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

Abstract

BackgroundAn excess incidence of brain cancer in farmers has been noted in several studies. The National Institute for Occupational Safety and Health developed the Upper Midwest Health Study (UMHS) as a case–control study of intracranial gliomas and pesticide uses among rural residents. Previous studies of UMHS participants, using “ever-never” exposure to farm pesticides and analyzing men and women separately, found no positive association of farm pesticide exposure and glioma risks. The primary objective was to determine if quantitatively estimated exposure of pesticide applicators was associated with an increased risk of glioma in male and female participants.MethodsThe 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.ResultsNo 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.ConclusionsThese 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.

The Upper Midwest Health Study: Industry and occupation of glioma cases and controls

“…A hospital-based case–control study in northeast China found statistically significant increased risk of glioma among those with occupational exposures to microwaves or to pesticides [Hu et al, 1998], while to date we have seen no association between pesticides and glioma in our study population [Ruder et al, 2004; Carreón et al, 2005; Yiin et al, 2012]. …”

“…These exposures of interest were our a priori hypotheses of exposures possibly associated with increased risk of glioma. Comprehensive evaluations have been completed only for the highest priority exposures—pesticides and solvents [Hein et al, 2008, 2010; Ruder et al, 2009a; Yiin et al, 2012], for which exposure assessment for questionnaire responses was done, and for farm activities, based on a comprehensive questionnaire [Ruder et al, 2009b]. …”

Genetic and molecular epidemiology of adult diffuse glioma

“…As shown in Box 1, a number of other non-genetic risk factors have not been linked to or not consistently linked to adult glioma risk including, pesticides or chlorinated solvent exposures [158][159][160] , obesity/high BMI, cigarette smoking [161][162][163][164][165] , alcohol consumption 164 traumatic brain injury 166,167168169 .…”

Occupational exposure to pesticides and central nervous system tumors: results from the CERENAT case–control study

“…More recent studies have used re ned pesticide exposure assessment based on detailed questionnaires and/or expertise and analyzed CNS tumor by subtypes. In the Upper Midwest Study, a large case-control study in the USA including 341 brain tumors in women and 457 in men, no increase in risk was observed for glioma with pesticide exposure globally (Ruder et al 2006;Yiin et al 2012), in men (Ruder et al 2004), and only a trend restricted to carbamate insecticide use in women (Carreón et al 2005). Another case-control study in Nebraska observed an increase in risk only for workers involved in farming for 55 years and over (Lee et al 2005).…”