High pesticide exposure events and subjective cognitive complaints among US farmers

BACKGROUND: Pesticides may contribute to cognitive impairment in older adults, but empirical data are limited. We investigated whether high pesticide exposure events (HPEEs) were associated with subjective cognitive complaints among older US farmers. METHODS: We analyzed data from 2365 farmers (aged 70 ± 10 years) who enrolled in the Agricultural Health Study (AHS) in 1993-1997 and participated in the Pesticide And Sense of Smell (PASS) study in 2020-2021. HPEEs were assessed in AHS in 1993-1997, 1999-2003, 2005-2010, and in PASS in 2020-2021. Subjective cognitive complaints were measured in PASS, defined as a score ≥4 using the Cognitive Function Instrument. RESULTS: A history of HPEE was associated with subjective cognitive complaints. Using the HPEE reported at the PASS study as an example, compared with those who never had a HPEE, the risk ratio (RR) for those who ever had a HPEE was 1.59 (95 % confidence interval: 1.30, 1.95). The association appeared stronger with higher numbers of events (RR: 2.16 vs. 1.43 for ≥3 vs. 1-2 events), exposure via the respiratory/digestive tract vs. dermal contact only (RR: 1.89 vs. 1.34), and with a greater number of symptoms following HPEE exposure (2.22 for ≥2 symptoms, 1.56 for 1 symptom, and 1.36 for no symptom). Results were only slightly attenuated when analyzing HPEEs assessed at prior AHS surveys. For specific pesticides involved in the HPEE, we found positive associations for atrazine, 2,4-D, trifluralin and glyphosate. CONCLUSIONS: This study provides preliminary evidence that high pesticide exposure may contribute to subjective cognitive complaints among older farmers.