percentage of total radioactive residue extracted into water

d calculated as ppm of sodium chlorate equivalents

 

 

Chlorate was the major radioactive species present in urine with the chloride ion being the only other chlorine species present. Chlorate ranged from 65.0 to 98.3% of the total urinary radioactivity for animal 171 and 92.5 to 100% of the urinary radioactivity for animal 172.

Conclusions:
No bioaccumulation potential based on study results
In conclusion, chlorate is rapidly absorbed and excreted in steers. Radiochlorine was present in edible tissues primarily as chloride ion, with lesser amounts of chlorate. The proportion of chloride and chlorate was highly tissue dependent. In contrast, chlorate was the major chlorine species present in urine of steers, indicating that the kidney actively excretes chlorate. Because there was a large difference between the proportion of the total residue present as chloride in tissue and urine, it can be concluded that chloride was actively retained, while chlorate was actively excreted.
Executive summary:

The objectives of this study were to determine total radioactive residues and chlorate residues in edible tissues of cattle administered at three levels of sodium [36Cl]chlorate over a 24-h period and slaughtered after a 24-h withdrawal period. Three sets of cattle, each consisting of a heifer and a steer, were intraruminally dosed with a total of 21, 42, or 63 mg of sodium [36Cl]chlorate/kg of body weight. To simulate a 24-h exposure, equal aliquots of the respective doses were administered to each animal at 0, 8, 16, and 24 h. Urine and feces were collected in 12-h increments for the duration of the 48-h study. At 24 h after the last chlorate exposure, cattle were slaughtered and edible tissues were collected. Urine and tissue samples were analyzed for total radioactive residues and for metabolites. Elimination of radioactivity in urine and feces equaled 20, 33, and 48% of the total dose for the low, medium, and high doses, respectively. Chlorate and chloride were the only radioactive chlorine species present in urine; the fraction of chlorate present as a percentage of the total urine radioactivity decreased with time regardless of the dose. Chloride was the major radioactive residue present in edible tissues, comprising over 98% of the tissue radioactivity for all animals. Chlorate concentrations in edible tissues ranged from nondetectable to an average of 0.41 ppm in skeletal muscle of the high-dosed animals. No evidence for the presence of chlorite was observed in any tissue.

Endpoint:
basic toxicokinetics in vivo
Type of information:
experimental study
Adequacy of study:
weight of evidence
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
other: Non-GLP and non-guideline study. Only 2 animals were used in this preliminary study.
Objective of study:
toxicokinetics
GLP compliance:
no
Species:
cattle
Route of administration:
oral: feed
Vehicle:
other: vegetable oil lubricated gelatine capsules were prepared
Duration and frequency of treatment / exposure:
54 hour(s)
Remarks:
Doses / Concentrations:
Males: 62.5 and 130.6 mg/kg bw
No. of animals per sex per dose / concentration:
Males: 2
Females: 0
Preliminary studies:
Results:
- Adsorption:
62.1-67.9% of the dose was absorbed. Results suggest that chlorate and/or metabolites are rapidly absorbed.
- Distribution;
Recoveries for all tissues were between 91-121% together. The small and large intestine contained 8.2 and 5.2% for the low and the high dose steer, respectively. A significant fraction the radiolabelled chlorine was recovered from edible tissues. These residues were composed of chloride and chlorate. The liver and the kidney contained high concentrations suggesting that total residue is eliminated rapidly. Chlorate represented 28-57% of the total radioactive residues in skeletal muscle, and a smaller percentage of total residue in liver, kidney and adipose tissue. In total 88.8 and 89.9% radioactivity was recovered from the low and the high dose steer, respectively.
- Excretion:
Urine was the major excretion route of radiochlorine with approximately 39-47% eliminated in urine by slaughter. In total 56.9-75.5%. Parent chlorate was 65-100% of the urinary radiochlorine; chloride is one of the other radiochlorine species present. 1.7 and 0.4% of the total dose was excreted in the faeces for the low dose and the high dose steer, respectively. 10% is not accounted for. Excretion via respiration is ruled out. it is assumed that this 10% is present on those parts of the hide of the animals that were not sampled (contaminated with saliva, urine and faeces).
- Tox. behaviour:
During the live phase of the test the high dosage steer stopped consuming food on day 2. faecal output stopped entirely during 36-48 h (12-24 h after a capsule broke, see Overall remarks).
Toxicokinetic parameters:
half-life 2nd:
Toxicokinetic parameters:
half-life 1st:
Toxicokinetic parameters:
half-life 3rd:

Absorption & Distribution

Edible tissues contained a significant fraction of the dosed radiochlorine at slaughter. By virtue of its large proportion of the carcass, skeletal muscle contained the largest fraction of the radiochlorine retained in the body. However, tissues with excretory function such as the liver (bile) and kidney (urine) contained higher concentrations of total residues, also suggesting that the total residue is eliminated rapidly.

Summation of the total amount of radiochlorine recovered in nongastrointestinal tissues and in the urine of the steers indicates that 62.1-67.9% of the dosed chlorate was absorbed by steers 172 and 171, respectively. For edible tissues, total radioactive residues were greatest in kidney (226-236 ppm), followed by liver (70-81 ppm), skeletal muscle (53-47 ppm), and adipose tissue (29-38 ppm).

 

Table 1. Concentrations of radiochlorine, recoveries of radiochlorine in tissues, and total recoveries of radiochlorine in steers 171 and 172. 

 

Steer 171

Steer 172

Fraction

ppm

μCi

%

ppm

μCi

%

Urine

 

796.4

38.6

 

1864.7

46.9

Feces

 

34.8

1.7

 

14.

0.4

 

Edible tissuesa

 

 

 

Liver

69.6

9.7

0.5

80.7

10.0

0.3

Kidney

226.0

5.6

0.3

235.5

6.2

0.2

Skeletal muscle

52.9

285.2

9.3

46.9

163.3

4.1

Adipose tissue

37.8

NA

NA

29.2

NA

NA

 

Inedible tissuesb

 

Totals

200.5

10.1

 

179.5

4.6

Brain

76.4

1.4

0.1

59.3

1.2

0.0

Lung

171.8

12.0

0.6

163.4

10.0

0.3

Spleen

129.4

2.5

0.1

125.6

2.3

0.1

Skin

140.7

121.3

6.1

149.2

141.7

3.6

Heart

93.0

4.3

0.2

102.7

4.7

0.1

Diaphragm

73.5

2.0

0.1

74.8

2.0

0.1

Remains of C solidc

73.0

24.7

0.7

116.2

57.8

1.5

Remains of C liquidc

99.2

14.9

6.6

 

0.0

0.0

Bone

71.1

130.7

6.6

65.5

128.2

3.2

Stomach complexd

140.1

215.8

10.8

460.4

836.9

21.0

Small intestine

269.0

98.5

4.9

320.7

118.0

3.0

Large intestine

245.0

65.5

3.3

312.3

87.5

2.2

Blood

187.9

68.5

3.4

244.1

67.7

1.7

Bile

190.6

0.3

0

240.3

1.9

0.0

 

totals

762.4

38.2

 

1459.9

36.8

Cage wash

 

4.6

0.2

 

49.4

1.2

 

totals

1771.7

88.8

 

2567.9

89.9

a traditionally edible tissues in the

b traditionally non-edible tissues in the

c remains of C, remains of carcass; a liquid portion was collected for animal 171 only

d the stomach complex consisted of the rumen, reticulum, omasum, and abomasum

Excretion

Urine was the major excretory route of radiochlorine with approximately 39-47% of the total administered dose being eliminated in urine by slaughter. In contrast, fecal elimination of radiochlorine was minimal with steers 171 and 172 excreting only 1.7 and 0.4% of the total dose, respectively.

 

Metabolism

The speciation of radioactive residues present in edible tissues of cattle is shown in Table 2. For steer 171 (low dose), parent chlorate represented from 1.3 to 28.4% of the total radioactive residue, depending on the tissue. Total radioactive residues in liver were comprised almost entirely of chloride, with the concentration of chlorate residue being 0.7 ppm. Chlorate residue concentrations in skeletal muscle, kidney, and adipose tissue were 14.2, 25.9, and 2.0 ppm, respectively. For steer 172, chlorate concentrations ranged from 1.3 ppm in liver to 67.0 ppm in kidney. Skeletal muscle and adipose tissue had intermediate concentrations of chlorate at 21.1 and 11.7 ppm, respectively.

Table2. Speciation of total radioactive residues in edible tissues of cattlea

 

 

Steer 171

Steer 172

 

TRRb

extractabilityc

Chloride

 

Chlorate

 

TRRb

extractabilityc

Chloride

 

Chlorate

 

Tissue

(ppmd)

(%)

%

ppmd

%

ppmd

(ppmd)

(%)

%

ppmd

%

ppmd

Adipose tissue

37.8

99.4

94.9

35.9

5.2

2.0

29.2

74.6

59.8

17.5

40.2

11.7

Skeletal muscle

52.9

110.4

73.3

38.8

26.7

14.1

46.9

100.7

56.0

26.3

44.9

21.1

Liver

69.6

98.2

98.8

52.3

1.3

0.7

80.7

95.4

98.5

46.2

1.6

1.3

kidney

226

96.4

88.6

200

11.5

25.9

236

97.1

71.6

169

28.4

67.0

a reported values are means from duplicate analysis

b TRR, total radioactive residues

c percentage of total radioactive residue extracted into water

d calculated as ppm of sodium chlorate equivalents

 

 

Chlorate was the major radioactive species present in urine with the chloride ion being the only other chlorine species present. Chlorate ranged from 65.0 to 98.3% of the total urinary radioactivity for animal 171 and 92.5 to 100% of the urinary radioactivity for animal 172.

Conclusions:
No bioaccumulation potential based on study results
In conclusion, chlorate is rapidly absorbed and excreted in steers. Radiochlorine was present in edible tissues primarily as chloride ion, with lesser amounts of chlorate. The proportion of chloride and chlorate was highly tissue dependent. In contrast, chlorate was the major chlorine species present in urine of steers, indicating that the kidney actively excretes chlorate. Because there was a large difference between the proportion of the total residue present as chloride in tissue and urine, it can be concluded that chloride was actively retained, while chlorate was actively excreted.
Executive summary:

The objectives of this study were to determine total radioactive residues and chlorate residues in edible tissues of cattle administered at three levels of sodium [36Cl]chlorate over a 24-h period and slaughtered after a 24-h withdrawal period. Three sets of cattle, each consisting of a heifer and a steer, were intraruminally dosed with a total of 21, 42, or 63 mg of sodium [36Cl]chlorate/kg of body weight. To simulate a 24-h exposure, equal aliquots of the respective doses were administered to each animal at 0, 8, 16, and 24 h. Urine and feces were collected in 12-h increments for the duration of the 48-h study. At 24 h after the last chlorate exposure, cattle were slaughtered and edible tissues were collected. Urine and tissue samples were analyzed for total radioactive residues and for metabolites. Elimination of radioactivity in urine and feces equaled 20, 33, and 48% of the total dose for the low, medium, and high doses, respectively. Chlorate and chloride were the only radioactive chlorine species present in urine; the fraction of chlorate present as a percentage of the total urine radioactivity decreased with time regardless of the dose. Chloride was the major radioactive residue present in edible tissues, comprising over 98% of the tissue radioactivity for all animals. Chlorate concentrations in edible tissues ranged from nondetectable to an average of 0.41 ppm in skeletal muscle of the high-dosed animals. No evidence for the presence of chlorite was observed in any tissue.

Endpoint:
basic toxicokinetics
Type of information:
read-across from supporting substance (structural analogue or surrogate)
Adequacy of study:
weight of evidence
Justification for type of information:
See the RAAF document.
Reason / purpose for cross-reference:
read-across: supporting information
Reason / purpose for cross-reference:
read-across source
Details on absorption:
- Absorption & Distribution
In the article it is mentioned that blood data will be presented as a separate report and also a separate summary (Oliver et al. 2007). Total radioactive residues increased with dose for all edible tissues ranging from a low of 6 ppm (chlorate equivalents) in skeletal muscle of the low-dose cattle to a high of 79.6 ppm (chlorate equivalents) in kidneys of the high-dose animals. Total radioactive residues were generally the lowest in adipose tissue and skeletal muscle and were the greatest in kidneys. Speciation of the radioactivity using ion chromatography revealed that total radioactive residues were composed nearly exclusively of chloride (Cl-) ion. Average chlorate residues ranged from a low of 0.02 ppm in adipose tissue of low-dose animals to approximately 0.4 ppm in kidneys and skeletal muscle of the medium- and high-dose animals, respectively.
Details on distribution in tissues:
- Absorption & Distribution
In the article it is mentioned that blood data will be presented as a separate report and also a separate summary (Oliver et al. 2007). Total radioactive residues increased with dose for all edible tissues ranging from a low of 6 ppm (chlorate equivalents) in skeletal muscle of the low-dose cattle to a high of 79.6 ppm (chlorate equivalents) in kidneys of the high-dose animals. Total radioactive residues were generally the lowest in adipose tissue and skeletal muscle and were the greatest in kidneys. Speciation of the radioactivity using ion chromatography revealed that total radioactive residues were composed nearly exclusively of chloride (Cl-) ion. Average chlorate residues ranged from a low of 0.02 ppm in adipose tissue of low-dose animals to approximately 0.4 ppm in kidneys and skeletal muscle of the medium- and high-dose animals, respectively.
Details on excretion:
On the average, low-, medium-, and high-dosed animals eliminated about 20, 33, and 48% of the administeredradiochlorine by the end of the 48 h study period. Radiochlorine balance was not conducted during this study; therefore, the total recovery of radiochlorine was not calculated. It is apparent from the excretory data that the percentage of radiochlorine excreted during the study period was dose-dependent. Urine was the primary route of radiochlorine excretion containing roughly 78, 69, and 72% of the total radiochlorine excreted by the low-, medium-, and hight-dosed animals, respectively.
Details on metabolites:
- Metabolism
Urine residues were composed of chlorate and chloride ion. Chromatographic evidence of chlorite in urine was not encountered for any of the urine samples. Chlorate represented between 13.9 and 89.4% of the urinary radioactivity depending on the collection time and dose. Regardless of the dosing level, the fraction of radioactivity present as chlorate decreased with time. The higher chlorate composition of urine collected in the 12 h prior to slaughter clearly demonstrates the active excretion of chlorate by the kidney.

Absorption & Distribution

In the article it is mentioned that blood data will be presented as a separate report and also a separate summary (Oliver et al. 2007). Total radioactive residues increased with dose for all edible tissues ranging from a low of 6 ppm (chlorate equivalents) in skeletal muscle of the low-dose cattle to a high of 79.6 ppm (chlorate equivalents) in kidneys of the high-dose animals. Total radioactive residues were generally the lowest in adipose tissue and skeletal muscle and were the greatest in kidneys. Speciation of the radioactivity using ion chromatography revealed that total radioactive residues were composed nearly exclusively of chloride (Cl-) ion. Average chlorate residues ranged from a low of 0.02 ppm in adipose tissue of low-dose animals to approximately 0.4 ppm in kidneys and skeletal muscle of the medium- and high-dose animals, respectively.

 

Table 1: Radiochemical composition of a [36Cl]chlorate and [36Cl]chloride fortification standard and composition of the same standard after fortification into blank tissue and urine matrices with subsequent extraction and analysis by ion chromatography

 

 

 

Percentage composition

 

 

standarda

Fortified blankb

Item

Fraction

Chloride

Chlorate

Chloride

Chlorate

Liver

 

47.9 ± 0.3

52.1 ± 0.3

51.5

48.5

Kidney

 

47.6 ± 0.2

52.3 ± 0.2

49.2

51.7

Adipose tissue

 

47.8 ± 0.3

52.3 ± 0.3

48.1

51.9

Skeletal muscle

Frozen

 48.5 ± 1.6

51.5 ± 1.6

49.5

50.6

 

Refrigerated

48.0 ± 0.2

52.0 ± 0.2

49.9

50.1

Urine

0-12 h

47.9 ± 0.2

52.2 ± 0.2

48.8

51.3

 

12-24 h

47.6 ± 0.4

52.4 ± 0.4

47.2

52.8

 

24-36 h

48.1 ± 0.5

51.9 ± 0.5

47.2

52.8

 

36-48 h

48.1 ± 0.3

51.9 ± 0.3

46.9

49.1

a prior to each day’s analytical run the chlorate/chloride standard was injected onto the io chromatography system and radiochemical composition was determined by trapping the chloride and chlorate peaks in liquid scintillation vials; radiochlorine was quantified using LSC. Data are presented as means ± standard deviations.

b means of duplicate determinations.

 

 

 

Excretion

 

Table 2: Elimination of radiochlorine (percent of total dosea) in urine and feces of cattle dosed with sodium [36Cl]chlorate:

 

 

 

 

Collection period

 

animal

sex

fraction

0-12 h

12-24 h

24-36 h

36-48 h

totals

 

 

 

21 mg/kg dose

175

Heifer

Urine

1.1

2.4

5.6

5.0

14.1

 

 

Feces

0.0

1.5

2.9

2.5

6.9

 

 

Totals

1.1

3.9

8.5

7.5

21.0

178

Steer

Urine

1.7

5.0

4.8

4.6

16.1

 

 

Feces

0.0

0.0

1.0

1.0

2.0

 

 

Totals

1.7

5.0

5.6

5.6

18.1

 

 

42 mg/kg dose

177

Heifer

Urine

5.3

7.8

3.5

3.7

20.3

 

 

Feces

1.1

4.0

4.5

3.1

12.7

 

 

Totals

6.4

11.8

8.0

6.8

33.0

174

Steer

Urine

2.2

9.6

6.2

7.1

25.1

 

 

Feces

0.0

0.4

3.5

3.6

7.5

 

 

Totals

2.2

10.0

9.7

10.7

32.6

 

 

63 mg/kg dose

176

Heifer

Urine

20.2

20.2

10.0

6.3

47.1

 

 

Feces

0.3

0.3

4.2

3.3

10.9

 

 

Totals

20.5

20.5

14.2

9.6

58.0

173

Steer

Urine

1.6

8.2

6.0

8.2

24.0

 

 

Feces

NA

NA

NA

NA

NA

 

 

Totals

1.6

8.2

6.0

8.2

38.6

a doses of radiochlorine: heifer 175, 214 μCi; steer 178, 288 μCi; heifer 177, 528 μCi; steer 174, 757 μCi; heifer 176, 714 μCi and steer 173, 1133 μCi.

b NA = not applicable. For safety reasons, feces excreted from times 0 to 48 h were collected and pooled after steer 173 had been removed from the metabolism crate for slaughter. 

 

 

 

Metabolism

Urine residues were composed of chlorate and chloride ion. Chromatographic evidence of chlorite in urine was not encountered for any of the urine samples. Chlorate represented between 13.9 and 89.4% of the urinary radioactivity depending on the collection time and dose. Regardless of the dosing level, the fraction of radioactivity present as chlorate decreased with time. The higher chlorate composition of urine collected in the 12 h prior to slaughter clearly demonstrates the active excretion of chlorate by the kidney.

 

Table 3: Chemical composition of radiochlorine excreted into urine of cattle dosed with 21, 42, or 63 mg/kg of body weight of [36Cl]chloratea

 

 

 

Collection period (h)

 

 

Chloride

Chlorate

Chloride

Chlorate

Chloride

Chlorate

Chloride

Chlorate

Dose

Animal

(%)

(%)

(%)

(%)

(%)

(%)

(%)

(%)

Low

175 heifer

10.5

89.6

39.4

60.7

40.2

59.4

83.2

15.8

 

178 steer

31.4

68.6

47.9

56.4

50.8

49.2

88.1

11.9

 

Average

21.0

79.1

43.7

58.6

45.5

54.3

85.7

13.9

Medium

177 heifer

16.7

83.3

31.0

69.1

43.8

56.2

74.2

25.8

 

174 steer

4.6

95.5

37.5

65.7

42.7

57.3

79.6

20.2

 

Average

10.7

89.4

34.3

67.4

43.3

56.8

76.9

23.0

High

176 heifer

11.5

88.5

19.5

80.1

20.5

79.5

59.7

40.3

 

173 steer

21.6

78.4

32.8

73.7

34.4

65.3

52.7

47.2

 

Average

16.6

83.5

26.2

76.9

27.5

72.4

56.2

43.8

a results are expressed as a percentage of the total radioactivity excreted during the indicated time period

Conclusions:
No bioaccumulation potential based on study results
The only measurable metabolite of chlorate present in cattle tissues is chloride a chlorite intermediate was not detected. Data reported in this study indicate that the vast majority of chlorate-related residues present in edible tissues of cattle are present as chloride ion and that chlorate residues remaining in edible tissues are measured in parts per billion rather than parts per million. The major route of excretion is the urine.
Executive summary:

The objectives of this study were to determine total radioactive residues and chlorate residues in edible tissues of cattle administered at three levels of sodium [36Cl]chlorate over a 24-h period and slaughtered after a 24-h withdrawal period. Three sets of cattle, each consisting of a heifer and a steer, were intraruminally dosed with a total of 21, 42, or 63 mg of sodium [36Cl]chlorate/kg of body weight. To simulate a 24-h exposure, equal aliquots of the respective doses were administered to each animal at 0, 8, 16, and 24 h. Urine and feces were collected in 12-h increments for the duration of the 48-h study. At 24 h after the last chlorate exposure, cattle were slaughtered and edible tissues were collected. Urine and tissue samples were analyzed for total radioactive residues and for metabolites. Elimination of radioactivity in urine and feces equaled 20, 33, and 48% of the total dose for the low, medium, and high doses, respectively. Chlorate and chloride were the only radioactive chlorine species present in urine; the fraction of chlorate present as a percentage of the total urine radioactivity decreased with time regardless of the dose. Chloride was the major radioactive residue present in edible tissues, comprising over 98% of the tissue radioactivity for all animals. Chlorate concentrations in edible tissues ranged from nondetectable to an average of 0.41 ppm in skeletal muscle of the high-dosed animals. No evidence for the presence of chlorite was observed in any tissue.

Endpoint:
basic toxicokinetics
Type of information:
experimental study
Adequacy of study:
weight of evidence
Study period:
May 2004 - July 2004
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
other: The study is reliable with some restrictions. It is not performed under GLP and no batch nr. is given.
Objective of study:
toxicokinetics
Qualifier:
equivalent or similar to guideline
Guideline:
OECD Guideline 417 (Toxicokinetics)
GLP compliance:
no
Radiolabelling:
yes
Species:
cattle
Strain:
other: three-quarter blood Loala (Angus/Loala_Loala)
Sex:
male/female
Details on test animals or test system and environmental conditions:
TEST ANIMALS
- Source: Auction Effertz, Ltd. (Bismarck, ND)
- Age at study initiation: no data
- Weight at study initiation: heifers 103.5±4.9kg; steers 159.7±23.0kg
- Fasting period before study: no info
- Housing: housed in concrete-floored pens covered with wood shavings
- Individual metabolism cages: Throughout the dosing and withdrawal periods animals were housed in metabolism crates
- Diet (e.g. ad libitum): ad lib, alfalfa and grass mixture and cracked corn daily
- Water (e.g. ad libitum): ad lib
- Acclimation period: 18 days


ENVIRONMENTAL CONDITIONS
- Temperature (°C): no data
- Humidity (%): no data
- Air changes (per hr): no data
- Photoperiod (hrs dark / hrs light): no data


IN-LIFE DATES: From: May 2004 To: July 2004
Route of administration:
other: intraruminally
Vehicle:
unchanged (no vehicle)
Duration and frequency of treatment / exposure:
The total daily dose for each animal was divided into four equal aliquots that were administered at 0, 8, 16, and 24 h.
Remarks:
Doses / Concentrations:
21, 42, or 63 mg of sodium [36Cl]chlorate/kg of body weight
No. of animals per sex per dose / concentration:
Three sets of cattle, each consisting of a heifer and a steer.
Control animals:
no
Positive control reference chemical:
No.
Details on dosing and sampling:
PHARMACOKINETIC STUDY (Absorption, distribution,metabolism, excretion)
- Tissues and body fluids sampled: urine, faeces, blood, edible tissues
- Time and frequency of sampling: urine and faeces: collected in 12 h intervals during dosing and withdrawal periods; blood: collected through jugular catheters at regular intervals
- Other: edible tissues: cattle were slaughtered 24 h after the last administration of sodium chlorate. Edible tissues were collected for the analysis of total residues and chlorate residues
Statistics:
Not applicable.
Details on absorption:
- Absorption & Distribution
In the article it is mentioned that blood data will be presented as a separate report and also a separate summary (Oliver et al. 2007). Total radioactive residues increased with dose for all edible tissues ranging from a low of 6 ppm (chlorate equivalents) in skeletal muscle of the low-dose cattle to a high of 79.6 ppm (chlorate equivalents) in kidneys of the high-dose animals. Total radioactive residues were generally the lowest in adipose tissue and skeletal muscle and were the greatest in kidneys. Speciation of the radioactivity using ion chromatography revealed that total radioactive residues were composed nearly exclusively of chloride (Cl-) ion. Average chlorate residues ranged from a low of 0.02 ppm in adipose tissue of low-dose animals to approximately 0.4 ppm in kidneys and skeletal muscle of the medium- and high-dose animals, respectively.
Details on distribution in tissues:
- Absorption & Distribution
In the article it is mentioned that blood data will be presented as a separate report and also a separate summary (Oliver et al. 2007). Total radioactive residues increased with dose for all edible tissues ranging from a low of 6 ppm (chlorate equivalents) in skeletal muscle of the low-dose cattle to a high of 79.6 ppm (chlorate equivalents) in kidneys of the high-dose animals. Total radioactive residues were generally the lowest in adipose tissue and skeletal muscle and were the greatest in kidneys. Speciation of the radioactivity using ion chromatography revealed that total radioactive residues were composed nearly exclusively of chloride (Cl-) ion. Average chlorate residues ranged from a low of 0.02 ppm in adipose tissue of low-dose animals to approximately 0.4 ppm in kidneys and skeletal muscle of the medium- and high-dose animals, respectively.
Details on excretion:
On the average, low-, medium-, and high-dosed animals eliminated about 20, 33, and 48% of the administeredradiochlorine by the end of the 48 h study period. Radiochlorine balance was not conducted during this study; therefore, the total recovery of radiochlorine was not calculated. It is apparent from the excretory data that the percentage of radiochlorine excreted during the study period was dose-dependent. Urine was the primary route of radiochlorine excretion containing roughly 78, 69, and 72% of the total radiochlorine excreted by the low-, medium-, and hight-dosed animals, respectively.
Details on metabolites:
- Metabolism
Urine residues were composed of chlorate and chloride ion. Chromatographic evidence of chlorite in urine was not encountered for any of the urine samples. Chlorate represented between 13.9 and 89.4% of the urinary radioactivity depending on the collection time and dose. Regardless of the dosing level, the fraction of radioactivity present as chlorate decreased with time. The higher chlorate composition of urine collected in the 12 h prior to slaughter clearly demonstrates the active excretion of chlorate by the kidney.

Absorption & Distribution

In the article it is mentioned that blood data will be presented as a separate report and also a separate summary (Oliver et al. 2007). Total radioactive residues increased with dose for all edible tissues ranging from a low of 6 ppm (chlorate equivalents) in skeletal muscle of the low-dose cattle to a high of 79.6 ppm (chlorate equivalents) in kidneys of the high-dose animals. Total radioactive residues were generally the lowest in adipose tissue and skeletal muscle and were the greatest in kidneys. Speciation of the radioactivity using ion chromatography revealed that total radioactive residues were composed nearly exclusively of chloride (Cl-) ion. Average chlorate residues ranged from a low of 0.02 ppm in adipose tissue of low-dose animals to approximately 0.4 ppm in kidneys and skeletal muscle of the medium- and high-dose animals, respectively.

 

Table 1: Radiochemical composition of a [36Cl]chlorate and [36Cl]chloride fortification standard and composition of the same standard after fortification into blank tissue and urine matrices with subsequent extraction and analysis by ion chromatography

 

 

 

Percentage composition

 

 

standarda

Fortified blankb

Item

Fraction

Chloride

Chlorate

Chloride

Chlorate

Liver

 

47.9 ± 0.3

52.1 ± 0.3

51.5

48.5

Kidney

 

47.6 ± 0.2

52.3 ± 0.2

49.2

51.7

Adipose tissue

 

47.8 ± 0.3

52.3 ± 0.3

48.1

51.9

Skeletal muscle

Frozen

 48.5 ± 1.6

51.5 ± 1.6

49.5

50.6

 

Refrigerated

48.0 ± 0.2

52.0 ± 0.2

49.9

50.1

Urine

0-12 h

47.9 ± 0.2

52.2 ± 0.2

48.8

51.3

 

12-24 h

47.6 ± 0.4

52.4 ± 0.4

47.2

52.8

 

24-36 h

48.1 ± 0.5

51.9 ± 0.5

47.2

52.8

 

36-48 h

48.1 ± 0.3

51.9 ± 0.3

46.9

49.1

a prior to each day’s analytical run the chlorate/chloride standard was injected onto the io chromatography system and radiochemical composition was determined by trapping the chloride and chlorate peaks in liquid scintillation vials; radiochlorine was quantified using LSC. Data are presented as means ± standard deviations.

b means of duplicate determinations.

 

 

 

Excretion

 

Table 2: Elimination of radiochlorine (percent of total dosea) in urine and feces of cattle dosed with sodium [36Cl]chlorate:

 

 

 

 

Collection period

 

animal

sex

fraction

0-12 h

12-24 h

24-36 h

36-48 h

totals

 

 

 

21 mg/kg dose

175

Heifer

Urine

1.1

2.4

5.6

5.0

14.1

 

 

Feces

0.0

1.5

2.9

2.5

6.9

 

 

Totals

1.1

3.9

8.5

7.5

21.0

178

Steer

Urine

1.7

5.0

4.8

4.6

16.1

 

 

Feces

0.0

0.0

1.0

1.0

2.0

 

 

Totals

1.7

5.0

5.6

5.6

18.1

 

 

42 mg/kg dose

177

Heifer

Urine

5.3

7.8

3.5

3.7

20.3

 

 

Feces

1.1

4.0

4.5

3.1

12.7

 

 

Totals

6.4

11.8

8.0

6.8

33.0

174

Steer

Urine

2.2

9.6

6.2

7.1

25.1

 

 

Feces

0.0

0.4

3.5

3.6

7.5

 

 

Totals

2.2

10.0

9.7

10.7

32.6

 

 

63 mg/kg dose

176

Heifer

Urine

20.2

20.2

10.0

6.3

47.1

 

 

Feces

0.3

0.3

4.2

3.3

10.9

 

 

Totals

20.5

20.5

14.2

9.6

58.0

173

Steer

Urine

1.6

8.2

6.0

8.2

24.0

 

 

Feces

NA

NA

NA

NA

NA

 

 

Totals

1.6

8.2

6.0

8.2

38.6

a doses of radiochlorine: heifer 175, 214 μCi; steer 178, 288 μCi; heifer 177, 528 μCi; steer 174, 757 μCi; heifer 176, 714 μCi and steer 173, 1133 μCi.

b NA = not applicable. For safety reasons, feces excreted from times 0 to 48 h were collected and pooled after steer 173 had been removed from the metabolism crate for slaughter. 

 

 

 

Metabolism

Urine residues were composed of chlorate and chloride ion. Chromatographic evidence of chlorite in urine was not encountered for any of the urine samples. Chlorate represented between 13.9 and 89.4% of the urinary radioactivity depending on the collection time and dose. Regardless of the dosing level, the fraction of radioactivity present as chlorate decreased with time. The higher chlorate composition of urine collected in the 12 h prior to slaughter clearly demonstrates the active excretion of chlorate by the kidney.

 

Table 3: Chemical composition of radiochlorine excreted into urine of cattle dosed with 21, 42, or 63 mg/kg of body weight of [36Cl]chloratea

 

 

 

Collection period (h)

 

 

Chloride

Chlorate

Chloride

Chlorate

Chloride

Chlorate

Chloride

Chlorate

Dose

Animal

(%)

(%)

(%)

(%)

(%)

(%)

(%)

(%)

Low

175 heifer

10.5

89.6

39.4

60.7

40.2

59.4

83.2

15.8

 

178 steer

31.4

68.6

47.9

56.4

50.8

49.2

88.1

11.9

 

Average

21.0

79.1

43.7

58.6

45.5

54.3

85.7

13.9

Medium

177 heifer

16.7

83.3

31.0

69.1

43.8

56.2

74.2

25.8

 

174 steer

4.6

95.5

37.5

65.7

42.7

57.3

79.6

20.2

 

Average

10.7

89.4

34.3

67.4

43.3

56.8

76.9

23.0

High

176 heifer

11.5

88.5

19.5

80.1

20.5

79.5

59.7

40.3

 

173 steer

21.6

78.4

32.8

73.7

34.4

65.3

52.7

47.2

 

Average

16.6

83.5

26.2

76.9

27.5

72.4

56.2

43.8

a results are expressed as a percentage of the total radioactivity excreted during the indicated time period

Conclusions:
No bioaccumulation potential based on study results
The only measurable metabolite of chlorate present in cattle tissues is chloride a chlorite intermediate was not detected. Data reported in this study indicate that the vast majority of chlorate-related residues present in edible tissues of cattle are present as chloride ion and that chlorate residues remaining in edible tissues are measured in parts per billion rather than parts per million. The major route of excretion is the urine.
Executive summary:

The objectives of this study were to determine total radioactive residues and chlorate residues in edible tissues of cattle administered at three levels of sodium [36Cl]chlorate over a 24-h period and slaughtered after a 24-h withdrawal period. Three sets of cattle, each consisting of a heifer and a steer, were intraruminally dosed with a total of 21, 42, or 63 mg of sodium [36Cl]chlorate/kg of body weight. To simulate a 24-h exposure, equal aliquots of the respective doses were administered to each animal at 0, 8, 16, and 24 h. Urine and feces were collected in 12-h increments for the duration of the 48-h study. At 24 h after the last chlorate exposure, cattle were slaughtered and edible tissues were collected. Urine and tissue samples were analyzed for total radioactive residues and for metabolites. Elimination of radioactivity in urine and feces equaled 20, 33, and 48% of the total dose for the low, medium, and high doses, respectively. Chlorate and chloride were the only radioactive chlorine species present in urine; the fraction of chlorate present as a percentage of the total urine radioactivity decreased with time regardless of the dose. Chloride was the major radioactive residue present in edible tissues, comprising over 98% of the tissue radioactivity for all animals. Chlorate concentrations in edible tissues ranged from nondetectable to an average of 0.41 ppm in skeletal muscle of the high-dosed animals. No evidence for the presence of chlorite was observed in any tissue.

Endpoint:
basic toxicokinetics
Type of information:
read-across from supporting substance (structural analogue or surrogate)
Adequacy of study:
weight of evidence
Justification for type of information:
See the RAAF document.
Reason / purpose for cross-reference:
read-across: supporting information
Reason / purpose for cross-reference:
read-across source
Details on absorption:
- Absorption & Distribution
Edible tissues contained 1.0 ± 0.1% of the dosed radiochlorine at slaughter, kidneys > adipose tissue > liver >
skeletal muscle. Nonedible tissues contained an average of 3.9 ± 0.7% of the dosed activity, with bone, skin, and blood retaining the largest percentage of radiochlorine, largely due to the fairly large masses of these fractions.
Details on distribution in tissues:
- Absorption & Distribution
Edible tissues contained 1.0 ± 0.1% of the dosed radiochlorine at slaughter, kidneys > adipose tissue > liver >
skeletal muscle. Nonedible tissues contained an average of 3.9 ± 0.7% of the dosed activity, with bone, skin, and blood retaining the largest percentage of radiochlorine, largely due to the fairly large masses of these fractions.
Details on excretion:
- Excretion:
The major part of the dosed radioactivity was excreted via the urine. By the time of slaughter (30h), the cumulative excretion of radiochlorine in urine was 83.1 ± 2.6% of the total dosed activity. During the first 12h of the study 56.2 ± 8.5% of the dose was excreted in the urine. Across all doses, feces contained a cumulative 1.1 ± 1.8% of the administered radiochlorine.
Details on metabolites:
- Metabolism
In no instance was chlorite ion detected in urine or fecal samples. Urinary radiochlorine composition was greater than 97% chlorate, regardless of dose or time of radiochlorine excretion. Chlorate comprised from 39 to 77% of the total fecal residue. In contrast to the composition of residues in excreta, tissue residues were composed primarily of chloride ion rather than chlorate ion.

Absorption & Distribution

Edible tissues contained 1.0 ± 0.1% of the dosed radiochlorine at slaughter, kidneys > adipose tissue > liver >skeletal muscle. Nonedible tissues contained an average of 3.9 ± 0.7% of the dosed activity, with bone, skin, and blood retaining the largest percentage of radiochlorine, largely due to the fairly large masses of these fractions.

Table 1: Distribution and recoveries of radiochlorine in tissues and excreta of pigsa

 

Low dosea

 

Medium dose

 

High dose

 

 

%

%

%

%

%

%

 

Gilt

Barrow

Gilt

Barrow

Gilt

Barrow

 

388

390

387

393

389

392

 

Edible tissues

 

 

 

Adipose tissue

0.0b

0.0

0.0

0.0

0.0

0.0

Kidney

0.0

0.0

0.1

0.1

0.0

0.0

Liver

0.1

0.1

0.1

0.1

0.1

0.1

Skeletal muscle

1.1

1.0

0.8

0.7

0.9

0.7

Total in category

1.2

1.1

1.0

0.9

1.0

0.8

 

Inedible tissuesb

Blood

0.6

0.4

0.4

0.4

0.5

0.4

Brain

0.0

0.0

0.0

0.0

0.0

0.0

Diaphragm

0.0

0.0

0.0

0.0

0.0

0.0

GI tissues

0.4

0.4

0.3

0.3

0.4

0.5

GI contents

0.6

0.4

0.4

0.3

0.2

0.5

Lung

0.1

0.1

0.1

0.1

0.1

0.1

Skin

1.3

1.1

0.7

0.9

0.7

1.0

Spleen

0.0

0.0

0.0

0.0

0.0

0.0

Thyroid gland

0.0

0.0

0.0

0.0

0.0

0.0

Heart

0.0

0.0

0.0

0.0

0.0

0.0

Bone

2.0

1.8

1.4

1.4

1.2

1.6

Bile

0.0

0.0

0.0

0.0

0.0

0.0

Remainder of carcass

0.1

0.1

0.1

0.1

0.0

0.1

Total in category

5.1

4.3

3.4

3.5

3.1

4.2

 

Urine

0-12 h

46.6

55.0

62.3

63.0

54.4

44.8

0-12 h spill

 

 

 

 

10.2

0.7

12-24 h

28.6

25.2

4.0

21.4

18.4

33.4

24-30 h

4.5

3.3

14.3

2.4

1.7

4.1

Total in category

79.7

83.5

80.6

86.8

84.7

83.0

 

Feces

0-12 h

NFc

0.0

1.7

NF

0.0

0.0

12-24 h

1.3

NF

1.0

NF

NF

NF

24-30 h

0.4

0.0

1.7

0.1

0.0

0.2

Total in category

1.7

0.0

4.5

0.1

0.0

0.2

Cage wash

7.7

8.1

8.2

6.3

7.1

8.5

Total recovery

95.4

97.0

97.7

97.6

95.9

96.7

Data are expressed as percentages of the total radiochlorine administered.

a doses were delivered in approximately 500 mL of 7.5, 15, and 22.5 mM sodium[36Cl]chlorate in drinking water.

b items contaiting 0% radioactivity did not necessarily have nondetectable residues; generally the tissues were not of sufficient mass to contain > 0.1% of the dosed radiochlorine.

c NF, no feces were excreted during the indicated time period.

 

Excretion

The major part of the dosed radioactivity was excreted via the urine. By the time of slaughter (30 h), the cumulative excretion of radiochlorine in urine was 83.1 ± 2.6% of the total dosed activity. During the first 12h of the study 56.2 ± 8.5% of the dose was excreted in the urine. Across all doses, feces contained a cumulative 1.1 ± 1.8% of the administered radiochlorine.

 

Metabolism

In no instance was chlorite ion detected in urine or fecal samples. Urinary radiochlorine composition was greater than 97% chlorate, regardless of dose or time of radiochlorine excretion. Chlorate comprised from 39 to 77% of the total fecal residue. In contrast to the composition of residues in excreta, tissue residues were composed primarily of chloride ion rather than chlorate ion.

Table 2: Chlorate composition of urinary and fecal radiochlorine in pigs administered [36Cl]Chlorate in drinking watera

 

Low doseb

 

Medium dose

 

High dose

 

 

%

%

%

%

%

%

 

Gilt

Barrow

Gilt

Barrow

Gilt

Barrow

Time

388

390

387

393

389

392

 

Urine

 

 

 

0-12

100.0

100.0

100.0

100.0

100.0

100.0

12-24

96.2

99.7

98.5

99.1

98.5

98.5

24-30

99.3

99.1

100.0

100.0

97.4

99.5

 

Fecesc

24-30

38.8

65.1

50.9

73.1

53.3

76.6

Data are expressed as the percentage of the total radiochlorine excreted as parent chlorate; the balance of the radiochlorine was excreted solely as chlorine ion.

a doses were delivered in approximately 500 mL of 7.5, 15, and 22.5 mM sodium[36Cl]chlorate in drinking water.

c residues in feces were speciated only for the 24-30 h time period

 


Table 3: Total radioactive residues, chloride residues, and chlorate residues in edible tissues and thyroid glands of swine.

 

 

 

Tissue

 

 

 

liver

kidney

Skeletal muscle

Adipose tissue

Thyroid gland

Dose (mg/kg)

animal

sex

TRRa(ppm)

Cl-b(ppm)

ClO3-c(ppm)

TRRa(ppm)

Cl-b(ppm)

ClO3-c(ppm)

TRRa(ppm)

Cl-b(ppm)

ClO3-c(ppm)

TRRa(ppm)

Cl-b(ppm)

ClO3-c(ppm)

TRRa(ppm)

Cl-b(ppm)

ClO3-c(ppm)

20

390

Barrow

0.74

0.74

0.01

1.75

1.68

0.07

0.52

0.45

0.09

1.50

1.23

0.27

19.8

12.9

6.4

 

388

Gilt

0.92

0.91

0.01

2.40

2.05

0.30

0.53

0.47

0.06

1.51

1.40

0.11

18.2

7.8

10.3

 

 

Average

 

0.82

0.01

 

1.86

0.18

 

0.46

0.07

 

1.31

0.19

19.0

10.3

8.4

40

393

Barrow

1.00

0.99

0.02

2.55

2.39

0.17

0.63

0.55

0.08

1.43

1.24

0.17

18.3

6.2

11.9

 

387

Gilt

1.19

1.18

0.02

2.94

2.69

0.24

0.89

0.83

0.07

1.62

1.52

0.09

14.0

9.9

3.4

 

 

Average

 

1.09

0.02

 

2.54

0.20

 

0.69

0.07

 

1.38

0.13

16.2

8.1

7.7

60

392

Barrow

2.11

2.09

0.03

5.03

4.87

0.17

1.28

0.97

0.26

2.83

2.26

0.58

59.8

17.0

41.9

 

389

Gilt

1.67

1.61

0.05

4.46

4.24

0.22

1.43

1.31

0.10

2.75

2.35

0.40

17.6

8.1

9.1

 

 

Average

 

1.68

0.04

 

4.55

0.19

 

1.14

0.18

 

2.30

0.49

38.7

 

25.4

a TRR, total radioactive chlorine residues expressed in parts per million of chlorate equivalents; the sum of the chloride and chlorate fractions may not equal TRR due to rounding.

b Chloride residue calculated by multiplying the percentage chloride in extracted sample by the ppm total radioactive tissue. The concentrations of chloride do not reflect the physiological concentration of chloride in tissues, only that fraction of total residue present as radioactive chloride ion.

c Chlorate residue calculated by multiplying the percentage chlorate in extracted sample by the ppm of total radioactive residues.

Conclusions:
No bioaccumulation potential based on study results
This study clearly demonstrates that chlorate was rapidly absorbed and excreted in the urine of swine. There was no evidence for the existence of chlorite in urine or tissues of swine was generated in this study.
Executive summary:

An experimental chlorate-based product has been shown to be efficacious in eliminating economically important, Gram-negative human pathogens in the gastrointestinal tracts of food animals. Prior to the commercial marketing of such a product, the magnitude and chemical nature of residues remaining in edible tissues must be determined. Thus, the objective of this study was to determine the tissue distribution and elimination of sodium [36Cl]chlorate in orally dosed swine. Three sets of pigs, each consisting of a barrow and a gilt, were orally dosed with a total of 20, 40, or 60 mg of sodium [36Cl]chlorate per kg body weight via the drinking water. Urine and feces were collected throughout the 30 h study. Twenty-four hours after the last exposure to [36Cl]chlorate, each pig was harvested and both edible and inedible tissues were collected. Urine and tissue samples were analyzed for total radioactive residues and for chlorate metabolites. Elimination of radioactivity in urine averaged 81.6, 83.7, and 83.9% of the total dose for the low, medium, and high doses, respectively. Fecal elimination of radioactivity averaged 1.1% of the dosed radiochlorine across all doses. Parent chlorate always represented greater than 97.4% of the urinary radiochlorine with the remaining radiochlorine being excreted as chloride ion. Chlorate represented 39-77% of fecal radioactivity, depending upon dose. Chlorate concentrations in edible tissues ranged from 0.01 to 0.49 ppm, with residues in liver and skeletal muscle generally lower than those in kidney and adipose tissue. Chlorate residues were concentrated in thyroid tissues (7.7-25.4 ppm) relative to edible tissues. No evidence for the presence of chlorite was observed in excreta or in tissues. Results of this study suggest that further development of chlorate as a preharvest food safety tool in swine merits consideration.

Endpoint:
basic toxicokinetics
Type of information:
experimental study
Adequacy of study:
weight of evidence
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
other: The study is reliable with some restrictions. It is not performed under GLP and no batch nr. is given.
Objective of study:
toxicokinetics
Qualifier:
equivalent or similar to guideline
Guideline:
OECD Guideline 417 (Toxicokinetics)
GLP compliance:
no
Radiolabelling:
yes
Species:
other: swine
Strain:
other: crossbred swine
Sex:
male/female
Details on test animals or test system and environmental conditions:
TEST ANIMALS
- Source: North Dakota State University swine herd
- Age at study initiation: No data
- Weight at study initiation: barrows 9.2±0.4kg, gilts 8.2±0.8kg
- Fasting period before study: no info
- Housing: housed by gender in concrete-floored pens
- Individual metabolism cages: no info
- Diet (e.g. ad libitum): ad lib
- Water (e.g. ad libitum): ad lib
- Acclimation period: 18-25 days


ENVIRONMENTAL CONDITIONS
- Temperature (°C): no data
- Humidity (%): no data
- Air changes (per hr): no data
- Photoperiod (hrs dark / hrs light): no data


IN-LIFE DATES: no info
Route of administration:
oral: drinking water
Vehicle:
other: aqueous solutions of 2.5 mM sodium nitrate
Details on exposure:
PREPARATION OF DOSING SOLUTIONS: Purified [36Cl]chlorate was diluted with nonradioactive sodium chlorate to a specific activity of 399 ± 1dpm/ µg. Three dosing solutions (1 L each) containing 7.5, 15, and 22.5 mM sodium [36Cl]chlorate, respectively, were prepared in aqueous solutions of 2.5 mM sodium nitrate. Sodium nitrate has been shown to increase the efficacy of chlorate in reducing pathogen numbers in live animals. The actual chlorate concentrations were 99.9-100.3% of target values. Each dosing solution was transferred to duplicate 1 L plastic water bottles (Kaytee; Kaytee Products, Chicago, IL) so that water bottles contained 498 ( 0.5 g of dosing solution. Sipper tubes, supplied with the water bottles, were attached, and the bottles were stored frozen until dosing.


VEHICLE
- Justification for use and choice of vehicle (if other than water): Sodium nitrate has been shown to increase the efficacy of chlorate in reducing pathogen numbers in live animals, presumably by inducing respiratory nitrate reductase in nitrate respiring bacteria.
- Concentration in vehicle: 2.5 mM sodium nitrate
- Amount of vehicle (if gavage): not applicable
- Lot/batch no. (if required): no info
- Purity: no info


HOMOGENEITY AND STABILITY OF TEST MATERIAL: no info
Duration and frequency of treatment / exposure:
The total dose was delivered to pigs within 6.1±0.8 h instead of the 24 h as originally planned.
Remarks:
Doses / Concentrations:
Orally dosed with a total of 20, 40, or 60 mg of sodium [36Cl]chlorate per kg body weight via the drinking water (or 3 dosing solutions containing 7.5, 15, and 22.5 mM sodium [36Cl]chlorate, respectively prepared in aquous solutions of 2.5 mM sodium nitrate).
No. of animals per sex per dose / concentration:
Three sets of pigs, each consisting of a barrow and a gilt.
Control animals:
no
Positive control reference chemical:
No.
Details on dosing and sampling:
PHARMACOKINETIC STUDY (Absorption, distribution, metabolism, excretion)
- Tissues and body fluids sampled: urine, faeces, blood, bile
- Time and frequency of sampling: urine and faeces: 0-12, 12-24 and 24-30h time periods; blood and bile: at time of sacrifice
- Other: at time of sacrifice: edible tissues (adipose tissue, skeletal muscle, liver, and kidney) and nonedible tissues (blood, bone, brain, diaphragm, GI contents, GI tract, heart, lung, skin, spleen, thyroid gland, and remainder of the carcass)
- Method type(s) for identification: Liquid scintillation counting
Statistics:
Not applicable.
Details on absorption:
- Absorption & Distribution
Edible tissues contained 1.0 ± 0.1% of the dosed radiochlorine at slaughter, kidneys > adipose tissue > liver >
skeletal muscle. Nonedible tissues contained an average of 3.9 ± 0.7% of the dosed activity, with bone, skin, and blood retaining the largest percentage of radiochlorine, largely due to the fairly large masses of these fractions.
Details on distribution in tissues:
- Absorption & Distribution
Edible tissues contained 1.0 ± 0.1% of the dosed radiochlorine at slaughter, kidneys > adipose tissue > liver >
skeletal muscle. Nonedible tissues contained an average of 3.9 ± 0.7% of the dosed activity, with bone, skin, and blood retaining the largest percentage of radiochlorine, largely due to the fairly large masses of these fractions.
Details on excretion:
- Excretion:
The major part of the dosed radioactivity was excreted via the urine. By the time of slaughter (30h), the cumulative excretion of radiochlorine in urine was 83.1 ± 2.6% of the total dosed activity. During the first 12h of the study 56.2 ± 8.5% of the dose was excreted in the urine. Across all doses, feces contained a cumulative 1.1 ± 1.8% of the administered radiochlorine.
Details on metabolites:
- Metabolism
In no instance was chlorite ion detected in urine or fecal samples. Urinary radiochlorine composition was greater than 97% chlorate, regardless of dose or time of radiochlorine excretion. Chlorate comprised from 39 to 77% of the total fecal residue. In contrast to the composition of residues in excreta, tissue residues were composed primarily of chloride ion rather than chlorate ion.

Absorption & Distribution

Edible tissues contained 1.0 ± 0.1% of the dosed radiochlorine at slaughter, kidneys > adipose tissue > liver >skeletal muscle. Nonedible tissues contained an average of 3.9 ± 0.7% of the dosed activity, with bone, skin, and blood retaining the largest percentage of radiochlorine, largely due to the fairly large masses of these fractions.

Table 1: Distribution and recoveries of radiochlorine in tissues and excreta of pigsa

 

Low dosea

 

Medium dose

 

High dose

 

 

%

%

%

%

%

%

 

Gilt

Barrow

Gilt

Barrow

Gilt

Barrow

 

388

390

387

393

389

392

 

Edible tissues

 

 

 

Adipose tissue

0.0b

0.0

0.0

0.0

0.0

0.0

Kidney

0.0

0.0

0.1

0.1

0.0

0.0

Liver

0.1

0.1

0.1

0.1

0.1

0.1

Skeletal muscle

1.1

1.0

0.8

0.7

0.9

0.7

Total in category

1.2

1.1

1.0

0.9

1.0

0.8

 

Inedible tissuesb

Blood

0.6

0.4

0.4

0.4

0.5

0.4

Brain

0.0

0.0

0.0

0.0

0.0

0.0

Diaphragm

0.0

0.0

0.0

0.0

0.0

0.0

GI tissues

0.4

0.4

0.3

0.3

0.4

0.5

GI contents

0.6

0.4

0.4

0.3

0.2

0.5

Lung

0.1

0.1

0.1

0.1

0.1

0.1

Skin

1.3

1.1

0.7

0.9

0.7

1.0

Spleen

0.0

0.0

0.0

0.0

0.0

0.0

Thyroid gland

0.0

0.0

0.0

0.0

0.0

0.0

Heart

0.0

0.0

0.0

0.0

0.0

0.0

Bone

2.0

1.8

1.4

1.4

1.2

1.6

Bile

0.0

0.0

0.0

0.0

0.0

0.0

Remainder of carcass

0.1

0.1

0.1

0.1

0.0

0.1

Total in category

5.1

4.3

3.4

3.5

3.1

4.2

 

Urine

0-12 h

46.6

55.0

62.3

63.0

54.4

44.8

0-12 h spill

 

 

 

 

10.2

0.7

12-24 h

28.6

25.2

4.0

21.4

18.4

33.4

24-30 h

4.5

3.3

14.3

2.4

1.7

4.1

Total in category

79.7

83.5

80.6

86.8

84.7

83.0

 

Feces

0-12 h

NFc

0.0

1.7

NF

0.0

0.0

12-24 h

1.3

NF

1.0

NF

NF

NF

24-30 h

0.4

0.0

1.7

0.1

0.0

0.2

Total in category

1.7

0.0

4.5

0.1

0.0

0.2

Cage wash

7.7

8.1

8.2

6.3

7.1

8.5

Total recovery

95.4

97.0

97.7

97.6

95.9

96.7

Data are expressed as percentages of the total radiochlorine administered.

a doses were delivered in approximately 500 mL of 7.5, 15, and 22.5 mM sodium[36Cl]chlorate in drinking water.

b items contaiting 0% radioactivity did not necessarily have nondetectable residues; generally the tissues were not of sufficient mass to contain > 0.1% of the dosed radiochlorine.

c NF, no feces were excreted during the indicated time period.

 

Excretion

The major part of the dosed radioactivity was excreted via the urine. By the time of slaughter (30 h), the cumulative excretion of radiochlorine in urine was 83.1 ± 2.6% of the total dosed activity. During the first 12h of the study 56.2 ± 8.5% of the dose was excreted in the urine. Across all doses, feces contained a cumulative 1.1 ± 1.8% of the administered radiochlorine.

 

Metabolism

In no instance was chlorite ion detected in urine or fecal samples. Urinary radiochlorine composition was greater than 97% chlorate, regardless of dose or time of radiochlorine excretion. Chlorate comprised from 39 to 77% of the total fecal residue. In contrast to the composition of residues in excreta, tissue residues were composed primarily of chloride ion rather than chlorate ion.

Table 2: Chlorate composition of urinary and fecal radiochlorine in pigs administered [36Cl]Chlorate in drinking watera

 

Low doseb

 

Medium dose

 

High dose

 

 

%

%

%

%

%

%

 

Gilt

Barrow

Gilt

Barrow

Gilt

Barrow

Time

388

390

387

393

389

392

 

Urine

 

 

 

0-12

100.0

100.0

100.0

100.0

100.0

100.0

12-24

96.2

99.7

98.5

99.1

98.5

98.5

24-30

99.3

99.1

100.0

100.0

97.4

99.5

 

Fecesc

24-30

38.8

65.1

50.9

73.1

53.3

76.6

Data are expressed as the percentage of the total radiochlorine excreted as parent chlorate; the balance of the radiochlorine was excreted solely as chlorine ion.

a doses were delivered in approximately 500 mL of 7.5, 15, and 22.5 mM sodium[36Cl]chlorate in drinking water.

c residues in feces were speciated only for the 24-30 h time period

 


Table 3: Total radioactive residues, chloride residues, and chlorate residues in edible tissues and thyroid glands of swine.

 

 

 

Tissue

 

 

 

liver

kidney

Skeletal muscle

Adipose tissue

Thyroid gland

Dose (mg/kg)

animal

sex

TRRa(ppm)

Cl-b(ppm)

ClO3-c(ppm)

TRRa(ppm)

Cl-b(ppm)

ClO3-c(ppm)

TRRa(ppm)

Cl-b(ppm)

ClO3-c(ppm)

TRRa(ppm)

Cl-b(ppm)

ClO3-c(ppm)

TRRa(ppm)

Cl-b(ppm)

ClO3-c(ppm)

20

390

Barrow

0.74

0.74

0.01

1.75

1.68

0.07

0.52

0.45

0.09

1.50

1.23

0.27

19.8

12.9

6.4

 

388

Gilt

0.92

0.91

0.01

2.40

2.05

0.30

0.53

0.47

0.06

1.51

1.40

0.11

18.2

7.8

10.3

 

 

Average

 

0.82

0.01

 

1.86

0.18

 

0.46

0.07

 

1.31

0.19

19.0

10.3

8.4

40

393

Barrow

1.00

0.99

0.02

2.55

2.39

0.17

0.63

0.55

0.08

1.43

1.24

0.17

18.3

6.2

11.9

 

387

Gilt

1.19

1.18

0.02

2.94

2.69

0.24

0.89

0.83

0.07

1.62

1.52

0.09

14.0

9.9

3.4

 

 

Average

 

1.09

0.02

 

2.54

0.20

 

0.69

0.07

 

1.38

0.13

16.2

8.1

7.7

60

392

Barrow

2.11

2.09

0.03

5.03

4.87

0.17

1.28

0.97

0.26

2.83

2.26

0.58

59.8

17.0

41.9

 

389

Gilt

1.67

1.61

0.05

4.46

4.24

0.22

1.43

1.31

0.10

2.75

2.35

0.40

17.6

8.1

9.1

 

 

Average

 

1.68

0.04

 

4.55

0.19

 

1.14

0.18

 

2.30

0.49

38.7

 

25.4

a TRR, total radioactive chlorine residues expressed in parts per million of chlorate equivalents; the sum of the chloride and chlorate fractions may not equal TRR due to rounding.

b Chloride residue calculated by multiplying the percentage chloride in extracted sample by the ppm total radioactive tissue. The concentrations of chloride do not reflect the physiological concentration of chloride in tissues, only that fraction of total residue present as radioactive chloride ion.

c Chlorate residue calculated by multiplying the percentage chlorate in extracted sample by the ppm of total radioactive residues.

Conclusions:
No bioaccumulation potential based on study results
This study clearly demonstrates that chlorate was rapidly absorbed and excreted in the urine of swine. There was no evidence for the existence of chlorite in urine or tissues of swine was generated in this study.
Executive summary:

An experimental chlorate-based product has been shown to be efficacious in eliminating economically important, Gram-negative human pathogens in the gastrointestinal tracts of food animals. Prior to the commercial marketing of such a product, the magnitude and chemical nature of residues remaining in edible tissues must be determined. Thus, the objective of this study was to determine the tissue distribution and elimination of sodium [36Cl]chlorate in orally dosed swine. Three sets of pigs, each consisting of a barrow and a gilt, were orally dosed with a total of 20, 40, or 60 mg of sodium [36Cl]chlorate per kg body weight via the drinking water. Urine and feces were collected throughout the 30 h study. Twenty-four hours after the last exposure to [36Cl]chlorate, each pig was harvested and both edible and inedible tissues were collected. Urine and tissue samples were analyzed for total radioactive residues and for chlorate metabolites. Elimination of radioactivity in urine averaged 81.6, 83.7, and 83.9% of the total dose for the low, medium, and high doses, respectively. Fecal elimination of radioactivity averaged 1.1% of the dosed radiochlorine across all doses. Parent chlorate always represented greater than 97.4% of the urinary radiochlorine with the remaining radiochlorine being excreted as chloride ion. Chlorate represented 39-77% of fecal radioactivity, depending upon dose. Chlorate concentrations in edible tissues ranged from 0.01 to 0.49 ppm, with residues in liver and skeletal muscle generally lower than those in kidney and adipose tissue. Chlorate residues were concentrated in thyroid tissues (7.7-25.4 ppm) relative to edible tissues. No evidence for the presence of chlorite was observed in excreta or in tissues. Results of this study suggest that further development of chlorate as a preharvest food safety tool in swine merits consideration.

Endpoint:
basic toxicokinetics
Type of information:
read-across from supporting substance (structural analogue or surrogate)
Adequacy of study:
weight of evidence
Justification for type of information:
See the RAAF document.
Reason / purpose for cross-reference:
read-across: supporting information
Reason / purpose for cross-reference:
read-across source
Details on absorption:
- Absorption & Distribution
Tissues with the highest percentages of the administered radiochlorine were carcass remains (4.6 ± 2.9%), skin (3.2 ± 1.9%), and GI tract (1.3 ±1.1%). When the data were expressed on a concentration basis (fresh tissue weight; chlorate equivalents), The four tissues with the highest concentration of radiochlorine were the plasma (0.94 ± 0.53 ppm), whole blood (0.76 ± 0.43 ppm), testes (0.66 ± 0.36 ppm), and lung (0.61 ± 0.35 ppm). The four tissues with the lowest concentrations of radiochlorine were the carcass remains (0.24 ± 0.13 ppm), bone (0.24 ± 0.13 ppm), adipose tissue (0.17 ± 0.10 ppm), and muscle (0.14 ± 0.08 ppm).
Details on distribution in tissues:
- Absorption & Distribution
Tissues with the highest percentages of the administered radiochlorine were carcass remains (4.6 ± 2.9%), skin (3.2 ± 1.9%), and GI tract (1.3 ±1.1%). When the data were expressed on a concentration basis (fresh tissue weight; chlorate equivalents), The four tissues with the highest concentration of radiochlorine were the plasma (0.94 ± 0.53 ppm), whole blood (0.76 ± 0.43 ppm), testes (0.66 ± 0.36 ppm), and lung (0.61 ± 0.35 ppm). The four tissues with the lowest concentrations of radiochlorine were the carcass remains (0.24 ± 0.13 ppm), bone (0.24 ± 0.13 ppm), adipose tissue (0.17 ± 0.10 ppm), and muscle (0.14 ± 0.08 ppm).
Details on excretion:
- Excretion
Urine was the major route of radiochlorine excretion. The mean, cumulative elimination of radiochorine via the urine was 79% (range 65-91%). The majority was excreted within 6h. Approximately 1.7% of the administered dose was excreted via the feces.
Metabolites identified:
yes
Details on metabolites:
- Metabolism
The extracts from liver and kidney contained only [36Cl]chloride ion. Except for one replicate analysis from muscle of rat 19, in which 1.9% of the radiochlorine was parent compound, all detected muscle radioactivity was [36Cl]chloride ion. Extracts of carcass remains were, likewise. In no case was chlorite detected in rat tissues.

Tissues with the highest percentages of the administered radiochlorine were carcass remains (4.6 ± 2.9%), skin (3.2 ± 1.9%), and GI tract (1.3 ±1.1%). When the data were expressed on a concentration basis (fresh tissue weight; chlorate equivalents), The four tissues with the highest concentration of radiochlorine were the plasma (0.94 ± 0.53 ppm), whole blood (0.76 ± 0.43 ppm), testes (0.66 ± 0.36 ppm), and lung (0.61 ± 0.35 ppm). The four tissues with the lowest concentrations of radiochlorine were the carcass remains (0.24 ± 0.13 ppm), bone (0.24 ± 0.13 ppm), adipose tissue (0.17 ± 0.10 ppm), and muscle (0.14 ± 0.08 ppm).

 Table 1: Disposition, elimination, and total recovery of radiochlorine (% of dose) in rats orally dosed with [36Cl]chlorate

 

 

animal

 

 

 

 

 

 

 

 

 

 

 

rat 5

rat 19

rat 26

rat 27

mean

SD

 

 

 

 

 

 

 

tissues

21.9

4.5

15.4

7.5

12.3

7.9

 

 

 

 

 

 

 

 

 

feces

 

 

 

 

0-24 h

3.0

0.05

0.04

0.6

0.9

1.4

24-48 h

1.5

0.03

0.09

0.3

0.5

0.7

48-72 h

0.6

0.06

0.1

0.5

0.3

0.3

total

5.1

0.1

0.2

1.4

1.7

2.3

 

 

 

 

 

 

 

 

 

urine

 

 

 

 

0-6 h

9.4

45.8

32.5

56.7

36.1

20.4

6-12 h

27.2

32.7

27.9

17.2

26.3

6.5

12-18 h

9.0

5.5

5.1

3.8

5.8

2.2

18-24 h

4.1

2.2

1.9

1.1

2.3

1.3

24-32 h

1.5

1.8

1.2

1.1

1.4

0.3

32-40 h

2.3

1.0

1.5

0.9

1.4

0.7

40-48 h

3.1

0.2

2.5

0.6

1.6

1.4

48-60 h

2.9

0.7

2.8

1.0

1.8

1.1

60-72 h

5.1

0.5

2.6

1.1

2.4

2.1

total

64.6

90.4

78.0

83.5

79.1

10.9

expiratory gases

0.0

0.0

0.0

0.0

0.0

0.0

cage rinse

1.4

0.3

2.2

1.3

1.3

0.8

total recovery

93.0

95.3

95.7

93.7

94.4

1.3

 

Table 2: Concentrations of radioactive residues (ppm fresh tissue weight; chlorate equivalents) in tissues of rats dosed orally with [36Cl]chlorate and slaughtered 72 h after dosing.

 

rat 5

rat 19

rat 26

rat 27

 

 

tissue

(ppm)

(ppm)

(ppm)

(ppm)

mean

SD

adipose tissue

0.28

0.05

0.08

0.05

0.17

0.10

blood

1.17

0.29

1.09

0.50

0.76

0.43

brain

0.53

0.14

0.52

0.22

0.35

0.20

bone

0.34

0.10

0.35

0.16

0.24

0.13

diaphragm

0.51

0.10

0.36

0.16

0.28

0.19

GI tract

0.61

0.12

0.46

0.20

0.35

0.23

heart

0.53

0.14

0.46

0.23

0.34

0.18

kidney

0.68

0.18

0.67

0.28

0.45

0.26

liver

0.45

0.12

0.40

0.18

0.29

0.16

lung

0.95

0.24

0.86

0.40

0.61

0.35

muscle

0.21

0.06

0.20

0.10

0.14

0.08

plasma

1.43

0.36

1.36

0.62

0.94

0.53

skin

0.62

0.18

0.52

0.27

0.40

0.20

spleen

0.66

0.17

0.56

0.27

0.42

0.23

testes

1.04

0.27

0.90

0.45

0.66

0.36

carcass remains

0.35

0.09

0.34

0.15

0.24

0.13

thymus

0.59

0.17

0.60

0.27

0.41

0.22

 

Excretion

Urine was the major route of radiochlorine excretion. The mean, cumulative elimination of radiochorine via the urine was 79% (range 65-91%). The majority was excreted within 6h. Approximately 1.7% of the administered dose was excreted via the feces.

 

Metabolism

The extracts from liver and kidney contained only [36Cl]chloride ion. Except for one replicate analysis from muscle of ratwhich 1.9% of the radiochlorine was parent compound, all detected muscle radioactivity was [36Cl]chloride ion. Extracts of carcass remains were, likewise, primarily composed of chloride. In no case was chlorite detected in rat tissues.

Conclusions:
No bioaccumulation potential based on study results
This study clearly demonstrates that chlorate was rapidly absorbed and excreted in the urine. Chlorate was metabolized only to chloride in rats.
Executive summary:

A novel preharvest technology that reduces certain pathogenic bacteria in the gastrointestinal tracts of food animals involves feeding an experimental sodium chlorate-containing product (ECP) to animals 24-72 h prior to slaughter. To determine the metabolism and disposition of the active ingredient in

ECP, four male Sprague-Dawley (±350 g) rats received a single oral dose of sodium [36Cl]chlorate (3.0 mg/kg body weight). Urine, feces, and respired air were collected for 72 h. Radiochlorine absorption was 88-95% of the administered dose, and the major excretory route was the urine. Parent chlorate was the major species of radiochlorine present in urine at 6 h (±98%) but declined sharply by 48 h (±10%); chloride was the only other species of radiochlorine detected. Except for carcass remains (4.6% of dose), skin (3.2%), and gastrointestinal tract (1.3%), remaining tissues contained relatively low quantities of radioactivity, and >98% of radiochlorine remaining in the liver, kidney, and skeletal muscle was chloride. Chlorite instability was demonstrated in rat urine and bovine urine. The previously reported presence of chlorite in excreta of chlorate-dosed rats was shown to be an artifact of the analytical methods employed. Results from this study indicate that chlorate is rapidly absorbed and reduced to chloride, but not chlorite, in rats.

Endpoint:
basic toxicokinetics
Type of information:
experimental study
Adequacy of study:
weight of evidence
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
other: The study is reliable with some restrictions. It is not performed under GLP and no batch nr. is given.
Objective of study:
toxicokinetics
Qualifier:
equivalent or similar to guideline
Guideline:
OECD Guideline 417 (Toxicokinetics)
GLP compliance:
no
Radiolabelling:
yes
Species:
rat
Strain:
Sprague-Dawley
Sex:
male
Details on test animals or test system and environmental conditions:
TEST ANIMALS
- Source: Harlan Sprague-Dawley (Indianapolis, IN)
- Age at study initiation: no data
- Weight at study initiation: 349 (25.8 g)
- Housing: hanging stainless steel cages for the prestudy period and for the duration of the study period they were housed in glass metabolism cages
- Individual metabolism cages: yes
- Diet (e.g. ad libitum): ad lib, Purina Mills Rat Chow
- Water (e.g. ad libitum): ad lib
- Acclimation period: no data


ENVIRONMENTAL CONDITIONS
- Temperature (°C): no data
- Humidity (%): no data
- Air changes (per hr): no data
- Photoperiod (hrs dark / hrs light): no data


IN-LIFE DATES: no data
Route of administration:
oral: gavage
Vehicle:
water
Details on exposure:
PREPARATION OF DOSING SOLUTIONS: Sodium [36Cl]chlorate was formulated in water (2 mg/mL), and 0.5 mL (5.4 íCi) was given by gavage.
Duration and frequency of treatment / exposure:
Single oral dose by gavage; rats were sacrificed 72h after being dosed.
Remarks:
Doses / Concentrations:
Sodium chlorate was formulated in water (2 mg/mL) and 0.5 mL was given. Target dose: 3.0 mg/kg bw.
No. of animals per sex per dose / concentration:
6 male rats: 2 controls + 4 test animals
Control animals:
yes, concurrent vehicle
Positive control reference chemical:
No.
Details on study design:
- Dose selection rationale: Dose was nearly 50-fold greater than the dose used by Abdel-Rahmen et al., but about 10-fold less than sodium chlorate doses shown to be effective at reducing pathogens in livestock species.
Details on dosing and sampling:
PHARMACOKINETIC STUDY (Absorption, distribution, metabolism, excretion)
- Tissues and body fluids sampled (delete / add / specify): urine, faeces, blood, plasma, serum, cage washes
- Time and frequency of sampling: Urine, feces, and respired air were collected for 72 h. Excreta samples were collected at 6 h intervals for the first 24 h (0-6, 6-12, 12-18, and 18-24 h), 8 h intervals for the second 24 h (24-32, 32-40, and 40-48 h), and at 12 h intervals for the last 24 h (48-60 and 60-72 h) of the study. To study the stability of some potential chlorate metabolites, a single 5 μl sample of urine from each rat was collected at the 6 h time point for the immediate determination of radiochemical composition.
- Method type(s) for identification: Liquid scintillation counting
- Other: respired gases, adipose tissue, bone (femur), brain, diaphragm, GI tract, heart, kidney, liver, lungs, skin, spleen, testes, thymus, skeletal muscle, and 'carcass remains', and the thyroid gland was not specifically removed.
Statistics:
Not applicable.
Details on absorption:
- Absorption & Distribution
Tissues with the highest percentages of the administered radiochlorine were carcass remains (4.6 ± 2.9%), skin (3.2 ± 1.9%), and GI tract (1.3 ±1.1%). When the data were expressed on a concentration basis (fresh tissue weight; chlorate equivalents), The four tissues with the highest concentration of radiochlorine were the plasma (0.94 ± 0.53 ppm), whole blood (0.76 ± 0.43 ppm), testes (0.66 ± 0.36 ppm), and lung (0.61 ± 0.35 ppm). The four tissues with the lowest concentrations of radiochlorine were the carcass remains (0.24 ± 0.13 ppm), bone (0.24 ± 0.13 ppm), adipose tissue (0.17 ± 0.10 ppm), and muscle (0.14 ± 0.08 ppm).
Details on distribution in tissues:
- Absorption & Distribution
Tissues with the highest percentages of the administered radiochlorine were carcass remains (4.6 ± 2.9%), skin (3.2 ± 1.9%), and GI tract (1.3 ±1.1%). When the data were expressed on a concentration basis (fresh tissue weight; chlorate equivalents), The four tissues with the highest concentration of radiochlorine were the plasma (0.94 ± 0.53 ppm), whole blood (0.76 ± 0.43 ppm), testes (0.66 ± 0.36 ppm), and lung (0.61 ± 0.35 ppm). The four tissues with the lowest concentrations of radiochlorine were the carcass remains (0.24 ± 0.13 ppm), bone (0.24 ± 0.13 ppm), adipose tissue (0.17 ± 0.10 ppm), and muscle (0.14 ± 0.08 ppm).
Details on excretion:
- Excretion
Urine was the major route of radiochlorine excretion. The mean, cumulative elimination of radiochorine via the urine was 79% (range 65-91%). The majority was excreted within 6h. Approximately 1.7% of the administered dose was excreted via the feces.
Metabolites identified:
yes
Details on metabolites:
- Metabolism
The extracts from liver and kidney contained only [36Cl]chloride ion. Except for one replicate analysis from muscle of rat 19, in which 1.9% of the radiochlorine was parent compound, all detected muscle radioactivity was [36Cl]chloride ion. Extracts of carcass remains were, likewise. In no case was chlorite detected in rat tissues.

Tissues with the highest percentages of the administered radiochlorine were carcass remains (4.6 ± 2.9%), skin (3.2 ± 1.9%), and GI tract (1.3 ±1.1%). When the data were expressed on a concentration basis (fresh tissue weight; chlorate equivalents), The four tissues with the highest concentration of radiochlorine were the plasma (0.94 ± 0.53 ppm), whole blood (0.76 ± 0.43 ppm), testes (0.66 ± 0.36 ppm), and lung (0.61 ± 0.35 ppm). The four tissues with the lowest concentrations of radiochlorine were the carcass remains (0.24 ± 0.13 ppm), bone (0.24 ± 0.13 ppm), adipose tissue (0.17 ± 0.10 ppm), and muscle (0.14 ± 0.08 ppm).

 Table 1: Disposition, elimination, and total recovery of radiochlorine (% of dose) in rats orally dosed with [36Cl]chlorate

 

 

animal

 

 

 

 

 

 

 

 

 

 

 

rat 5

rat 19

rat 26

rat 27

mean

SD

 

 

 

 

 

 

 

tissues

21.9

4.5

15.4

7.5

12.3

7.9

 

 

 

 

 

 

 

 

 

feces

 

 

 

 

0-24 h

3.0

0.05

0.04

0.6

0.9

1.4

24-48 h

1.5

0.03

0.09

0.3

0.5

0.7

48-72 h

0.6

0.06

0.1

0.5

0.3

0.3

total

5.1

0.1

0.2

1.4

1.7

2.3

 

 

 

 

 

 

 

 

 

urine

 

 

 

 

0-6 h

9.4

45.8

32.5

56.7

36.1

20.4

6-12 h

27.2

32.7

27.9

17.2

26.3

6.5

12-18 h

9.0

5.5

5.1

3.8

5.8

2.2

18-24 h

4.1

2.2

1.9

1.1

2.3

1.3

24-32 h

1.5

1.8

1.2

1.1

1.4

0.3

32-40 h

2.3

1.0

1.5

0.9

1.4

0.7

40-48 h

3.1

0.2

2.5

0.6

1.6

1.4

48-60 h

2.9

0.7

2.8

1.0

1.8

1.1

60-72 h

5.1

0.5

2.6

1.1

2.4

2.1

total

64.6

90.4

78.0

83.5

79.1

10.9

expiratory gases

0.0

0.0

0.0

0.0

0.0

0.0

cage rinse

1.4

0.3

2.2

1.3

1.3

0.8

total recovery

93.0

95.3

95.7

93.7

94.4

1.3

 

Table 2: Concentrations of radioactive residues (ppm fresh tissue weight; chlorate equivalents) in tissues of rats dosed orally with [36Cl]chlorate and slaughtered 72 h after dosing.

 

rat 5

rat 19

rat 26

rat 27

 

 

tissue

(ppm)

(ppm)

(ppm)

(ppm)

mean

SD

adipose tissue

0.28

0.05

0.08

0.05

0.17

0.10

blood

1.17

0.29

1.09

0.50

0.76

0.43

brain

0.53

0.14

0.52

0.22

0.35

0.20

bone

0.34

0.10

0.35

0.16

0.24

0.13

diaphragm

0.51

0.10

0.36

0.16

0.28

0.19

GI tract

0.61

0.12

0.46

0.20

0.35

0.23

heart

0.53

0.14

0.46

0.23

0.34

0.18

kidney

0.68

0.18

0.67

0.28

0.45

0.26

liver

0.45

0.12

0.40

0.18

0.29

0.16

lung

0.95

0.24

0.86

0.40

0.61

0.35

muscle

0.21

0.06

0.20

0.10

0.14

0.08

plasma

1.43

0.36

1.36

0.62

0.94

0.53

skin

0.62

0.18

0.52

0.27

0.40

0.20

spleen

0.66

0.17

0.56

0.27

0.42

0.23

testes

1.04

0.27

0.90

0.45

0.66

0.36

carcass remains

0.35

0.09

0.34

0.15

0.24

0.13

thymus

0.59

0.17

0.60

0.27

0.41

0.22

 

Excretion

Urine was the major route of radiochlorine excretion. The mean, cumulative elimination of radiochorine via the urine was 79% (range 65-91%). The majority was excreted within 6h. Approximately 1.7% of the administered dose was excreted via the feces.

 

Metabolism

The extracts from liver and kidney contained only [36Cl]chloride ion. Except for one replicate analysis from muscle of ratwhich 1.9% of the radiochlorine was parent compound, all detected muscle radioactivity was [36Cl]chloride ion. Extracts of carcass remains were, likewise, primarily composed of chloride. In no case was chlorite detected in rat tissues.

Conclusions:
No bioaccumulation potential based on study results
This study clearly demonstrates that chlorate was rapidly absorbed and excreted in the urine. Chlorate was metabolized only to chloride in rats.
Executive summary:

A novel preharvest technology that reduces certain pathogenic bacteria in the gastrointestinal tracts of food animals involves feeding an experimental sodium chlorate-containing product (ECP) to animals 24-72 h prior to slaughter. To determine the metabolism and disposition of the active ingredient in

ECP, four male Sprague-Dawley (±350 g) rats received a single oral dose of sodium [36Cl]chlorate (3.0 mg/kg body weight). Urine, feces, and respired air were collected for 72 h. Radiochlorine absorption was 88-95% of the administered dose, and the major excretory route was the urine. Parent chlorate was the major species of radiochlorine present in urine at 6 h (±98%) but declined sharply by 48 h (±10%); chloride was the only other species of radiochlorine detected. Except for carcass remains (4.6% of dose), skin (3.2%), and gastrointestinal tract (1.3%), remaining tissues contained relatively low quantities of radioactivity, and >98% of radiochlorine remaining in the liver, kidney, and skeletal muscle was chloride. Chlorite instability was demonstrated in rat urine and bovine urine. The previously reported presence of chlorite in excreta of chlorate-dosed rats was shown to be an artifact of the analytical methods employed. Results from this study indicate that chlorate is rapidly absorbed and reduced to chloride, but not chlorite, in rats.

Endpoint:
basic toxicokinetics
Type of information:
read-across from supporting substance (structural analogue or surrogate)
Adequacy of study:
weight of evidence
Justification for type of information:
See the RAAF document.
Reason / purpose for cross-reference:
read-across: supporting information
Reason / purpose for cross-reference:
read-across source
Details on absorption:
See 'Remarks on results'
Details on distribution in tissues:
See 'Remarks on results'
Details on excretion:
See 'Remarks on results'
Details on metabolites:
See 'Remarks on results'

Whole blood total radioactivity was dose dependent. At all dose levels, total radioactivity increased rapidly for the first 4–6 h following administration of each aliquot, then reached an apparent asymptote by 8 h when the next aliquot was given. From 8– 24 h after the last aliquot (i.e. 32–48 h) the level of whole blood total radioactivity declined very little. Total radioactivity was greater in serum than in whole blood indicating that chlorate or its metabolites were present at higher levels in the serum rather than in the cell fraction.

Chlorate concentrations increased rapidly in serum following each aliquot administration, but typically fell below the LOQ (0.5 ppm) or to very low levels by the following aliquot administration. The concentration maximum in all cases occurred 2 h after administration of the fourth chlorate aliquot (i.e. 26 h). In the high-dose heifer, chlorate had an estimated half-life of absorption of 0.9 h resulting in a peak serum chlorate concentration of 20.5 ppm. With an estimated half-life of elimination of 9.6 h, serum chlorate concentrations declined prior to administration of subsequent chlorate aliquots.

Pharmacokinetic parameters calculated by noncompartmental methods are shown below. Because the study was designed to provide preliminary residue data, there were only one or two animals per treatment.

 

Table 1: Noncompartmental pharmacokinetic analyses of blood serum data

Dose level (mg/kg)

sex

AUCa

Cmax

T1/2b

63

Heifer

425.3

20.5

9.6

42

Steer

179.8

11.6

6.9

42

Heifer

223.6

12.4

11.0

21

Steer

NAc

NAc

NAc

21

Heifer

39.4

5.5

6.9

a calculated from 0-48 hours

b calculated from 26-48 hours

c the values were too low to evaluate

 

Conclusions:
No bioaccumulation potential based on study results
When radiolabeled chlorate was dosed intraruminally, radioactivity rapidly appeared in the systemic circulation, suggesting that rapid absorption of the chlorate molecule occurred. Chemical reduction of chlorate to chloride could occur in either the rumen or the blood, or both. Chloride is a naturally abundant, and vital, extracellular anion, so chloride converted from chlorate concentrates in the blood as it combines with the systemic pool of chloride. Chlorate on the other hand is rapidly eliminated from the blood either through urinary excretion or through reduction to chloride, or both.
Executive summary:

Six Loala cattle were assigned (one heifer and one steer per treatment) to one of three intraruminal doses of radiolabeled sodium [36Cl]chlorate (21, 42, or 63 mg/ kg body weight) administered in four equal aliquots over a 24-h period. Blood and serum were collected (29 samples in 48 h). Total radioactive residues were measured and the radioactive moieties were speciated. Chlorate appeared

rapidly in blood and serum after dosing. For animals administered a dose of 42 or 63 mg/kg, the half-life of absorption was estimated at 0.6–0.9 h. Serum chlorate concentrations progressively increased with aliquot administration until peaking at 6–21 parts per million at 26 h. Between aliquot administrations, serum chlorate levels typically peaked in 3.5 h or less. The half-life of chlorate elimination ranged between 6.9 and 11 h, depending on the dose. Ultimately, absorption of chlorate removes it from its desired site of action, the lower gastrointestinal tract, thereby reducing its efficacy. Further research is needed to develop a chlorate formulation that will allow passage to the lower gastrointestinal tract.

Endpoint:
basic toxicokinetics
Type of information:
experimental study
Adequacy of study:
weight of evidence
Study period:
May 2004 - July 2004
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
other: The study is reliable with some restrictions. It is not performed under GLP and no batch nr. is given.
Objective of study:
toxicokinetics
Qualifier:
equivalent or similar to guideline
Guideline:
OECD Guideline 417 (Toxicokinetics)
GLP compliance:
no
Radiolabelling:
yes
Species:
cattle
Strain:
other: three-quarter blood Loala (Angus/Loala_Loala) heifers and steers
Sex:
male/female
Details on test animals or test system and environmental conditions:
TEST ANIMALS
- Source: Auction Effertz, Ltd. (Bismarck, ND)
- Age at study initiation: no data
- Weight at study initiation: heifers: 103.5±4.9kg and steers: 159.7±23.0kg
- Fasting period before study: no info
- Housing: housed in concrete-floored pens covered with wood shavings
- Individual metabolism cages: no data
- Diet (e.g. ad libitum): ad lib
- Water (e.g. ad libitum): ad lib
- Acclimation period: 18 days


ENVIRONMENTAL CONDITIONS
- Temperature (°C): no data
- Humidity (%): no data
- Air changes (per hr): no data
- Photoperiod (hrs dark / hrs light): no data


IN-LIFE DATES: From: May 2004 To: July 2004
Route of administration:
other: intraruminally
Vehicle:
other: dosing was intraruminally with gelatin capsules
Details on exposure:
PREPARATION OF DOSING SOLUTIONS: Sodium [36Cl]chlorate formulated onto a proprietary carrier was weighed into 19 (outer diameter) x 50 mm (length) gelatin capsules. The amount of formulated material weighed into capsules was based on the body weight of each animal and the fact that the total dose was administered as 4 equal aliquots. Sodium nitrate formulated onto a proprietary carrier was weighed into 19 x 50 mm gelatin capsules so that each animal received a total of 14 mg/kg of body weight during the 24 h dosing period. Immediately prior to the administration of each aliquot of the dose, a 2.5 x 45 cm (width x length) PVC pipe was inserted between the wall of the ruminal cannula and the cannula cap into the rumen and through the ruminal fiber mat. Capsules (chlorate and nitrate) were then dropped into the protruding end of the pipe and were gently placed in the rumen using a plunger constructed from a piece of a smaller diameter PVC pipe.
Duration and frequency of treatment / exposure:
The dose was divided into 4 aliquots which were delivered at 8-h intervals to more closely simulate chlorate exposure during a 24-h administration as a feed additive.
Remarks:
Doses / Concentrations:
21.4, 42.7, or 63.8 mg/kg BW
Sodium nitrate (14 mg/kg BW, in 4 aliquots) was co-administered with the chlorate to stimulate bacterial nitrate reductase activity.
No. of animals per sex per dose / concentration:
One steer and one heifer were dosed at each of three levels of sodium chlorate: 6 animals in total.
Control animals:
no
Positive control reference chemical:
No.
Details on dosing and sampling:
PHARMACOKINETIC STUDY (Absorption, distribution, metabolism, excretion)
- Tissues and body fluids sampled: blood, serum
- Time and frequency of sampling: Blood was collected relative to first chlorate dose at h 0, 0.5, 1, 2, 4, 6, 8, 8.5, 9, 10, 12, 14, 16, 16.5, 17, 18, 20, 22, 24, 24.5, 25, 26, 28, 30, 32, 36, 40, 44, and 48. One animal (high-dose steer) pulled its only h 48 blood (taken at slaughter) was available.
- Method type(s) for identification: silver cartridge chlorate assay, HPLC, Liquid scintillation counting
Statistics:
Not applicable.
Details on absorption:
See 'Remarks on results'
Details on distribution in tissues:
See 'Remarks on results'
Details on excretion:
See 'Remarks on results'
Details on metabolites:
See 'Remarks on results'

Whole blood total radioactivity was dose dependent. At all dose levels, total radioactivity increased rapidly for the first 4–6 h following administration of each aliquot, then reached an apparent asymptote by 8 h when the next aliquot was given. From 8– 24 h after the last aliquot (i.e. 32–48 h) the level of whole blood total radioactivity declined very little. Total radioactivity was greater in serum than in whole blood indicating that chlorate or its metabolites were present at higher levels in the serum rather than in the cell fraction.

Chlorate concentrations increased rapidly in serum following each aliquot administration, but typically fell below the LOQ (0.5 ppm) or to very low levels by the following aliquot administration. The concentration maximum in all cases occurred 2 h after administration of the fourth chlorate aliquot (i.e. 26 h). In the high-dose heifer, chlorate had an estimated half-life of absorption of 0.9 h resulting in a peak serum chlorate concentration of 20.5 ppm. With an estimated half-life of elimination of 9.6 h, serum chlorate concentrations declined prior to administration of subsequent chlorate aliquots.

Pharmacokinetic parameters calculated by noncompartmental methods are shown below. Because the study was designed to provide preliminary residue data, there were only one or two animals per treatment.

 

Table 1: Noncompartmental pharmacokinetic analyses of blood serum data

Dose level (mg/kg)

sex

AUCa

Cmax

T1/2b

63

Heifer

425.3

20.5

9.6

42

Steer

179.8

11.6

6.9

42

Heifer

223.6

12.4

11.0

21

Steer

NAc

NAc

NAc

21

Heifer

39.4

5.5

6.9

a calculated from 0-48 hours

b calculated from 26-48 hours

c the values were too low to evaluate

 

Conclusions:
No bioaccumulation potential based on study results
When radiolabeled chlorate was dosed intraruminally, radioactivity rapidly appeared in the systemic circulation, suggesting that rapid absorption of the chlorate molecule occurred. Chemical reduction of chlorate to chloride could occur in either the rumen or the blood, or both. Chloride is a naturally abundant, and vital, extracellular anion, so chloride converted from chlorate concentrates in the blood as it combines with the systemic pool of chloride. Chlorate on the other hand is rapidly eliminated from the blood either through urinary excretion or through reduction to chloride, or both.
Executive summary:

Six Loala cattle were assigned (one heifer and one steer per treatment) to one of three intraruminal doses of radiolabeled sodium [36Cl]chlorate (21, 42, or 63 mg/ kg body weight) administered in four equal aliquots over a 24-h period. Blood and serum were collected (29 samples in 48 h). Total radioactive residues were measured and the radioactive moieties were speciated. Chlorate appeared


rapidly in blood and serum after dosing. For animals administered a dose of 42 or 63 mg/kg, the half-life of absorption was estimated at 0.6–0.9 h. Serum chlorate concentrations progressively increased with aliquot administration until peaking at 6–21 parts per million at 26 h. Between aliquot administrations, serum chlorate levels typically peaked in 3.5 h or less. The half-life of chlorate elimination ranged between 6.9 and 11 h, depending on the dose. Ultimately, absorption of chlorate removes it from its desired site of action, the lower gastrointestinal tract, thereby reducing its efficacy. Further research is needed to develop a chlorate formulation that will allow passage to the lower gastrointestinal tract.

Description of key information

The toxicokinetic profile of the substance was derived from a weight of evidence apporach on the relevant available information collated in the dossier, and in cases where data for potassium chlorate were not available or to support data that were found for potassium chlorate, tests performed with sodium chlorate were used in this dossier. Read across is possible for these two substances, because the toxicity of the test substance is expected to be related to the chlorate ion and not to the sodium or potassium ion.


 


There is only one study on dermal absorption available for sodium chlorate (Kane, 2007).


There is one study available for potassium chlorate on toxicokinetics (Abdel-Rahman, 1985) and there are five studies available for sodium chlorate:


- Smith, 2005A


- Smith, 2005B


- Smith, 2006


- Hakk, 2007


- Oliver, 2007

Key value for chemical safety assessment

Additional information

TOXICOKINETICS


Sodium and potassium both play an important role in physiological processes and their toxicity is low. The American Food and Nutrition Board set an Adequate Intake (AI) for potassium at 4.7 g/day (78 mg/kg d) for all adults and an AI for sodium has been set at 1.5 g/day (25 mg/kg d) for young adults and 1.3 g/day (22 mg/kg d) for elderly. An upper limit of intake has not been set for potassium because healthy people excrete excess potassium with their urine. The upper limit for sodium intake has been set at 2.3 g/day (38 mg/kg d) considering effects of higher levels of sodium intake on blood pressure (Panel on Dietary Reference Intakes for Electrolytes and Water, Standing Committee on the Scientific Evaluation of Dietary Reference Intakes Food and Nutrition Board, 2004). Furthermore both sodium and potassium chlorate almost totally dissociate in water, producing sodium/potassium cations and chlorate anions.


 


Chlorate is rapidly absorbed and excreted in the urine. In rats, about 66-90.7 % of the dose was eliminated in the urine, whereas only 0.1-5.1% of the dose was eliminated in the faeces, demonstrating that the major excretion route was via the urine. Similar excretion patterns were observed in beef cattle and in growing swine. Summation of the total amount of radiochlorine recovered in nongastrointestinal tissues and in the urine indicates that 63.3 to 95.5% of the dosed chlorate was absorbed in ruminant and nonruminant animals (see table).


 


Table 7.1.1. Radiochlorine absorption in rats, beef cattle and growing swine.












































Species



Rats



BeEf cattle



Swine



Sex/dose



M


(3 mg/kg)



M


63 mg/kg



M


126 mg/kg



M


(65 mg/kg)



F


(61 mg/kg)



Urine1



80.4



38.8



48.1



91.5



91.8



Tissues2



12.3



29.3



15.2



4.0



3.5



Total absorbed



92.7



70.1



63.3



95.5



95.3



1including cage wash


2radiochloride recovered in nongastrointestinal tissues.


 


Chlorate was widely distributed among tissues. No determination of radiochlorine concentrations in thyroid gland were conducted in rats or beef cattle. In swine, relative high concentration of parent chlorate was retained in the thyroid gland whatever the dose administered. Radiochemical analysis of extracted radiochlorine from thyroid of these swine clearly indicated that chloride and chlorate were present, suggesting that chlorate will accumulate in the thyroid tissues of treated animals (as observed for perchlorate).


In contrast to previous reports (Abdel-Rahman et al, 1985), suggesting that rats metabolize chlorate to chlorite, and that chlorite was excreted as an urinary metabolite, no evidence for the existence of chlorite in urine or in the tissues of rats, cattle or swine was generated in recent studies (Hakk et al, 2007; Smith et al., 2005a, 2005b and 2006). Chlorate was found to be metabolized only to chloride in both ruminant and nonruminant animals.


Consequently, it can be considered that chlorate is rapidly absorbed (88 to 95% in rats) and excreted in the urine. The only stable metabolite of chlorate was found to be chloride and was detected in both urine and tissues in rats.


 


DERMAL ABSORPTION


A comparative in vitro dermal penetration study using human and rat skin (Kane, 2007) shows that rat skin is considerably more permeable than human skin following application at the low dose level (150 µg/cm2). At the high dose level (5 mg/cm2), the permeability of human and rat skin was similar. The total absorbable percentage was 0.51% and 3.37% for human and rat skin for the high dose, and 1.85% and 18.09% for human and rat skin for the low dose.


The steady-state absorption rates for sodium chlorate were low, with values of 0.446 µg/cm2/hr (human) and 0.467 µg/cm2/hr (rat) at the high dose level and 0.166µg/cm2/hr (human) and 4.875 µg/cm2/hr (rat) at the low dose level, showing that sodium chlorate does not rapidly penetrate the skin.