Background/Purpose:

Several studies have reported an association between exposure to pesticides and the risk of systemic lupus erythematosus (SLE). However, this association has not yet been examined in an urban population, where residential pesticide exposure is more common than agricultural exposure. The purpose of this study was to assess the risk of SLE associated with residential exposure to pesticides in an urban population of predominantly African-American females.

Methods:

Female patients with SLE were identified via 6 hospital databases and community screening in 3 predominantly African-American neighborhoods in Boston, Massachusetts. Each SLE patient was reviewed by a rheumatologist and confirmed to have ≥4 ACR criteria for SLE. Subjects without SLE were female volunteers from the same neighborhoods, screened for the absence of connective tissue disease by questionnaire and finger stick anti-nuclear antibody. In-person interviews from April 2002 to August 2003 determined type and frequency of pesticide exposure prior to SLE diagnosis or corresponding reference age in subjects without SLE. Subjects were considered exposed to pesticides if they had ever required an exterminator for an ant, cockroach, or termite problem. The risks associated with exposure to pesticides were analyzed using multivariable logistic regression models, adjusted for age, race, parity, employment status, educational attainment, smoking status, and place of birth.

Results:

93 SLE patients and 170 subjects without SLE were matched by age and race, with similar baseline characteristics (see table). Patients with SLE were more likely to have had exposure to pesticides than subjects without SLE (65% vs. 51%, p=0.03). Pesticide exposure was associated with SLE, even after controlling for potential confounders (OR 2.24, 95% CI 1.28-3.93). A dose-response effect for increased frequency of exterminator service use was not statistically significant (p for trend=0.21).

Conclusion:

Residential exposure to pesticides in an urban community of predominantly African-American women was associated with an increased risk of SLE, even after controlling for potential confounders. Our findings demonstrate that previous reports of an association between pesticide exposure and SLE may be applicable to urban African-American women, a population at increased risk for SLE. As our results may be limited by recall bias and/or residual confounding, additional research is needed to determine whether pesticide exposure is implicated in SLE pathogenesis, or is instead serving as a surrogate for a related exposure such as pest burden or poor living conditions.  

Table. Characteristics of subjects with and without SLE*

*Unless indicated otherwise, values are the number (%).

†By chi-square test. Wilcoxon rank-sum test was used for age.

‡Before age at diagnosis or corresponding reference age.