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Developmental toxicity / teratogenicity

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Administrative data

Endpoint:
developmental toxicity
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.

Data source

Reference
Reference Type:
study report
Title:
Unnamed
Year:
2013
Report Date:
2013

Materials and methods

Test guideline
Qualifier:
according to
Guideline:
other: OECD Guidelines for Testing of Chemicals No. 422 “Combined Repeated Dose Toxicity Study with the Reproduction/Developmental Toxicity Screening Test” (adopted 22 March 1996).
Deviations:
no
GLP compliance:
yes (incl. certificate)
Limit test:
no

Test material

Reference
Name:
Unnamed
Type:
Constituent
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
Details on test animals 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 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.
Details on mating procedure:
Animals were paired on a 1 male: 1 female basis within each dose group, for a period of up to fourteen days. Cage tray-liners were checked each morning for the presence of ejected copulation plugs and each female was examined for the presence of a copulation plug in the vagina. A vaginal smear was prepared for each female and the stage of oestrus or the presence of sperm was recorded. The presence of sperm within the vaginal smear and/or vaginal plug in situ was taken as positive evidence of mating (Day 0 of gestation) and the males were subsequently returned to their original holding cages (unless required for additional pairing). Mated females were housed individually during the period of gestation and lactation.
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.
Duration of test:
Up to eight weeks.
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.

Examinations

Maternal examinations:
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.

REPRODUCTIVE SCREENING:
Pregnancy and Parturition:
Each pregnant female was observed at approximately 0830, 1230 and 1630 hours and around the period of expected parturition. Observations were carried out at approximately 0830 and 1230 hours at weekends and public holidays. The following was recorded for each female:
i) Date of pairing
ii) Date of mating
iii) Date and time of observed start of parturition
iv) Date and time of observed completion of parturition


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)

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. Any females which failed to achieve pregnancy or produce a litter were killed on or after Day 25 post coitum.

All adult animals, 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





















Ovaries and uterine content:
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).
Fetal examinations:
Not examined.
Statistics:
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
Indices:
Litter Responses:
The standard unit of assessment was considered to be the litter, therefore values were first calculated for each litter and the group mean was calculated using their individual litter values. Group mean values included all litters reared to termination (Day 5 of age).

i) Implantation Losses (%)
Group mean percentile pre-implantation and post-implantation loss were calculated for each female/litter as follows:
% pre – implantation loss = [(Number of corpora lutea - Number of implantation sites) ÷ Number of corpora lutea] x 100
% post – implantation loss =[(Number of implantation sites - Total number of offspring born) ÷ Number of implantation sites] x 100

ii) Live Birth and Viability Indices
The following indices were calculated for each litter as follows:
Live Birth Index (%) = (Number of offspring alive on Day 1 ÷ Number of offspring born) x 100
Viability Index (%) = (Number of offspring alive on Day 4 ÷ Number of offspring alive on Day 1 ) x 100

iii) Sex Ratio (% males)
Sex ratio was calculated for each litter value on Day 1 and 4 post partum, using the following formula:
(Number of male offspring ÷ Total number of offspring) x 100
Historical control data:
Normal range data for the different parameters examined were used in comparison against the test data.

Results and discussion

Results: maternal animals

Maternal developmental toxicity

Details on maternal toxic effects:
Maternal toxic effects:no effects

Details on maternal toxic effects:
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.

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.

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

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

REPRODUCTIVE PERFORMANCE:
Mating:
There were no treatment-related effects on mating performance.

Fertility:
There were no treatment-related effects on fertility.
One female treated with 100 mg/kg bw/day A.I. was non-pregnant. No histopathological correlates were evident in the male or female reproductive organs to suggest the cause of this missing pregnancy.

Gestation Length:
There were no differences in gestation lengths. The distribution for treated females was comparable to controls. The gestation lengths were between 22 and 23½ days.

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:
Adults:
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 findings were detected.

Effect levels (maternal animals)

open allclose all
Dose descriptor:
NOEL
Effect level:
1 000 mg/kg bw/day
Based on:
act. ingr.
Basis for effect level:
other: other:
Dose descriptor:
NOEL
Remarks:
(systemic toxicity)
Effect level:
1 000 mg/kg bw/day
Based on:
act. ingr.
Basis for effect level:
other: maternal toxicity

Results (fetuses)

Details on embryotoxic / teratogenic effects:
Embryotoxic / teratogenic effects:not examined

Fetal abnormalities

Abnormalities:
not specified

Overall developmental toxicity

Developmental effects observed:
not specified

Any other information on results incl. tables

Litter Responses:

In total nine females from control and 100 mg/kg bw/day A.I. dose groups and ten females from 350 and 1000 mg/kg bw/day A.I. dose groups gave birth to a live litter and successfully reared young to Day 5 age. The following assessment of litter response is based on all litters reared to termination on Day 5 of lactation/age.

Offspring Litter Size, Sex Ratio and Viability:

No significant differences were detected for corpora lutea, implantation counts, litter size or litter viability for treated animals when compared to controls. Statistical analysis of the data did not reveal any significant intergroup differences.

There were no intergroup differences in sex ratio (percentage male offspring) for litters from treated groups compared to controls. Statistical analysis of the data did not reveal any significant intergroup differences.

Pre and post implantation losses were increased in all treated groups when compared to control females. Statistical analysis of the data did not reveal any significant intergroup differences and a true dose related response was not evident. The number of corpora lutea, implantation sites and number of offspring born were also comparable to control females therefore the intergroup differences were considered not to be of toxicological importance.

Offspring Growth and Development:

There were no toxicologically significant effects detected.

Statistical analysis of the litter, offspring weights or surface righting reflex data did not reveal any significant intergroup differences.

No obvious clinical signs of toxicity were detected for offspring from treated females when compared to controls. The incidental clinical signs detected throughout the control and treated groups, consisting of small size, no milk in stomach, found dead or missing, were considered to be low incidence findings observed in offspring in studies of this type and were considered unrelated to test item toxicity.

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.

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., equivalent to 800 mg/kg bw/day active acid.

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.