Cancer risk assessment carcinogens

The carcinogenic potential of the profiled substance is qualitatively evaluated, when appropriate, using existing toxicokinetic, genotoxic, and carcinogenic data. ATSDR does not currently assess cancer potency or perform cancer risk assessments. Minimal risk levels (MRLs) for noncancer end points (if derived) and the end points from which they were derived are indicated and discussed. 

This study, like that of Fisher and Allen (1993), incorporated a linear multistage model. However, the mechanism of trichloroethylene carcinogenicity appears to be non-genotoxic, and a non-linear model (as opposed to the linearized multistage model) has been proposed for use along with PBPK modeling for cancer risk assessment. The use of this non-linear model has resulted in a 100-fold increase in the virtually safe lifetime exposure estimates (Clewell et al. 1995). 

Littlefield, N. A., Farmer, J. H., Gaylor, D. W. and Sheldon, W. G. (1979). Effects of dose and time in a long-term, low-dose carcinogenic study. In Innovations in Cancer Risk Assessment (EDOlStudy) (Staffa, J.A. and Mehlman, M.A. Eds.). Pathotox Publishers, Chicago, IL, pp. 17-34. 

Cancer risk assessment is basically a two-step procedure, involving a qualitative assessment of how likely it is that a compound is a human carcinogen, and a quantitative assessment of the cancer risk that is likely to occur at given exposure levels and duration of exposure. 

The following overview of the US-EPA revised quantitative approach for cancer risk assessment is based on the final version of the Guidelines for Carcinogen Risk Assessment (US-EPA 2005). 

Woo, Y.-T. and Lai, D.Y., (2010) QSAR analysis of genotoxic and nongenotoxic carcinogens a state-of-the-art overview, in Cancer Risk Assessment Chemical Carcinogenesis from Biology to Standards Quantification (eds G. Hsu and T. Stedeford), John Wiley and Sons, Ltd., Hoboken, N.J., pp. 517-556. 

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