[Methods of extrapolating risk from from high to low doses and their effect on determining MAC values]

The author discussed problems arising from the use of different mathematical dose-response models for extrapolation of cancer risk from high to low doses. On the one hand, a linearized, multistage model, commonly used for evaluating cancer risk resulting from exposure to chemical carcinogens in the communal environment, frequently underestimates a real risk. On the other hand, the application of nonlinear models for describing the relationship between exposure and response sizes in occupational exposures, and linearized ones in communal exposures leads to ridiculous assessments, namely it sometimes appears that an inhabitant of Lodz is at the same cancer risk caused by inhalation exposure to benzo(a)pyrene like a worker employed in the coke-chemical industry and exposed to doses a dozen times higher than MAC values. A considerable overestimation of risk will also yield additional problems related with the acceptance of these values. Therefore, the author proposed to use, whenever possible, nonlinear models for establishing dose-response relationships both in communal and occupational exposures, and maximum likelihood method for estimating model parameters.