Hydrocarbon exposure and chronic renal disease.

The study objective was to investigate further the potential role of long-term exposure to hydrocarbons (HCs) in the development of idiopathic chronic glomerulopathy (ICG) using a more refined measurement of HC exposure. A total of 321 pairs of cases and controls, matched by age, gender, and geographical area, were assembled. A detailed questionnaire was blindly administered to cases and controls to collect information on occupational and medical history and sociodemographic data. By integrating quantified measurements of HC exposure from a variety of sources with each subject's occupational history, a lifetime HC exposure score could be estimated and expressed in parts per million (ppm). Cases had an hydrocarbon exposure mean score of 165 ppm (median 48 ppm) as compared to 162 ppm (median 43 ppm) for controls (P = 0.757). When using hydrocarbon exposure as a dichotomous variable with a cutoff point at 100 ppm, cases had a higher proportion of exposed than controls, but the difference was not statistically significant at the 0.05 level, even after controlling for possible confounders through logistic regression. Subgroup analyses showed mixed results. In most subgroups differences between cases and controls tended to become significant when hydrocarbon was used as a dichotomous variable. Results from this study do not sufficiently support the hypothesized association of HC exposure and ICG in general. Subgroup analyses need further investigations. Efforts to generate accurate estimates of lifetime HC exposure should be emphasized for future investigations.