Subjective fears and objective data: an epidemiologic study of environmental health concerns

A political emergency arose in 1985 for the province of Alberta, Canada, because allegations of increased health risk had frightened rural Alberta residents exposed for 28 years to the airborne effluent of sour gas processing plants. In an epidemiologic study that took 3 months in the field, cross-sectional and cohort comparisons were conducted for these residents and for two carefully selected control groups. Clinical examinations were conducted with objective methods and criteria. No excess rates were found in the exposed group for any life-threatening or seriously disabling conditions. For the exposed group in the index area the reported cardinal symptoms were slightly higher than in the main unexposed reference group, but the observed cardinal signs were slightly lower. This project shows that scientifically sound strategies can be used to investigate major health controversies. Rigorous clinical methods of measurement, incorporated into a classical epidemiologic study, can inspire confidence in the studied population and can make the results acceptable to clinicians and policy makers. The studies can be done rapidly in response to urgent or crisis situations without compromising methodologic rigor or the quality of the analyses.