Relative Risk = 1.0 + Kl (cumulative dose)
Absolute Risk = Relative Risk • Underlying Risk
Based on American national average lung cancer risk data for male and female smokers and nonsmokers, EPA calculated the cumulative exposures of 0.035 fiber/ml-yr and 0.35 fiber/ml-yr represent excess lung cancer risks of 10–4 for smokers and non-smokers respectively24). In this study, EPA method of calculation of excess lung cancer risk for smokers and non-smokers were used to compute proportionally excess lung cancer risks for categorizedquartile ranges of cumulative exposure in our study group.
Lung function tests (FVC, FEV1 and FEV1/FVC) were conducted on exposed population by a spirometer (Clinical ST-300 made by Fukoda Sungou Company) according to the method of American Thoracic Society).