Among the 51,035 male farmers, 338 injury deaths occurred over the average follow-up period of 13.3 years, which provided 730,234 person-years, for a rate of 46.3 injury deaths/100,000 person years. Farmers having a fatal injury were primarily white and 61% were from Iowa, representative of the cohort′s demographics (). Injury mortality increased with age, although decade-specific hazard ratios were not significantly increased. Decedents were similar to the entire cohort (at enrollment) with regard to body mass index. Individuals who were divorced or separated at enrollment were more likely to experience a fatal injury, as were decedents who reported experiencing difficulty with balance monthly or more frequently.Increased age, smoking, tremor, and depression were nonsignificantly associated with increased risk of fatal injury. Greater than high school education was associated with significantly decreased injury risk.
Enrollment demographics and medical conditions for all male farmers and for male fatal injuries in the Agricultural Health Study, 1993–2008.
Days per year of pesticide application but not years or cumulative days was significantly associated with fatal injury (60+ days per year application: Hazard Ratio (HR)=1.87; 95% Confidence Interval (CI)=1.10, 3.18; ptrend=0.02; ). Adjusting for ever drinking slightly attenuated this estimate (HR=1.67, 95%CI=0.95, 2.94). Use of chemical-resistant gloves was associated with a significant reduction in risk (HR=0.73; 95%CI=0.58, 0.93), but adding glove use to models did not change risk estimates for frequency of pesticide use (60+ days per year HR=1.92, 95%CI=1.13, 3.27; ptrend=0.04).
General pesticide use characteristics and fatal injury among male farmers in the Agricultural Health Study, 1993–2008.
After adjustment for age and state, ever use of seven of 49 pesticides was associated with significantly increased risk of fatal injury; none was associated with decreased risk (). Significant HRs were seen for ever use of five of 18 herbicides: 2,4,5-T, alachlor, butylate, metribuzin, and paraquat. No insecticide was significantly associated with risk, although there was a suggestive association with ever use of coumaphos (HR=1.39, 95%CI=0.97, 1.99). Of 4 fumigants evaluated, risk was significantly increased for users of carbon tetrachloride/carbon disulfide. Ziram was the only fungicide of 6 evaluated that was significantly associated with fatal injury. Adjusting the model for use of chemical-resistant gloves did not change the findings with the exception of increased HRs for paraquat (HRparaquat | gloves=1.56; 95%CI=1.18, 2.05) and parathion (HRparation | gloves=1.36; 95%CI=1.00, 1.84).
Ever/never pesticide use and fatal injury among male farmers in the Agricultural Health Study, 1993–2008.
In evaluating exposure-response for individual chemicals, we used frequency of use because this metric was associated with injury for use of any pesticide (). For 17 of 18 herbicides, we evaluated exposure-response; 14 were based on four categories of frequency of use (), three by median split only. Significant trends were observed for 2,4-D, butylate, and cyanazine. For 2,4-D, alachlor, and cyanazine, the HR was significant in the highest tertile of use. For the three herbicides analyzed by median-split, only chlorimuron-ethyl showed increased risk (HR >5 days/year=1.59; 95%CI=0.98, 2.60; ptrend=0.06). No insecticides showed an exposure-response relationship between days per year of application and fatal injury (data not shown). When we analyzed cumulative days of use for individual chemicals, only the trends for 2,4-D (HRhigh(>116 days) = 1.37; 95%CI=1.01, 1.88; ptrend=0.04) and cyanazine persisted (HRhigh(>56 days) =1.48; 95%CI=1.05, 2.01; ptrend=0.05); carbofuran was the sole insecticide that showed an exposure-response (HRhigh(>50.75 days) = 1.74; 95%CI=1.22, 2.50; ptrend=0.01).
Exposure-response associations for selected herbicides and fatal injury among male farmers in the Agricultural Health Study, 1993–2008.
Driving combines was associated with fatal injury, with an HR of 1.87 (95%CI=1.07, 3.27) for 31 or more days per , ptrend=0.03 (). Adjusting for smoking and alcohol use did not substantially change results. Daily tractor driving was associated with increased risk, though not significantly so (HR=1.41; 95%CI=0.79, 2.52). While livestock production was not associated with fatal injury, butchering animals was (HR=1.36; 95%CI=1.01, 1.84). Poultry production showed a significant association with fatal injury, approximately doubling the risk of fatal injury regardless of flock size (HRs ranged from 1.78 to 2.26). These factors were unrelated to days per year of pesticide application and adjusting for driving combines, butchering animals, or poultry production did not alter pesticide findings (data not shown).
Farm exposures and fatal injuries among male farmers in the Agricultural Health Study, 1993–2008.