A NESTED CASE-CONTROL STUDY OF NON-HODGKIN-LYMPHOMA AND SERUM ORGANOCHLORINE RESIDUES

Background The steady worldwide increase in the incidence of non-Hodgk in lymphoma during the past few decades remains mostly unexplained. Se veral studies suggest that there may be an association between the agr icultural use of the organochlorine 1,1,1-trichloro-2,2'bis(p-chloroph enyl)ethane (DDT) and increased. risk of non-Hodgkin lymphoma. We have investigated the association between risk of non-Hodgkin lymphoma and body burden of selected organochlorines in the general population in a nested case-control study. Methods We measured prediagnostic serum c oncentrations of DDT, its metabolites, and other organochlorines, incl uding polychlorinated biphenyls (PCBs), in 74 cases of non-Hodgkin lym phoma and 147 matched controls identified from a prospective cohort of 25 802 adults, established in 1974 in Washington County, Maryland, US A. We report results for total lipid-corrected serum concentrations of DDT and total PCBs. Findings There was a strong dose-response relatio n between quartiles of total lipid-corrected serum PCB concentrations and risk of non-Hodgkin lymphoma overall (odds ratios by quartile: 1.0 ; 1.3 [95% CI 0.5-3.3]; 2-8 [1.1-7.6]); and 4.5 [1.7-12.0]; p for tren d=0.0008) and separately in men and in women. There was also evidence suggesting that seropositivity for the Epstein-Barr virus early antige n potentiated the effects of serum PCBs. By contrast, total lipid-corr ected serum concentrations of DDT were not associated with risk of non -Hodgkin lymphoma. Interpretation These results should be regarded as hypothesis-generating. Before causal inferences can be made about expo sure to PCBs and increased risk of non-Hodgkin lymphoma, our findings require replication and the biological plausibility of the association needs further investigation.