Pesticide use and adult-onset asthma among male farmers in the Agricultural Health Study

¹ Epidemiology Branch, NIEHS, NIH, DHHS, Research Triangle Park, NC
² Biostatistics Branch, NIEHS, NIH, DHHS, Research Triangle Park, NC
³ Division of Respiratory Disease Studies, NIOSH, CDC, DHHS, Morgantown, WV
⁴ Occupational and Environmental Epidemiology Branch, NCI, NIH, DHHS, Rockville, MD

^* To whom correspondence should be addressed. E-mail: hoppin1{at}niehs.nih.gov.

	Abstract

Although specific pesticides have been associated with wheeze in farmers, little is known about pesticides and asthma. We used data from 19,704 male farmers in the Agricultural Health Study to evaluate lifetime use of 48 pesticides and prevalent adult-onset asthma, defined as doctor-diagnosed asthma after age 20. We categorized asthma cases as allergic (N=127) and non-allergic (N=314) based on their history of eczema or hayfever. We used polytomous logistic regression controlling for age, state, smoking, and body mass to assess pesticide associations.

High pesticide exposure events were associated with a doubling of both allergic and non-allergic asthma. For ever use, 12 individual pesticides were associated with allergic asthma and four with non-allergic asthma. For allergic asthma, coumaphos (odds ratio (OR)=2.34, 95% Confidence Interval (CI)=1.49,3.70), heptachlor (OR=2.01, 95%CI=1.30,3.11), parathion (OR=2.05, 95%CI=1.21,3.46), 80/20 mix (carbon tetrachloride/carbon disulfide) (OR=2.15, 95%CI=1.23,3.76) and ethylene dibromide (OR=2.07, 95%CI=1.02,4.20), all had odds ratios greater than 2.0 and significant exposure-response trends. For non-allergic asthma, DDT had the strongest association (OR=1.41, 95%CI=1.09,1.84) but with little evidence of increasing asthma with increasing use. Current animal handling and farm activities did not confound these results. We saw little evidence that allergy alone was driving these associations.

Pesticides may be an overlooked contributor to asthma risk among farmers.