Benzenamine, N-phenyl-, reaction products with styrene and 2,4,4-trimethylpentene

Toxicity to reproduction

Administrative data

Endpoint:

screening for reproductive / developmental toxicity

Type of information:

experimental study

Adequacy of study:

key study

Study period:

2006

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Cross-reference

Reason / purpose for cross-reference:

reference to other study

Data source

Reference

Reference Type:

other: SIDS Dossier data

Title:

Unnamed

Year:

2006

Report date:

2003

Materials and methods

Test guideline

Qualifier:

according to guideline

Guideline:

OECD Guideline 422 (Combined Repeated Dose Toxicity Study with the Reproduction / Developmental Toxicity Screening Test)

Deviations:

not specified

GLP compliance:

yes

Limit test:

no

Test material

Test material information

Constituent 1

Reference substance name:

68442-68-2

Cas Number:

68442-68-2

IUPAC Name:

68442-68-2

Test material form:

liquid: viscous

Details on test material:

CAS No: 68442-68-2
EINECS No: 270-485-3
EINECS Name: Benzenamine, N-phenyl-, styrenated
CAS Name: Benzenamine, N-phenyl-, styrenated
Substance type: organic
Physical status: liquid
Purity: > 98 % w/w
Result: Molecular weight: 320

Test animals

Species:

rat

Strain:

other: Crl:CD® (SD) IGS BR

Sex:

male/female

Details on test animals or test system and environmental conditions:

Not specified

Administration / exposure

Route of administration:

oral: gavage

Vehicle:

corn oil

Details on exposure:

The test material was administered by gavage to three groups each of ten male and ten female Sprague-Dawley Crl:CD® (SD) IGS BR strain rats, for up to fifty-four consecutive days, at dose levels of 50, 250 and 600 mg/kg/day. A control group of ten males and ten females was dosed with vehicle alone (corn oil).

Details on mating procedure:

Pairing of animals within each dose group was undertaken on a one male:one female basis on Day 15 of the study, to produce litters. The presence of sperm within the vaginal smear and/or vaginal plug in situ was taken as positive evidence of mating.

Analytical verification of doses or concentrations:

not specified

Details on analytical verification of doses or concentrations:

Not specified from the OECD SIDS documentation.

Duration of treatment / exposure:

14 days prior to mating, throughout mating and gestation and continuing through lactation day 3. Equates to:
Males: 43 days; Females: up to 54 days

Frequency of treatment:

daily

Details on study schedule:

Pairing of animals within each dose group was undertaken on a one male:one female basis on Day 15 of the study, to produce litters.

Doses / concentrations

Remarks:

Doses / Concentrations:
0, 50, 250 and 600 mg/kg/day
Basis:
actual ingested

No. of animals per sex per dose:

Ten males and ten females per dose.

Control animals:

yes, concurrent vehicle

Details on study design:

Not specified

Positive control:

Not specified

Examinations

Parental animals: Observations and examinations:

Clinical signs, behavioural assessments, bodyweight development, food and water consumption were monitored during the study. Haematology and blood chemistry were evaluated prior to mating on five selected males and females from each dose group.
Extensive functional observations were performed on five selected parental males from each dose group after the completion of the mating phase, and for five selected parental females rom each dose group on Day 4 post partum.

Pregnancy and parturition: The following was recorded for each female:
i) Date of mating
jj) Date and time of observed start of parturition
iii) Date and time of observed completion of parturition
iv) Duration of gestation

Oestrous cyclicity (parental animals):

Not specified

Sperm parameters (parental animals):

Not specified

Litter observations:

Daily clinical observations were performed on all surviving offspring, together with litter size and offspring weights and assessment of developmental landmarks.

Postmortem examinations (parental animals):

Males were terminated on Day 43, followed by the termination of all surviving females and offspring on Day 5 post partum. All animals were subjected to a gross necropsy examination and histopathological evaluation of selected tissues was performed.

Postmortem examinations (offspring):

Not specified

Statistics:

Not specified

Reproductive indices:

Not specified

Offspring viability indices:

Not specified

Results and discussion

Results: P0 (first parental generation)

General toxicity (P0)

Clinical signs:

no effects observed

Body weight and weight changes:

no effects observed

Food consumption and compound intake (if feeding study):

no effects observed

Organ weight findings including organ / body weight ratios:

effects observed, treatment-related

Histopathological findings: non-neoplastic:

effects observed, treatment-related

Description (incidence and severity):

liver and thyroid gland

Other effects:

not examined

Reproductive function / performance (P0)

Reproductive function: oestrous cycle:

not examined

Reproductive function: sperm measures:

not examined

Reproductive performance:

no effects observed

Details on results (P0)

Mortality: No treatment-related deaths were detected.
Clinical Observations: No clinically observable signs of toxicity were detected.
Behavioural Assessments: No treatment-related effects were detected.
Functional Performance Tests: No treatment-related effects were detected.
Sensory reactivity Assessments: No treatment-related effects were detected.
Bodyweights: No adverse effect on bodyweight was observed for males throughout the treatment period, or for females during the maturation, gestation or lactation phases of the study.
Food Consumption: No adverse effect on dietary intake was detected for males throughout the treatment period, or for females during the maturation, gestation or lactation phases of the study.
Water Consumption: No overt intergroup differences were detected. Haematology: No treatment-related changes were detected prior to mating.
Blood Chemistry: Elevated alkaline phosphatase levels were detected for males treated with 600 mg/kg/day. Males treated with 600 and 250 mg/kg/day also showed reduced cholesterol levels. No such effects were detected for females treated with 600 or 250 mg/kg/day or for animals of either sex treated with 50 mg/kg/day.
Necropsy of Adults: No treatment-related macroscopic abnormalities were detected for the interim death female or for the remaining animals at terminal kill.
Organ Weights: Elevated liver and adrenal weights, both absolute and relative to terminal bodyweights, were detected for animals of either sex treated with 600 mg/kg/day.
Histopathology: Histopathological examination of adult tissue revealed the following treatment-related changes:
Liver: Centrilobular hepatocyte enlargement was observed for animals of either sex treated with 600 and 250 mg/g/day, with the effect extending into the female 50 mg/kg/day dose group.
Thyroid glands: Follicular cell hypertrophy was observed for males treated with 600 and probably also at 250 mg/kg/day. No such effects were detected for females at these dose levels, or for animals of either sex treated with 50 mg/kg/day.
Mating: No adverse effects on mating performance, fertility or gestation were detected.

Effect levels (P0)

Key result

Dose descriptor:

NOAEL

Effect level:

250 mg/kg bw/day (actual dose received)

Based on:

test mat.

Sex:

male/female

Basis for effect level:

organ weights and organ / body weight ratios

histopathology: non-neoplastic

Results: F1 generation

General toxicity (F1)

Clinical signs:

not examined

Mortality / viability:

mortality observed, treatment-related

Description (incidence and severity):

see Details on results (offspring)

Body weight and weight changes:

no effects observed

Sexual maturation:

not examined

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)

Developmental Screening:
Litter Observations: There were no clinical signs to suggest an effect of treatment.
Offspring Viability: Mean offspring weights for treated animals were comparable to controls.
Offspring Development: Offspring from the 600 mg/kg/day dose group showed less successful completion of surface righting assessments. There were no treatment-related differences in pinna unfolding.
Necropsy of Offspring: No treatment-related macroscopic abnormalities were detected for the interim death offspring or for the remaining offspring at terminal kill.

Effect levels (F1)

Key result

Dose descriptor:

NOAEL

Generation:

F1

Effect level:

250 mg/kg bw/day (actual dose received)

Based on:

test mat.

Sex:

male/female

Basis for effect level:

other: Increase in pre-implantation losses

Overall reproductive toxicity

Reproductive effects observed:

not specified

Applicant's summary and conclusion

Conclusions:

The NOAEL for reproductive toxicity was therefore considered to be 250 mg/kg/day.

Executive summary:

Study conducted to OECD test guidance in compliance with GLP. Data included for OECD SIDS dossier. Treatment-related effects on reproduction were observed at 600 mg/kg/day. These were confined to an increase in pre-implantation losses, resulting in lower offspring numbers at this dose level. The NOAEL for reproductive toxicity was therefore considered to be 250 mg/kg/day. Read across to supporting substance, CAS No. 68442 -68 -2, by structural analogue.

This substance has been supported under Environmental Protection Agency’s (EPA’s) High Production Volume (HPV) Challenge Program. The American Chemical Councils RAPA Panel, has derived a “Substituted Diphenylamines” category of chemicals for this substance, please refer to EPA reference 201-14700A located at

 

http://www.epa.gov/hpv/pubs/summaries/subdipha/c13378rt.pdf

 

Relying on several factors specified in EPA’s guidance document on “Development of Chemical Categories in the HPV Challenge Program,” in which use of chemical categories is encouraged, the chemicals constitute a chemical category on the following basis:

 

Structural Similarity. A key factor supporting the classification of these chemicals as a category is their structural similarity (see Figure 1). All share a common starting material; Diphenylamine (Benzenamine, N-phenyl-, CAS# 122-39-4), a common synthetic pathway, and all compounds in this category are diamines with various substitutions.

 

Similarity of Physicochemical Properties. The similarity of the physicochemical properties of these materials parallels their structural similarity. All are off-white to light brown solids or viscous liquids intended for use as antioxidants in finished rubber articles or as antidegradant additives that extend the useful life of heavy-duty industrial functional fluids used in high-speed, high-temperature and/or high-load applications. As a class, these amine-based antidegradant compounds are less migratory (more polymer-bound) and less staining than the Substituted p-Phenylenediamine antidegradants. The use of these materials requires that they be stable under high temperatures. Their low volatility is due to their low vapor pressure, highly viscous or solid form. The existing information for these materials indicates that they have low water solubility and high flash points.

 

Toxicological Similarity. Review of existing published and unpublished test data for Substituted Diphenylamines shows the aquatic and mammalian toxicity among the materials within this category are similar.

 

Mammalian Toxicology - Reproductive and Developmental Toxicity. Data from reproductive and developmental toxicity studies were reviewed. Sufficient data are not available to adequately represent the Substituted Diphenylamines for the purposes of the HPV Program, and additional testing is proposed, and additional testing is proposed. It is proposed to test the smallest aryl- and akyl-substituted materials.

 

Conclusion. Based upon the data reviewed in “Substituted Diphenylamines” category of chemicals, the physicochemical and toxicological properties of the Substituted Diphenylamine category members are similar and follow a regular pattern as a result of that structural similarity. Therefore, the definition of a chemical category has been met, and read across is considered appropriate for the category of chemical.