Procedures for Calculating Cessation Lag
Environmental regulations aimed at reducing cancer risks usually have the effect of reducing exposure to a carcinogen at the time the regulation is implemented. The reduction of cancer risk may occur shortly after the reduced exposure or after a considerable period of time. The time of risk reduction associated with exposure reduction will vary by compound. Some recommended measures of the economic benefits associated with environmental regulations are sensitive to the timing of the risk reductions and cannot be effectively addressed by the conventional dose-response procedures. This paper introduces the concept and methodologies for calculating cessation lag effects, with the specific goal of answering the following questions: (1) How many cancer cases are avoided at age t after cessation (or reduction) of exposure concentration? and (2) How long does the effect of an exposure last after exposure has terminated (or been reduced)? The proposed procedures do not require more information than what is required by the conventional dose-response procedures for which cumulative or an averaged lifetime exposure is used.