Objectives A medical history of allergy, and particularly asthma, has been associated with an inverse risk of non-Hodgkin’s lymphoma (NHL). As occupational exposure to specific organic dusts is a risk factor for asthma, we explored risk of lymphoma and its major subtypes in relation to organic dusts.

Method In 1999–2004, 324 incident lymphoma cases and 464 population controls, frequency matched to cases by age and gender, were recruited among adult residents in Sardinia, Italy. Expert industrial hygienists assessed exposure to organic dust overall, and specific organic dusts. The odds ratio (OR) for lymphoma (all types) and its major subtypes, and its 95% confidence interval, was calculated using unconditional logistic regression.

Results Exposure to organic dust in general was inversely associated with risk of lymphoma (all types) (OR = 0.7, 95% CI 0.4–1.2), with a declining trend by duration and level of exposure. The inverse association was apparently more pronounced for exposure to flour dust and wood dust, but not to natural or artificial textile fibres. A consistent inverse risk was observed for B-cell lymphoma (OR = 0.6, 95% CI 0.3–1.0), and it was likewise for its major subtypes, namely diffuse large cell lymphoma (DLBCL), follicular lymphoma (FL) and chronic lymphocytic leukaemia (CLL). Age <= 18 at first exposure conveyed a further decrease in lymphoma risk (OR = 0.5, 95% CI 0.2–1.2).

Conclusions Although with interpretative limitations due to the small study size, our results suggest that exposure to flour dust and wood dust might contribute a reduction in risk of malignant lymphoma.