Epidemiology human genotoxicity

Valid epidemiological studies are preferable for the quantitative risk assessment of genotoxic carcinogens for the purpose of deriving a tolerable intake. If such data are available, for example in the working environment, they can be used quantitatively to convert work exposure to lifetime exposure, i.e., to convert intermittent exposure to continuous exposure (see Section 5.1 for adjustment of concentrations). However, as addressed in Chapter 3, valid human data are seldom available. 

There have been many epidemiological studies on coffee intake and human cancer. Since we have indentified one of major genotoxic substance in coffee, thorough experimental studies are urgently required to evaluate the hazards of coffee. 

Based on the available human and animal data, the subcommittee concluded that inhalation of JP-5, JP-8, and DFM vapors does not present a carcinogenic risk to humans. That conclusion is supported by studies that show that these military fuels are not genotoxic. However, laboratory studies provided evidence of potential carcinogenicity of DFM via the dermal route. Epidemiological studies show skin-cancer excesses in certain industrial workers, such as machine operators, whose skin might come into contact with lubricating oils derived from coal tar or petroleum. Exposure conditions in the studies that resulted in excessive skin damage are unlikely to occur on Navy ships. 

Promoters and carcinogens involved in human cancer induction were first discovered through carefully conducted epidemiological studies, and then tested in animal models or in in vitro systems. Newer techniques use exfoliated cells or cells in culture to ascertain exposure to these genotoxic materials. ... 

With regard to human health effects of MBOCA, the few available studies were either case reports of acute occupational exposure or involved intermediate or chronic epidemiological studies. Acute exposures to MBOCA were by the inhalation, oral, or dermal routes, although in some studies it was difficult to clearly define the exposure route. Intermediate exposures were by either inhalation and/or dermal contact no intermediate oral exposure studies were located. Chronic exposure in humans occurred by inhalation and/or dermal contact no chronic oral studies were located. No information is available regarding immunological, neurologic, reproductive, developmental, or genotoxic effect in humans by any route of exposure. Studies on cancer incidence in humans after inhalation and/or dermal exposure to MBOCA were located. 

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