Prevalence of antinuclear antibodies in a rural population

Exposure to environmentally and occupationally encountered toxicants can be associated with the development of certain autoimmune diseases and with th e induction of antinuclear antibodies (ANA). Some chemicals used in the agr icultural industry are known to affect immune function but their roles in t he induction of autoimmunity in general, and ANA in particular, have not be en reported previously. This study was undertaken to establish the prevalen ce of ANA in a rural population and to determine environmental and occupati onal exposures with which they are associated. This cross-sectional study r epresented one component of an interdisciplinary project (Prairie Ecosystem Study [PECOS], Eco-Research Program, Tri-Council Secretariat of Canada des igned to explore, in a rural population, the roles of environmental exposur es as determinants of human health status. information regarding lifetime, current, and main occupational exposures in the rural-dwelling study popula tion was derived from a self-administered questionnaire. Sera from consenti ng subjects, collected during the months of February and March 1996, were a ssayed for ANA by indirect immunofluorescence on HEp-2 cells. The study pop ulation comprised 322 adult subjects (mean age 49.3 +/- 14.7 yr; range 16-8 7 yr). Statistical analyses adjusted for age and sex revealed that the pres ence of ANA among the participants was associated with a current agricultur al occupation that included oilseed production, hog production, or poultry production. There was a significant association between ANA positivity and a current main farming operation of crop production. There was also an asso ciation among individual participants between lifetime exposure to the inse cticide class of pesticides and the presence of ANA. In this rural study po pulation, ANA positivity was significantly associated with lifetime exposur e specifically to carbamate, organochlorine including aldrin, chlordane, di eldrin, endrin, heptachlor, and lindane, but excluding DDT and methoxychlor ), and pyrethroid insecticides and to phenoxyacetic acid herbicides, includ ing 2,4-D. After adjustment for age, sex, and other insecticide exposures, multivariate analyses indicated that ANA positivity was associated with cur rent oilseed production and with lifetime exposure to pyrethroid insecticid es. In a rural population, ANA were associated with production of certain c rops and certain animals and exposure to specific pesticides. The data indi cate that some occupational exposures related to the agricultural industry are associated with the presence of ANA, a serologic expression of autoimmu nity.