TABLE 7.8 Case-Control Studies of Parkinson’s Disease and Insecticide Exposure

Reference, Country



Exposure Determination

Insecticide Exposure

OR (95% CI or p)

Adjusted OR (95% CI or p)


Butterfield et al., 1993

63 patients with early-onset PD; diagnosed before age 51 years; referred by physicians or other patients;

68 persons diagnosed with rheumatoid arthritis; frequency-matched for sex, birth year, year of diagnosis;

Self-report questionnaire;

Ever lived in fumigated house

3.29 (p=0.068)

5.25 (p=0.045)

Adjusted for age, age at diagnosis, race, sex, educational level, family history of PD;


Reconstruction of employment, exposure history

Ever lived within 1/4 mile of agricultural spraying

1.99 (p=0.106)

1.99 (p=0.099)


Mean duration of disease 9 years from diagnosis;

41% response


Insecticide exposure over 10 times per year

4.04 (p=0.002)

5.75 (p=0.001)

7.24 (2.29–22.92)

also adjusted for smoking;


69% response


4.30 (1.35–13.67)

also adjusted for eating seeds and nuts, rural residency, and past residence in fumigated house;


Participation very low in cases, controls

Gorell et al., 1998

144 PD patients receiving primary medical care from single health system; diagnostic criteria used;

MMSE result under 24 excluded;

464 controls frequency-matched for age, race, sex; controls reporting symptoms of potentially undiagnosed PD excluded;

MMSE result under 24 excluded

Questionnaire administered face to face by trained interviewers;

Residential insecticide spraying

1.02 (0.62–1.65)

1.03 (0.63–1.7)

Adjusted for race, age, sex, smoking status;


Gardening insecticide exposure

0.88 (0.58–1.36)

0.90 (0.58–1.38)

Questionnaire distinguished insecticide from herbicide, fungicide exposures;

Lifetime-exposure measure calculated from responses;

Farm residence insecticide exposure

1.4 (0.76–2.59)

1.28 (0.69–2.4)

Mean duration of disease 2.4 years from diagnosis

Exposure up to time of diagnosis

Occupational insecticide exposure:



Only four patients, 11 controls could identify one or more subclasses of insecticides they were exposed to


3.11 (1.56–6.15)

3.55 (1.75–7.18)

<10 years

2.39 (0.89–6.4)

>10 years

5.80 (1.99–16.97)

Adjusted for farming

3.15 (1.54–6.49)

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