Reaction mass of [[(2-hydroxyethyl)imino]bis(methylene)]bisphosphonic acid and Phosphonic acid, P-[(tetrahydro-2-hydroxy-2-oxido-4H-1,4,2-oxazaphosphorin-4-yl)methyl]-

Repeated dose toxicity: oral

Administrative data

Endpoint:

short-term repeated dose toxicity: oral

Remarks:

combined repeated dose and reproduction / developmental screening

Type of information:

migrated information: read-across based on grouping of substances (category approach)

Adequacy of study:

key study

Study period:

The in-life phase of the study was conducted between 13 June 2012 (first day of treatment) and 04 August 2012 (final necropsy).

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

other: Study conducted to GLP and in compliance with agreed protocols, with no or minor deviations from standard test guidelines and/or minor methodological deficiencies, which do not effect the quality of the relevant results.

Cross-reference

Reason / purpose for cross-reference:

reference to same study

Data source

Reference

Reference Type:

study report

Title:

Unnamed

Year:

2013

Report date:

2013

Materials and methods

Test guideline

Qualifier:

according to guideline

Guideline:

OECD Guideline 422 (Combined Repeated Dose Toxicity Study with the Reproduction / Developmental Toxicity Screening Test)

Deviations:

no

GLP compliance:

yes (incl. QA statement)

Limit test:

no

Test material

Test material information

Constituent 1

Reference substance name:

[[(2-hydroxyethyl)imino]dimethylene]bisphosphonic acid, sodium salt

EC Number:

244-743-0

EC Name:

[[(2-hydroxyethyl)imino]dimethylene]bisphosphonic acid, sodium salt

Cas Number:

22036-78-8

Molecular formula:

C4H12NNaO7P2, C4H11NNa2O7P2 and C4H10NNa3O7P2 (Constituent 1, linear form) C4H12NNaO7P2 and C4H11NNa2O7P2 (Constituent 2, cyclic form) The molecular formula and molecular weights represented that of the speciated species of the sodium salt

IUPAC Name:

[[(2-hydroxyethyl)imino]dimethylene]bisphosphonic acid, sodium salt

Test material form:

semi-solid (amorphous): gel

Remarks:

migrated information: paste

Details on test material:

Identification : [[(2-hydroxyethyl)imino]bis(methylene)]-bisphosphonic acid, equilibrium mixture with 4-(Phosphonomethyl)-2-hydroxy-2-oxo-1,4,2-oxazaphosphorinane, sodium salt
CAS number : 22036-78-8
Identifier : TIS O3270
Description : White paste
Batch number : LE12579A
Date received : 03 April 2012
Storage conditions: Room temperature in the dark
Expiry date : 01 August 2013
Test item water content: 10.95%

Test animals

Species:

rat

Strain:

Wistar

Sex:

male/female

Details on test animals or test system and environmental conditions:

TEST ANIMALS
- Source: Obtained from Harlan Laboratories U.K. Ltd.
- Age at study initiation: approximately twelve weeks old.
- Weight at study initiation: At the start of treatment the males weighed 306 to 351g, the females weighed 189 to 219g.
- Fasting period before study: No
- Housing: Initially, all animals were housed in groups of five in solid floor polypropylene cages with stainless steel mesh lids and softwood flake bedding. During the pairing phase, animals were transferred to polypropylene grid floor cages suspended over trays lined with absorbent paper on a one male: one female basis within each dose group. Following evidence of successful mating, the males were returned to their original cages. Mated females were housed individually during gestation and lactation in solid floor polypropylene cages with stainless steel mesh lids and softwood flakes.
- Diet (e.g. ad libitum): The animals were allowed free access to food. A pelleted diet was used.
- Water (e.g. ad libitum): The animals were allowed free access to water. Mains drinking water was supplied from polycarbonate bottles attached to the cage.
- Acclimation period: five days

ENVIRONMENTAL CONDITIONS
- Temperature (°C): The temperature was set to achieve target values of 21 ± 2°C
- Humidity (%): The relative humidity control was set to achieve target values of 55 ± 15%
- Air changes (per hr): at least fifteen air changes per hour
- Photoperiod (hrs dark / hrs light): twelve hours continuous light and twelve hours darkness

Administration / exposure

Route of administration:

oral: gavage

Vehicle:

other: Distilled water

Details on oral exposure:

PREPARATION OF DOSING SOLUTIONS:
The test item was prepared at the appropriate concentrations as a solution in Distilled water. Formulations were prepared fortnightly and stored at approximately 4ºC in the dark.

All formulation were adjusted for 10.95% water content. All dose levels of expressed in terms of Active Ingredient

The test item was administered daily by gavage using a stainless steel cannula attached to a disposable plastic syringe. Control animals were treated in an identical manner with 5 ml/kg of Distilled water.
The volume of test and control item administered to each animal was based on the most recent scheduled body weight and was adjusted at regular intervals.

Analytical verification of doses or concentrations:

yes

Details on analytical verification of doses or concentrations:

Samples of test item formulations were taken and analysed for concentration of test item.

The concentration of test item in the test item formulations was determined by Inductively Coupled Plasma Mass Spectrometry (ICP-MS) using an external standard technique.

The results indicate that the prepared formulations were within ± 3% of the nominal concentration.

Duration of treatment / exposure:

Up to eight weeks (including a two week pre-pairing phase, pairing, gestation and early lactation).

Frequency of treatment:

The test item was administered daily.

Doses / concentrations

Remarks:

Doses / Concentrations:
0 (control), 100 (low), 350 (intermediate) and 1000 (high) mg/kg bw/day (Active Ingredient)
Basis:
actual ingested

No. of animals per sex per dose:

10 males and 10 females per dose (including control)

Control animals:

yes, concurrent vehicle

Details on study design:

- Dose selection rationale: Dose levels were chosen based on the results of a 7-day range-finding study.

Chronological Sequence of Study:
i) Groups of ten male and ten female animals were treated daily at the appropriate dose level throughout the study (except for females during parturition where applicable). The first day of dosing was designated as Day 1 of the study.
ii) Prior to the start of treatment and once weekly thereafter, all animals were observed for signs of functional/behavioural toxicity.
iii) On Day 15, animals were paired on a 1 male: 1 female basis within each dose group for a maximum of fourteen days.
iv) Following evidence of mating (designated as Day 0 post coitum) the males were returned to their original cages and females were transferred to individual cages.
v) On completion of the pairing phase (during Week 6), five selected males per dose group were evaluated for functional/sensory responses to various stimuli.
vi) Pregnant females were allowed to give birth and maintain their offspring until Day 5 post partum. Litter size, offspring weight and sex, surface righting and clinical signs were also recorded during this period.
vii) At Day 4 post partum, five selected females per dose group were evaluated for functional/sensory responses to various stimuli.
viii) Blood samples were taken from five males from each dose group for haematological and blood chemical assessments on Day 42. The male dose groups were killed and examined macroscopically on Day 43.
ix) Blood samples were taken from five randomly selected females from each dose group for haematological and blood chemical assessment on Day 4 post partum. At Day 5 post partum, all females and surviving offspring were killed and examined macroscopically. Any female which did not produce a pregnancy was also killed and examined macroscopically.

Positive control:

No positive control.

Examinations

Observations and examinations performed and frequency:

CLINICAL OBSERVATIONS:
All animals were examined for overt signs of toxicity, ill-health and behavioural change immediately before dosing, up to thirty minutes after dosing, and one and five hours after dosing, during the working week. Animals were observed immediately before dosing, soon after dosing, and one hour after dosing at weekends and public holidays (except for females during parturition where applicable). All observations were recorded.

FUNCTIONAL OBSERVATIONS:
Prior to the start of treatment and at weekly intervals thereafter, all animals were observed for signs of functional/behavioural toxicity. Functional performance tests were also performed on five selected males and females from each dose level, prior to termination, together with an assessment of sensory reactivity to various stimuli.

BEHAVIOURAL ASSESSMENTS:
Detailed individual clinical observations were performed for each animal using a purpose built arena. The following parameters were observed:
Gait, Hyper/Hypothermia, Tremors, Skin colour, Twitches, Respiration, Convulsions, Palpebral closure, Bizarre/Abnormal/Stereotypic behaviour Urination, Salivation, Defecation, Pilo-erection, Transfer arousal, Exophthalmia, Tail elevation, Lachrymation.

FUNCTIONAL PERFORMANCE TESTS:
- Motor Activity
- Forelimb/Hindlimb Grip Strength
- Sensory Reactivity


BODY WEIGHT:
Individual body weights were recorded on Day 1 (prior to dosing) and then weekly for males until termination and weekly for females until mating was evident. Body weights were then recorded for females on Days 0, 7, 14 and 20 post coitum, and on Days 1 and 4 post partum.

FOOD CONSUMPTION:
During the pre-pairing period, weekly food consumption was recorded for each cage of adults. This was continued for males after the mating phase. For females showing evidence of mating, food consumption was recorded for the periods covering post coitum Days 0-7, 7-14 and 14-20. For females with live litters, food consumption was recorded on Days 1 and 4 post partum.

Food efficiency (the ratio of body weight change/dietary intake) was calculated retrospectively for males throughout the study period (with the exception of the mating phase) and for females during the pre-pairing phase. Due to offspring growth and milk production, food efficiency could not be accurately calculated for females during gestation and lactation.

WATER CONSUMPTION:
Water intake was observed daily by visual inspection of water bottles for any overt changes.

LABORATORY INVESTIGATIONS:
Haematological and blood chemical investigations were performed on five males and five females selected from each test and control group prior to termination (Day 42 for males and Day 4 post partum for females).

HAEMATOLOGY:
The following parameters were measured on blood collected into tubes containing potassium EDTA anti-coagulant:
Haemoglobin (Hb)
Erythrocyte count (RBC)
Haematocrit (Hct)
Erythrocyte indices
- mean corpuscular haemoglobin (MCH)
- mean corpuscular volume (MCV)
- mean corpuscular haemoglobin concentration (MCHC)
Total leucocyte count (WBC)
Differential leucocyte count - neutrophils (Neut)
- lymphocytes (Lymph)
- monocytes (Mono)
- eosinophils (Eos)
- basophils (Bas)
Platelet count (PLT)
Reticulocyte count (Retic) - Methylene blue stained slides were prepared but reticulocytes were not assessed
Prothrombin time (CT) was assessed by ‘Innovin’ and Activated partial thromboplastin time (APTT) was assessed by ‘Actin FS’ using samples collected into sodium citrate solution (0.11 mol/l).

BLOOD CHEMISTRY:
The following parameters were measured on plasma from blood collected into tubes containing lithium heparin anti-coagulant:
Urea
Calcium (Ca++)
Glucose
Inorganic phosphorus (P)
Total protein (Tot.Prot.)
Aspartate aminotransferase (ASAT)
Albumin
Alanine aminotransferase (ALAT)
Albumin/Globulin (A/G) ratio (by calculation)
Alkaline phosphatase (AP)
Sodium (Na+)
Creatinine (Creat)
Potassium (K+)
Total cholesterol (Chol)
Chloride (Cl-)
Total bilirubin (Bili)
Bile acids (Bile)

Sacrifice and pathology:

PATHOLOGY:
Adult males were killed by intravenous overdose of a suitable barbiturate agent followed by exsanguination on Day 43. Adult females were killed by intravenous overdose of a suitable barbiturate agent followed by exsanguination on Day 5 post partum. Surviving offspring were terminated via intracardiac overdose of sodium pentobarbitone. Any females which failed to achieve pregnancy or produce a litter were killed on or after Day 25 post coitum.

For all females, the uterus was examined for signs of implantation and the number of uterine implantations in each horn was recorded. This procedure was enhanced; as necessary, by staining the uteri with a 0.5% ammonium polysulphide solution (Salewski 1964).

All adult animals and offspring, including those dying during the study, were subjected to a full external and internal examination, and any macroscopic abnormalities were recorded.

ORGAN WEIGHTS:
The following organs, removed from animals that were killed at the end of the study, were dissected free from fat and weighed before fixation:
Adrenals, Prostate, Brain, Seminal vesicles, Epididymides, Spleen, Heart, Testes, Kidneys, Thymus, Liver, Thyroid (weighed post-fixation with Parathyroid), Ovaries, Uterus (weighed with Cervix), Pituitary (post fixation).

HISTOPATHOLOGY:
Samples of the following tissues were removed from all animals:
Adrenals
Ovaries
Aorta (thoracic)
Pancreas
Bone & bone marrow (femur including stifle joint)
Bone & bone marrow (sternum)
Pituitary
Prostate
Brain (including cerebrum, cerebellum and pons)
Oesophagus
Caecum
Rectum
Coagulating gland
Salivary glands (submaxillary)
Colon
Sciatic nerve
Duodenum
Seminal vesicles
Epididymides
Skin (hind limb)
Eyes
Spinal cord (cervical, mid-thoracic and lumbar)
Gross lesions
Heart
Spleen
Ileum (including peyer’s patches)
Stomach
Jejunum
Thyroid/parathyroid
Kidneys
Trachea
Liver
Testes
Lungs (with brochi)
Thymus
Lymph nodes (cervical and mesenteric)
Urinary bladder
Mammary gland
Uterus/Cevix
Muscle (skeletal)
Vagina

All tissues were despatched to the histology processing Test Site for processing.
Microscopic examination was conducted by the Study Pathologist

Other examinations:

-Mating
-Pregnancy and Parturition
- Litter Data
- Physical development (offspring)

Statistics:

Where considered appropriate, quantitative data was subjected to statistical analysis to detect the significance of intergroup differences from control; statistical significance was achieved at a level of p<0.05. Statistical analysis was performed on the following parameters:

Grip Strength, Motor Activity, Body Weight, Body Weight Change, Food Consumption during gestation and lactation, Pre-Coital Interval, Gestation Length, Litter Size, Litter Weight, Sex Ratio, Corpora Lutea, Implantation Sites, Implantation Losses, Viability Indices, Offspring Body Weight, Offspring Body Weight Change, Offspring Surface Righting, Haematology, Blood Chemistry, Absolute Organ Weights, Body Weight-Relative Organ Weights

Results and discussion

Results of examinations

Clinical signs:

no effects observed

Mortality:

no mortality observed

Body weight and weight changes:

no effects observed

Food consumption and compound intake (if feeding study):

no effects observed

Food efficiency:

no effects observed

Water consumption and compound intake (if drinking water study):

no effects observed

Ophthalmological findings:

not examined

Haematological findings:

no effects observed

Clinical biochemistry findings:

no effects observed

Urinalysis findings:

not examined

Behaviour (functional findings):

no effects observed

Organ weight findings including organ / body weight ratios:

no effects observed

Gross pathological findings:

no effects observed

Histopathological findings: non-neoplastic:

no effects observed

Histopathological findings: neoplastic:

not examined

Details on results:

MORTALITY:
There were no unscheduled deaths.

CLINICAL OBSERVATIONS:
No clinical signs of toxicity were detected in any treated animal.

BEHAVIOURAL ASSESSMENTS:
Weekly open field arena observations did not reveal any treatment-related effects for treated animals when compared to controls.
All inter and intra group differences in behavioural scores were considered to be a result of normal variation for rats of the strain and age used, and the differences were of no toxicological importance.

FUNCTIONAL PERFORMACE TEST:
There were no treatment-related changes in functional performance. Statistical analysis of the data did not reveal any significant intergroup differences.

SENSORY REACTIVITY ASSESSMENTS:
There were no treatment-related changes in sensory reactivity.

BODYWEIGHT:
There were no toxicologically significant effects detected in body weight development.

Females treated with 350 mg/kg bw/day A.I. showed a statistically significant increase in body weight gain during the first week of treatment. An increase in body weight gain is considered not to represent an adverse effect of treatment and in the absence of a dose related response the intergroup difference was considered not to be toxicologically significant. Females treated with 1000 mg/kg bw/day A.I. showed a slight reduction in body weight gain during lactation. Statistical analysis of the data did not reveal any significant intergroup differences and the majority of individual values were within normal ranges for rats of the strain and age, used, therefore this slight reduction was considered not to be of toxicological importance.

FOOD CONSUMPTION:
No adverse effect on food consumption or food efficiency was detected in treated animals when compared to control animals.

Females treated with 1000 and 350 mg/kg bw/day showed a statistically significant increase in food consumption during the final week of gestation. An increase in food consumption is not considered to represent an adverse effect of treatment.

WATER CONSUMPTION:
Daily visual inspection of water bottles did not reveal any significant intergroup differences.

HAEMATOLOGY:
There were no toxicologically significant effects detected in the haematological parameters examined.

Females treated with 1000 mg/kg bw/day A.I. showed a statistically significant reduction in total leucocycte count and neutrophil count. All individual values were within the normal ranges for rats of the strain and age used, therefore, the intergroup differences were considered not to be of toxicological importance.

BLOOD CHEMISTRY:
There were no toxicologically significant effects detected in the blood chemical parameters examined.

Males from all treatment groups showed statistically significant reductions in cholesterol and inorganic phosphorus and a statistically significant increase in chloride concentration. The majority of individual values were within the normal ranges for rats of the strain and age used and in the absence of true dose related responses the intergroup differences were considered not to be of toxicological importance. Males treated with 1000 mg/kg bw/day A.I. had a statistically significant increase in bile acid. In the absence of any associated histopathological correlates the intergroup difference was considered not to be of toxicological importance. Males treated with 100 mg/kg bw/day A.I. showed a statistically significant increase in urea. In the absence of a true dose related response the intergroup difference was considered not to be of toxicological importance. Females treated with 1000 and 350 mg/kg bw/ay A.I. showed a statistically significant reduction in creatinine. Females treated with 1000 mg/kg bw/day A.I. also showed a statistically significant reduction in calcium concentration. The majority of individual values were within the normal ranges for rats of the strain and age used, therefore, the intergroup differences were considered not to be of toxicological significance.

PATHOLOGY:
NECROPSY:
Offspring:
No treatment-related macroscopic abnormalities were detected for interim death or terminal kill offspring. The incidental findings observed were those occasionally observed in reproductive studies of this type and were considered to be unrelated to toxicity of the test item.

Adults:
No toxicologically significant macroscopic abnormalities were detected.
One female treated with 1000 mg/kg bw/day A.I. and one female treated with 100 mg/kg bw/day A.I. had a dark spleen at necropsy. In the absence of any histology correlates the intergroup differences were considered not to be of toxicological importance. One control male had reddened lungs. In the absence of treatment this was considered to be an incidental finding.


ORGAN WEIGHTS:
No toxicologically significant effects were detected in the organ weights measured.

Males treated with 1000 mg/kg bw/day A.I. showed a statistically significant increase in pituitary weight both absolute and relative to terminal body weight. Males treated with 350 mg/kg bw/day A.I. showed a statistically significant increase in thyroid weight both absolute and relative to terminal body weight. Female treated with 1000 mg/kg bw/day A.I. showed a statistically significant reduction in thyroid weight, both absolute and relative to terminal body weight. Females treated with 1000 mg/kg bw/day A.I. also showed a statistically significant reduction in adrenal weight both absolute and relative to terminal body weight. In the absence of any histology correlates the intergroup differences were considered not to be of toxicological importance.

HISTOPATHOLOGY:
No treatment related microscopic findings were detected.

Effect levels

1

Dose descriptor:

NOEL

Remarks:

(Systemic toxicity)

Effect level:

1 000 mg/kg bw/day (nominal)

Based on:

act. ingr.

Sex:

male/female

Basis for effect level:

other: The oral administration of test item to rats by gavage, at dose levels of 100, 350 and 1000 mg/kg bw/day A.I., did not result in any toxicologically significant effects.

2

Dose descriptor:

NOEL

Remarks:

(reproductive toxicity)

Effect level:

1 000 mg/kg bw/day (nominal)

Based on:

act. ingr.

Sex:

male/female

Basis for effect level:

other: There were no treatment-related effects detected in the reproductive parameters observed.

Target system / organ toxicity

Critical effects observed:

not specified

Any other information on results incl. tables

Reproductive Performance:

Mating: There were no treatment-related effects on mating for treated animals.

Fertility: There were no treatment-related effects on fertility.

Gestation Lengths: There were no differences in gestation lengths. The distribution for treated females was comparable to controls.

Litter Responses:

Offspring Litter Size, Sex Ratio and Viability: Of the litters born, litter size at birth and subsequently on Day 1 and 4 post partum were comparable to controls. Sex ratio was also comparable to controls.

Offspring Growth and Development: Offspring body weight gain and litter weights at birth and subsequently on Day 1 and 4 post partum were comparable to controls. Surface righting was also comparable to controls.

No clinically observable signs of toxicity were detected for offspring from all treatment groups.

Applicant's summary and conclusion

Conclusions:

The oral administration of [[(2-hydroxyethyl)imino]bis(methylene)]-bisphosphonic acid, equilibrium mixture with 4-(Phosphonomethyl)-2-hydroxy-2-oxo-1,4,2-oxazaphosphorinane, sodium salt to rats by gavage, at dose levels of 100, 350 and 1000 mg/kg bw/day A.I., did not result in any toxicologically significant effects. The ‘No Observed Effect Level’ (NOEL) for systemic toxicity was therefore considered to be 1000 mg/kg bw/day A.I.

The ‘No Observed Effect Level’ (NOEL) for reproductive toxicity was considered to be 1000 mg/kg bw/day A.I.

Executive summary:

Introduction.

The study was designed to investigate the systemic toxicity and potential adverse effects of the test item on reproduction (including offspring development) and is compatible with the requirements of the OECD Guidelines for Testing of Chemicals No. 422 “Combined Repeated Dose Toxicity Study with the Reproduction/Developmental Toxicity Screening Test” (adopted 22 March 1996).

This study was also designed to be compatible with the Commission Regulation (EC) No 440/2008 of 30 May 2008 laying down test methods pursuant to Regulation (EC) No 1907/2006 of the European Parliament and of the Council on the Registration, Evaluation, Authorisation and Restriction of Chemicals (REACH).

 

Methods.

The test item was administered by gavage to three groups, each of ten male and ten female Wistar Ha:RccHan:WIST strain rats, for up to eight weeks (including a two week pre-pairing phase, pairing, gestation and early lactation for females), at dose levels of 100, 350 and 1000 mg/kg bw/day A.I. (adjusting for 10.95% water content). A control group of ten males and ten females was dosed with vehicle alone (Distilled water).

Clinical signs, behavioural assessments, body weight change, food and water consumption were monitored during the study. 

Pairing of animals within each dose group was undertaken on a one male: one female basis within each treatment group on Day 15 of the study, with females subsequently being allowed to litter and rear their offspring to Day 5 of lactation.

During the lactation phase, daily clinical observations were performed on all surviving offspring, together with litter size and offspring weights and assessment of surface righting reflex.

Extensive functional observations were performed on five selected males from each dose group after the completion of the pairing phase, and for five selected parental females from each dose group on Day 4 post partum. Haematology and blood chemistry were evaluated prior to termination on five selected males and females from each dose group. 

Adult males were terminated on Day 43, followed by the termination of all females and offspring on Day 5 post partum. Any female which did not produce a pregnancy was terminated on or after Day 25 post coitum. All animals were subjected to a gross necropsy examination and histopathological evaluation of selected tissues was performed.

 

Results.

Adult Responses:

Mortality.There were no unscheduled deaths.

Clinical Observations.No clinical signs of toxicity were detected in any treated animal.

Behavioural Assessment.There were no treatment-related changes in the behavioural parameters measured.

Functional Performance Tests.There were no treatment-related changes in functional performance.

Sensory Reactivity Assessments.There were no treatment-related changes in sensory reactivity.

Body Weight.There were no toxicologically significant effects detected in body weight development.

Food Consumption.No adverse effect on food consumption or food efficiency was detected in treated animals.

Water Consumption.No adverse effect on water consumption was detected.

 

Reproductive Performance:

Mating.There were no treatment-related effects on mating for treated animals.

Fertility.There were no treatment-related effects on fertility.

Gestation Lengths.There were no differences in gestation lengths. The distribution for treated females was comparable to controls.

 

Litter Responses:

Offspring Litter Size, Sex Ratio and Viability.Of the litters born, litter size at birth and subsequently on Day 1 and 4 post partum were comparable to controls. Sex ratio was also comparable to controls.

Offspring Growth and Development.Offspring body weight gain and litter weights at birth and subsequently on Day 1 and 4 post partum were comparable to controls. Surface righting was also comparable to controls.

No clinically observable signs of toxicity were detected for offspring from all treatment groups.

 

Laboratory Investigations:

Haematology.There were no toxicologically significant effects detected in the haematological parameters examined.

Blood Chemistry.There were no toxicologically significant effects detected in the blood chemical parameters examined.

 

Pathology:

Necropsy. No toxicologically significant macroscopic abnormalities were detected.

Organ Weights. No toxicologically significant effects were detected in the organ weights measured.

Histopathology. No treatment related microscopic abnormalities were detected.

 

Conclusion.

The oral administration of [[(2-hydroxyethyl)imino]bis(methylene)]-bisphosphonic acid, equilibrium mixture with 4-(Phosphonomethyl)-2-hydroxy-2-oxo-1,4,2-oxazaphosphorinane, sodium saltto rats by gavage, at dose levels of 100, 350 and 1000 mg/kg bw/day A.I., did not result in any toxicologically significant effects. The ‘No Observed Effect Level’ (NOEL) for systemic toxicity was therefore considered to be 1000 mg/kg bw/day A.I.

The ‘No Observed Effect Level’ (NOEL) for reproductive toxicity was considered to be 1000 mg/kg bw/day A.I.