AGE AND SMOKING-ADJUSTED LUNG-CANCER INCIDENCE IN A UTAH COUNTY WITH A STEEL MILL

In a recent study of urban air pollution, a Utah county with a steel m ill was compared with a county without a steel mill. The result was th at 38% of respiratory cancer deaths could be attributed to the air pol lution emanating from the mill. Rates for smoking in this previous stu dy were not adjusted, but assumed rates were similar in both counties. We used smoking information obtained from an ongoing radon and lung c ancer case-control study to adjust for smoking, and no difference was found in incidence rates of respiratory cancer in the county with the steel mill, compared with the other urban counties and the rural count ies among male and female nonsmokers and male smokers. There was a sli ght excess of lung cancer among female smokers in the county with the steel mill when compared with the other urban counties (rate ratio [RR ] = 1.3, 95% confidence interval [95% Cl] = 1.0-1.6), but there was no effect in nonsmoking women. We conclude that the findings of the prev ious study can be explained by differences in smoking rates between th e county with the steel mill and the other counties.