Reaction mass of 2,2'-[methylenebis(2,1-phenyleneoxymethylene)]bis(oxirane) and 2,2'-[methylenebis(4,1-phenyleneoxymethylene)]bis(oxirane) and 2-({2-[4-(oxiran-2-ylmethoxy)benzyl]phenoxy}methyl)oxirane

Developmental toxicity / teratogenicity

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

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

other: Study was conducted according to GLP as well as the EPA: TSCA test Guidelines( EPA, 1985).

Data source

Reference

Reference 1

Reference Type:

study report

Title:

Unnamed

Year:

1987

Report date:

1987

Reference 2

Reference Type:

publication

Title:

Unnamed

Year:

1988

Materials and methods

Test guideline

Qualifier:

according to guideline

Guideline:

other: The EPA: TSCA test guidelines ( EPA, 1985)

GLP compliance:

yes

Limit test:

no

Test material

Test material information

Constituent 1

Reference substance name:

2,2'-[(1-methylethylidene)bis(4,1-phenyleneoxymethylene)]bisoxirane

EC Number:

216-823-5

EC Name:

2,2'-[(1-methylethylidene)bis(4,1-phenyleneoxymethylene)]bisoxirane

Cas Number:

1675-54-3

Molecular formula:

C21H24O4

IUPAC Name:

2,2'-[propane-2,2-diylbis(4,1-phenyleneoxymethylene)]dioxirane

Details on test material:

BADGE (Lot TB8509141) was obtained from Dow Chemical and was prepared from a re-crystallization of BADGE from D.E.R. 331 epoxy resin. The test material was analyzed by differential scanning calorimetry and found to be at least 99.1% pure. Infrared and mass spectrums identified the material as BADGE.

Test animals

Species:

rabbit

Strain:

New Zealand White

Details on test animals or test system and environmental conditions:

Female rabbits were received from a commercial supplier, evaluated for general health by a laboratory veterinarian, and were housed singly (suspended stainless steel cages with feed crock and pressure-activated nipple watering system) in rooms designed to maintain adequate environmental conditions and photocycle for rabbits.

Animals were provided food (4oz per day prior to study start, 8oz per day during gestation) and water ad libitum throughout the study. Food was analyzed for nutritional content and contaminants by the supplier. The water was obtained from a municipal water source, analyzed periodically for chemical parameters and biological contaminants by the municipal water department.

Animals were randomized to dose group based on body weights using a computer randomization program. They were identified via a unique animal identification number on a metal ear tag.

Administration / exposure

Route of administration:

other: dermal

Vehicle:

other: PEG 400 (polyethylene glycol)

Details on exposure:

Groups of 26 inseminated rabbits were treated dermally to varying dose levels of BADGE. A section on the back was clipped free of hair, and test material spread uniformly over the area. The test site was covered and the held in place a minimum of 6 hours. Following the occlusion period, the bandage was removed.

Analytical verification of doses or concentrations:

yes

Details on analytical verification of doses or concentrations:

The dose solutions were analyzed by liquid chromatography.

The stability of the test material in the vehicle PEG 400 (polyethylene glycol) was determined to be a minimum of 41 days.

Details on mating procedure:

Females were injected IV with 50 USP units of chorionic gonadotropin to stimulate ovulation following artificial insemination. The day of insemination was considered GD 0.

Duration of treatment / exposure:

minimum of 6 hours/day, GD6-18. Test material was uniformly spread over the clipped area (approximately 10 x 15 cm) using a syringe and blunt-tipped needle. An occlusive bandage of absorbent gauze and non-absorbent cotton was then placed over the dosing area on the back. The bandage was held in place for a minimum of 6 hours using a lycra/spandex jacket. Following the occlusion period, the bandage and jacket were removed.

Frequency of treatment:

daily

Duration of test:

28 days

No. of animals per sex per dose:

26 inseminated rabbits/dose

Control animals:

yes, concurrent vehicle

Details on study design:

Groups of 26 inseminated rabbits were treated dermally to varying dose levels of BADGE. A section on the back was clipped free of hair, and test material spread uniformly over the area. The test site was covered and then held in place a minimum of 6 hours. Following the occlusion period, the bandage was removed.

Examinations

Maternal examinations:

All animals were observed daily for indications of toxicity. The test site was assessed daily for irritation using the OECD (1983) rating scale. In addition, it was ranked for exfoliation and fissuring according to a set scale. Body weights were recorded on GD 0, 6, 9, 12, 15, 19, 28. Maternal liver weights and gravid uterine weights were recorded at time of sacrifice. Liver and skin (test site and virgin site) were preserved.

Ovaries and uterine content:

Fetal examinations included the following: position and number in utero, number of live and dead, number and position of resorption sites, number of corpora lutea, sex, alterations, and body weight. Uteri of non-pregnant animals were stained and examined.

Fetal examinations:

Fetal examinations also included the following: sex, alterations, and body weight. Tissues from half of all fetuses were examined microscopically in addition

Statistics:

Descriptive statistics (mean and SD) were evaluated for skin lesions. Maternal and fetal body weights, gravid uterine weight, absolute and relative organ weights were evaluated by a Bartlett's test for equality of variances. Based on the outcome, a parametric or nonparametric ANOVA was performed. If the ANOVA was significant, analysis by Dunetts test or Wilcoxon Rank-Sum test with Bonferroni's correction was performed.

Statistical frequencies of pre-implantation loss, resorptions, fetal alterations, number of corpora lutea and implantations, and litter size were made by a censored Wilcoxon test with Bonferroni correction. Pregnancy rate was analyzed by the Fisher exact probability test. Statistical outliers were identified by a sequential outlier test, but were not excluded from analyses.

Indices:

1) number and position of fetuses in utero, 2) number of live and dead fetuses, 3) number and position of resorption sites, 4) the number of corpora lutea, and 5) the sex and body weight of each fetus.

Pre- and post-implantation loss

Historical control data:

no data

Results and discussion

Results: maternal animals

Maternal developmental toxicity

Details on maternal toxic effects:

Maternal toxic effects:yes

Details on maternal toxic effects:
The dose solutions were analyzed by liquid chromatography and were found to be 105-114% of the targeted concentrations and were homogeneous throughout the study.

Maternal Observations
Dose-related increases in erythema, exfoliation, fissuring, hemmorhage, and edema at the test site were noted at 100 and 300 mg/kg/day. There were no remarkable observations at 30 mg/kg/day for skin changes, body weights, or liver weights. The pregnancy rate of rabbits at 30 mg/kg/day was decreased, and the distribution of male/female fetuses was different than a binomial distribution. A lack of dose-response makes the finding spurious.

Effect levels (maternal animals)

Dose descriptor:

NOAEL

Effect level:

30 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:
Fetal Observations
There was no statistically significant increase in malformations or variations in any dose group as compared to the control.

Effect levels (fetuses)

1

Dose descriptor:

LOAEL

Effect level:

> 300 mg/kg bw/day (nominal)

Basis for effect level:

other: embryotoxicity

2

Dose descriptor:

LOAEL

Effect level:

> 300 mg/kg bw/day (nominal)

Basis for effect level:

other: fetotoxicity

Fetal abnormalities

Abnormalities:

not specified

Overall developmental toxicity

Developmental effects observed:

not specified

Any other information on results incl. tables

Dermal application of DGEBPA to pregnant rabbits produced maternal toxicity as exhibited by a dose-related increase in erythema, fissuring, hemorrhage and edema at the site of application. Pregnant rabbits in the 300 mg/kg/day treatment group exhibited moderate to severe erythema, fissures, hemorrhage and slight edema resulting in a maximum mean skin irritation/damage score of 2.7 for erythema/eschar, 2.6 or greater for erythema and/or edema is considered to represent significant maternal toxicity in the rabbit by the Test Rules Development Branch, U.S.E.P.A. (Locke, 1985). The degree of erythema, fissuring and hemorrhage observed in high dose rabbits clearly meets and exceeds the standard for adequate maternal toxicity communicated by the Test Rules Development Branch, U.S.E.P.A. and represents a type of damage to the integument which dramatically altered the integrity of the skin. In general, the skin lesions observed in rabbits in the 100 mg/kg/day dose group were less severe than the lesions observed in rabbits in the high dose group and did not develop to the extent which would result in a mean skin irritation/damage score of 2.0 or greater. However, the individual skin response in rabbits in the 100 mg/kg/day dose group showed considerable variation with some rabbits in this group developing lesions of similar severity to that observed in rabbits from the 300 mg/kg/day dose group. The average dermal response of rabbits in the 30 mg/kg/day dose group was characterized as barely perceptible erythema and was indistinguishable from erythema caused by the occlusive bandages/jacket used to hold the test material in place. Since most pregnant control rabbits showed similar low levels of skin erythema, the skin response observed in rabbits from the 30 mg/kg/day dose group was not considered toxicologically significant. No other treatment-related clinical signs or systemic toxicity were observed in this study.

Although dermal exposure of pregnant rabbits to 300 mg DGEBPA/kg body weight/day produced maternal toxicity, no indication of embryo/fetal toxicity or teratogenicity was observed at any dose level tested. The statistically significant decrease in pregnancy rate and deviation from a binomial distribution of the fetal sex ratio observed in the 30 mg/kg/day dose group were considered random events in view of the lack of a dose-response for these parameters. A small number of fetuses scattered throughout the dose levels exhibited malformations. Although the majority of these malformations occurred in the DGE BPA exposure groups, the frequency of specific malformations were low and did not show a dose-response. In addition, most of the malformations observed also occurred at low frequencies in historical control New Zealand White rabbit data generated in this laboratory and thus were not considered due to exposure to DGEBPA.

Applicant's summary and conclusion

Conclusions:

The no observed-adverse-effect level for maternal toxicity is 30 mg/kg bw. The embryo/ fetal no observed-effect level was >300 mg/kg body weight.

Executive summary:

Diglycidyl ether of bisphenol A (DGEBPA) was tested for its embryo/fetal toxicity and teratogenicity in pregnant rabbits. DGEBPA was applied daily to the backs (clipped free of hair) of New Zealand White rabbits at dose levels of 0 (polyethylene glycol, vehicle control), 30, 100 or 300 mg/kg body weight/day at a dose volume of 1 ml/kg body weight/day on days 6 through 18 of gestation. Twenty six inseminated rabbits were used per dose group resulting in a minimum of 20 pregnant rabbits per exposure level. An occlusive bandage of absorbent gauze and non-absorbent cotton was placed over the dosing area on the back of each rabbit. The bandage was held in place for a minimum of 6 hours/day using a lycra/spandex jacket. Following the occlusion period the bandage and jacket were removed.

Maternal toxicity was observed among pregnant rabbits in the 300 mg/kg dose group as evidenced by moderate to severe erythema, fissures, hemorrhage and slight edema at the exposure site. Similar, but less severe skin lesions were observed in pregnant rabbits in the 100 mg/kg/day exposure group. Skin effects (slight erythema) observed in pregnant rabbits in the 30 mg/kg/day dose group were not considered toxicicologically significant. No evidence of embryo/fetal toxicity or teratogenicity was observed at any dose level resulting in a embryo/fetal no-observed-effect level of 300 mg/kg body weight/day.