Association between cumulative airborne dioxin exposure and non-Hodgkin's lymphoma risk in a nested case-control study within the French E3N cohort

Background: Dioxins are a family of chemical molecules that are chlorinated, lipophilic, and bio-accumulative. They are thought to enhance the risk of non-lymphoma Hodgkin's due to their known carcinogenic properties (NHL). This is the first epidemiological research to investigate the relationship between repeated emissions of airborne dioxin exposure and the risk of NHL. Objective: A case-control study nested within the French E3N cohort of 98,995 women covered by the health insurance provider of the national education system evaluated the association between cumulative airborne dioxin exposure and NHL risk. Materials and methods: NHL incident cases (368) and controls (368) were compared. Over the duration of the study, participants' residential histories and the locations of industrial sites were gathered (1990-2008). Using a Geographic Information System (GIS)-based exposure index, the cumulative exposure to airborne dioxins for each participant was calculated at the individual address level. The odds ratios (OR) and 95 % confidence intervals (CI) were calculated using multivariable conditional logistic regression models (CI). Results: The log-transformed continuous cumulative dioxin exposure index was substantially correlated with the risk of NHL (OR1.2 (95 % CI 1.0,1.4) for an increase in log-TEQ/m2 of 4.4, or one standard deviation). The combined chronic lymphocytic leukemia (CLL) and small lymphocytic lymphoma (SLL) subtype was significantly associated with NHL histological subtypes (OR 1.6 (95 % CI 1.1,2.3)). Conclusion: The findings of this study demonstrate a significant positive correlation between cumulative airborne dioxin exposure and the risk of NHL in women, and more specifically, a significant positive association for the CLL & SLL subtype. These results help to support the attempts to reduce the exposure to dioxins in the air.