Dose Extrapolation Outside the United States

The Netherlands National Institute for Public Health and the Environment (RIVM), an environmental regulatory agency, has long made a distinclion between threshold and nonthreshold carcinogens. The Agency (Baars et al. 2001) stated  

In evaluating the toxicity of chemical substances, distinction must be made between two fundamental different approaches. Genotoxic carcinogens are assumed to exert their activity also at the smallest dose, i.e., by definition a threshold for genotoxic activity does not exist. Toxic effects other than genotoxic carcinogenicity, however, are assumed to occur via receptor interaction, which implies that a certain threshold needs to be exceeded before a toxic effect will occur. 

---