Residential exposure to polychlorinated biphenyls and organochlorine pesticides and risk of childhood leukemia.
BACKGROUND
Incidence of childhood leukemia in industrialized countries rose significantly during 1975-2004, and the reasons for the increase are not understood.


OBJECTIVE
We used carpet dust as an exposure indicator to examine the risk of childhood leukemia in relation to residential exposure to persistent organochlorine chemicals: six polychlorinated biphenyl (PCB) congeners and the pesticides alpha- and gamma-chlordane, p,p'-DDT (dichlorodiphenyltrichloroethane), p,p'-DDE (dichlorodiphenyldichloroethylene), methoxychlor, and pentachlorophenol.


METHODS
We conducted a population-based case-control study in 35 counties in northern and central California in 2001-2006. The study included 184 acute lymphocytic leukemia (ALL) cases 0-7 years of age and 212 birth certificate controls matched to cases by birth date, sex, race, and Hispanic ethnicity. We collected carpet dust samples from the room where the child spent the most time before diagnosis (similar date for controls) using a specialized vacuum.


RESULTS
Detection of any PCB congener in the dust conferred a 2-fold increased risk of ALL [odds ratio (OR) = 1.97; 95% confidence interval (CI), 1.22-3.17]. Compared with those in the lowest quartile of total PCBs, the highest quartile was associated with about a 3-fold risk (OR = 2.78; 95% CI, 1.41-5.48), and the positive trend was significant (p = 0.017). Significant positive trends in ALL risk were apparent with increasing concentrations of PCB congeners 118, 138, and 153. We observed no significant positive associations for chlordane, DDT, DDE, methoxychlor, or pentachlorophenol. The associations with PCBs were stronger among non-Hispanic whites than among Hispanics despite similar distributions of PCB levels among controls in each racial/ethnic group.


CONCLUSIONS
Our findings suggest that PCBs, which are considered probable human carcinogens and cause perturbations of the immune system, may represent a previously unrecognized risk factor for childhood leukemia.
Ward
Mary H
MH
Division of Cancer Epidemiology and Genetics, National Cancer Institute, National Institutes of Health, Department of Health and Human Services, Bethesda, Maryland 20892-7240, USA. wardm@mail.nih.gov
Colt
Joanne S
JS
Metayer
Catherine
C
Gunier
Robert B
RB
Lubin
Jay
J
Crouse
Vonda
V
Nishioka
Marcia G
MG
Reynolds
Peggy
P
Buffler
Patricia A
PA
D002648:Child; D002675:Child, Preschool; D004781:Environmental Exposure; D004785:Environmental Pollutants / Q000633:toxicity*; D005260:Female; D006630:Hispanic or Latino; D006801:Humans; D006843:Hydrocarbons, Chlorinated / Q000633:toxicity*; D007223:Infant; D007231:Infant, Newborn; D007938:Leukemia / Q000139:chemically induced* / Q000453:epidemiology / Q000208:ethnology; D008297:Male; D010575:Pesticides / Q000633:toxicity*; D011078:Polychlorinated Biphenyls / Q000633:toxicity*; D012307:Risk Factors; D044465:White People
D004785:Environmental Pollutants; D006843:Hydrocarbons, Chlorinated; D010575:Pesticides; D011078:Polychlorinated Biphenyls