Parkinsonism Signs and Symptoms in Agricultural Pesticide Handlers in Washington State

Objectives: Examine associations between pesticide exposure and signs or symptoms of parkinsonism. Methods: Prior to the 2014 pesticide spray season, the authors examined 38 active pesticide handlers aged 35 to 65 (median: 43.5) who participated in the State of Washington’s cholinesterase monitoring program in the Yakima Valley, where cholinesterase-inhibiting insecticides are applied in fruit orchards. A movement disorder specialist assessed the workers using the Unified Parkinson’s Disease Rating Scale (UPDRS) motor subscore 3 (UPDRS3). Participants also self-reported work and medical histories, including the UPDRS activities of daily living subscore 2 (UPDRS2). The authors explored the relation between these scores and lifetime occupational pesticide exposure while accounting for age. Results: All participants were Hispanic men born in Mexico who had worked in agriculture for 4 to 43 years (median: 21 years, including 11 years applying pesticides, mostly in the United States). Ten participants (26%) reported difficulty with one or more UPDRS2 activities of daily living (maximum = 2), and nine (24%) had a UPDRS3 >0 (maximum = 10). The most common symptom and sign, respectively, were excess saliva (n = 6) and action tremor (n = 5). UPDRS2 and UPDRS3 scores were unrelated to the number of years applying pesticides, but UPDRS3, especially action tremor, was positively associated with living on or by a farm. Conclusions: Symptoms and signs of parkinsonism were absent to mild in this small sample of active workers who apply cholinesterase-inhibiting insecticides in Washington State, USA. Future studies should be larger and examine older, retired workers with greater cumulative exposure to agricultural pesticides at work and home, including other types of agricultural pesticides.