AN ALTERNATIVE APPROACH FOR INVESTIGATING THE CARCINOGENICITY OF INDOOR AIR-POLLUTION - PETS AS SENTINELS OF ENVIRONMENTAL CANCER RISK

Traditionally, the cancer risks associated with radon, environmental t obacco smoke (ETS), and similar indoor residential exposures have been evaluated through either laboratory experiments in rodents or epidemi ology studies in people. Laboratory studies have the advantage of bein g controlled experiments, but their utility as estimators of human ris k is limited by the uncertainties of extrapolating from rodents, to pe ople and from high doses to those typically experienced in the home. T hese experiments also subject animals to noxious exposures, causing su ffering that map be considered cruel. Traditional epidemiology studies evaluate human risk directly, at tile exposure levels present in resi dences; however, these studies are limited by their potential For misc lassification, biased recall, and uncontrolled confounding. Thr long r ime intervals involved between exposure and disease (often 30 years or more) make accurate recall particularly problematic. In this paper we discuss the limitations of these traditional approaches, especially a s they relate to residential studies of radon and ETS. The problems as sociated with the maximum tolerated dose in rodent bioassays and expos ure misclassification in traditional epidemiology are particularly exa mined. A third approach that supplements the traditional approaches an d overcomes some of their limitations is suggested. This approach, dub bed per epidemiology, estimates residential cancer risk examining the exposure experience of pet dogs with naturally occurring cancers, The history of yet epidemiology is reviewed and its strengths and limitati ons are examined.