Comparing a Hypothetical Cancer Risk Assessment of Exposure to Cigarette Smoke to the Results of Epidemiological Studies. Stephen T. Washburn and Daune Arsnow, ENVIRON Corporation, 214 Carnegie Center, Princeton, New Jersey 08540
Although the use of human health risk assessment continues to expand, concerns remain regarding potential uncertainties in each step of the process, especially when evaluating chronic exposures to complex chemical mixtures. For example, toxicity criteria may be limited or unavailable for many chemicals of potential concern, and it is rarely possible to quantitatively evaluate the affects of synergism or antagonism. Furthermore, in most instances, the conclusions of a risk assessment cannot be confirmed using information from exposed populations due to a lack of adequate epidemiological data. However, the availability of numerous epidemiological studies involving exposure to cigarette smoke represents an opportunity to evaluate the extent to which hypothetical cancer risk assessments based on standard U.S. EPA methodologies produce results consistent with data from exposed populations. In this paper, the results of a hypothetical risk assessment conducted using concentrations of specific chemical carcinogens detected in cigarette smoke are compared to the results of these epidemiological studies. The range of exposures to the constituents of cigarette smoke are estimated based on published studies and standard U.S. EPA assumptions (where available), and hypothetical risks are calculated using cancer slope factor (SF) values from U.S. EPA sources such as the Integrated Risk Information System (IRIS). The objective of this exercise is to determine whether or not the range of estimated cancer risks based on standard U.S. EPA exposure assessment methodologies and toxicity criteria is similar in magnitude to the cancer risk estimated based on epidemiological studies.