Benzene-1,2,4-tricarboxylic acid 1,2-anhydride, oligomeric reaction products with ethane- l,2-diol

Developmental toxicity / teratogenicity

Administrative data

Endpoint:

developmental toxicity

Type of information:

migrated information: read-across based on grouping of substances (category approach)

Adequacy of study:

key study

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

other: Scientifically valid study, no information on GLP

Data source

Reference

Reference Type:

publication

Title:

Developmental toxicity evaluation of phthalic acid, one of the metabolites of phthalic acid esters, in rats

Author:

Ema M, Miyawaki E, Harazono A, Kawashima K

Year:

1997

Bibliographic source:

Toxicol. Letters 93: 109-115

Materials and methods

Test guideline

Qualifier:

equivalent or similar to guideline

Guideline:

OECD Guideline 414 (Prenatal Developmental Toxicity Study)

Deviations:

yes

Remarks:

no data on dose validation

GLP compliance:

not specified

Limit test:

no

Test material

Test material information

Constituent 1

Reference substance name:

1,3-dioxo-2-benzofuran-5-carboxylic acid

IUPAC Name:

1,3-dioxo-2-benzofuran-5-carboxylic acid

Constituent 2

Reference substance name:

Phthalic acid

EC Number:

201-873-2

EC Name:

Phthalic acid

Cas Number:

88-99-3

IUPAC Name:

phthalic acid

Test material form:

not specified

Details on test material:

obtained from Aldrich Chemicals, Milwaukee, WI, USA. 99.5% purity

Test animals

Species:

rat

Strain:

Wistar Kyoto (WKY)

Details on test animals or test system and environmental conditions:

TEST ANIMALS
- Source:
- Age at study initiation: (P) 12 wks
- Fasting period before study: no
- Use of restrainers for preventing ingestion (if dermal): yes/no
- Diet (e.g. ad libitum): F-1 basal diet (Funabashi Farm, Funabashi, Japan), ad libitum
ENVIRONMENTAL CONDITIONS
- Temperature (°C): 2 ± 1
- Humidity (%): 55 ± 5

Administration / exposure

Route of administration:

oral: feed

Details on exposure:

The administration in the feed was selected because of the necessity to expose to large amounts of phthalic acid (PA) and the slight solubility of PA in water and oil (Budavari, et al. 1996). The diet was prepared fresh weekly. A predetermined amount of PA was weighed and added to a small aliquot of ground basal diet and hand-blended. This premix was then added to a preweighed ground basal diet and blended with a mill for 30 min. The control rats were fed a basal diet only, ad libitum.

Analytical verification of doses or concentrations:

not specified

Details on mating procedure:

Virgin female rats were mated overnight with male rats. The day when sperm were detected in the vaginal smear was considered to be day 0 of pregnancy.

Duration of treatment / exposure:

GD 7-16

Frequency of treatment:

daily

Duration of test:

20 days (gestation)

Doses / concentrations

Remarks:

Doses / Concentrations:
1.25%, 2.5% and 5.0%, equivalent to 1021 mg/kg, 1763 mg/kg and 2981 mg/kg, respectively
Basis:
nominal in diet

No. of animals per sex per dose:

11

Control animals:

yes, plain diet

Examinations

Maternal examinations:

Clinical observations were made daily. Maternal body weight and food consumption were recorded daily and average daily intake calculated by the method of Tyl, et al, 1988. The pregnant rats were sacrificed on GD 20.

Ovaries and uterine content:

The peritoneal cavity and uterus were opened and the numbers of live and dead fetuses and resorptions were counted. The gravid uterus was removed and the rats weighed again.

Fetal examinations:

The live fetuses removed from the uterus were sexed, weighed and inspected for external malformations and malformations within the oral cavity. Approximately two-thirds of each litter, randomly selected, were fixed in 99% ethanol, stained with alizarin red S (Kawamura, et al, 1990) and examined for skeletal malformations. The remaining live fetuses in each litter were fixed in Bouin's solution and examined for internal malformations using the free-hand razor blad sectioning method of Wilson (1965).

Statistics:

The litter was the unit for statistical comparisons. Analysis of variance and Dunnett's multiple comparison test, Kruskal-Wallis test and Mann-Whitney test or Fisher's exact test were used as appropriate. The 0.05 level of probability was used as the criterion for significance.

Results and discussion

Results: maternal animals

Maternal developmental toxicity

Details on maternal toxic effects:

Maternal toxic effects:yes. Remark: Decreased food consumption (GD 7-16) and body weight gain in the mid and high dose group.

Details on maternal toxic effects:
No deaths or clinical signs of toxicity were observed in pregnant rats of any groups. The maternal body weight gain on days 7-16 in the 2.5 and 5.0% groups and the adjusted weight gain in the 5.0% group were significantly lower than those in the control group. The maternal body weight gain on days 16-20 in the 5.0% group was significantly higher than that in the control group. A significantly decreased food consumption on days 7-16 in the 2.5 and 5.0% groups and a significantly increased food consumption on days 16-20(no PA in diet) in the 1.25, 2.5 and 5.0% groups were found.

Effect levels (maternal animals)

1

Dose descriptor:

NOAEL

Effect level:

1 021 mg/kg bw/day (nominal)

Based on:

test mat.

Basis for effect level:

other: maternal toxicity

2

Dose descriptor:

NOAEL

Effect level:

1 763 mg/kg bw/day (nominal)

Based on:

test mat.

Basis for effect level:

other: developmental toxicity

Results (fetuses)

Details on embryotoxic / teratogenic effects:

Embryotoxic / teratogenic effects:no effects

Details on embryotoxic / teratogenic effects:
No significant differences between the PA-treated groups and the control group were detected in the numbers of corpora lutea per litter, implantations per litter, resorptions and dead fetuses per litter and live fetuses per litter, incidence of post-implantation loss per litter, and sex ratio of live fetuses. The weight of male fetuses in the 5.0% group was significantly lighter than that in the control group, although no significantly decreased weight of female fetuses was found in any PA-treated groups. No fetuses with external, skeletal and internal malformations were found in any groups. A few types of skeletal variations in the vertebrae and sternebrae were observed in the control and PA-treated groups. The incidence of fetuses with skeletal variations was not significantly different between the PA­ treated groups and the control group. The degree of ossification indicated by the number of the ossification centers of the caudal vertebrae in the 5.0% group was significantly lower than that in the control group.

Fetal abnormalities

Abnormalities:

not specified

Overall developmental toxicity

Developmental effects observed:

not specified

Any other information on results incl. tables

In this study, the dosage as high as possible, which should be expected to induce maternal toxicity, was given to pregnant rats to characterize the effects of PA on embryo-fetal development. The dosage level was determined based on the description of Arnold (1990) in which the highest dose level should not exceed 5% of diet because there is concern about nutrientdilution. According to expectation, the two higher dosage levels used in the present study were maternally toxic. Pronounced effects of PA on the maternal body weight and food consumption during pregnancy were observed and the decreased rate of these indexes was roughly proportional to the dose. Although significant decreases in the body weight gain and food consumption were foundat 2.5 and 5.0%, no significant changes in maternal parameters were detected at 1.25%. These findings suggest that maternal toxicity is induced by PA at dietary doses of 2.5% and above, but not at a dietary dose of 1.25%.

While no significant changes in the numbers of resorptions and dead fetuses per litter and live fetuses per litter were found in any PA-treated groups, significant decreases in the fetal weight and degree of ossification were detected at 5.0%. It seems likely that PA possesses adverse effects on prenatal development of rat offspring at a dietary dose of 5% and that PA has no adverse effects on fetal development at dietary doses of 2.5% and below.

No fetuses with malformations were found in any PA-treated groups. Although several typesof skeletal variations were observed after administration of PA, neither a significant difference between the PA-treated groups and the control group nor a consistent trend was detected in the incidence of these alterations. It is apparent that PA is not developmentally toxic in rats even at a dietary dose which induces maternal toxicity. The data of this study indicates that the no-observed adverse effect levels of PA for maternal and developmental toxicity under these experimental conditions are lower than 5.0 and 2.5%, respectively.

Applicant's summary and conclusion

Conclusions:

A teratology study was undertaken with phthalic acid in Wistar-KY rats at doses of 1.25, 2.5 and 5.0% in the diet during gestational days 7-16. Signs of maternal toxicity were observed in the mid and high dose groups, as decreased food consumption and decreased body weight gain. No external, skeletal or internal malformations were observed in any of the groups of fetuses. There was a decrease in the mean body weight of male fetuses in the high dose group. The maternal and fetal NOAELs were 1.25% and 2.5%, equivalent to 1021 and 1763 mg/kg bw, respectively. This study is informative for evaluation of the toxicity of members of the cyclic acid anhydride category, and is adequate for classification and risk assessment.