Talc did not induce dominant lethal mutations or chromosomal aberrations in bone- marrow cells of rats treated in vivo, or chromosomal aberrations in human cells in vitro. Talc was not mutagenic to yeast or to bacteria in a host-mediated assay3

A. Evidence for carcinogenicity to humans (inadequate) The epidemiological studies and case reports considered with regard to producers and users of 2,4,5-trichlorophenol and 2,4,5-trichlorophenoxyacetic acid (2,4,5T) (see also summaries on chlorophenols and chlorophenoxy herbicides, pp. 154 and 156) also relate to TCDD exposure, since those products may contain TCDD as an impurity. Only studies of particular relevance to TCDD exposure are considered here. Aggregation of six relatively small cohortsl-6 shows 37 deaths from cancer, with 33.3 expected, among 956 men likely to have been exposed to TCDD during the manufacture or