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Toxicological information

Developmental toxicity / teratogenicity

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Administrative data

Endpoint:
developmental toxicity
Type of information:
migrated information: read-across from supporting substance (structural analogue or surrogate)
Adequacy of study:
weight of evidence
Study period:
08/1987-10/1988
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
other: GLP-study according to OECD guideline 414.

Data source

Reference
Reference Type:
study report
Title:
Unnamed
Year:
1988
Report Date:
1988

Materials and methods

Test guideline
Qualifier:
according to
Guideline:
OECD Guideline 414 (Prenatal Developmental Toxicity Study)
Deviations:
yes
Remarks:
only 2 dose levels
GLP compliance:
yes

Test material

Reference
Name:
Unnamed
Type:
Constituent
Details on test material:
- Name of test material (as cited in study report): propylene glycol n-butyl ether (PnB) as surrogate for tripropylene glycol butyl ether
- Physical state: clear, colourless liquid
- Analytical purity: >98%
- Lot/batch No.: XZ 95410.00
- Stability under test conditions: stable up to 200°C
- Storage condition of test material: at ambient temperature in the dark

Test animals

Species:
rat
Strain:
Wistar
Details on test animals and environmental conditions:
TEST ANIMALS
- Source: F. Winkelmann Versuchstierzucht GmbH & Co. KG, Borchen, Germany
- Age at study initiation: 13 weeks (females) & 14 weeks (males)
- Weight at study initiation: 182 to 218 g (females)
- Fasting period before study: none
- Housing: five females per cage and males individually housed in suspended steel cages fitted with wire-mesh floors and fronts
- Diet (e.g. ad libitum): ad libitum
- Water (e.g. ad libitum): ad libitum
- Acclimation period: ca. one week

ENVIRONMENTAL CONDITIONS
- Temperature (°C): 20-22°C
- Humidity (%): at least 40%
- Air changes (per hr): 8-10
- Photoperiod (hrs dark / hrs light): 12/12

Administration / exposure

Route of administration:
dermal
Vehicle:
propylene glycol
Details on exposure:
TEST SITE
- Area of exposure: shaved back skin
- coverage: 20cm2
- Type of wrap if used: no wrap (uncovered)
- Time intervals for shavings or clipplings: no data

REMOVAL OF TEST SUBSTANCE
- Washing (if done): prior to daily application the treated skin was cleaned with lukewarm water moistened sponge
- Time after start of exposure: 24 hours

TEST MATERIAL
- Amount(s) applied (volume or weight with unit): 1.5 ml/kg body weight
- Concentration (if solution): ratios of 40:60 and 12:60 PnB in propylene glycol
- Constant volume or concentration used: yes

VEHICLE
- Justification for use and choice of vehicle (if other than water): based on preliminary dermal irritation study and the pilot dermal embryotoxicity study it was decided to apply the test substance in a solution with propylene glycol
- Amount(s) applied (volume or weight with unit): 1.5 ml/kg body weight

USE OF RESTRAINERS FOR PREVENTING INGESTION: yes (neck collars)
Analytical verification of doses or concentrations:
yes
Details on analytical verification of doses or concentrations:
Samples were taken from each test solution and stored at 4°C until analysis. Samples were diluted with acetone and analyzed by gas chromatography using a flame ionization detector.
For gas chromatographic conditions see attachment provided below.
Details on mating procedure:
- Impregnation procedure: cohoused
- If cohoused:
- M/F ratio per cage: 1/2
- Length of cohabitation: overnight untill detection of sperm cells in the female (max. 4 days)
- Males found to have mated were assigned to each group in rotation
- Proof of pregnancy: sperm in vaginal smear referred to as day 0 of pregnancy
Duration of treatment / exposure:
day 6 to 16 of pregnancy
Frequency of treatment:
daily
Duration of test:
untill day 21 of pregnancy
Doses / concentrationsopen allclose all
Remarks:
Doses / Concentrations:
1.0 ml/kg bw/d
Basis:
nominal conc.
Remarks:
Doses / Concentrations:
0.3 ml/kg bw/d
Basis:
nominal conc.
No. of animals per sex per dose:
20
Control animals:
yes, concurrent vehicle
Details on study design:
- Dose selection rationale: based on results of a preliminary dermal toxicity study showing that PnB was well-tolerated by pregnant female rats applied dermally at levels up to 1.0 ml/kg bw/day
- Rationale for animal assignment: random

Examinations

Maternal examinations:

DETAILED CLINICAL OBSERVATIONS: Yes
- Time schedule: general condition and behaviour of the animals was checked daily and local skin reactions, if any, were recorded

BODY WEIGHT: Yes
- Time schedule for examinations: animals were individually weighed on day 0, day 6, day 16 and day 21 of pregnancy

FOOD CONSUMPTION : Yes
-quatitiy of food consumed by each animal of each group was determined during the following periods: day 0 to day 6 and day 6 to day 16 and day 16 to day 21.

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

POST-MORTEM EXAMINATIONS: Yes
- Sacrifice on gestation day 21
- Organs examined: both ovaries, uterus, kidneys and the liver
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
- Number of early resorptions: Yes
- Number of late resorptions: Yes
Fetal examinations:
- External examinations: Yes: [all per litter]
- Soft tissue examinations: Yes: [half per litter]
- Skeletal examinations: Yes: [half per litter]
- Head examinations: No data
Statistics:
For the statistical analyses of differences in degree of ossification between the test and control groups Student's t-test was applied to transformed ossification values expressed in degrees.
Statistical analysis of differences in body weight, food consumption, organ weights, litter data, foetus weights and lengths and placenta weights was carried out by applying analysis of (co)-variance, with body weights on day 0 as the covariable, followed by Dunnet's multiple comparison test, wherea skeletal and visceral anomalies were evaluated by the Chi-square test.
Indices:
Percentage of pre-implantation loss (PRIL) was calculated for each litter according to the formula below.

PRIL=100%*(number of corpora lutea-number of implantation sites/number of corpora lutea)

Percentage of post-implantation loss (POIL) was calculated for each litter according to the formula below.

POIL=100%*(number of implantation sites-number of live pubs/number of implantation sites)

Degree of ossification (DgO) of foetus skeletons was calculated for each litter according to the formula below.

DgO=number of bones without ossification (or with incomplete ossification)/number of bones examined

Results and discussion

Results: maternal animals

Maternal developmental toxicity

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

Details on maternal toxic effects:
Minor skin reaction were observed. However, these were not considered of importance to the study. There were no statistical differences in body weight and food intake, in the weight of ovaries, uterus, kidneys and liver between control- and test groups.

Effect levels (maternal animals)

open allclose all
Dose descriptor:
NOAEL
Effect level:
880 mg/kg bw/day (nominal)
Basis for effect level:
other: developmental toxicity
Dose descriptor:
NOAEL
Effect level:
880 mg/kg bw/day (nominal)
Basis for effect level:
other: maternal toxicity

Results (fetuses)

Details on embryotoxic / teratogenic effects:
Embryotoxic / teratogenic effects:no effects

Details on embryotoxic / teratogenic effects:
No compound related visceral and skeletal malformations, anomalies or variants were observed at any dose level.

Fetal abnormalities

Abnormalities:
not specified

Overall developmental toxicity

Developmental effects observed:
not specified

Applicant's summary and conclusion

Conclusions:
Propylene glycol n-butyl ether did not induce developmental effects up to 1.0 ml/kg bw/day (highest dose level tested).
Executive summary:

Three groups of 25 mated Wistar rats recieved dermal applications ofg 0, 0.3 and 1.0 ml/kg bw/day propylene glycol n-butyl ether (DOWANOL PnB) from day 6 -16 of pregnancy. The control group was treated with 1.5 ml propylene glycol/kg bw/day. The PnB in the test groups was provided as two mixtures in propylene glycol at the ratios 12:60 and 40:60. Because of the non-occluded applications, collars were used to prevent oral uptake. The study was conducted according to OECD guideline 414.

No mortality, and no abnormalities in condition and behaviour occurred. Minor skin reactions were observed in the PnB. These were not considered of importance for the study. There were no statistical differences in body weight and food intake, in the weight of ovaries, uterus, kidneys and liver between control- and test groups.

Maternal performance was comparable in all groups. no compound related visceral and skeletal malformations, anomalies or variants were observed, that could be related to the treatment with PnB.

The limit concentration of 1.0 ml/kg bw/day produced minor local skin reactions, but no further toxicity in the dams. Daile dermal applications of 0.3 or 1.0 ml/kg bw/day from day 6 through 16 of pregnancy did not induce embryo/foeto toxicity nor teratogenic effects.