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Toxicological information

Developmental toxicity / teratogenicity

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Administrative data

Endpoint:
developmental toxicity
Type of information:
experimental study
Adequacy of study:
key study
Study period:
Not specifically documented but indicated to be second half of 1980
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
other: Study well documented, meets generally accepted scientific principles, acceptable for assessment
Cross-referenceopen allclose all
Reason / purpose:
reference to same study
Reason / purpose:
reference to other study

Data source

Reference
Reference Type:
study report
Title:
Unnamed
Year:
1980
Report Date:
1980

Materials and methods

Test guideline
Qualifier:
no guideline followed
Principles of method if other than guideline:
Method: other
Pregnant rats were exposed for 6 hours /day over the period of organogenesis to test atmospheres containing 0, 50, 150 or 300 ppm. Whole body exposure.
GLP compliance:
no
Limit test:
yes

Test material

Reference
Name:
Unnamed
Type:
Constituent
Details on test material:
- Name of test material (as cited in study report): Glycidol
- Molecular weight (if other than submission substance): 74.08
- Physical state: odourless, colourless liquid

Test animals

Species:
rat
Strain:
other: Cpb:WU; Wistar random
Details on test animals and environmental conditions:
TEST ANIMALS
- Source: Central Institute for the Breeding of Laboratory Animals TNO, Zeist, The Netherlands.
- Age at study initiation: Approximately 13 weeks old.
- Weight at study initiation: Group mean weight range on day 0 was 179 - 185.3 g
- Fasting period before study: During the exposure periods, the test animals had no access to food or water.
- Housing: Individually housed in stainless steel cages, fitted with wire mesh floors and fronts for the acclimatisation period. Following acclimatization, two females were caged with one male.
- Diet (e.g. ad libitum): stock diet for rats ad libitum, when animals were not exposed to the test substance.
- Water (e.g. ad libitum): Unfluoridated drinking water when test animals not exposed to the test susbtance.
- Acclimation period: One week

ENVIRONMENTAL CONDITIONS
- Temperature (°C): 23 ± 1°C
- Humidity (%): 40 - 70%
- Air changes (per hr): Not documented
- Photoperiod (hrs dark / hrs light): 12 hour light/dark cycle.

IN-LIFE DATES: From: To: Not documented

Administration / exposure

Route of administration:
inhalation
Type of inhalation exposure (if applicable):
whole body
Vehicle:
unchanged (no vehicle)
Details on exposure:
GENERATION OF TEST ATMOSPHERE / CHAMBER DESCRIPTION
- Exposure apparatus: The exposure chambers consisted of 2 pyrex tube sections (internal diameter 15cm), pieced together in a horizontal position. The total length of the chamber was 90cm and it was fitted with gas sampling ports at the inlet and outlet. To prevent crowding of the animals and to minimise filtration of the insoired air by the animals' fur, the exposure chamber was fitted with an interior of perforated stainless steel plate allowing five animals to be kept separated.
- Method of holding animals in test chamber: Not documented
- Source and rate of air: Not documented
- Method of conditioning air: Not documented
- System of generating particulates/aerosols: Glycidol was evaporated by passing a filtered compressor generated airflow through a glass-evaporator containing the test substance. The glycidol airflow was mixed with filtered air from the compressed airline to provide the glycidol concentration desired.
- Temperature, humidity, pressure in air chamber: 22°C for the 50 and 150ppm test atmospheres and 25°C for the 300ppm test atmospheres.
- Air flow rate: 10L/min
- Air change rate: Not documented
- Method of particle size determination: Not documented
- Treatment of exhaust air: Not documented

TEST ATMOSPHERE
- Brief description of analytical method used: Gas chromatography. Samples were taken at regular intervals with a gas-tight syringe and injected into the gas chromatograph. The peak areas obtained were compared with peak areas obtained by injecting known amounts of a standard solution of glycidol in ether and from this, the glycidol concentration in the test atmospheres was calculated.
- Samples taken from breathing zone: Not documented

Analytical verification of doses or concentrations:
yes
Details on analytical verification of doses or concentrations:
The analysis of test atmospheres was carried out by gas-chromatography. Samples were taken at regular intervals with a gas-tight syringe and injected into the gas chromatograph. The peak areas obtained were compared with peak areas obtained by injecting known amounts of a standard solution of glycidol in ether and from this, the glycidol concentration in the test atmospheres was calculated.
Details on mating procedure:
- Impregnation procedure: cohoused
- If cohoused: 2 females were housed with one male.
- M/F ratio per cage: 2 females to one male.
- Length of cohabitation: Not documented

- Verification of same strain and source of both sexes: No information provided
- Proof of pregnancy: sperm in vaginal smear referred to as day 0 of pregnancy
Duration of treatment / exposure:
from day 6 - 16 of pregnancy
Frequency of treatment:
Six hours per day from day 6 to 16 of organogenesis
Duration of test:
21 days
Doses / concentrations
Remarks:
Doses / Concentrations:
0, 50, 150, 300 ppm
Basis:
no data
No. of animals per sex per dose:
50 adult male and 100 adult female rats were used in the study. 24 females mated per group.
The numbers of pregnant females allocated to each group were:
0 ppm - 21
53 ppm - 21
145 ppm - 19
253 ppm - 22

Control animals:
yes
Details on study design:
Sex: female
Duration of test: treatment from day 6 to 16 of gestation and on day 21 of pregnancy the females were killed.

Examinations

Maternal examinations:
CAGE SIDE OBSERVATIONS: No data

DETAILED CLINICAL OBSERVATIONS: Yes
- Time schedule: Daily

BODY WEIGHT: Yes
- Time schedule for examinations: Day 0 of pregnancy, day 6, 16 and day 21.

FOOD CONSUMPTION AND COMPOUND INTAKE (if feeding study): Yes - days 0 - 6, day 6 - 16 and day 16 - 21
- Food consumption for each animal determined and mean daily diet consumption calculated as g food/kg body weight/day: yes
- Compound intake calculated as time-weighted averages from the consumption and body weight gain data: No data

WATER CONSUMPTION AND COMPOUND INTAKE (if drinking water study): No data

POST-MORTEM EXAMINATIONS: Yes
- Sacrifice on gestation day 21
- Organs examined: Ovaries and uterus.
Ovaries and uterine content:
The ovaries and uterine content was examined after termination: Yes
Examinations included:
- Gravid uterus weight: Yes
- Number of corpora lutea: Yes
- Number of implantations: Yes - in both uterine horns
- Number of early resorptions: Yes - only the placenta was visible
- Number of late resorptions: Yes - placental and embryonic tissue visible at termination
- Other: Weight of the ovaries
Fetal examinations:
- External examinations: No data
- Soft tissue examinations: Yes: [ half per litter ]
- Skeletal examinations: Yes: [half per litter ]
- Head examinations: No data
Statistics:
Student t-test was applied to transformed ossification values to determine the differences in the degree of ossification between test and control groups. Statistical analysis of differences in body weight, food consumption, organ weights, litter data, foetus weights and placenta weights was carried out by applying the Student t-test. Skeletal and visceral anomalies were evaluated by the chi-square test.
Indices:
Standard indices for percentage pre-implantation loss; percentage post-implantation loss and degree of ossification were calculated using equations set out in the report
Historical control data:
No information provided

Results and discussion

Results: maternal animals

Maternal developmental toxicity

Details on maternal toxic effects:
Maternal toxic effects:yes

Details on maternal toxic effects:
Mortalities were observed at the top dose level of 300ppm with one death on day 11. Due to the very adverse effects seen at this dose level, the concentraiton was reduced to 250ppm from day 12 to completion of the study. 3 more mortalities were observed at this dose level. Only 4 females did not show evidence of mating, with a pregnancy range of 79.2 to 91.7% across the dose groups. Focal alopecia was observed in some animals of the low and mid dose groups, with the fur of one animal in the mid dose groups and 3 in the high dose group showing yellow discolouration. Some evidence of illness in matenal animals was observed in the mid and top dose group all bar 2 had recovered by day 21 of pregnancy.
During the pre-treatment period, body weights were comparable across all dose groups. Animals in the top dose group lost weight during treatment and animals in the mid and low dose groups gained less weight than the control animals. A dose related decrease in food consumption and in food efficiency was observed during the treatment period. During the post-treatment preiod, food efficiency was significantly increased in the top dose group compared to that of the controls.
At necropsy, no gross changes attributable to the test substance were recorded. The number of corpura lutea were comparable in all groups. In the 145 ppm dose group, the number of implantation sites was relatively high and through that, the pre-implantation loss relatively low. In the top dose group, the numbers of early and late resorptions were increased and the number of live foetuses decreased, resulting in an increased post-implantation loss. In the top dose, foetus weights, ovary weights and uterus weights were decreased. No altered foetuses were observed in the mid-dose group.

Effect levels (maternal animals)

Dose descriptor:
NOAEC
Effect level:
53 ppm
Based on:
test mat.
Basis for effect level:
other: maternal toxicity

Results (fetuses)

Details on embryotoxic / teratogenic effects:
Embryotoxic / teratogenic effects:yes

Details on embryotoxic / teratogenic effects:
On examination of the foetal soft tissue, only one severely malformed foetus was observed which belonged to the control group. It was observed to have hydrocephalus internus and severe eye defects. The number of foetuses showing unilateral increased renal pelvic cavitation was higher in the top dose group than in the controls. The incidence of foetuses showing visceral variant bilateral was lower in the top dose group than in the controls. No foetal soft tissue malformations attributable to the test substance were observed.
Skeletal malformations were observed in 2 foetuses in each of the groups examined. The malformations consisted of misshapen sternebrae in 2 foetuses of the control group, 2 foetuses of the mid-dose groups nad one foetus of the top dose group. In the top dose group, another foetus of a different litter was missing its tail. The incidence of minor skeletal anomalies was similar in all dose groups. The incidence of unilaterally observed supernumerary ribs and dislocated sternebrae was significantly increased in the top dose group in comparison to the controls. There was also a variation in the degree of ossification of foetal skeletons observed, specifically in the ossification of metatarsals, sternebrae and cervical vertebral bodies. However, this variation in ossification reflects what is normally found in skeletons of foetuses in the strain of rat used.

Effect levels (fetuses)

Dose descriptor:
NOAEC
Effect level:
145 ppm
Based on:
test mat.
Basis for effect level:
other: embryotoxicity

Fetal abnormalities

Abnormalities:
not specified

Overall developmental toxicity

Developmental effects observed:
not specified

Any other information on results incl. tables

The mean number of live foetuses per litter was decreased at 300 ppm, as well the foetal weights, ovary and uterus
weights. A dose-related decrease in food consumption and food efficiency was observed during treatment. 
The foetuses at 300 ppm dose group showed no substance related skeletal and visceral abnormalities. However some
minor skeletal variants have to be examined in the top-dose and mid-dose group.

Applicant's summary and conclusion

Conclusions:
In this embryotoxicity / teratogenicity study in the rat a decreased number of live foetuses per litter, foetal weights, ovary and uterus weights were observed. The NOAEL for embryotoxicity was determined to be 145 ppm (equivalent to 0.45 mg/L). The NOAEC for maternal rats was determined to be 53 ppm while the NOAEC was determined to be 145 ppm for embryo/foetotoxicity.
Executive summary:

In a study conducted by Koeter and Appelman (1980) the test substance, Glycidol, was examined for its ability to cause reproductive toxicity when administered to female rats. The test animals were exposed via inhalation, at concentrations of 0, 50, 150 and 300ppm, although due to overt toxicity observed at the highest dose level, this was reduced to 250ppm after 11 days exposure. The female rats were mated and pregnancy was confirmed by the presence of sperm in a vaginal smear (day 0 of pregnancy). The females were exposed to the test substance for 6 hours, from days 6 to 16 of pregnancy.

Clinical observations and body weight were recorded from day 0 to day 21, at which point the animals were sacrificed. The uterus and ovaries were removed and examined and the number of corpura lutea, implantation sites and the number of early and late resorptions were recorded. Half the foetueses from each litter were examined for soft tissue abnormalities and half for skeletal malformations. Under the conditions of this study, the NOAEC for maternal rats was determined to be 53ppm while the NOAEC was determined to be 145ppm (0.45 mg/L) for embryo/foetotoxicity. Under the conditions of this study, the test substance does not require classification for developmental or teratogenic effects according to Regulation EC No. 1272/2008 or Directive 67/548/EEC.