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Toxicological information

Toxicity to reproduction

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Administrative data

Endpoint:
screening for reproductive / developmental toxicity
Type of information:
experimental study
Adequacy of study:
key study
Study period:
28 October 2013 to 22 May 2014
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
guideline study

Data source

Reference
Reference Type:
study report
Title:
Unnamed
Year:
2014
Report date:
2014

Materials and methods

Test guideline
Qualifier:
according to guideline
Guideline:
OECD Guideline 421 (Reproduction / Developmental Toxicity Screening Test)
Deviations:
yes
Remarks:
The right kidney of one female was identified to have an increased pelvic space, but tissue was not retained for histopathological examination.
GLP compliance:
yes
Limit test:
no

Test material

Constituent 1
Reference substance name:
5,5-Dimethylimidazolidine-2,4-dione, reaction products with oxirane
EC Number:
701-388-0
Cas Number:
26850-24-8
IUPAC Name:
5,5-Dimethylimidazolidine-2,4-dione, reaction products with oxirane
Test material form:
other: pale yellow solid block
Details on test material:
- Name of test material (as cited in study report): Dantocol DHE
- Physical state: pale yellow solid block
- Lot/batch No.: M5469330
- Storage condition of test material: room temperature in the dark
Specific details on test material used for the study:
Identification : Dantocol (CAS # 26850-24-8)
Description : Yellow very viscous liquid
Chemical Name : Di-(2-Hydroxyethyl)-5, 5-Dimethylhydantoin
Purity : 99%
Batch Number : M9416741
Label : DANTOCOL (R) DHE Lot No M9416741
Date Received : 05 August 2013
Storage Conditions : Room temperature in the dark
Expiry Date : 22 February 2014
No correction for purity was made.

Test animals

Species:
rat
Strain:
Wistar
Details on species / strain selection:
Wistar Han™:RccHan™:WIST
Sex:
male/female
Details on test animals or test system and environmental conditions:
The animals were allowed free access to food and water.

The animals were housed in a single air-conditioned room within the laboratories. The rate of air exchange was at least fifteen air changes per hour and the low intensity fluorescent lighting was controlled to give twelve hours continuous light and twelve hours darkness. Environmental conditions were continuously monitored by a computerized system, and print-outs of hourly temperatures and humidities are included in the study records. The Study Plan target ranges for temperature and relative humidity were 22 ± 3 °C and 30 ± 70% respectively; Short term fluctuations from these targets were considered not to have affected the purpose or integrity of the study.

Administration / exposure

Route of administration:
oral: gavage
Vehicle:
water
Details on exposure:
The test item was administered by gavage to three groups, each of twelve male and twelve female Wistar Han™: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 30, 300 and 1000 mg/kg bw/day. A control group of twelve males and twelve females was dosed with vehicle alone (Distilled water).
Analytical verification of doses or concentrations:
yes
Details on analytical verification of doses or concentrations:
Samples of the test item formulation were taken and analyzed for concentration of Dantocol (CAS # 26850-24-8) at Harlan Laboratories Ltd., Shardlow, UK, Analytical Services.
Duration of treatment / exposure:
Eight weeks (including a two week pre-pairing phase, pairing, gestation and early lactation for females). 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. Adult males were terminated on Day 43, and females with litters were sent to necropsy on Day 5 post partum. Female 93 given 1000 mg/kg bw/day which did not achieve pregnancy was terminated on Day 25 post coitum. All animals were subjected to a gross necropsy examination and histopathological evaluation of reproductive tissues was performed.
Frequency of treatment:
Daily
Doses / concentrationsopen allclose all
Dose / conc.:
0 mg/kg bw/day (nominal)
Dose / conc.:
30 mg/kg bw/day (nominal)
Dose / conc.:
300 mg/kg bw/day (nominal)
Dose / conc.:
1 000 mg/kg bw/day (nominal)
No. of animals per sex per dose:
Twelve/sex/dose
Control animals:
yes, concurrent vehicle
Positive control:
No

Examinations

Parental animals: Observations and examinations:
Clinical signs, body weight change, dietary intake and water consumption were monitored during the study. Mating, fertility and gestation length were monitored to evaluate the reproductive performance of the parental animals.
Litter observations:
For each litter the following was recorded:
i. Number of offspring born
ii. Number of offspring alive recorded daily and reported on Days 1 and 4 post partum
iii. Sex of offspring on Days 1 and 4 post partum
iv. Clinical condition of offspring from birth to Day 5 post partum
v. Individual offspring weights on Days 1 and 4 post partum (litter weights were calculated retrospectively from this data)
Postmortem examinations (parental animals):
For all females, the uterus was examined for signs of implantation and the number of uterine implantations in each horn was recorded. 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 and histopathology of the following were undertaken:
Coagulating gland
Prostate
Epididymides
Seminal vesicles
Ovaries
Testes
Mammary gland (females only)
Uterus/Cervix
Pituitary
Vagina
Postmortem examinations (offspring):
All offspring were subjected to a full external and internal examination, and any macroscopic abnormalities were recorded.
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. The homogeneity of variance from mean values was analyzed using Bartlett’s test. Intergroup variance were assessed using suitable ANOVA, or if required, ANCOVA with appropriate covarities. Any transformed data were analyzed to find the lowest treatment level that showed a significant effect using the Williams Test for parametric data or the Shirley Test for nonparametric data. If no dose response was found but the data shows non-homogeneity of means, the data were analyzed by a stepwise Dunnett’s (parametric) or Steel (non-parametric) test to determine significant difference from the control group. Where the data were unsuitable for these analyses, pair-wise tests was performed using the Student t-test (parametric) or the Mann-
Whitney U test (non-parametric).
Reproductive indices:
Mating performance, pregnancy and parturition
Offspring viability indices:
Implantation Losses (%), Live Birth and Viability Indices, Sex Ratio (% males)

Results and discussion

Results: P0 (first parental generation)

General toxicity (P0)

Clinical signs:
no effects observed
Description (incidence and severity):
There were no treatment-related clinical signs for any of the animals throughout the study.

Male 76 receiving 1000 mg/kg bw/day showed pilo-erection and hunched posture between Days 21 and 39 of the study. Given the isolated nature of these observations, they were considered not to be related to treatment with the test item.
Dermal irritation (if dermal study):
not examined
Mortality:
no mortality observed
Description (incidence):
There were no unscheduled deaths on the study.
Body weight and weight changes:
no effects observed
Description (incidence and severity):
There was no effect of treatment with the test item at any dose level on body weight development in males. For the treated females, group mean body weight gains during the pre-pairing, gestation and lactation phases remained similar to controls indicating no effect of treatment with the test item.
Food consumption and compound intake (if feeding study):
no effects observed
Description (incidence and severity):
There was no effect of treatment with the test item on dietary intake and food conversion efficiency in males when compared with controls. Treated females also did not show any effect of treatment on food intake and food conversion efficiency (only measured during the pre-pairing phase) as indicated by similar group mean values across all groups including controls.
Food efficiency:
not specified
Water consumption and compound intake (if drinking water study):
no effects observed
Description (incidence and severity):
Daily visual inspection of water bottles did not indicate any intergroup differences between water consumption in treated and control animals of both sexes.
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
Description (incidence and severity):
Qualitative examination of the stages of spermatogenesis in the testis did not reveal any treatment-related abnormalities in the integrity of the various cell types present within the different stages of the sperm cycle. No treatment-related microscopic abnormalities were observed in the evaluation of the ovarian follicles and corpora lutea of the ovaries.
Histopathological findings: neoplastic:
no effects observed
Other effects:
no effects observed

Reproductive function / performance (P0)

Reproductive function: oestrous cycle:
not examined
Reproductive function: sperm measures:
no effects observed
Reproductive performance:
no effects observed
Description (incidence and severity):
Mating performance remained unaffected by treatment with the test item at all dose levels. With the exception of one control pair, all animals mated within the first four days of pairing. There was no appreciable difference in pre-coital interval in treated animals with respect to controls. No treatment-related effects on fertility were seen in animals given the test item when compared with controls. Female 93 given 1000 mg/kg bw/day did not achieve pregnancy following evidence of mating. There was no effect of treatment on gestation length; all littering females showed gestation length between 22 to 23½ days.

In total twelve females from the control, 30, and 300 mg/kg bw/day dose groups and eleven females from 1000 mg/kg bw/day dose group gave birth to a live litter and successfully reared young to Day 5 of age. In the absence of any histopathological correlates in the reproductive organs of the one non-pregnant female (No.93) or in the male partner (No.81) to elucidate the cause of the non-pregnancy this intergroup difference was considered to be incidental and of no toxicological importance.

There were no differences for corpora lutea, implantation sites and pre- or post-implantation sites between treated and control animals. Litter size, viability and sex ratio were similar across all groups including controls.

Effect levels (P0)

Key result
Dose descriptor:
NOEL
Effect level:
> 1 000 mg/kg bw/day (nominal)
Based on:
test mat.
Sex:
male/female
Basis for effect level:
clinical signs
mortality
body weight and weight gain
gross pathology
reproductive performance

Target system / organ toxicity (P0)

Key result
Critical effects observed:
no

Results: F1 generation

General toxicity (F1)

Clinical signs:
no effects observed
Description (incidence and severity):
There were no clinical signs for the offspring at any dose level considered to be related to treatment with the test item.
Dermal irritation (if dermal study):
not examined
Mortality / viability:
no mortality observed
Description (incidence and severity):
Litter size, viability and sex ratio were similar across all groups including controls.
Body weight and weight changes:
no effects observed
Description (incidence and severity):
There was no effect of treatment with the test item on litter weights or offspring body weight development when compared with controls.
Food consumption and compound intake (if feeding study):
not examined
Food efficiency:
not examined
Water consumption and compound intake (if drinking water study):
not examined
Ophthalmological findings:
not examined
Haematological findings:
not examined
Clinical biochemistry findings:
not examined
Urinalysis findings:
not examined
Sexual maturation:
not examined
Anogenital distance (AGD):
not examined
Nipple retention in male pups:
not examined
Organ weight findings including organ / body weight ratios:
no effects observed
Gross pathological findings:
no effects observed
Description (incidence and severity):
There were no treatment-related macroscopic abnormalities for interim death or terminal kill offspring.
Histopathological findings:
no effects observed
Description (incidence and severity):
There were no treatment-related microscopic findings.
Other effects:
no effects observed
Description (incidence and severity):
Litter size, viability and sex ratio were similar across all groups including controls. The results of surface righting reflex were similar across all groups including controls.

Developmental neurotoxicity (F1)

Behaviour (functional findings):
not examined

Developmental immunotoxicity (F1)

Developmental immunotoxicity:
not examined

Effect levels (F1)

Key result
Dose descriptor:
NOEL
Generation:
F1
Effect level:
> 1 000 mg/kg bw/day (nominal)
Based on:
test mat.
Sex:
male/female
Basis for effect level:
viability
clinical signs
mortality
body weight and weight gain
gross pathology
histopathology: non-neoplastic
histopathology: neoplastic

Target system / organ toxicity (F1)

Key result
Critical effects observed:
no

Overall reproductive toxicity

Key result
Reproductive effects observed:
no
Lowest effective dose / conc.:
1 000 mg/kg bw/day (nominal)
Treatment related:
no

Applicant's summary and conclusion

Conclusions:
The oral (gavage) administration of the test substance to male and female rats at dose levels of 30, 300 and 1000 mg/kg bw/day did not elicit any treatment related systemic or reproductive effects. A ‘No Observed Effect Level’ (NOEL) for systemic and reproductive toxicity was considered to be greater than 1000 mg/kg bw/day (highest dose tested).
Executive summary:

In a reproductive and developmental toxicity study the substance was administered to rats (12/sex/dose) by oral gavage at dose levels of 0, 30, 300 or 1000 mg/kg bw/day. No effects were reported in the reproductive or developmental parameters monitored during the study and the NOEL is greater than 1000 mg/kg bw/day, this being the highest dose tested.