CARCINOGENIC EFFECTS OF DIESEL EMISSIONS AND LUNG-CANCER - THE EPIDEMIOLOGIC EVIDENCE IS NOT CAUSAL

The effects of diesel engine exhaust in lung carcinogenesis have been evaluated by several scientific organizations and government agencies. This complex issue has required a multidisciplinary approach includin g atmospheric measurements, toxicology, chemical carcinogenesis, epide miology, and risk assessment. One important aspect of the epidemiologi cal studies that deserves further attention is the confounding effects of cigarette smoking. Only some epidemiological studies have statisti cally adjusted for cigarette smoking, usually by years of smoking, cig arettes per day, or pack-years. Some studies obtained smoking informat ion from proxy interviews. However, differences in ''tar'' intake, int erpuff interval, depth of inhalation, and other smoking behavior patte rns were not evaluated. These smoking parameters are rarely collected for occupational data analysis, yet the inability to adjust statistica lly for such parameters may result in a small degree of residual confo unding. Because the highest odds ratios for lung cancer associated wit h diesel engine exhaust are usually less than 2 or 1.5, possible resid ual confounding effects of smoking may have resulted in spurious assoc iations.