Tributyl O-acetylcitrate

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:

key study

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

other: guideline study under GLP

Data source

Reference

Reference Type:

study report

Title:

Unnamed

Year:

2002

Report date:

2002

Materials and methods

Test guideline

Test guideline 1

Qualifier:

equivalent or similar to guideline

Guideline:

other: OECD 408 modified

Test guideline 2

Qualifier:

equivalent or similar to guideline

Guideline:

other: EC Method B26, modified

Test guideline 3

Qualifier:

equivalent or similar to guideline

Guideline:

other: US EPA OPPTS 870.3100 modified

Principles of method if other than guideline:

90 day repeated dose study with reproduction (in utero) phase added

GLP compliance:

yes

Limit test:

no

Test material

Test material information

Constituent 1

Test material form:

liquid: viscous

Details on test material:

Citroflex A-4, Acetyl tributyl citrate, 99.9 % purity

Test animals

Species:

rat

Strain:

Wistar

Details on test animals or test system and environmental conditions:

Wistar Han rats

Administration / exposure

Route of administration:

oral: feed

Analytical verification of doses or concentrations:

yes

Details on mating procedure:

F0 males and females were treated for four weeks prior to mating until scheduled sacrifice. They cohabitated and mated. Males were sacrificed and toxicity was assessed as for a 28-day repeated dose study. Females (P) were placed in separate cages and allowed to deliver, nurse and wean offspring.

Duration of treatment / exposure:

12 weeks: P generation females: 4 weeks premating, mating for 1 week, gestation for 3 weeks, littering and lactation for 3 weeks.
P generation males: 4 weeks.

Frequency of treatment:

daily in feed

Duration of test:

13 weeks plus in utero, nursing and weaning.

Doses / concentrations

Remarks:

Doses / Concentrations:
0, 100, 300 and 1000 mg/kg/day
Basis:
nominal in diet

No. of animals per sex per dose:

25

Control animals:

yes, plain diet

Details on study design:

At the completion of the in utero phase, rats that had been exposed to ATBC from before conception, through gestation and continuously from the time of birth were selected (20 unrelated males and 20 unrelated females per dose group for the main study; and 10 unrelated males and 10 unrelated females for the control and high dose recovery groups) and transferred to the 13-week study.

Examinations

Maternal examinations:

Parental animals were evaluated for reproductive endpoints (mating performance, fertility, gestation length and parturition, litter size, numbers of implantations, survival and growth), and F1 animals were evaluated for sexual maturation (balano-preputial separation, vaginal opening, anogenital distance, retained areolae in males, sperm assessments), estrous cyclicity, physical appearance, ophthalmologic effects, neurobehavioral effects, growth, food consumption, survival, hematology, blood chemistry, urinalysis, peroxisome proliferation, organ weights, gross pathology and histopathology. A full range of tissues were retained for the F0 males and females and reproductive organ tissues were retained for F1 males and females. Microscopic examinations were performed on a standard set of tissues for F0 males and females, as well as tissues found to be abnormal at necropsy.

Ovaries and uterine content:

Animals allowed to deliver litters naturally.

Fetal examinations:

F1 animals were evaluated for sexual maturation (balano-preputial separation, vaginal opening, anogenital distance, retained areolae in males, sperm assessments), estrous cyclicity, physical appearance, ophthalmologic effects, neurobehavioral effects, growth, food consumption, survival, hematology, blood chemistry, urinalysis, peroxisome proliferation, organ weights, gross pathology and histopathology. A full range of tissues were retained for the F0 males and females and reproductive organ tissues were retained for F1 males and females.

Statistics:

For organ weights and body weight changes, homogeneity of variance was tested using Bartlett’s test followed by Behrens-fisher test or Dunnett’s test as appropriate. Macroscopic pathology and histopathology data were assessed using Fisher’s Exact test. Estrus cycles were analyzed using the Cochran-Armitage trend test. Other statistical tests used as appropriate were: Williams’ test for a dose-related response; Student’s t-test; Shirley’s non-parametric test for a dose-related response; Steel’s test; and Wilcoxon rank sum test. Significance level was p<0.05.

Results and discussion

Results: maternal animals

Maternal developmental toxicity

Details on maternal toxic effects:

Maternal toxic effects:no effects

Details on maternal toxic effects:
Estrous cycles, mating performance, fertility, gestation length and parturition, were all unaffected by treatment. Litter size, survival and growth were similar in all groups and within expected historical control ranges. Although numbers of implantations and litter size at 1000 mg/kg/day were marginally lower than concurrent control group levels, they were within the laboratory’s historical control ranges.

Effect levels (maternal animals)

Key result

Dose descriptor:

NOAEL

Effect level:

1 000 mg/kg bw/day (nominal)

Based on:

test mat.

Basis for effect level:

other: developmental toxicity

Maternal abnormalities

Abnormalities:

no effects observed

Results (fetuses)

Details on embryotoxic / teratogenic effects:

Embryotoxic / teratogenic effects:no effects

Details on embryotoxic / teratogenic effects:
Anogenital distance and sexual maturation in both sexes and retention of areolae in male offspring were unaffected by treatment. There were no adverse effects on sperm motility, counts or morphology. There were no findings at necropsy of surplus offspring that were considered to be treatment-related.

Effect levels (fetuses)

Key result

Dose descriptor:

NOAEL

Effect level:

1 000 mg/kg bw/day (nominal)

Based on:

test mat.

Sex:

male/female

Basis for effect level:

other: no treatment-related effects at highest dose tested.

Fetal abnormalities

Abnormalities:

not specified

Overall developmental toxicity

Key result

Developmental effects observed:

no

Applicant's summary and conclusion

Conclusions:

A modified protocol was undertaken in a developmental toxicity study on an analogue, acetyl tributyl citrate (ATBC). The material was given in a dietary study to male and female Han Wistar rats for four weeks prior to mating, throughout mating and, for females only, through gestation, littering, lactation and weaning. Males were sacrificed after 4 weeks. Twenty F1 rats each were randomly selected to continue in longer dietary studies. Surplus F1 animals were sacrificed and necropsied. Reproductive and repeated dose effects were evaluated for P animals, and in F1 animals after an additional 13 weeks. The NOAELs for both repeated dose toxicity and reproductive and developmental toxicity were 1000 mg/kg bw/d. Data can be read-across between the analogues (triethyl citrate, citric acid and acetyl tributyl citrate) based on common break-down products. This is adequate to fulfill the information requirements, to be the basis for classification and labelling decisions, and for risk assessment.