1,2,3-trichloropropane

Basic toxicokinetics

Administrative data

Endpoint:

basic toxicokinetics

Type of information:

experimental study

Adequacy of study:

key study

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

other: - scientifically sound study, generally guideline compliant - non-GLP

Data source

Reference

Reference Type:

publication

Title:

Comparative disposition and metabolism of 1,2,3-trichloropropane in rats and mice.

Author:

Mahmood NA, Overstreet D & Burka LT.

Year:

1991

Bibliographic source:

Drug Metab Dispos. 1991 Mar-Apr;19(2):411-8.

Materials and methods

Objective of study:

absorption

distribution

excretion

metabolism

Test guideline

Qualifier:

equivalent or similar to guideline

Guideline:

OECD Guideline 417 (Toxicokinetics)

Deviations:

yes

Remarks:

: only one dose level used in rats

GLP compliance:

no

Test material

Test material information

Constituent 1

Reference substance name:

1,2,3-trichloropropane

EC Number:

202-486-1

EC Name:

1,2,3-trichloropropane

Cas Number:

96-18-4

Molecular formula:

C3H5Cl3

IUPAC Name:

1,2,3-trichloropropane

Details on test material:

- Name of test material (as cited in study report): 1,2,3-trichloropropane
- Substance type: chlorinated short-chain hydrocarbon
- Physical state: liquid
- Analytical purity: unlabeled substance: 98 %; labeled substance: > 93 %
- Impurities (identity and concentrations): unlabeled: not reported; labeled: major radiochemical impurity (ca. 5%) is thought to be 2-[ 14C]2,3-dichloropropene
- Purity test date: not reported
- Lot/batch No.: not reported
- Provider: unlabeled substance: Fluka Chemical Corp. (Ronkonkoma, NY); labeled substance: DuPont Biomedical Products (Boston, MA).
- Expiration date of the lot/batch: not reported
- Radiochemical purity (if radiolabelling): labeled substance > 93 %
- Specific activity (if radiolabelling): labeled substance 57 mCi/mmol,
- Locations of the label (if radiolabelling): 2-[ 14C]1,2,3-TCP
- Expiration date of radiochemical substance (if radiolabelling): not reported
- Stability under test conditions: not reported, expected to be stable
- Storage condition of test material: not reported

Radiolabelling:

yes

Test animals

Species:

other: rat and mouse

Strain:

other: F344 rats and B6C3F1 mice

Sex:

male/female

Details on test animals or test system and environmental conditions:

TEST ANIMALS
- Source: Charles River Breeding Laboratories (Wilmington, MA).
- Age at study initiation: not reported
- Weight at study initiation: Male rats: 180-250 g, Female rats: 170-180 g, Male mice: 30 g
- Fasting period before study: no
- Housing: individually in the metabolism cages for separate collections of excreta or Metabowl-Mark III glass metabolism cages (Jencons, Hemel Hempstead, Herfordshire, UK) for analysis of exhaled air
- Individual metabolism cages: yes
- Diet (e.g. ad libitum): rat chow, ad libitum
- Water (e.g. ad libitum): water, ad libitum
- Acclimation period: not reported


ENVIRONMENTAL CONDITIONS
- not reported

Administration / exposure

Route of administration:

oral: gavage

Vehicle:

corn oil

Details on exposure:

PREPARATION OF DOSING SOLUTIONS:


VEHICLE
- Justification for use and choice of vehicle (if other than water): not reported, but cornoil is a standard vehicle for volatile lipophilic solvents like 1,2,3-trichloropropane
- Concentration in vehicle: rats: 6 mg/mL, mice: 30 or 60 mg/7 mL
- Amount of vehicle (if gavage): rats: 5 mL/Kg bw, mice 7 mL/Kg bw
- Lot/batch no. (if required): not reported
- Purity: not reported


HOMOGENEITY AND STABILITY OF TEST MATERIAL:
as 1,2,3-trichloropropane is a stable lipophilic solvent the homogeneity and stability of the the test material is of no concern

Duration and frequency of treatment / exposure:

single treatment via gavage

Doses / concentrations

Remarks:

Doses / Concentrations:
rats: 30 mg/Kg bw
mice: 30, 60 mg/Kg bw

No. of animals per sex per dose / concentration:

- unclear from the report
- 3 animals were analysed per time point

Control animals:

no

Positive control reference chemical:

no

Details on study design:

- Dose selection rationale:
- Rationale for animal assignment (if not random):

Details on dosing and sampling:

PHARMACOKINETIC STUDY (Absorption, distribution, excretion)
- Tissues and body fluids sampled (delete / add / specify): urine, faeces, blood, plasma, serum or other tissues, cage washes, bile
- Time and frequency of sampling:
- Other:


METABOLITE CHARACTERISATION STUDIES
- Tissues and body fluids sampled (delete / add / specify): urine, faeces, tissues, cage washes, bile
- Time and frequency of sampling:
- From how many animals: (samples pooled or not)
- Method type(s) for identification (e.g. GC-FID, GC-MS, HPLC-DAD, HPLC-MS-MS, HPLC-UV, Liquid scintillation counting, NMR, TLC)
- Limits of detection and quantification:
- Other:


TREATMENT FOR CLEAVAGE OF CONJUGATES (if applicable): not applicable

Statistics:

Statistical analysis was performed using a pairwise comparison of variance (one-sided t test). Values were considered statistically significant at p -.5 0.05.

Results and discussion

Preliminary studies:

no data

Toxicokinetic / pharmacokinetic studies

Details on absorption:

1,2,3-trichloropropane is rapidly absorbed as can be expected for a small lipophilic chlorinated solvent molecule (see table 1 for details).

Details on distribution in tissues:

1,2,3-trichloropropane is easily distributed to all tissues via the blood circulation.
After 6 h post dosing the highest concentrations in male rats are found in fore stomach, glandular stomach, small and large intestine, adipose tissue liver and kidneys (see table 1)
Between 6 and 24 h in male rats the concentration of radioactivity rised markedly in the liver and in the kidneys and in all other tissues, while declining in stomach (drastically), intestine, lung and spleen. No significant difference in any tissue was found at this timepoint between male and female rats.
60 h post dosing the highest concentration of radioactivity was present in the liver, kidneys and fore stomach of rats of both sexes. In females in all three tissues concentrations were higher than in males though statistically significant only for the fore stomach.
Male mice after 60 h showed generally the same distribution pattern of radioactivity as compared to rats but the concentrations of the 30 mg/Kg dose group have generally lower levels than the rats that were dosed also with 30 mg/Kg bw (see table 2). The 60 mg/Kg bw mice on the other hand showed radioactivity levels comparable to the 30 mg/Kg dosed rats.
The relative distribution of the radioactivity did not vary with the different doses in mice. On the contrary the tissues concentrations are roughly proportional to the dose.
50 to 80 % of the radioactivity of the tissues of rats at 24 and 60 h were not extractable indicating that 1,2,3-trichloropropane and/or its metabolites react with cellular constituents.
The different radioactivity levels found in equally dosed rats and mice is in good agreement with the higher tolerance of mice towards 1,2,3-trichloropropane in repeated dose experiments and indicates a faster metabolism in mice compared to rats.
The blood brain barrier is not effective against 1,2,3-trichloropropane as the brain shows generally the same concentration levels as the blood.

Transfer into organs

Test no.:

#1

Transfer type:

blood/brain barrier

Observation:

distinct transfer

Details on excretion:

> 90 % of the 1,2,3-trichloropropane derived radioactivity was excreted within 60 h post dosing in male and female rats and mice (see table 4).
There is no significant difference in the pattern of excretion routes between rats and mice (see table 4).
The major route is via urine (50 - 60 %) while feces and exhalation (mainly as carbon dioxide, only 2 % as unchanged 1,2,3-trichloropropane) account both for approximately 20 % at 60 h.
At 24 h already more than 50 % of the administered radioactivity was excreted in total in rats.
No significant sex differences were found in rats.
Mice exhaled radioactive carbon dioxide significantly faster than rats proposing a faster metabolism in rats.
Kinetics of excretion via the different routes were not significantly different in the two mice dose groups.

Toxicokinetic parameters

Test no.:

#1

Toxicokinetic parameters:

other: 24 h already more than 50 % of the administered radioactivity was excreted in total in rats

Metabolite characterisation studies

Metabolites identified:

yes

Details on metabolites:

About 20 % of the administered radioactivity were exhaled as carbon dioxide indicating extensive metabolisation in both species.
In rat urine the major metabolite (40 % of radioactivity) is N-acetyl-S-(3-chloro-2-hydroxypropy1)-L-cysteine (ACPC), a mercapturic acid that might be a product either of cytochrome P450 mediated oxidation at C2 (forming dichloroacetone) followed by reaction with glutathion and finally reduction to the respective alcohol or by direct nucleophilic substitution of two chlorine atoms, forming an intermediate sulfonium ion which is later hydrolized. The intermediate sulfonium ion species as well as the dichloroacetone are reactive molecules that can interact with biologic macromolecules.
ACPC is only a minor metabolite in mice urine while S-(3-chloro-2-hydroxypropy1)-L-cysteine (CPC) is the second most abundant metabolite in mice urine.
The major metabolite in mice urine could not be identified.
The major metabolite of rat bile is 2-(S-glutathionyl)malonic acid (GMA) also a metabolite indicative of a combination of oxidative metabolism plus glutathion scavenging.

Any other information on results incl. tables

- table 1: Concentration (µg eq/g tissue) of radioactivity in tissues of male and female F344 rats following administration of 30 mg/kg of [14C]-1,2,3-trichloropropane vs. time

Tissue	6 hr	24 hr		60 hr
	Male	Male	Female	Male	Female
Blood	1.6 ± 0.4	3.1 ± 0.4	2.3 ± 0.3	1.5 ± 0.4	3.2 ± 0.9
Liver	12.6 ± 5.2	20.4 ± 5.2	24.1 ± 2.7	8.6 ± 1.4	11.0± 1.5
Kidney	14.3 ± 2.4	16.8 ± 4.3	22.5 ± 1.1	8.0 ± 1.6	13.1 ± 3.2
Skin	1.5 ± 0.4	2.6 ± 0.6	2.8 ± 0.5	1.6 ± 0.2	2.2 ± 0.3
Adipose	26.5 + 6.4	4.3 ± 1.3	1.9 ± 0.8	0.8 ± 0.1	1.7 ± 0.8
Muscle	0.8 ± 0.1	1.3 ± 0.6	1.0 ± 0.3	0.6 ± 0.2	0.7 ± 0.2
Brain	1.8.1. 0.7	33 ± 1.1	3.7 ± 0.2	1.9 ± 0.4	2.4 ± 0.1
Spleen	6.7 ± 5.0	3.7 ± 1.6	5.3 ± 0.6	1.9 ± 0.6	3.3 ± 0.0 a
Lungs	4.9 ± 2.4	3.4 ± 0.8	4.8 ± 0.1	2.0 ± 0.1	3.2 ± 0.6
Heart	2.0 ± 0.7	3.9 ± 1.0	3.7 ± 0.9	2.2 ± 1.1	3.0 ± 0.5
Stomach
Fore	21.5.6 ± 18.0	33.7 ± 18.9	25.8 ± 2.6	5.7 ± 0.5	11.6 ± 2.2 a
Glandular	98.7 ± 3E4	11.6 ± 5.9	7.8 ± 2.7	2.4 ± 0.2	3.3 ± 0.5
Intestine
Small	54.0 ± 17.1	9.5 ± 3.9	9.6 ± 4.0	1.9 ± 1.9	3.1 ± 0.3
Large	22.0 ± 7.4	19.0 ± 9.8	26.0 ± 18.1	3.2 ± 0.1	2.9 ± 0.3

a: Significantly different from males at the same time point (p < 0.05).

Values are mean ± SD from three rats.

- table 2: Concentration (µg eq/g tissue) of 1,2,3-trichloropropane-derived radioactivity in tissues of male B6C3F1 mice at 60 hr post-dosing

Tissue	60 mg/kg	30 mg/kg
Blood	1.1 ± 0.3	0.3 ± 0.2 a
Liver	7.8 ± 2.2	4.0 ± 0.7 a
Kidney	5.1 ± 0.6"	3.0 ± 0.5 a
Skin	1.4 ± 0.4	1.0 ± 0.2
Adipose	1.1 ±0.3	0.5 ± 0.2
Muscle	0.8 ± 0.3	0.6 ± 0.1
Brain	1.4 ± 0.1	0.3 ± 0.1 a
Spleen	0.7 ± 0.8	1.3 ± 0.3
Lungs	1.3 ± 1.1	0.8 ± 0.4 a
Heart	1.8 ± 0.2	0.4 ± 0.2
Stomach
Fore	8.6 ± 1.7 a	4.6 ± 1.5
Glandular	1.8 ± 0.5	1.1 ±0.3 a
Intestine
Small	1.9 ± 0.4	0.8 ± 0.2
Large	2.1 ± 1.8	2.2 ± 1.8

a: Significantly different from males at the same time point (p < 0.05).

Values are mean ± SD from three rats.

- table 3: Non extractable radioactivity in selected tissues of female F344 rats 24 and 60 hr after administration of 30 mg/Kg 1,2,3-trichloropropane

Tissue	24hr	60 hr	24hr	60 hr
	ng eq nonextraciablel/ mg protein		% nonextractable
Forestomach	780 ± 120	490 ± 100	54± 18	50 ± 6
Liver	900 ± 40	620 ± 90	71± 4	83 ± 1
Kidney	980 ± 70	720 ± 40	62± 5	67 ± 5

- table 4: Distribution and excretion of 1,2,3-trichloropropane-derived radioactivity in male and female rats and male mice 60 hr after oral administration (30 mg/kg)

Tissue	Male Rats	Female Rats	Male Mice
	% of total dose
Blood	0.6 ± 0.1	0.9 ± 0.2	0.1 ± 0.04
Liver	1.4 ± 0.2	1.2 ± 0.3	0.6 ± 0.03
Kidney	0.3 ± 0.1	0.3 ± 0.1	0.1 ± 0.01
Skin	1.1 ± 0.1	1.0 ±0.1	0.5 ± 0.1
Adipose	0.4 ± 0.1	0.6 ± 0.3	0.2 ± 0.1
Muscle	1.1 ± 0.3	1.0 ± 0.4	1.0 ± 0.2
Urine	57.1 ± 6.2	49.8 ± 4.3	64.0 ± 5.5
Feces	21.1 ± 4.9	19.4 ± 2.2	16.0 ± 6.0
CO2	17.7 ± 0.4	18.5 ± 0.6	20.2 ± 1.8
Volatiles	1.5 ± 0.5	1.4 ± 0.8	0.6 ± 0.4

Values are mean ± SD from three rats.

Applicant's summary and conclusion

Conclusions:

Interpretation of results (migrated information): low bioaccumulation potential based on study results
A toxicokinetic study was conducted administering 1,2,3-trichloropropane once via gavage to male and female F344 rats (30 mg/Kg bw) and male B6C3F1 mice (30 and 60 mg/Kg bw) .
The bioavailability via the oral route is high (close to 100 %), the metabolism is fast and the substance is excreted up to 90 % within 60 h in both species. Therefore the potential for bioaccumulation is regarded as low.
Metabolites are formed trough oxidation as well as reaction with glutathion. Thereby reactive intermediates are formed that probably react with biological molecules explaining significant amounts of non extractable radioactivity in liver, kidneys and forestomach.
Routes of excretion are equal between both sexes of rats and also male mice, while mice generally show indications for a faster metabolism of 1,2,3-trichloropropane.
These three organs are very likely the target organs of toxicity after oral exposure in both species.

Executive summary:

In the present toxicokinetic study (Mahmood (1991) 14C-labeled 1,2,3-trichloropropane was administered once via gavage to male and female F344 rats (30 mg/Kg bw) and male B6C3F1 mice (30 and 60 mg/Kg bw).

Animals were held in metabolic cages to sample urine, feces and exhaled air. At certain time points 3 animals were sacrificed to analyse the distribution of radioactivity in the blood and the different tissues. In addition in rats excretion of 1,2,3 -trichloropropane and its metabolites in the bile was examined between 0.5 and 5 h post dosing. Some of the major metabolites were identified in rat and mouse urine and rat bile via NMR and mass spectroscopy.

The bioavailability via the oral route is high (close to 100 %), the metabolism is fast and the substance is excreted up to 90 % in rats and close to 100 % in mice within 60 h. The excretion pattern is 20% via feces in both species, 50 % and 65 % via urine and 20 and 15% via exhalation rats and mice respectively. Exhalation is mainly as carbon dioxide and only minor amounts as unmetabolised 1,2,3 -trichloropropane.

Nevertheless a combined amount about 4 % of the radioactivity is found in liver, kidneys, skin, adipose tissue and muscles of rats and a total amount of about 2.5 % in male mice in these tissues 60 h after application. Therefore a low bioaccumulation potential is determined for 1,2,3 -trichloropropane.

Metabolites are formed through oxidation as well as reaction with glutathion (N-acetyl-S-(3-chloro-2-hydroxypropy1)-L-cysteine (ACPC), rat urine; S-(3 -chloro-2 -hydroxypropy1)-L-cysteine (CPC), mice urine; 2 -(S-glutathionyl)malonic acid (GMA), rat bile). Thereby reactive intermediates are formed that probably react with biological molecules explaining significant amounts of non extractable radioactivity in liver, kidneys and forestomach.

Routes of excretion are equal between both sexes of rats and also male mice, while mice generally show indications for a faster metabolism of 1,2,3-trichloropropane.

These three organs are very likely the target organs of toxicity after oral exposure in both species.