Investigation of systemic lupus erythematosus in Nogales, Arizona

In 1996, a citizens group in Nogales, Arizona, reported to the Arizona Depa rtment of Health their concerns about a possible excess prevalence of syste mic lupus erythematosus (SLE) due to exposure to environmental contaminatio n in the area. The authors conducted a two-phase study in which the objecti ves of phase I were to identify potential SLE cases and to determine the pr evalence of SLE and the objectives of phase II were to identify potential r isk factors associated with the development of SLE and to evaluate the poss ible association between SLE and environmental exposure to pesticides and i norganic compounds. Participants included 20 confirmed cases and 36 control s. The authors found the prevalence of SLE to be 103 cases per 100,000 popu lation (95 percent confidence interval: 56, 149), two to seven times higher than the prevalence in the US population. They detected elevated levels of 1,1-dichloro-2,2-bis-(p-chorophenyl)ethylene and organophosphate metabolit es among cases and controls. In both, levels were higher than the reference mean for the US population. The authors found no statistical association b etween elevated levels of pesticides and disease status. Their results show that the prevalence of SLE in Nogales is higher than the reported prevalen ce in the US population and that both cases and controls had past exposure to chlorinated pesticides and have ongoing exposure to organophosphates.