Ambient benzene at the residence and risk for subtypes of childhood leukemia, lymphoma and CNS tumor

Exposure to benzene increases the risk for acute myeloid leukemia and possibly other types of cancer in adults. For children, only limited evidence about benzene and cancer exists. A few studies have indicated that benzene may increase risk for some subtypes of childhood cancer but not for others. We aimed to investigate if outdoor levels of benzene at the residence increase the risk for subtypes of leukemia, lymphoma and CNS tumor in children. We identified 1,989 children diagnosed with leukemia, lymphoma or CNS tumor during 1968-1991 in the Danish Cancer Registry and randomly selected 5,506 control children from the Danish population, matched on sex, age and calendar time. We traced residential history of all children from 9 months before birth to time of diagnosis, calculated outdoor benzene concentration at all addresses and summarized cumulative exposure over fetal and childhood periods separately. We used conditional logistic regression for the statistical analyses. Benzene exposure during childhood above the 90th percentile was associated with relative risks for acute lymphocytic leukemia (ALL) and acute myeloid leukemia (AML) of 1.0 (95% confidence intervals (CI): 0.6-1.7) and 1.9 (95% CI: 0.3-11.1), respectively, when compared with exposure levels below the median. For CNS tumors, there was a tendency of lower risk for ependymoma and higher risk for medulloblastoma in association with higher exposure. In conclusion, benzene was associated with higher risk for childhood AML, but not ALL, which is consistent with the few previous studies.