The upper midwest health study: a case–control study of pesticide applicators and risk of glioma

The study included 798 histologically confirmed primary intracranial glioma cases (45？% with proxy respondents) and 1,175 population-based controls, all adult (age 18–80) non-metropolitan residents of Iowa, Michigan, Minnesota, and Wisconsin. The analyses used quantitatively estimated exposure from questionnaire responses evaluated by an experienced industrial hygienist with 25？years of work on farm pesticide analyses. Odds ratios (ORs) and 95？% confidence intervals (CIs) using unconditional logistic regression modeling were calculated adjusting for frequency-matching variables (10-year age group and sex), and for age and education (a surrogate for socioeconomic status). Analyses were separately conducted with or without proxy respondents.No significant positive associations with glioma were observed with cumulative years or estimated lifetime cumulative exposure of farm pesticide use. There was, a significant inverse association for phenoxy pesticide used on the farm (OR 0.96 per 10？g-years of cumulative exposure, CI 0.93-0.99). No significant findings were observed when proxy respondents were excluded. Non-farm occupational applicators of any pesticide had decreased glioma risk: OR 0.72, CI 0.52-0.99. Similarly, house and garden pesticide applicators had a decreased risk of glioma: OR 0.79, CI 0.66-0.93, with statistically significant inverse associations for use of 2,4-D, arsenates, organophosphates, and phenoxys.These results are consistent with our previous findings for UMHS of reported farm pesticide exposure and support a lack of positive association between pesticides and glioma.Several studies have shown that working on a farm or in the agricultural industry, particularly for men [1,2], may lead to higher risks of glioma and other brain cancer [3-8], while others have not [9-12].The National Institute for Occupational Safety and Health (NIOSH) developed the Upper Midwest Health Study (UMHS) as a case–control study of intracranial gliomas among rural residen