N,N'-propane-1,3-diylbis[3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionamide]

Developmental toxicity / teratogenicity

Administrative data

Endpoint:

developmental toxicity

Type of information:

read-across from supporting substance (structural analogue or surrogate)

Adequacy of study:

key study

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

guideline study with acceptable restrictions

Justification for type of information:

Additional documentation, provided within the IUCLID Assessment Reports (Section 13), supports the read-across approach.

Cross-reference

Reason / purpose for cross-reference:

read-across: supporting information

Reference

Endpoint:

developmental toxicity

Type of information:

read-across from supporting substance (structural analogue or surrogate)

Adequacy of study:

key study

Justification for type of information:

Additional documentation, provided within the IUCLID Assessment Reports (Section 13), supports the read-across approach.

Reason / purpose for cross-reference:

read-across source

Dose descriptor:

NOAEL

Effect level:

2 000 mg/kg bw/day

Based on:

test mat.

Basis for effect level:

other: no adverse effects at highest dose tested

Abnormalities:

no effects observed

Dose descriptor:

NOAEL

Effect level:

2 000 mg/kg bw/day

Based on:

test mat.

Sex:

male/female

Basis for effect level:

other: no adverse effects at highest dose tested

Abnormalities:

no effects observed

Developmental effects observed:

no

Data source

Reference

Reference Type:

study report

Title:

Unnamed

Year:

1983

Report date:

1983

Materials and methods

Test guideline

Qualifier:

according to guideline

Guideline:

OECD Guideline 414 (Prenatal Developmental Toxicity Study)

Deviations:

no

GLP compliance:

yes

Limit test:

yes

Test material

Test material information

Constituent 1

Reference substance name:

N,N'-hexane-1,6-diylbis[3-(3,5-di-tert-butyl-4-hydroxyphenylpropionamide]

EC Number:

245-442-7

EC Name:

N,N'-hexane-1,6-diylbis[3-(3,5-di-tert-butyl-4-hydroxyphenylpropionamide]

Cas Number:

23128-74-7

Molecular formula:

C40H64N2O4

IUPAC Name:

N,N'-hexane-1,6-diylbis[3-(3,5-di-tert-butyl-4-hydroxyphenyl)propanamide]

Test material form:

not specified

Details on test material:

- Purity: Commercial grade

Test animals

Species:

rabbit

Strain:

New Zealand White

Details on test animals or test system and environmental conditions:

TEST ANIMALS
- Source: Cheshire Rabbit Farms, Ranch Rabbits, and Buxted Rabbit Co. Ltd.
- Weight at study initiation: 3.5 to 4.6 kg (preliminary study), 2.8 to 3.6 kg (teratogenicity study)
- Housing: Housed individually in metal cages equipped with sheet stainless steel sides, back and top, a stainless steel wire front and an aluminium perforated floor panel. Individual undercage plastic trays were lined with absorbent paper, which was inspected and changed daily.
- Diet: ad libitum
- Water: ad libitum
- Acclimation period: At least 10 days

ENVIRONMENTAL CONDITIONS
- Temperature (°C): 18 ± 3
- Humidity (%): 55 ± 15
- Photoperiod: Natural lighting in the room was supplemented by artificial light between 7.00 am and 9.00 pm

Administration / exposure

Route of administration:

oral: gavage

Vehicle:

other: 1% methylcellulose

Details on exposure:

PREPARATION OF DOSING SOLUTIONS: The highest required concentration of suspension was prepared by trituration of weighed compound with vehicle using a mortar and pestle to form a smooth mixture, then addition of further vehicle to required volume. Further mixing was carried out using a "Silverson" Laboratory mixer. The lower concentrations were prepared by serial dilution with the vehicle. The suspensions were prepared freshly each day.

VEHICLE
- Concentration in vehicle: 5, 10, 20% w/v
- Amount of vehicle: 10 mL/kg

Analytical verification of doses or concentrations:

no

Details on mating procedure:

Does were mated with males of proven fertility; once coitus had been observed, each female was allowed to remain with the male for at least one hour. Seventy-two of those dams which successfully completed coitus were each injected intravenously with 25 i.u. of Chorulon® (luteinizing hormone) to promote ovulation. The day of mating was considered as Day 0 of pregnancy. Mating was phased over consecutive week days ensuring that no more than 16 animals were mated on any one day.

Duration of treatment / exposure:

GD 7 to 19

Frequency of treatment:

Once daily

Doses / concentrations

Doses / concentrations 1

Dose / conc.:

500 mg/kg bw/day (nominal)

Doses / concentrations 2

Dose / conc.:

1 000 mg/kg bw/day (nominal)

Doses / concentrations 3

Dose / conc.:

2 000 mg/kg bw/day (nominal)

No. of animals per sex per dose:

Control, 500 mg/kg groups: 18
1000 mg/kg group: 19
2000 mg/kg group: 17

Control animals:

yes, concurrent vehicle

Details on study design:

- Dose selection rationale: Dosages were based on a prior preliminary study (0, 100, 500, and 2000 mg/kg/day).
Results from preliminary study: At the maximum practical dosage of 2000 mg/kg/day animals showed pale discolouration of faeces and slightly lower mean bodyweight gain. There were no other signs of reaction considered attributable to treatment. No treatment related deaths were observed. Mean food consumption at 2000 mg/kg/day was consistently marginally lower than among control animals. There were no macroscopic findings at terminal autopsy that appeared attributable to treatment.
- Rationale for animal assignment: Mating was phased over consecutive week days ensuring that no more than 16 animals were mated on any one day. On each of these days, mated does were allocated to four groups equalising distribution as far as possible, as to number allocated, source of animals and male to which they were mated. Following allocation, does were re-assigned to cages in the experimental room.

Examinations

Maternal examinations:

CAGE SIDE OBSERVATIONS:
- Time schedule: All animals were regularly handled and observed daily. Obvious changes or signs of reaction to treatment were recorded. Any animals that died or were killed for reasons of animal welfare were weighed and subjected to post mortem.

BODY WEIGHT:
- Time schedule for examinations: All rabits were weighed on Days 1, 7, 9, 11, 15, 20, 24, and 29 of gestation.

FOOD CONSUMPTION: The food intake of all rabbits was measured from weigh-day to weigh-day.

Ovaries and uterine content:

On Day 29 of pregnancy the animals were killed by cervical dislocation, dissected and examined for congenital abnormalities and macroscopic pathological changes in maternal organs; the ovaries and uteri were examined immediately to determine:
(a) number of corpora lutea
(b) number and distribution of live young
(c) number and distribution of embryonic/foetal deaths
(d) individual foetal weights
(e) foetal abnormalities

Fetal examinations:

- External examinations: Yes
- Soft tissue examinations: Yes
- Skeletal examinations: Yes
- Head examinations: Yes

Statistics:

Statistical analyses were performed routinely on litter data and incidences of skeletal anomalies and skeletal variants using the litter as the basic sample unit. Non-parametric methods (Kruskal-Wallis and Jonckheere tests) were employed since these values rarely follow a normal distribution.

Results and discussion

Results: maternal animals

General toxicity (maternal animals)

Clinical signs:

effects observed, treatment-related

Description (incidence and severity):

The majority of animals at 2000 mg/kg/day showed pale discolouration of faeces throughout the treatment period. At 1000 mg/kg/day approximately half of the animals occasionally showed pale discolouration of faeces during the treatment period. There were no other signs of reaction considered attributable to treatment.

Mortality:

mortality observed, non-treatment-related

Description (incidence):

Single dosed animals at 500 and 2000 mg/kg/day, and one in the control group died or were killed. No treatment relationship was considered to be indicated.

Body weight and weight changes:

effects observed, non-treatment-related

Description (incidence and severity):

Intergroup variation in bodyweight gain generally appeared unrelated to dosage, although at all dosages mean gain during the first two days of treatment was slightly lower than among control animals. Overall weight gain at 1000 and to a lesser extent 2000 mg/kg/day was greater than that of control animals.

Food consumption and compound intake (if feeding study):

effects observed, non-treatment-related

Description (incidence and severity):

At all dosages mean food consumption during the first four days of the dosing period was similar to that of control animals. Thereafter individual mean test group values tended to be higher than, or similar to, those of control animals.

Gross pathological findings:

effects observed, non-treatment-related

Description (incidence and severity):

There were no macroscopic findings at terminal autopsy that were considered attributable to treatment.

Details on results:

Pregnancy rate, as judged by the numbers of animals pregnant at termination, was high in all groups.

Maternal developmental toxicity

Number of abortions:

no effects observed

Pre- and post-implantation loss:

effects observed, non-treatment-related

Description (incidence and severity):

Intergroup differences among mean values for litter size, and pre- and post implantation loss were not statistically significant (P >0.05).

Total litter losses by resorption:

no effects observed

Early or late resorptions:

no effects observed

Description (incidence and severity):

A single animal, from the control group, showed total litter loss.

Dead fetuses:

no effects observed

Changes in number of pregnant:

no effects observed

Effect levels (maternal animals)

Key result

Dose descriptor:

NOAEL

Effect level:

2 000 mg/kg bw/day

Based on:

test mat.

Basis for effect level:

other: no adverse effects at highest dose tested

Maternal abnormalities

Key result

Abnormalities:

no effects observed

Results (fetuses)

Fetal body weight changes:

no effects observed

Changes in litter size and weights:

no effects observed

External malformations:

effects observed, non-treatment-related

Description (incidence and severity):

The incidence of malformed foetuses appeared unaffected by treatment; although the incidence at 500 mg/kg/day was higher than in the control group, the incidence at 1000 mg/kg/day was lower, and at 2000 mg/kg/day no malformations were observed.

Skeletal malformations:

effects observed, non-treatment-related

Description (incidence and severity):

Incidences skeletal anomalies were not adversely affected at any dosage and the only differences to be statistically significantly (P <0.05) related to lower incidences of skeletal anomalies at 500 and 2000 mg/kg/day. At all dosages the incidence of foetuses with extra thoracolumbar rib and of foetuses with variant sternebrae tended to be similar to the control incidence; there were no statistically significant differences (P >0.05).

Visceral malformations:

no effects observed

Effect levels (fetuses)

Key result

Dose descriptor:

NOAEL

Effect level:

2 000 mg/kg bw/day

Based on:

test mat.

Basis for effect level:

other: no adverse effects at highest dose tested

Fetal abnormalities

Key result

Abnormalities:

no effects observed

Overall developmental toxicity

Developmental effects observed:

no

Applicant's summary and conclusion

Conclusions:

There were no adverse effects on maternal toxicity, litter parameters, incidences of malformations, visceral and skeletal anomalies, and skeletal variants up to the highest dose tested.

Executive summary:

In this assessment of the effect of the test substance on pregnancy of the rabbit, daily dosages of 0, 500, 1000 and 2000 mg/kg were administered by intragastric intubation during Days 7 to 19 inclusive of pregnancy. This study was conducted following OECD Guideline 414. On Day 29, animals were killed, litter values determined and fetuses examined for visceral and skeletal abnormality.

Dosages were based on a prior preliminary study in which at the maximum practical dosage of 2000 mg/kg/day animals showed pale discolouration of faeces and slightly lower mean bodyweight gain. In the main study, animals dosed at 2000 mg/kg/day, and to a lesser extent at 1000 mg/kg/day, showed pale discolouration of the faeces during the treatment period. There were no adverse effect on mean food consumption or weight gain that was clearly attributable to treatment and overall weight gain at 1000 mg/kg/day, and to a lesser extent at 2000 mg/kg/day, was greater than for control animals. There was no adverse effect on litter parameters as assessed by mean values for litter size, pre- and post implantation loss, and litter and mean foetal weight. Incidences of malformations, visceral and skeletal anomalies and skeletal variants were not adversely affected by treatment.