Health effects from chronic low-level exposure to hydrogen sulfide

The acute toxic effects of hydrogen sulfide have been known for decades. Ho wever, studies investigating the adverse health effects from chronic, low-l evel exposure to this chemical are limited. In this study, the authors comp ared symptoms of adverse health effects, reported by residents of two commu nities exposed mainly to chronic, low-levels of industrial sources of hydro gen sulfide, to health effects reported by residents in three reference com munities in which there were no known industrial sources of hydrogen sulfid e. Trained interviewers used a specially created, menu-driven computer ques tionnaire to conduct a multi-symptom hearth survey. The data-collection pro cess and questions were essentially the same in the reference and exposed c ommunities. The two exposed communities responded very similarly to questio ns about the major categories. When the authors compared responses of the e xposed communities with those of the reference communities, 9 of the 12 sym ptom categories had iterated odds ratios greater than 3.0. The symptoms rel ated to the central nervous system had the highest iterated odds ratio (i.e ., 12.7; 95% confidence interval = 7.59, 22.09), followed by the respirator y category (odds ratio = 11.92; 95% confidence interval = 6.03, 25.72), and the blood category (odds ratio = 8.07; 95% confidence interval = 3.64, 21. 18). Within the broader health categories, individual symptoms were also el evated significantly. This study, like all community-based studies, had sev eral inherent limitations. Limitations, and the procedures the authors used to minimize their effects on the study outcomes, are discussed. The result s of this study emphasize the need for further studies on the adverse healt h effects related to long-term, chronic exposure to hydrogen sulfide.