A case‐control study of Parkinson's disease in a horticultural region of British Columbia

Abstract

We compared personal histories of 127 cases and 245 controls to identify possible environmental risk factors for idiopathic parkinsonism (IP). Of our controls, 121 had cardiac disease (CD) and 124 were randomly selected from electoral lists (voters). Using logistic regression and adjusting for sex and age, we ran separate analyses: IP versus CD and IP versus voters. A full occupational history was collected, as was known contact with all pesticides associated with the tree fruit sector of the agricultural industry. We found a significant association between IP and having had an occupation in which exposure through handling or directly contacting pesticides was probable, but no specific chemicals were associated with IP. We conclude that although occupations involving the use of agricultural chemicals may predispose to the development of IP, it seems likely that the pathogenesis is multifactorial rather than related to a specific agent.

Epidemiology and etiology of Parkinson’s disease: a review of the evidence

“…Similar to overall pesticide exposure, the population-based study of 250 incident cases mentioned above [316] found no association for occupational (men only) or home-based (men and women) exposure to herbicides. The other studies that found no association [131,292,299,301,315,325] were all smaller (100-150 cases); several did not adjust for smoking [292,299,301,315].…”

“…None of five such studies reported an association for exposure to fungicides overall [290,292,316,321,324]. The MSA study [324] reported a significant dose-response relationship between cumulative hours of fungicide exposure in men above 65 years (p for trend 0.02).…”

“…In most studies of pesticides in relation to PD exposure was assessed retrospectively as a broad category, rather than examining specific substances. Of 38 case-control studies, 19 reported increased risk of PD [147,154,156,[289][290][291][292][293][294][295][296][297][298][299][300][301][302][303][304] with ORs ranging between 1.3 and 3.7 for most studies. One study reported an OR of 7.0 (p value <0.05) [289] and another an OR of 10.9 (95% CI 2.5-48.0) [301].…”

“…Of 18 studies that analyzed exposure to herbicides, 10 found increased risk of PD, either for herbicides as a group of substances, or for specific herbicides, such as paraquat, nitrile herbicides or 2,4-Dichlorophenoxyacetic acid [153,154,290,293,302,304,[321][322][323][324], with ORs ranging between 1.6 and 5.8. The other 8 studies reported no association between herbicides and PD [131,143,292,299,301,315,316,325].…”

“…Four other studies that assessed paraquat specifically, however, found no association [292,301,304,316,317], although one [304] reported increased risk of PD following exposure to 2,4-Dichlorophenoxyacetic acid (OR 2.59, 95% CI 1.03-6.48). A population-based Californian study [323] assessed historical pesticide residential exposure through a combination of interviews, geographical information system (GIS), and California Pesticide Use Reports.…”