Investigation of Health Effects of Hydrogen Sulfide from a Geothermal Source

Abstract

Little is known about health effects from chronic exposure to hydrogen sulfide (H₂S). The city of Rotorua, New Zealand, is exposed to H₂S by virtue of its location over a geothermal field. In this study, the authors classified areas within Rotorua as high-, medium, or low-H₂S exposure areas. Using 1993-1996 morbidity data, standardized incidence ratios were calculated for neurological, respiratory, and cardiovascular effects. Poisson regression analysis was used to confirm results. Results showed exposure-response trends, particularly for nervous system diseases, but also for respiratory and cardiovascular diseases. Data on confounders were limited to age, ethnicity, and gender. The H₂S exposure assessment had limitations. Assumptions were that recent exposure represented long-term exposure and that an individual's entire exposure was received at home. The results of this study strengthen the suggestion that there are chronic health effects from H₂S exposure. Further investigation is warranted.