In practice, mainly 2 of the mathematical models shown in Figure 1 have been used for risk assessment of substances that are genotoxic and carcinogenic, and only by some agencies. These are the linearized multistage model and low dose linear extrapolation (OneHit) from a point within the experimental dose-response curve. The latter model has received wider use because of its lower data requirements, its general applicability to a wide variety of different datasets and its inherent conservatism. Neither model wouldreflect any non-linearities in biological processes at low intakes. Figure 1 Low dose extrapolation from animal carcinogenicity data using various models.

BMR- Benchmark Response ; BMDL 10(%) - Benchmark Dose Lower Limit