of subjects with subjective symptoms of dermal sensitivity, itching, or eczema was increased with increased estimated time of exposure. Physical examination confirmed the presence of more skin disease in more highly exposed workers, but patch tests were not performed to differentiate allergic from irritant reactions. The study did not provide details about the effects that were included in the term skin disease, and it is not possible to determine how long the dermal effects were present in the workers.
Risk factors for farm-related dermatitis were examined in a cross-sectional study of male farmers in Iowa (n=382) and the wives of farmers (n=256), who completed a health and exposure questionnaire (Park et al., 2001). Among the men, the risk of dermatitis during the previous year was not increased with application of insecticides on field crops (OR=0.63, 95% CI=0.25–1.56) or with application of insecticides to livestock (OR=1.29, 95% CI=0.66–2.50). A history of allergy was the only risk factor meaningfully associated with dermatitis. The study was population-based, but the authors acknowledge a low response rate.
Gamsky and colleagues (1992) studied dermatitis in California farm workers and compared grape, citrus, and tomato workers. The study identified a wide array of pesticides used, including elemental sulfur in the vineyards. Grape workers experienced the highest prevalence of dermatitis, but their exposures were not well characterized, and there were many possible confounders. Other studies have examined dermatologic effects of pesticides with similar problems of multiple confounders and poorly characterized exposure (Cellini and Offidani, 1994; Cole et al., 1997; Matsushita et al., 1980).
One study of Gulf War veterans examined the potential dermatologic effects of pesticide exposure during the war in concert with other symptoms and exposures. Proctor and colleagues (1998) studied the symptom experience of a stratified random sample of two cohorts of Gulf War veterans from Massachusetts (Ft. Devens) (n=220) and New Orleans (n=71), both consisting of active-duty, reserve, and National Guard troops deployed to the Gulf War area. The control group (n=50) consisted of veterans who had been deployed to Germany during the Gulf War. Subjects completed symptom checklists, exposure questionnaires, other tests, and interviews. The greatest differences between case subjects and the control group were in dermatologic symptoms (such as skin rash, eczema, and skin allergy), neuropsychologic symptoms (such as difficulty in concentrating and in learning new material), and gastrointestinal symptoms (such as stomach cramps and excessive gas). With multiple regression and adjustment for other exposures, pesticide exposure was associated with neurologic symptoms and musculoskeletal symptoms but was not found to be related to dermatologic, gastrointestinal, neuropsychologic, or psychologic symptoms.
Many of the studies on dermatitis and insecticide exposure examined workers with continuing exposures to insecticides, so it is not possible to determine whether the dermatitis was a short- or long-term health effect of insecticide exposure. In addition, those studies examined agricultural workers who experienced multiple confounding exposures that are not always subject to control. Although case studies and review articles discuss an increased incidence of short-term dermatitis after handling pesticides, there is a limited amount of information about the long-term dermatologic effects of insecticide exposure. Several of the insecticides reviewed in this report have been found to be potential sensitizers, and reexposure to those agents could result in allergic contact dermatitis in sensitized persons.