Statistical techniques applied to environmental health sciences

National Institute Of Environmental Health Sciences

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Abstract

We have recently guided the data analysis for several projects, primarily involving data from the Agricultural Health Study (AHS), a cohort of licensed pesticide applicators (mostly farmers) from Iowa and North Carolina. One project probed a possible relationship between pesticide exposure and depression among male private applicators in the AHS. We used inverse probability weighting to account for exclusions due to missing data and polytomous logistic regression to estimate odds ratios. Ever use of fumigants as a class and several individual pesticides were associated with depression. In light of the growing evidence that suggests that pesticide use contributes to respiratory symptoms, we are using data from the AHS to evaluate the association of 79 currently used pesticides with two types of wheeze: allergic wheeze and non-allergic wheeze. Allergic wheeze required self-report of one or more episodes of wheeze during the past year plus history of doctor-diagnosed hay fever; non-allergic wheeze required the wheeze symptom but without history of hay fever. We used polytomous logistic regression to compare those with each of the two types of wheeze to controls (those without wheeze symptoms). Of the 79 pesticides studied, with exposure assessed dichotomously (current use or not), 20 were associated with non-allergic wheeze (18 positively, 2 negatively) and 17 were associated with allergic wheeze (16 positively, 1 negatively) with ten pesticides common to both types of wheeze. Investigation of other aspects of the epidemiology of respiratory disease and symptoms in relationship to farming exposures, including pesticides, is continuing.