A study of mortality near sour gas refineries in southwest Alberta: an epidemic unrevealed.

Concerns about excesses in a wide array of adverse health outcomes have been expressed for over 25 years by a rural population in southwestern Alberta, living downwind from natural gas refineries. Among these has been the perception that deaths have occurred more frequently than ought to have been expected. As part of a large field epidemiologic study undertaken during the summer of 1985 to investigate possible health effects in this area, a residential cohort study was carried out to study mortality. The cohort was defined as all those individuals who resided in the area in 1970. A total of 30,175 person-years of risk within Alberta were experienced by this cohort during 1970-84. The deaths during this period were enumerated by resident reports and by manual record linkage with the death records of the Alberta Bureau of Vital Statistics. Age- and sex-standardized mortality ratios, based on expected rates from 2 pre-specified demographically similar, non-metropolitan Southern Alberta populations, were 0.88 and 0.84 respectively, neither of which was significantly different from unity. These data cannot address the question of etiology but they can do much to allay the anxieties of a community convinced it had experienced an epidemic of death.