Occupational exposure to high molecular weight allergens and lymphoma risk among Italian adults.

OBJECTIVES Exposure to high molecular weight (HMW) allergens that provoke immune reactivity through an IgE-mediated pathway has been associated with a decreased risk of B-cell lymphoma. The present analysis was conducted to assess the associations between occupational exposure to specific HMW allergens and the risk of B-cell, T-cell, and Hodgkin's lymphomas. METHODS We analyzed data from 2,290 incident lymphoma cases and 1,771 population-based controls enrolled in a multicenter study of hematolymphopoietic malignancies conducted in Italy between 1991 and 1993. All cases were histologically or cytologically confirmed. Controls were frequency-matched to cases based on age, sex, and study center. An industrial hygienist evaluated HMW occupational exposure classifications after an asthma-specific job exposure matrix was applied to participants' job histories. Unconditional logistic regression was used to assess associations between occupational exposures that occurred > or = 10 years before the date of lymphoma diagnosis and B-cell, T-cell, and Hodgkin's lymphomas. RESULTS Ten percent of cases and 11% of controls were occupationally exposed to HMW allergens. Exposed individuals had a decreased risk for all lymphomas combined (odds ratio, 0.78; 95% confidence interval, 0.63-0.97), particularly for B-cell lymphomas (odds ratio, 0.75; 95% confidence interval, 0.59-0.94). The decreased risks for all lymphomas were also observed when HMW allergen exposure was limited to animal and latex allergens. CONCLUSIONS These findings support the hypothesis that occupational exposure to immunologically active HMW allergens is inversely associated with the risk for lymphoma. The effect of exposure to specific allergens warrants further assessment.