Organochlorine compounds in carpet dust and non-hodgkin lymphoma risk

Purpose The incidence of non-Hodgkin lymphoma (NHL) has risen over the past several decades, and a substantial portion of the increase remains unexplained. In this population-based case–control study in Iowa and metropolitan Detroit, Los Angeles, and Seattle, we examined NHL risk and exposure to organochlorine compounds using concentrations measured in household carpet dust as an exposure indicator. Methods We identified NHL cases, uninfected with HIV, diagnosed between 1998 and 2000 among residents aged 20 to 74 and selected controls using random-digit-dialing and Medicare eligibility files. Used vacuum bags were collected from participants who had owned at least half of their carpets for at least 5 years. The current analysis is based on dust samples from 603 Caucasian cases and 443 Caucasian controls. Results Age of the home was a significant predictor of organochlorine levels in carpet dust, with the highest concentrations found in homes built before 1960 and the lowest in homes built after 1980. There was a statistically significant elevation in NHL risk if DDE (metabolite of DDT) was detected in the dust (odds ratio OR = 1.3, 95% confidence interval CI = 1.0–1.7) or if at least one of the five polychlorinated biphenyl congeners (PCB 105, PCB 138, PCB 153, PCB 170, PCB 180) was detected (OR = 1.5, 95% CI = 1.2–2.0). When levels above the detection limit were divided into tertiles, risk was significantly elevated in the top tertiles of DDE and PCB 180, and in the top two tertiles of total PCBs. There were significant positive trends in risk with increasing concentrations of DDE and PCB 180 (Ptrend = 0.02 and 0.03, respectively), but not for total PCBs. Conclusion Our data suggest an increased risk of NHL from exposure to DDE and PCB 180. Previous studies using other approaches have had inconsistent findings. Additional studies are needed to evaluate how well carpet dust represents historic exposure to organochlorine compounds. Results from blood samples of study participants may help to clarify the relationship between organochlorine exposure and NHL risk.