Hexamethylene diacrylate

Developmental toxicity / teratogenicity

Administrative data

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

Remarks:

However, only a single dose was tested which showed maternal toxicity and embryotoxic effects.

Data source

Reference

Reference 1

Reference Type:

study report

Title:

Unnamed

Year:

1983

Report date:

1983

Reference 2

Reference Type:

publication

Title:

Unnamed

Year:

1983

Report date:

1983

Reference 3

Reference Type:

publication

Title:

Unnamed

Year:

1982

Report date:

1982

Materials and methods

Test guideline

Qualifier:

equivalent or similar to guideline

Guideline:

OECD Guideline 414 (Prenatal Developmental Toxicity Study)

Deviations:

yes

Remarks:

; only a single dose was tested.

Principles of method if other than guideline:

The aim of the study was to evaluate the embryo/fetal toxicity and teratogenic effects of the test substance when administered by gavage to pregnant rats from day 6 to day 15 of gestation. The test material was administered to a group of 22 female rats at a single dose level of 750 mg/kg bw. Another group served as a common control and received only corn oil.

GLP compliance:

not specified

Test material

Test material information

Constituent 1

Reference substance name:

Hexamethylene diacrylate

EC Number:

235-921-9

EC Name:

Hexamethylene diacrylate

Cas Number:

13048-33-4

Molecular formula:

C12H18O4

IUPAC Name:

hexane-1,6-diyl bisacrylate

Details on test material:

- Name of test material (as cited in study report): 1,6-Hexanediol diacrylate; coded as C-255
- Analytical purity: no data given
- Impurities (identity and concentrations): no data given
- Lot/batch No.: 3-81
- Physical state: light amber liquid
- Storage condition of test material: room temperature

Test animals

Species:

rat

Strain:

Sprague-Dawley

Details on test animals or test system and environmental conditions:

TEST ANIMALS
- Source: Charles River Breeding Laboratories, Inc. Kingston, New York
- Age at study initiation: ca. 5 weeks
- Weight at study initiation:
- Fasting period before study:
- Housing: individual in elevated wire-mesh cages; during mating two females were housed with one male
- Diet: Purina Rodent Laboratory Chow, ad libitum
- Water: ad libitum
- Acclimation period: ca. 9 weeks

ENVIRONMENTAL CONDITIONS
- Temperature (°C): 24-25 °C
- Humidity (%): 57 +- 4.8 %
- Photoperiod (hrs dark / hrs light): 12/12

Administration / exposure

Route of administration:

oral: gavage

Vehicle:

corn oil

Details on exposure:

PREPARATION OF DOSING SOLUTIONS:
The amount of compound required for each group was weighed, filled to volume with the vehicle and stirred on a magnetic stirrer. The prepared dilutions were transferred to amber bottles and labelled. Before use, the prepared dilutions were well shaken and the animals were dosed while the solutions were mixed on a magnetic stirrer. Fresh solutions were prepared weekly.

VEHICLE:
- Duke´s Corn Oil, a yellow liquid was received from the C.F. Sauer Co. Richmond, Virginia and used as vehicle.
- Lot/batch no.: 80235

Analytical verification of doses or concentrations:

no

Details on mating procedure:

Following a health status examination by a staff veterinarian, the males and females (1 male per 2 females) were placed in breeding cages for a maximum of 3 weeks. Females were rotated after the tenth day of mating. Mating was confirmed by the presence of a vaginal plug or by daily examination of vaginal smears for the presence of sperm. The day that mating was confirmed was designated as day 0 of gestation for each female placed on study.

Duration of treatment / exposure:

day 6 to day 15 of gestation

Frequency of treatment:

daily

Duration of test:

until day 20 of gestation

Doses / concentrations

Remarks:

Doses / Concentrations:
750 mg/kg bw
Basis:
nominal conc.

No. of animals per sex per dose:

22 mated females

Control animals:

yes, concurrent vehicle

Examinations

Maternal examinations:

DETAILED CLINICAL OBSERVATIONS: mortality, moribundity and clinical signs
- Time schedule: daily

BODY WEIGHT: Yes
- Time schedule for examinations: on day 0, 6, 9, 12, 15 and 20 of gestation

WATER CONSUMPTION AND COMPOUND INTAKE:
- Time schedule for examinations: on day 6-8, 9-11, 12-14, 15-17 and 18-20 of gestation

POST-MORTEM EXAMINATIONS:
- Sacrifice on gestation day 20:
On day 20 of gestation, females were sacrificed by carbon dioxide asphyxiation and the fetuses were taken by cesarean section. Following gross examination of each dam, the number of corpora lutea per ovary and the number and placement of implantation sites, early and late resorptions, and live and dead fetuses in each uterine horn were recorded. Fetuses were removed from the placenta, individually identified, examined externally, weighed, sexed, and measured from the frontal-parietal suture to the base of the tail (crown-rump distance). Gravid and nongravid uterine weights (with ovaries attached) were recorded.
- Organ Weights:
Following careful dissection and trimming to remove fat and other contiguous tissue in a uniform manner, the gravid and nongravid uterine weights (with ovaries attached) of each female were taken for organ weighing.
- Tissue Preservation:
The uterus and ovaries of each dam, in addition to unusual lesions, were preserved in 10 % neutral buffered formalin.

Fetal examinations:

- Visceral Examination of Fetuses:
Approximately one-third of the fetuses from each litter were fixed in Bouin's solution, sectioned, and examined by Wilson's freehand razor technique (Wilson and Warkany, 1965), and sealed in plastic. The prepared sections were re-examined against a light box with the aid of magnification.
- Skeletal Examination of Fetuses:
After undergoing external examinations, approximately two-thirds of all fetuses from each litter were opened by longitudinal incision and the viscera examined grossly. The fetuses were then placed in M5 ethyl alcohol and the skeletons were stained in a potassium hydroxide - Alizarin red S solution (modified Staples and Schnell, 1964). Each skeleton was examined with the aid of magnification on a light box for bone alignment, degree of ossification, and anomalies. The number of sternebrae, ribs, caudal vertebrae, and bones of the extremities were noted and recorded. The fetuses examined by Wilson's technique were preserved In Bouin's solution and sealed in plastic after sectioning. The fetuses stained for skeletal examination were preserved in plastic in a glycerin ethanol (1:1) solution with several crystals of thymol to retard bacterial growth.

Statistics:

Survival was statistically analyzed by the National Cancer Institute Package (Thomas, Breslow, & Gart, 1977).
The mean maternal body weight changes (Days 0-6, 6-15, 15-20, and 0-20), mean maternal food and water consumptions (Days 6-9, 9-12, 12-15, 15-18, 18-20, and 6-20), percent males per litter, mean fetal body weights and lengths, fetal viability, percent resorptions, implantation efficiency, gravid and nongravid uterine weights, and the incidence of visceral and skeletal anomalies and variants were analyzed by Box's test for homogeneity of variances (Box, 1949). This test was followed by a one-way classification analysis of variance (ANOVA), if the variances proved to be homogenous. If the variances proved to be heterogenous, a rank transformation of data was performed, which was followed by Box´s test and ANOVA. If ANOVA of untransformed or transformed data was significant, Dunnet´s T-test was used for control vs. treatment group mean comparisons.
Pregnancy rates were analyzed by a test of multiple proportions using one degree of freedom Chi-square test with Yates´continuity correction. All pairwise comparisons were evaluated at the 5.0 % probability (one-tailed) level.

Results and discussion

Results: maternal animals

Maternal developmental toxicity

Details on maternal toxic effects:

Details on maternal toxic effects:
Mortality and Clinical Signs:
No mortality occured during treatment. An increased incidence of clincal symptoms was noted (wheezing, dyspnea, urine stains, wasted feed, rough haircoat, hunched pasture, bloody crust on the eyes, nase, snouth, and frontpaws, salivation and alopecia).
- Body weights:
Mean body weight changes lower than the control, but not statistically significant were observed in the treated group during the treatment phase.
- Food and water consumption:
In the treated group a statistically significant increase in water consumption was noted on days 18 and 20 and in total water consumption, compared to control.
- Gross pathology:
The most distinct alterations attributed to treatment were noted in the stomachs of the treated animals. The findings consisted of discoloured material or fluid in the stomach; gas distending the stomach; discoloured, ulcerated or raised areas in the glandular or nonglandular portion of the stomach. glandular mucosa smooth; walls thick or thin/smooth; and nonglandular mucosa thin and pale, or thick and rough. Other gross pathology findings were considered to be incidental in nature and showed no relation to treatment.
- Pregnancy rates, Corpora Lutea and Implantations:
Pregnancy rates, corpora lutea and implantations, and mean implantation efficiency (number of implantations per number of corpora lutea) were generally comparable for treated animals and controls.

Effect levels (maternal animals)

Dose descriptor:

LOAEL

Effect level:

750 mg/kg bw/day (nominal)

Basis for effect level:

other: maternal toxicity

Results (fetuses)

Details on embryotoxic / teratogenic effects:

Details on embryotoxic / teratogenic effects:
- Gross Pathology:
Skeletal examinations included incidences of cleft palate in 1 pup. A high incidence of dilated ureters was noted in both treated and control groups.
- Visceral and Skeletal Examinations:
A higher than control mean incidence of visceral variants was noted (but not statistically significant). Statistically significant increased mean incidence of skeletal variants was observed. The majority of the findings were due to delayed ossification of the various bone structures examined. The authors suggested that this response was resulting from the maternal toxicity noted.

Effect levels (fetuses)

Dose descriptor:

NOAEL

Effect level:

750 mg/kg bw/day (nominal)

Basis for effect level:

other: teratogenicity

Fetal abnormalities

Abnormalities:

not specified

Overall developmental toxicity

Developmental effects observed:

not specified

Any other information on results incl. tables

Only a single dose of 750 mg/kg bw was tested in this study. Taken together, maternal toxic effects as well as embryotoxic effects were observed. According to the authors, the embryotoxic effects resulted from maternal toxicity. Therefore, the results obtained for the offspring at a dose causing maternal toxicity (750 mg/kg bw/d), were not considered relevant for assessing the teratogenic potential of the test material.