reaction mass of isomers of: C7-9-alkyl 3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate

Endpoint summary

Key value for chemical safety assessment

Genetic toxicity in vivo

Description of key information

The substance was not mutagenic in bacteria (OECD 471, GLP) and not clastogenic in CHO cells (OECD 473, GLP). It was not genotoxic in the micronucleus assay in Chinese hamsters (OECD 474, GLP).

Link to relevant study records

Reference

Endpoint:

in vivo mammalian somatic cell study: cytogenicity / erythrocyte micronucleus

Remarks:

Type of genotoxicity: gene mutation

Type of information:

experimental study

Adequacy of study:

key study

Study period:

From July 03rd, 1989 to November 01st, 1989

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

other: Study performed according to international guidelines and GLP.

Qualifier:

according to guideline

Guideline:

OECD Guideline 474 (Mammalian Erythrocyte Micronucleus Test)

Deviations:

no

Qualifier:

according to guideline

Guideline:

EU Method B.12 (Mutagenicity - In Vivo Mammalian Erythrocyte Micronucleus Test)

Version / remarks:

Official Journal of the European Communities No L 251 137-139

Deviations:

no

Qualifier:

according to guideline

Guideline:

EPA OTS 798.5395 (In Vivo Mammalian Cytogenics Tests: Erythrocyte Micronucleus Assay)

Version / remarks:

Guidelines 52 FR 19080 (May 20, 1987; effective June 19, 1987), 798.5395.

Deviations:

no

GLP compliance:

yes

Type of assay:

micronucleus assay

Species:

hamster, Chinese

Strain:

other: Chinese hamster (Cricetulus griseus) random outbred strain

Sex:

male/female

Details on test animals or test system and environmental conditions:

TEST ANIMALS
- Strain as cited inthe reported: Chinese hamster (Cricetulus griseus) random outbred strain
- Source: CIBA-GEIGY Tierfarm, Sisseln.
- Weights at test initiation:
- tolerability test: females 27-33 g, males 31-33 g
- mutagenicity test: females 23-33 g, males 26-33 g
- Days of acclimatization: at least 3 days
- Diet: standard diet NAFAG No.924, ad libitum
- Water: tap water ad libitum

ENVIRONMENTAL CONDITIONS
- Temperature (°C): 21-23°C
- Humidity (%): 58-75%
- Air changes (per hr): air-conditioned room, no further details
- Photoperiod (hrs dark / hrs light): 12 hrs/12 hrs

Route of administration:

oral: gavage

Vehicle:

Klucel 0.5%

Duration of treatment / exposure:

The animals were sacrificed after 16, 24 and 48 hours post treatment

Frequency of treatment:

Single administration by gavage

Post exposure period:

16, 24 and 48 hours (8 female and 8 male animals per sampling time point were sacrificed)

Remarks:

Doses / Concentrations:
5000 mg/kg bw
Basis:
nominal conc.

No. of animals per sex per dose:

8

Control animals:

yes, concurrent vehicle

Positive control(s):

64 mg/kg bw Cyclophosphamide in 20 mL/kg Klucel 0.5% served for positive control substance. the animals were sacrificed after 24 hours following treatment.

Tissues and cell types examined:

Bone marrow smears.

Details of tissue and slide preparation:

Following sacrifice of the animals, bone marrow was harvested from the shafts of both femurs with fetal calf serum. After centrifugation small drops of the sediment mixture were transferred on the end of a slide, spread out with the aid of a polished cover glass and the preparations were air-dried. Within 24 hours, the slides were stained with undiluted May-Grünwald solution for 3 minutes and then with May-Grünwald solution/water (1:1) for 2 minutes. After being rinsed in distilled water, the slides were left immersed in diluted Giemsa solution (16.6%), for 10 miniutes. After rinsing with distilled water and air-drying, the slides were cleared in Xylene and mounted.
The slides of five animals from each sex showing the best differentiation between mature and polychromatic erythrocytes were selected for scoring. The slides of five female and five male animals each of the negative control group and of the dosage group sacrificed at 16, 24 and 48 hours post-treatment were examined. From the animals of the positive control group which were sacrificed 24 hours after application, the slides of five female and five male animals were scored. 1000 polychromatic erythrocytes per animal each were scored for the incidence of micronuclei. To determine the mitotic activity of the red compartment, the ratio of polychromatic to normochromatic erythrocytes was calculated for each animal by counting a total of 1000 erythrocytes. A low proportion of polychromatic erythrocytes was indicative for a mitosis inhibiting activity of the test substance.

Evaluation criteria:

A test substance is considered to be active in this test system if a statistically significant increase in the number of polychromatic erythrocytes with micronuclei in comparison with the negative control occurs at any sampling time.

Statistics:

Chi-squared test.

Sex:

male/female

Genotoxicity:

negative

Remarks:

There was no significant increase in the number of micronucleated polychromatic erythrocytes in the animals treated with 5000 mg/kg bw of the test item as compared with the negative control animals at all sampling times.

Toxicity:

yes

Remarks:

one case of mortality (male) was reported in the treatment group of 48 hours.

Vehicle controls validity:

valid

Negative controls validity:

valid

Positive controls validity:

valid

Additional information on results:

Tolerability test:
In the tolerability test the maximum dose of 5000 mg/kg bw caused no death in a group of four animals. Therefore, this dose was taken as the highest in the mutagenicity test.
Mutagenicity test:
The mutagenicity test was performed with the dosage of 5000 mg/kg bw.
One male animal died in the treatment group of 48 hours. The animals were treated once with 5000 mg/kg bw test material and bone marrow was harvested 16, 24 and 48 hours thereafter. There was no significant increase in the number of micronucleated polychromatic erythrocytes in the animals treated with the dose of 5000 mg/kg bw of test material as compared with the negative control animals at all three sampling times.
By contrast, the positive control (cyclophosphamide, 64 mg/kg bw, sampling time 24 hours) yielded a marked increase of the percentage of micronucleated cells. Here the mean percentage of polychromatic erythrocytes with micronuclei was 2.0. In comparison with the negative control (0.03 %) this value is highly significant (p <0.05).

Conclusions:

Interpretation of results (migrated information): negative
The test item was tested in an in vivo micronucleus test (MNT) according to the OECD TG 474 (1983) using Chinese hamster. No evidence of mutagenic effects was obtained in Chinese hamsters treatedby gavage with 5000 mg/kg bw test material.

Executive summary:

The test article was tested in an in vivo micronucleus test (MNT) according to the OECD TG 474 (1983) using Chinese hamster. The test item was administered by single gavage at a dose of 5000 mg/kg bw, which had been selected based on a preliminary tolerability test. The treated animals were sacrificed 16, 24 and 48 hours thereafter. From the bone marrow smears were made and evaluation of any mutagenic effect of the test item on polychromatic erythrocytes as manifested by micronuclei was done.

At all three sampling times, no statistically significant increase in the number of micronucleated polychromatic erythrocytes in comparison with the negative control animals could be evidenced. The respective positive control with cyclophosphamide (64 mg/kg bw) yielded an average of 2.0% polychromatic erythrocytes with micronuclei. This was significantly different from the negative vehicle controls (0.03%). It is concluded that no evidence of mutagenic effects was obtained in Chinese hamsters treated with the test article in the MNT.

Endpoint conclusion

Endpoint conclusion:

no adverse effect observed (negative)

Additional information

Additional information from genetic toxicity in vivo:

Ames test

In the presence and absence of rat liver S-9-microsomal activation system and at doses of 313-5'000 micrograms per plate, S-typhimurium strains TA 98, TA 100, TA 1535, and TA 1537 as well as E. coli strain WP2uvrA were tested for the induction of base-pair substitutions and frameshift mutations. The study was performed according to OECD testing guideline 471 and under GLP. No evidence of a mutagenic potential associated with the test substance was observed (Ciba-Geigy, 1989).

 

Chromosome Aberration

Chinese hamster ovary cells were treated in vitro at concentrations up to 1000 µg/ml with and without microsomal ac­tivation. The treat­ments lasted with microsomal activation for 3 hours and the expression periods were 15 hours and 39 hours (treatment periods not included). In the experiment without microsomal acti­vation the combined treatment and expression periods lasted for 18 and 42 hours. The analysis of the metaphases from tests with and without microsomal activation re­vealed no evidence for a clastogenic effect. The procedure followed OECD Guideline 473 and the principles of GLP (Ciba-Geigy, 1993)

In vivo micronucleus test

The substance was administered orally to groups of 24 female and 24 male animals each in the negative and in the 5'000 mg/kg dose group. The positive control group consisted of 8 female and 8 male animals. Treatment occurred in a single application. 16, 24 and 48 hours after application 8 female and 8 male animals per sampling time were sacrificed and bone-marrow smears were prepared. The procedure followed OECD Guideline 474 and the principles of GLP. No evidence of a mutagenic potential associated with the test substance was observed (Ciba-Geigy, 1989).

Justification for selection of genetic toxicity endpoint
GLP-compliant in vivo study following OECD test guideline.

Justification for classification or non-classification

Dangerous Substance Directive (67/548/EEC)

The available studies are considered reliable and suitable for classification purposes under 67/548/EEC. As a result the substance is not considered to be classified for mutagenicity under Directive 67/548/EEC.

Classification, Labelling, and Packaging Regulation (EC) No. 1272/2008

The available experimental test data are reliable and suitable for classification purposes under Regulation 1272/2008. As a result the substance is not considered to be classified for mutagenicity under Regulation (EC) No. 1272/2008.