Studies on mutagenesis in vitro by agents that generate oxygen free radicals have used both reversion assays (Loeb, et al., 1988; Cheng, et al., 1991; and for ward mutation assays (McBride et al., 1991). Reversion assays measure the frequency and types of mutations at a defined mutant locus on a DNA molecule. Forward mutation [...]
While damage of cellular DNA by environmental chemicals has been shown to be a key causal event in the etiology of certain human cancers, there are endogenous cellular processes that also damage DNA. These endogenous processes could contribute to spontaneous mutagenesis and might also be carcinogenic (Loeb, 1989). Many processes that damage DNA and [...]
Based predominately on epidemiological studies, only a small number of chemicals have been identified definitively as human carcinogens. For the most part, individuals exposed to high concentrations of these particular chemicals have exhibited an unusually high incidence of a specific tumor. There is increasing evidence that human cancers are causally associated with mutations in [...]