A collaborative study between the University of Otago, the University of California, and Stanford University

Hydrogen sulfide (H2S) is an odorous gas (the ‘rotten eggs’ smell) produced by many industrial processes and from natural sources.  Exposures to high H2S concentrations can have serious effects.  However, it is unknown whether long-term exposures to much lower concentrations have any health effects. The city of Rotorua, New Zealand, is the only city in the world that is sited on an active geothermal field. Around the city can be found geysers, boiling mud pools, and steaming, near-boiling water pools, with the ubiquitous odor of naturally-emitted H2S. The Rotorua population is regarded as the largest anywhere exposed to naturally occurring ambient concentrations of H2S and provides a unique natural experiment in which the relationship between H2S and health can be studied. We have taken advantage of this to carry out the largest study ever undertaken of possible long-term health effects of H2S.
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Solvents are widely used in the industry yet, surprisingly, much is still unknown about whether prolonged exposures to these chemicals cause health effects.  The Bay Area Solvent Study (BASS) is an epidemiologic research project designed to find out whether exposure to solvents has caused health effects, particularly nervous system effects or reproductive problems, among male motor vehicle mechanics. These mechanics frequently use solvents, often in spray cans, to clean brakes and engine parts. The results of the study will be used to help establish appropriate exposure limits for solvents in workplaces.


This research concerns the intersection of two of the world’s major health and environmental problems: tuberculosis (TB) and household air pollution. Tuberculosis remains one of the world’s most difficult diseases, with 2 billion people infected with the causal agent Mycobacterium tuberculosis. Infection rates in South Asia, including India and Nepal, are very high.

Much of the world (about 2.6 billion people), particularly in South Asia, is too poor to afford clean fuels—electricity or gas—for heating or cooking, and still use solid fuels (e.g., wood, animal dung, crop residues) for these purposes. Many families also use kerosene for cooking or lighting. Solid fuel burning emits much smoke, and kerosene, particularly in inexpensive wick stoves and lamps, emits fine particulates and chemicals. Previous epidemiology investigations, including our work in Nepal, has produced evidence that burning solid fuels or kerosene may promote TB, but uncertainties remain. The present case-control study, in the Kaski District of Nepal, will be the largest and most comprehensive epidemiology study ever to have investigated this issue. We anticipate that it will provide definitive evidence about whether emissions from solid fuel or kerosene are risk factors for TB disease or TB infection.