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Key value for chemical safety assessment

Additional information

Thiram was evaluated for possible mutagenic/genotoxic effects in in-vitro test systems using bacterial and mammalian cells and in in-vivo test systems using mice.

In the bacterial revertant assay, employing the standard plate test, thiram was positive in the presence or absence of metabolic activation in S. typhimurium strains, TA 100 and TA 1535. When tested for mutagenicity in mammalian cells, thiram showed no genotoxic potential.

In the in-vitro UDS assay to assess DNA damage in freshly isolated primary rat hepatocytes thiram did not induce unscheduled DNA synthesis even at concentration being cytotoxic as demonstrated by the net nuclear grain count and the percentage of nuclei with more than 6 or 20 grains.

Thiram did not induce micronuclei in bone marrow polychromatic erythrocytes in male and female CD-1 mice. Furthermore, in the in-vivo gene mutation test (mouse spot test) and chromosome aberration test with mouse germ cells (spermatogonia) test performed in mice, thiram revealed no mutagenic capacities.

Overall, it can be concluded that thiram is not genotoxic in-vivo.

Classification for mutagenicity: None.


Short description of key information:
Thiram was mutagenic in bacteria, but negative in mammalian test systems, including in-vivo assays.

Endpoint Conclusion: No adverse effect observed (negative)

Justification for classification or non-classification

see discussion