Registration Dossier

Administrative data

Key value for chemical safety assessment

Effects on fertility

Description of key information

Effect of the test substance on reproductive function in Swiss D-1 Mice.

Link to relevant study records
Reference
Endpoint:
reproductive toxicity, other
Type of information:
experimental study
Adequacy of study:
key study
Study period:
Experimental phase: 30 December 1986 to 21 December 1987.
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
test procedure in accordance with generally accepted scientific standards and described in sufficient detail
Qualifier:
according to
Guideline:
other: Reproductive Assessment by Continuous Breeding
Version / remarks:
The test protocol was devised by United States National Toxicology Program
Principles of method if other than guideline:
The test protocol was devised by the United States National Toxicology Program (NTP) for use in reproductive toxicity testing.

The design is called "Reproductive Assessment by Continuous. Breeding" (RACB). Swiss CD-1 (ICR)BR outbred albino mice are used for the RACB protocol. It consists of four related tasks, not all of which are necessarily performed for a given compound. These tasks include Task 1, dose finding; Task 2, continuous breeding phase; Task 3, identification of the affected sex; and Task 4, offspring assessment. This test protocol is designed to provide both time and cost-effective alternatives to multigeneration studies which produce similar reproductive data.
GLP compliance:
yes
Limit test:
no
Specific details on test material used for the study:
Test substance samples were analysed for low level impurities by packed and capillary column gas chromatography. Chromatographic purity was determined to be greater than 99%. Bulk stability studies indicated that neat test substance is stable when stored under nitrogen at temperatures up to 60°C for 14 days. Dosage formulation studies indicated no stability problems with the preparation of corn oil solutions at the 80 mg/mL level. Stability studies conducted on corn oil solutions of the test substance (10 mg/mL level) indicated no significant loss of chemical after three weeks storage in sealed glass bottles in the dark at room temperature, when the formulation was overlaid with nitrogen or argon.
Species:
mouse
Strain:
CD-1
Sex:
male/female
Details on test animals and environmental conditions:
TEST ANIMALS
- Source: Charles River Breeding Laboratories, Inc. (Kingston, NY)
- Females (if applicable) nulliparous and non-pregnant: Not stated
- Age at study initiation: 11 weeks (task 2 reproductive assessment)
- Weight at study initiation: Not stated
- Fasting period before study: Not stated
- Housing: The mice were housed 2 per cage by sex during quarantine and the 1-week pre-mating period in solid bottom polycarbonate cages with stainless steel wire lids. The animals were subsequently housed as breeding pairs or individually.
- Diet (e.g. ad libitum): pelleted rodent chow (NIH-07 diet) were provided ad libitum
- Water (e.g. ad libitum): ad libitum
- Acclimation period: 14 days quarantine period

ENVIRONMENTAL CONDITIONS
- Temperature (°C): 23 ± 2°C
- Humidity (%): Not stated
- Air changes (per hr): Not stated
- Photoperiod (hrs dark / hrs light): 14 hours light / 10 hours dark
Route of administration:
oral: gavage
Vehicle:
corn oil
Analytical verification of doses or concentrations:
yes
Details on analytical verification of doses or concentrations:
An aliquot each from all dosing stocks was analysed for test substance content using gas chromatography. The dosing formulations for the high dose were consistently within 90% of theoretical concentration. On one occasion the mid-dose concentration was 79% of theoretical value, while the remaining values were greater than 90%. The low dose concentrations (5 mg/mL, equivalent to 50 mg/kg) averaged 90% of nominal (range 83-98%).
Frequency of treatment:
Once daily
Dose / conc.:
50 mg/kg bw/day (nominal)
Remarks:
Task 2
Dose / conc.:
100 mg/kg bw/day (nominal)
Remarks:
Task 2
Dose / conc.:
200 mg/kg bw/day (nominal)
Remarks:
Task 2
No. of animals per sex per dose:
20 breeding pairs pairs per treatment group
40 breeding pairs for control group.
Control animals:
yes, concurrent vehicle
Parental animals: Observations and examinations:
DETAILED CLINICAL OBSERVATIONS: Yes
- Time schedule: daily

BODY WEIGHT: Yes
- Time schedule for examinations: Weeks 1, 2, 3, 6, 10 and 14. (week 1 represents the precohabitation phase; week 2 represents the first week of the contiuous breeding phase)


WATER CONSUMPTION: Yes
- Time schedule for examinations: Weeks 1, 2, 3, 6, 10 and 14. (week 1 represents the precohabitation phase; week 2 represents the first week of the contiuous breeding phase)

Litter observations:
PARAMETERS EXAMINED
The following parameters were examined in [F1] offspring: fertility (number producing a litter/number of breeding pairs), litters per pair, live pups per litter, proportion of pups born alive, sex of live pups and the pup body weights immediately after birth.

GROSS EXAMINATION OF DEAD PUPS: Yes for external and internal abnormalities; possible cause of death.

Statistics:
The Cochran-Armitage test was used to test for a dose-related trend in fertility (Task 2).

The number of litters and the number of live pups per litter was computed on a per fertile pair basis and then treatment group means determined. The proportion of live pups is defined as the number of pups born alive divided by the total number of pups produced by each pair. The sex ratio is expressed as the proportion of male pups born alive out of the total number of live pups born to each fertile pair. Dose group means for these parameters were tested for overall differences using the Kruskal-Wallis test and for ordered differences using Jonckheere's test. Pairwise comparisons of treatment group means were performed by applying the WilcoxMann- Whitney U test.

To remove the potential effect of the number of pups per litter on the average pup weight, an analysis of covariance was performed. The covariate used is average litter size including live and dead pups. Least squares estimates of dose group means, adjusted for litter size, were computed and tested for overall equality using an F-test and pairwise equality using a t-test. To control for possible sex differences, these analyses were performed on males, females, and both sexes combined. An analysis of covariance is also used to adjust organ weights for total body weight. Unadjusted body and organ weights were analysed using the Kruskal-Wallis and Wilcox-Mann-Whitney U tests. Dose-related trends are tested for by Jonckheere's test.
Clinical signs:
no effects observed
Mortality:
mortality observed, non-treatment-related
Description (incidence):
Six mice died or were sacrificed during this task. For two mice the cause of death could not be determined. The deaths of the other four mice were not considered related to treatment.
Body weight and weight changes:
effects observed, treatment-related
Description (incidence and severity):
Body weights at delivery of dams receiving 200 mg/kg of test substance were consistently less than control values; these reduced body weights were statistically significant after delivering the first, second, fourth and fifth litters. During the Task 2 holding period, body weights of lactating dams did not differ among control and treatment groups.
Food consumption and compound intake (if feeding study):
not examined
Food efficiency:
not examined
Water consumption and compound intake (if drinking water study):
effects observed, treatment-related
Description (incidence and severity):
The average daily consumption of drinking water was significantly increased in males and females treated with 50 mg/kg test substance during weeks 2 and 10. In the 100 mg/kg dose group, male and female consumption was significantly increased during week 10. Consumption was also significantly increased in the 200 mg/kg dose group for males and females during weeks 2, 10, and 14.
Ophthalmological findings:
not examined
Haematological findings:
not examined
Clinical biochemistry findings:
not examined
Urinalysis findings:
not examined
Behaviour (functional findings):
not examined
Immunological findings:
not examined
Organ weight findings including organ / body weight ratios:
no effects observed
Histopathological findings: non-neoplastic:
no effects observed
Histopathological findings: neoplastic:
not specified
Reproductive function: oestrous cycle:
not examined
Reproductive function: sperm measures:
not examined
Reproductive performance:
no effects observed
Fertility index was 100% for control and all test substance groups. The control and test substance groups did not significantly differ in number of litters per pair, litter size, proportion of live pups and proportion of male pups, female pup weight or combined pup weight at birth. Male absolute pup weights in the 200 mg/kg test group were significantly less than control values but this difference was not significant after pup weights were adjusted for litter size. The cumulative days to litter were essentially identical across groups.
Key result
Dose descriptor:
LOEL
Effect level:
200 mg/kg bw/day (nominal)
Based on:
test mat.
Sex:
male/female
Basis for effect level:
other: Body weights at delivery of dams receiving 200 mg/k bw/day of test substance
Key result
Dose descriptor:
NOEL
Effect level:
100 mg/kg bw/day (nominal)
Based on:
test mat.
Sex:
male/female
Basis for effect level:
other: No effects observed.
Key result
Critical effects observed:
no
Lowest effective dose / conc.:
200 mg/kg bw/day (nominal)
System:
other: Body weights at delivery of dams receiving 200 mg/kg test substance were consistently less than control values.
Clinical signs:
no effects observed
Dermal irritation (if dermal study):
not examined
Mortality / viability:
mortality observed, non-treatment-related
Description (incidence and severity):
Eleven F1 mice died during this task. The cause of death for four mice was not determined. The remaining deaths were not considered treatment related.
Body weight and weight changes:
effects observed, treatment-related
Description (incidence and severity):
Decreased male terminal body weights were observed at 200 mg/kg bw/day which were considered to be a symptom of general toxicity.
Food consumption and compound intake (if feeding study):
not examined
Food efficiency:
not examined
Water consumption and compound intake (if drinking water study):
no effects observed
Ophthalmological findings:
not examined
Haematological findings:
not examined
Clinical biochemistry findings:
not examined
Urinalysis findings:
not examined
Sexual maturation:
no effects observed
Organ weight findings including organ / body weight ratios:
effects observed, treatment-related
Description (incidence and severity):
At 200 mg/kg bw/day an increase in adjusted liver weights in both sexes with accompanying hepatocellular cell degeneration, along with a decrease in adjusted kidney weights in both sexes.
Gross pathological findings:
effects observed, treatment-related
Description (incidence and severity):
The livers of 5/20 test susbtance treated mice exhibited a slight reticular pattern.
Histopathological findings:
effects observed, treatment-related
Description (incidence and severity):
Dose-related histopathologic changes consistong of degeneration of hepatocytes and were observed in the liver of 19/20 test substance treated F1 males (200 mg/kg bw/day). The degeneration was limited to centrolobular regions of the hepatic lobules. The hepatocytes were pale, swollen and the cytoplasm had micro-vacuolisation and granularity. Slight to mild nuclear pleomorphism was present. Occasional individual liver cell necrosis was also present. Two males in the control group and two in the dosed group exhibited minimal to mild hepatitis. Minimal to mild fatty change was observed in the livers of four bromoformtreated male mice. This hepatocellular cell degeneration was observed in 200 mg/k bw/day treated F1 mice was considered to be related to general toxictiy.


Epididymal ductal epithelium degeneration was noted in both control and 200 mg/kg bw/day test substance treated F1 males, and was not considered treatment-related.
Other effects:
effects observed, treatment-related
Description (incidence and severity):
The postnatal survival among F1 pups in the 200 mg/kg bw/day test substance group was significantly lower compared to the control group. This decline was primarily attributed to three dams, which lost all their pups by postnatal day 4. One dam in the control group also lost her litter by postnatal day 4. Although these incidences are too low to evaluate statistically, they are consistent with a treatment effect on early maternal behaviour, early lactational failure, or postnatal developmental processes. A proper evaluation of such a connection would require additional studies and could not be assessed further.
Behaviour (functional findings):
not examined
Developmental immunotoxicity:
not examined
Some symptoms of general toxicity were noted in treated F1 mice. These included decreased male terminal body weights, increased adjusted liver weights in both sexes with accompanying hepatocellular cell degeneration, and decreased adjusted kidney weights in both sexes. The teast substance had no effect on epididymal sperm density, motility or morphology in the F1 generation.
Key result
Dose descriptor:
NOAEL
Generation:
F1
Effect level:
200 mg/kg bw/day (nominal)
Based on:
test mat.
Sex:
male/female
Basis for effect level:
viability
body weight and weight gain
organ weights and organ / body weight ratios
Key result
Dose descriptor:
NOEL
Generation:
F1
Effect level:
100 mg/kg bw/day (nominal)
Based on:
test mat.
Sex:
male/female
Basis for effect level:
other: No effects observed.
Key result
Critical effects observed:
no
Lowest effective dose / conc.:
200 mg/kg bw/day (nominal)
System:
hepatobiliary
Organ:
liver
Key result
Critical effects observed:
no
Lowest effective dose / conc.:
200 mg/kg bw/day (nominal)
System:
male reproductive system
Organ:
testes
Key result
Reproductive effects observed:
yes
Lowest effective dose / conc.:
200 mg/kg bw/day (nominal)
Treatment related:
yes
Relation to other toxic effects:
reproductive effects as a secondary non-specific consequence of other toxic effects
Conclusions:
Treatment with the test substance at up to 200 mg/kg bw/day had no effect reproduction or fertility in either the parental or F1 generation.  Treatment with test substance at 200 mg/kg treatment caused minimal to moderate histopathologic changes in the liver of second generation CD-1 mice.

The No Observed Effect Level (NOEL) for the study is considered to be 100 mg/kg bw/day.
 
Executive summary:

Introduction

The effect of the test substance on reproduction and fertility in Swiss CD-1 mice was assessed using a United States National Toxicology Program Reproductive Assessment by Continuous Breeding Protocol (RACB).

Method

Male and female Swiss CD-1 mice were used for the study.

The RACB protocol is divided into four tasks. Task 1 is 14-day toxicity range-finder, Task 2 is a continuous breading phase, Task 3 is a 1-week mating trial and task 4 is an assessment of offspring. As the test substance had no effect on fertility Task 3 was not conducted as part of this study.

Following dose range-finder study (Task 1) the dose levels selected for Task 2 were 50, 100 and 200 mg/kg bw/day. For task 2 there were 20 male and female breeding pairs per treatment group and 40 male and female breeding pairs for control animals). Animals were dosed daily by gavage using corn oil as the vehicle for a 7-day pre-cohabitation and a 98-day cohabitation period. The last litter born during the holding period following the continuous breeding phase is reared by the dam until weaning, after which treatment is initiated by the same route and at the same concentration as during Task 2. These animals are used for assessment of second generation fertility (Task 4).

Endpoints assessed were clinical signs, parental body weight and average consumption of drinking water during representative weeks, fertility (number producing a litter/number of breeding pairs), litters per pair, live pups per litter, proportion of pups born alive, sex of live pups and the pup body weights immediately after birth. For Task 4 the last and generally the fifth litter was reared and weaned from the control and 200 mg/kg and kept to sexual maturity (74 ± 10 days) while housed by sex two per cage (maximum) and receiving the same treatment as their parents. At sexual maturity a male and female from different litters within the same treatment group are cohabited for 7 days and then housed singly until delivery. The endpoints assessed for this mating trial are the same as Task 2 with the addition of checking for the presence of a copulatory plug.

Results

Task 2: 

 

Six mice died or were sacrificed during this task. For two mice the cause of death could not be determined. The deaths of the other four mice were not considered related to treatment.

 

Fertility index was 100% for control and test substance groups (breeding pair was designated fertile if they produced at least one live or dead pup. The control and bromoform groups did not significantly differ in number of litters per pair, litter size, proportion of live pups and proportion of male pups, female pup weight or combined pup weight at birth. Male absolute pup weights in the 200 mg/kg test substance group were significantly less than control values but this difference was not significant after pup weights were adjusted for litter size. The cumulative days to litter were essentially identical across groups.

 

Body weights at delivery of dams receiving 200 mg/kg of test substance were consistently less than control values; these reduced body weights were statistically significant after delivering the first, second, fourth and fifth litters. During the Task 2 holding period, body weights of lactating dams did not differ among control and treatment groups.

 

Male and female adults were weighed on representative weeks during Task 2 and simultaneously, the water consumption per cage, or per pair, was monitored. Test substance treatment had no significant effect on body weight of males or females. The average daily consumption of drinking water was significantly increased in males and females treated with 50 mg/kg of test substance during weeks 2 and 10. In the 100 mg/kg dose group, male and female consumption was significantly increased during week 10. Consumption was also significantly increased in the 200 mg/kg dose group for males and females during weeks 2, 10, and 14.

Task 4:

Eleven F1 mice died during this task. The cause of death for four mice was not determined. The remaining deaths were not considered treatment related. 

The postnatal survival among F1 pups in the 200 mg/kg bw/day test substance group was significantly lower compared to the control group. This decline was primarily attributed to three dams, which lost all their pups by postnatal day 4. One dam in the control group also lost her litter by postnatal day 4. Although these incidences are too low to evaluate statistically, they are consistent with a treatment effect on early maternal behaviour, early lactational failure, or postnatal developmental processes.

Test substance treatment had no apparent effect on fertility and reproduction in F1 mice. Some symptoms of general toxicity were noted in treated F1 mice. This included decreased male terminal body weights, increased adjusted liver weights in both sexes with accompanying hepatocellular cell degeneration and decreased adjusted kidney weights in both sexes. Epididymal ductal epithelium degeneration was noted in both control and bromoform-treated F1 males, and was not considered treatment-related.

 

Conclusion

Treatment with the test substance at up to 200 mg/kg bw/day had no effect reproduction or fertility in either the parental or F1generation.  Treatment with test substance at 200 mg/kg treatment caused minimal to moderate histopathologic changes in the liver of second generation CD-1 mice.

The No Observed Effect Level (NOEL) for the study is considered to be 100 mg/kg bw/day.

 

 

Effect on fertility: via oral route
Endpoint conclusion:
no adverse effect observed
Dose descriptor:
NOAEL
200 mg/kg bw/day
Study duration:
subchronic
Species:
mouse
Effect on fertility: via inhalation route
Endpoint conclusion:
no study available
Effect on fertility: via dermal route
Endpoint conclusion:
no study available

Effects on developmental toxicity

Description of key information

Teratogenic effect of the test susbtance in Sprague-Dawley Rats.

Link to relevant study records
Reference
Endpoint:
developmental toxicity
Type of information:
experimental study
Adequacy of study:
key study
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
study well documented, meets generally accepted scientific principles, acceptable for assessment
Qualifier:
no guideline followed
Principles of method if other than guideline:
No guideline was provided in the study and the age of the study (1983) predates the OECD 414 guideline. The study does; however, cover many of the endpoints included in the OECD 414 guideline, although exposure covered days 6 to 15 of gestation rather than 5 to 15 specified in the OECD 414 guideline.
GLP compliance:
no
Limit test:
no
Species:
rat
Strain:
Sprague-Dawley
Details on test animals and environmental conditions:
TEST ANIMALS
- Source: Biobreeding Ltd., Montreal, Quebec.
- Age at study initiation: Not stated.
- Weight at study initiation: 150-175 g
- Fasting period before study: Not stated.
- Housing: Each female rat was caged individually following pairing with a sire.
- Diet (e.g. ad libitum): ad libitum
- Water (e.g. ad libitum): ad libitum
- Acclimation period: 1 week

ENVIRONMENTAL CONDITIONS
- Temperature (°C): 21 ± 2°C
- Humidity (%): 40-60%
- Air changes (per hr):
- Photoperiod (hrs dark / hrs light): 12 hours light /12 hours dark

Route of administration:
oral: gavage
Vehicle:
corn oil
Details on exposure:
Pregnant rats were administered the test substance daily by oral intubation beginning on the 6th day of gestation and continuing until the 15th day of gestation.
Analytical verification of doses or concentrations:
no
Details on mating procedure:
Female rats were then paired overnight with a proven sire and the day on which sperm were seen in a vaginal smear was considered day 1 of gestation. The pregnant rats were then randomly divided into 4 groups (including the control) with each group having 15 rats.
Duration of treatment / exposure:
Rats were adminstered test substance from day 6 to day 15 day of gestation.
Frequency of treatment:
Daily
Dose / conc.:
0 mg/kg bw/day (nominal)
Remarks:
Vehicle Control
Dose / conc.:
50 mg/kg bw/day (nominal)
Dose / conc.:
100 mg/kg bw/day (nominal)
Dose / conc.:
200 mg/kg bw/day (nominal)
No. of animals per sex per dose:
15 rats per dose group.
Control animals:
yes, concurrent vehicle
Maternal examinations:

BODY WEIGHT: Yes
- Time schedule for examinations: The females were weighed on day 1 and days 6-15 of gestation as well as before and after caesarean section on day 22.


POST-MORTEM EXAMINATIONS: Yes
- Sacrifice on gestation day 22
- Organs examined: Maternal rats were subject to gross pathological assessment and the liver, hear, brain spleen and one kidney were removed and weighed. The following tissue samples were taken from each animal and fixed: brain, heart, pituitary, thyroid, parathyroid, thymus, lungs, trachea and bronchi, bronchial node, liver, kidney, adrenal gland, spleen, skeleton muscle, peripheral nerve, salivary gland, skin, bone marrow, ovaries, uterus and bladder.

- OTHER EXAMINATIONS: Materal blood samples were taken fro haematology, blood chemistry. A liver sampels was taken following gross pathology for analysis of liver enzyme activiity.


Fetal examinations:
At sacrifce on gestation day 22 foetuses were removed, weighed individually and examined for viability and external malformations.

Two pups from each dam were fixed in formalin for histological evaluation. Approximately two-thirds of the remaining live foetuses from each litter were placed in absolute ethanol for future staining of the skeleton with Alizarin red and subsequent examination for skeleton abnormalities. The rest of the foetuses were fixed in Bouin's fluid and studied for visceral changes.

Statistics:
An analysis of variance was carried out on all measurements where applicable, and when a significant difference occurred (P<0.05), Duncan's Multiple Range Test (SPSS version 8.1) was applied to determine the group or groups that were different from the control.
Clinical signs:
not specified
Dermal irritation (if dermal study):
not examined
Mortality:
no mortality observed
Body weight and weight changes:
no effects observed
Food consumption and compound intake (if feeding study):
not specified
Food efficiency:
not specified
Water consumption and compound intake (if drinking water study):
not specified
Ophthalmological findings:
not examined
Haematological findings:
no effects observed
Clinical biochemistry findings:
no effects observed
Urinalysis findings:
not examined
Behaviour (functional findings):
not examined
Immunological findings:
not examined
Organ weight findings including organ / body weight ratios:
no effects observed
Gross pathological findings:
no effects observed
Neuropathological findings:
not examined
Histopathological findings: non-neoplastic:
no effects observed
Histopathological findings: neoplastic:
not examined
Other effects:
no effects observed
Description (incidence and severity):
No efffects on measured liver enzyme activity was reported (i.e. it was not positively stated that there had been no changes and it is assumed that no effects occurred).
Number of abortions:
no effects observed
Pre- and post-implantation loss:
no effects observed
Total litter losses by resorption:
no effects observed
Early or late resorptions:
no effects observed
Dead fetuses:
effects observed, treatment-related
Description (incidence and severity):
There was some of evidence of dose related increase in sternebra aberrations and observations of interparietal anomalies in foetuses. These were considered to be caused by a foetal toxicity effect.
Changes in pregnancy duration:
not specified
Changes in number of pregnant:
no effects observed
Key result
Dose descriptor:
NOEL
Effect level:
200 mg/kg bw/day (nominal)
Based on:
test mat.
Basis for effect level:
other: No effects observed in maternal animals.
Key result
Abnormalities:
no effects observed
Fetal body weight changes:
no effects observed
Reduction in number of live offspring:
effects observed, treatment-related
Changes in sex ratio:
not specified
Changes in litter size and weights:
no effects observed
Changes in postnatal survival:
not examined
External malformations:
effects observed, treatment-related
Skeletal malformations:
effects observed, treatment-related
Description (incidence and severity):
There was some of evidence of dose related increase in sternebra aberrations and observations of interparietal anomalies in foetuses. These were considered to be caused by foetal toxic and not indicative of teratogenicity.
Visceral malformations:
no effects observed
Other effects:
effects observed, treatment-related
Description (incidence and severity):
Mild hilar dilation was observed in the kidneys of some treated foetuses but this was considered to spontaneous in nature.
Key result
Dose descriptor:
NOAEL
Effect level:
100 mg/kg bw/day (nominal)
Based on:
test mat.
Sex:
not specified
Basis for effect level:
other: Evidence of foetal toxicity.
Key result
Abnormalities:
no effects observed
Key result
Developmental effects observed:
no
Conclusions:
The test substance was not considered teratogenic to Sprague-Dawley rats. The study No Observed Effect Level (NOEL) for teratogenicity was 200 mg/kg bw/day (highest dose administered). There was some evidence of a foetal toxicity caused by the test substance. The study No Observed Adverse Effect Level (NOAEL) for foetal toxicity was considered to be 100 mg/kg bw/day. 
Executive summary:

Introduction

The teratogenic potential of the test substance toSprague-Dawley ratswas assessed using a study design that pre-dated the OCED 414 guideline, but which nevertheless covered many of the endpoints included in the guideline. 

 

Method

 Test substance was administered in corn oil by gavage to pregnant Sprague-Dawley rats from day 6 to day 15 of gestation at doses of 50, 100 or 200 mg/kg/day. A control group was administered corn oil only. Each group consisted of 15 rats and each rat was housed individually with free access to food and water.

On day 22 of gestation rates sacrificed and their viscera including the uteri were examined for pathological changes. The foetuses were removed, weighed individually and examined for viability and external malformations. Two pups from each dam were fixed in formalin for histological evaluation. Approximately two-thirds of the remaining live foetuses from each litter were placed in absolute ethanol for future staining of the skeleton with Alizarin red and subsequent examination for skeleton abnormalities. The rest of the foetuses were fixed in Bouin's fluid and studied for visceral changes.

Maternal rats were subject to gross pathological assessment and the liver, hear, brain spleen and one kidney were removed and weighed. The following tissue samples were taken from each animal and fixed: brain, heart, pituitary, thyroid, parathyroid, thymus, lungs, trachea and bronchi, bronchial node, liver, kidney, adrenal gland, spleen, skeleton muscle, peripheral nerve, salivary gland, skin, bone marrow, ovaries, uterus and bladder.

 

Maternal blood samples were taken for haematological and clinical chemistry assessments.

Following gross pathological examination a liver sample was taken from maternal animals for liver protein aniline hydroxylase (AH) and aminopyrine demethylase (APDM) activity.

Results

Body and Organ Weights: There were no effects on maternal weight, liver, kidney or spleen weights resulting from treatment with test substance.

Foetal effects: There were no effects or litter size, incidence of resorptions, foetal weight or incidence of visceral anomalies resulting from treatment with test substance.

Histopathology: There were no dose related histological, changes in mother or foetuses resulting from treatment with test substance. 

Haematology: Maternal haematological parameters assessed showed no affects from treatment with test substance.

Clinical Chemistry: Maternal clinical chemistry parameters assessed showed no affects from treatment with test substance.

Liver Enzymes: Maternal liver enzyme parameters assessed showed no affects from treatment with test substance.

Foetal toxicity: There was some of evidence of dose related increase in sternebra aberrations and observations of interparietal anomalies in foetuses at 100 and 200 mg/kg bw/day. These were considered to be the result of a foetal toxicity effect and not teratogenicity related.

 

Conclusion

The test substance was not considered teratogenic to Sprague-Dawley rats. The study No Observed Effect Level (NOEL) for teratogenicity was 200 mg/kg bw/day (highest dose administered).  

There was some evidence of a foetal toxicity caused by the test substance. The study No Observed Adverse Effect Level (NOAEL) for foetal toxicity was considered to be 100 mg/kg bw/day. 

Effect on developmental toxicity: via oral route
Endpoint conclusion:
no adverse effect observed
Dose descriptor:
NOAEL
100 mg/kg bw/day
Study duration:
subacute
Species:
rat
Effect on developmental toxicity: via inhalation route
Endpoint conclusion:
no study available
Effect on developmental toxicity: via dermal route
Endpoint conclusion:
no study available
Additional information

There was some of evidence of dose related increase in sternebra aberrations and observations of interparietal anomalies in foetuses at 100 and 200 mg/kg bw/day. These were considered to be the result of a foetal toxicity and not teratogenicity related.

Justification for classification or non-classification