Iso(C10-C14)alkyl (3,5-di-tert-butyl-4-hydroxyphenyl)methylthioacetate

Developmental toxicity / teratogenicity

Administrative data

Endpoint:

developmental toxicity

Type of information:

experimental study

Adequacy of study:

key study

Study period:

1986-08-06 to 1987-09-07

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

other: OECD guideline study, GLP

Data source

Reference

Reference Type:

study report

Title:

Unnamed

Year:

1987

Report date:

1987

Materials and methods

Test guideline

Qualifier:

according to guideline

Guideline:

OECD Guideline 414 (Prenatal Developmental Toxicity Study)

Deviations:

no

GLP compliance:

yes

Limit test:

no

Test material

Test material information

Constituent 1

Reference substance name:

Iso(C10-C14)alkyl (3,5-di-tert-butyl-4-hydroxyphenyl)methylthioacetate

EC Number:

404-800-4

EC Name:

Iso(C10-C14)alkyl (3,5-di-tert-butyl-4-hydroxyphenyl)methylthioacetate

Cas Number:

118832-72-7

Molecular formula:

C30H52O3S

IUPAC Name:

11-methyldodecyl 2-{[(3,5-di-tert-butyl-4-hydroxyphenyl)methyl]sulfanyl}acetate

Details on test material:

- Physical state: 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
- Strain: Crl:CD(SD)BR
- Source: Charles River Wiga GmbH, 8741 Sulzfeld, West Germany.
- Age at study initiation: female: 8 - 12 weeks old, male: sexually mature
- Weight at study initiation: female: 180 - 240 g, male: no data
- Housing: Prior to mating and during mating, the female rats were housed in groups of 20 to 25 in communal cages. Mated female rats were individually housed in solid floor Macrolon cages of type II with stainless steel lids
- Diet: ad libitum (Ssniff R 10)
- Water: ad libitum
- Acclimation period: At least 1 week prior to the start of mating

ENVIRONMENTAL CONDITIONS
- Temperature: 19 - 25 °C
- Humidity: 40 - 70 %
- Photoperiod: 12 hrs light/ 12 hrs dark

Administration / exposure

Route of administration:

oral: gavage

Vehicle:

arachis oil

Details on exposure:

PREPARATION OF DOSING SOLUTIONS:
The test article was daily prepared as solution In arachis oil. Separate preparations were made for each dose level.

Analytical verification of doses or concentrations:

yes

Details on analytical verification of doses or concentrations:

Samples for analysis were taken from dose formulations prepared for each dose level on 17.11.1986 (first week of treatment), deep-frozen immediately after formulation, and sent to the sponsor for analysis.

Details on mating procedure:

The male and female animals were mated at a ratio of 1 : 4 in cages during the night. Vaginal smears were examined in the morning for the presence of sperm and/or a vaginal plug. The day on which sperm and/or a vaginal plug were observed was designated day 0 of gestation.
Since an insufficient number of pregnant rats was obtained in groups 1 and 3, further animals were added to these groups, i.e. three inseminated females (group 1) and eleven inseminated females (group 3). This deviation from the protocol was not considered to have adversely affected the outcome of the study.

Duration of treatment / exposure:

The inseminated female rats were treated with the test substance daily from day 6 to 15 post-coitum (inclusive), maintained without treatment until day 20 post-coitum, and were sacrificed and examined on that day.

Frequency of treatment:

Once daily

Duration of test:

Until day 20 post-coitum

Doses / concentrations

Remarks:

Doses / Concentrations:
0, 50, 150 and 300 mg/kg bw/day
Basis:
actual ingested

No. of animals per sex per dose:

25 rats

Control animals:

yes, concurrent vehicle

Examinations

Maternal examinations:

CAGE SIDE OBSERVATIONS: Yes
- Time schedule: twice daily

BODY WEIGHT: Yes
- Time schedule for examinations: The body weight of each inseminated female rat was determined on days 0, 6 to 15, and 20 post-coitum, and evaluated for days 0, 6, 10, 15, and 20 post-coitum.

FOOD CONSUMPTION: Yes
The food consumption of each inseminated female was recorded for days 0 to 6, 6 to 10, 10 to 15, and 15 to 20 post-coitum.

POST-MORTEM EXAMINATIONS: Yes
On day 20 post-coitum the female rats were sacrificed by carbon dioxide gas, dissected, and examined macroscopically for pathological changes. Any abnormalities observed were recorded.
- Organs examined: ovaries and uteri

Ovaries and uterine content:

The ovaries and uteri were removed and examined and the following data recorded:
Number of corpora lutea in each ovary
Number and position of implantations subdivided into:
a: live foetuses
b: early resorptions
c: late resorptions
d: dead foetuses
Individual foetal weights
Sex of the foetuses

Fetal examinations:

All foetuses were examined for external malformations.
Half of the foetuses from each litter (taking every second foetus in accordance with the position of the uterine horn, if possible) were eviscerated and preserved in 95 per cent ethanol for determination of skeletal abnormalities (Alizarin staining technique). The remaining half was fixed in Bouin's fixative for determination of visceral abnormalities (Wilson technique).

Statistics:

For body weight, body weight gain, food consumption, litter weight, and foetal weights (overall, males, females), the analysis of variance was performed with one factor treatment.
In case of suspected significance, the four groups were compared at each time by the Newman-Keuls test for multiple comparisons (p < 0.05).
Number of corpora lutea, number of implantations, number of foetuses, preimplantation loss, post-implantation loss, and proportion of male foetuses (sex ratio) were statistically analysed using the Kruskal-Wallis test.
In case of suspected significance (probability > chi square < 0.05), the four groups were compared two by two using the Wilcoxon 2-sample test (normal approximation - with continuity correction of 0.5).
The statistical evaluation was performed with the standard software program SAS release 6.02.

Results and discussion

Results: maternal animals

Maternal developmental toxicity

Details on maternal toxic effects:

Maternal toxic effects:yes

Details on maternal toxic effects:
In group 4 (300 mg/kg), group mean body weight on days 0, 10, and 15 of gestation was statistically significantly lower than in the control group and group mean body weight gain was statistically significantly (p < 0.05) reduced during the treatment period, particularly during the early treatment period from day 6 to 10 of gestation when compared to the control group (- 113 per cent). Therefore, body weight gain was also reduced from day 6 to 15 of gestation (- 32 per cent). This finding is considered to be compound-related. A slightly reduced body weight gain during the treatment period from day 6 to 15 of gestation (- 14 per cent) was also observed in group 3 (150 mg/kg), therefore, group mean body weight on day 15 p.c. was lower than in the control group. This finding might be compound-related. Mean daily food consumption of group 4 (300 mg/kg) was statistically significantly (p < 0.05) reduced during the treatment period (- 25 per cent from day 6 to 15 p.c.). In group 3 (150 mg/kg) a slightly statistically significantly reduced mean daily food consumption was also observed during the treatment period (-10 per cent from day 6 to 15 p.c.). These findings are considered to be a toxic or slightly toxic effect of the test article, respectively.
There was no effect of treatment on pregnancy incidence. An unusual high number of non-pregnant animals was observed in group 3 (150 mg/kg). There was no effect of treatment on implantation and on post-implantation loss. Post-implantation loss was highest in the control group.

Effect levels (maternal animals)

Dose descriptor:

NOEL

Effect level:

50 mg/kg bw/day (nominal)

Based on:

test mat.

Basis for effect level:

other: maternal toxicity

Results (fetuses)

Details on embryotoxic / teratogenic effects:

Embryotoxic / teratogenic effects:no effects

Details on embryotoxic / teratogenic effects:
The mean number of fetuses per dam was similar in all groups. The sex distribution was not affected by treatment. Mean fetal weight was comparable In all groups. External malformations as rudimentarily developed tail and atresia ani were found in one fetus of group 3 (150 mg/kg). One further fetus of the same dose group had a visceral malformation as hydrocephalus. No skeletal malformations were found in any group. The incidence and nature of the external and visceral malformations are not considered to be related to treatment with the test substance. The incidence of skeletal and visceral variations was comparable in all groups and not attributable to treatment.

Effect levels (fetuses)

Dose descriptor:

NOEL

Effect level:

300 mg/kg bw/day (nominal)

Based on:

test mat.

Basis for effect level:

other: fetotoxicity

Fetal abnormalities

Abnormalities:

not specified

Overall developmental toxicity

Developmental effects observed:

not specified

Applicant's summary and conclusion

Conclusions:

Administration of the test article by oral gavage during the period of organogenesis (day 6 to 15 of gestation) at a dose level of 300 mg/kg elicited
maternal toxicity (reduced body weight gain, reduced food consumption) but no embryotoxicity or teratogenicity.

Executive summary:

In a GLP-compliant teratology study according to OECD guideline 414, groups of 25, 36, and 25 sexually mature and mated female rats received the test article by oral gavage at dosages of 50, 150, or 300 mg/kg daily for ten consecutive days from day 6 to 15 post-coitum. A further group of 28 rats of the same strain which received the vehicle (arachis oil) over the same period of time served as the control group. The animals were sacrificed on day 20 post-coitum. At 300 and at 150 mg/kg bw/day, reduced food consumption leading to reduced body weight gain of the dams was observed. There were no effects of treatment on pregnancy incidence and implantation; post-implantation loss was also not affected by treatment. There was no effect of treatment on the weight or sex of the foetuses. The mean number of foetuses per dam was similar in all groups. There was no effect of treatment on the incidence of foetuses showing external, visceral, or skeletal defects. In conclusion, administration of the test article by oral gavage during the period of organogenesis (day 6 to 15 of gestation) at a dose level of 300 mg/kg elicited maternal toxicity (reduced body weight gain, reduced food consumption) but no embryotoxicity or teratogenicity. At a dose level of 150 mg/kg, slight maternal toxicity (slightly reduced body weight gain and food consumption) was also observed but no embryotoxicity or teratogenicity. Administration of 50 mg/kg did not elicit maternal toxicity, embryotoxicity, or teratogenicity.