Plantation work and risk of Parkinson disease in a population-based longitudinal study.
BACKGROUND
Parkinson disease (PD) has an unknown cause; however, convincing evidence is emerging that indicates pesticides can selectively injure the dopaminergic system in laboratory animals. Retrospective studies in humans demonstrate a link between exposure to agricultural lifestyle factors and PD.


OBJECTIVE
To determine whether working on a plantation in Hawaii and exposure to pesticides are associated with an increased risk of PD decades later.


METHODS
Prospective cohort study based on the island of Oahu, Hawaii, with 30 years of follow-up. Years of work on a plantation were assessed by questionnaire at study enrollment in 1965. Self-reported information on pesticide exposure was collected at a separate examination 6 years later.


METHODS
Participants were 7986 Japanese American men born between 1900 and 1919 who were enrolled in the longitudinal Honolulu Heart Program.


METHODS
Incident PD was determined by medical record review or by an examination conducted by a study neurologist at a later date.


RESULTS
During follow-up, 116 men developed PD. Age-adjusted incidence increased significantly among men who worked more than 10 years on a plantation. The relative risk of PD was 1.0 (95% confidence interval, 0.6-1.6), 1.7 (95% confidence interval, 0.8-3.7), and 1.9 (95% confidence interval, 1.0-3.5) for men who worked on a plantation 1 to 10 years, 11 to 20 years, and more than 20 years compared with men who never did plantation work (P =.006, test for trend). Age-adjusted incidence of PD was higher in men exposed to pesticides than in men not exposed to pesticides although this was not statistically significant (P =.10, test for trend).


CONCLUSIONS
These longitudinal observations regarding plantation work in Hawaii support case-control studies suggesting that exposure to pesticides increases the risk of PD.
Petrovitch
Helen
H
Department of Medicine, University of Hawaii John A. Burns School of Medicine, USA. helen@phri.hawaii-health.com
Ross
G Webster
GW
Abbott
Robert D
RD
Sanderson
Wayne T
WT
Sharp
Dan S
DS
Tanner
Caroline M
CM
Masaki
Kamal H
KH
Blanchette
Patricia L
PL
Popper
Jordan S
JS
Foley
Daniel
D
Launer
Lenore
L
White
Lon R
LR
D000368:Aged; D000382:Agricultural Workers' Diseases / Q000453:epidemiology*; D000704:Analysis of Variance; D001213:Asian / Q000706:statistics & numerical data; D016001:Confidence Intervals; D005500:Follow-Up Studies; D006254:Hawaii / Q000453:epidemiology; D006801:Humans; D008137:Longitudinal Studies; D008297:Male; D008875:Middle Aged; D016273:Occupational Exposure / Q000706:statistics & numerical data*; D010300:Parkinson Disease / Q000453:epidemiology*; D010575:Pesticides / Q000009:adverse effects; D016016:Proportional Hazards Models; D011446:Prospective Studies; D018570:Risk Assessment; D011795:Surveys and Questionnaires
D010575:Pesticides