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Reverse Mutation Study (AMES).

The method was designed to meet the requirements of the OECD Guidelines for Testing of Chemicals No. 471 "Reverse Mutation Study", Method B14 of Commission Directive 92/69/EEC and the USA, EPA (TSCA) OPPTS harrnonised guidelines.

The test material was considered to be non-mutagenic under the conditions of this test.

Genetic toxicity in vitro. Chromosome aberration.

This report describes the results of an in vitro study for the detection of structural chromosomal aberrations in cultured mammalian cells. It supplements microbial systems insofar as it identifies potential mutagens which produce chromosomal aberrations rather than gene mutations (Scott et aI, 1990). The method used followed that described in the DECD Guidelines for Testing of Chemicals (1997) No. 473 "Genetic Toxicology: Chromosome Aberration Test" and Method Bl0 of Commission Directive 92/69/EEC. The study design also meets the requirements of the UK Department of Health Committee on Mutagenicity Guidelines for the Mutagenicity Testing of Chemicals.

The test material was shown to be non-clastogenic to human lymphocytes in vitro.

Genetic toxicity in vitro. CHO HPRT FORWARD MUTATION ASSAY.

The objective of this in vitro assay was to evaluate the ability of NBPT, N-(n-butyl) thiophosphoric triamide, to induce forward mutations at the hypoxanthine- guanine phosphoribosyl transferase (HGPRT) locus in Chinese hamster ovary cells under conditions with and without metabolic activation.

The protocol used was similar to the OECD Guidelines for Testing of Chemicals No. 476 'In Vitro Mammalian Cell Gene Mutation Tests', Commission Regulation (EC) No. 440/2008 and the United Kingdom Environmental Mutagen Society (Coleet al, 1990). The technique used is a plate assay using tissue culture flasks and 6-thioguanine (6­TG) as the selective agent.

The test material, NBPT, is considered negative for inducing forward mutations at the HGPRT locus in Chinese hamster ovary cells under both the S9 metabolic activation and nonactivation conditions of the assay.

Genetic toxicity in vivo. Micronucleus Test in the Mouse

The objective of this in vivo assay was to evaluate the ability of the test article, NBPT, to induce micronuclei in bone marrow polychromatic erythrocytes of ICR mice. This study was conducted using modifications of the procedures suggested by Heddle et al. (1983).

The test material, NBPT, did not induce a significant increase in micronuclei in bone marrow polychromatic erythrocytes under the conditions of this assay and is considered negative in the mouse bone marrow micronucleus test.


Short description of key information:
The submission substance is considered non-classified with regards to mammalian genotoxicity.

Endpoint Conclusion: No adverse effect observed (negative)

Justification for classification or non-classification

The submission substnce is considered non-classified with regards to mammalian genotoxicity.