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Toxicological information

Toxicity to reproduction

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Administrative data

Endpoint:
toxicity to reproduction
Remarks:
other: modified OECD 408 with in utero phase
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 with modifications, under GLP

Data source

Reference
Reference Type:
study report
Title:
Unnamed
Year:
2002
Report Date:
2002

Materials and methods

Test guideline
Qualifier:
according to
Guideline:
other: OECD 408 with in utero phase
Principles of method if other than guideline:
13 week repeated dose study using animals which were exposed in utero
GLP compliance:
yes
Limit test:
no

Test material

Reference
Name:
Unnamed
Type:
Constituent
Details on test material:
Citroflex A-4, acetyl tributyl citrate (ATBC), 99.9 % purity

Test animals

Species:
rat
Strain:
Wistar
Sex:
male/female

Administration / exposure

Route of administration:
oral: feed
Vehicle:
other: feed
Details on exposure:
F0 males and females were treated for four weeks prior to mating until scheduled sacrifice. The F1 male and female offspring were exposed in utero and from birth until the start of the 13-week study. The F1 offspring selected for the 13-week study were then provided the respective treated diets for 13-weeks.
Details on mating procedure:
Males and females cohabited for 1 week
Analytical verification of doses or concentrations:
yes
Duration of treatment / exposure:
P generation females were exposed to the diet during mating, gestation, littering and weaning. FI animals continued on the diet for 13 weeks.
Frequency of treatment:
daily
Doses / concentrations
Remarks:
Doses / Concentrations:
0, 100, 300 and 1000 mg/kg bw/d
Basis:
nominal in diet
No. of animals per sex per dose:
25
Control animals:
yes, plain diet

Examinations

Parental animals: Observations and examinations:
Parental animals were evaluated for reproductive endpoints (mating performance, fertility, gestation length and parturition, litter size, numbers of implantations, survival and growth), and. 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.
Oestrous cyclicity (parental animals):
yes
Sperm parameters (parental animals):
yes
Litter observations:
yes
Postmortem examinations (parental animals):
yes
Postmortem examinations (offspring):
yes
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.
Reproductive indices:
yes, in intact females carrying to term
Offspring viability indices:
yes

Results and discussion

Results: P0 (first parental generation)

General toxicity (P0)

Clinical signs:
no effects observed
Body weight and weight changes:
effects observed, treatment-related
Description (incidence and severity):
minor effects as a result of decreased food and water consumption
Food consumption and compound intake (if feeding study):
effects observed, treatment-related
Description (incidence and severity):
minor effects as a result of decreased food and water consumption
Organ weight findings including organ / body weight ratios:
no effects observed
Histopathological findings: non-neoplastic:
no effects observed
Other effects:
no effects observed

Reproductive function / performance (P0)

Reproductive function: oestrous cycle:
no effects observed
Reproductive function: sperm measures:
no effects observed
Reproductive performance:
no effects observed

Details on results (P0)

The general condition of parental animals was unaffected by treatment. Females in the 1000 mg/kg/day dose group showed an increased incidence of yellow staining in the perigenital and sacral regions. Body weight, body weight gain, food consumption and food conversion efficiency were unaffected. 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. 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. T

Effect levels (P0)

Dose descriptor:
NOAEL
Effect level:
1 000 mg/kg bw/day (nominal)
Based on:
test mat.
Sex:
male/female
Basis for effect level:
other: NOAELs as published in the study report were reevaluated by US. EPA to be as described above.
Remarks on result:
other: Generation: P and F1 (migrated information)

Results: P1 (second parental generation)

General toxicity (P1)

Clinical signs:
no effects observed

Results: F1 generation

General toxicity (F1)

Clinical signs:
no effects observed
Mortality / viability:
no mortality observed
Body weight and weight changes:
no effects observed
Sexual maturation:
no effects observed
Organ weight findings including organ / body weight ratios:
no effects observed
Gross pathological findings:
no effects observed
Histopathological findings:
no effects observed

Details on results (F1)

There were no findings at necropsy of surplus F1 offspring that were considered to be treatment-related. 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.

Effect levels (F1)

Dose descriptor:
NOAEL
Generation:
F1
Effect level:
1 000 mg/kg bw/day (nominal)
Based on:
test mat.
Sex:
male/female
Basis for effect level:
other: NOAELs as published in the study report were reevaluated by US. EPA to be as described above.
Remarks on result:
other: Generation: P and F1 (migrated information)

Overall reproductive toxicity

Reproductive effects observed:
not specified

Applicant's summary and conclusion

Conclusions:
A repeated dose dietary toxicity study was undertaken for a structural analogue, acetyl tributyl citrate (ATBC), in Wistar rats. Parental animals were exposed in the diet at doses up to 1000 mg/kg bw/d for 4 weeks, and during mating. There were no adverse effects observed in reproductive indices or in gross and histopathology in the P generation. There were no adverse effects seen after F1 animals were exposed to the substance at the same doses during gestation, parturition, weaning, and continuously throughout 13 weeks. The NOAEL for reproduction and for developmental toxicity was 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.