Leukemia risk in children exposed to benzene and PM10 from vehicular traffic: a case-control study in an Italian population.

Benzene, a recognized occupational leukemogen in adults, has been implicated by sparse and conflicting epidemiologic evidence in the etiology of childhood leukemia. We carried out a population-based case-control study in a northern Italy population involving 83 cases with childhood leukemia diagnosed in the years 1998-2009 and 332 matched controls. We assessed residential exposure to benzene and to particulate matter ≤10 µm (PM10) from motorized traffic using geocoded residences and detailed emission and dispersion modeling. Exposure to benzene, and to a lesser extent to PM10, appeared to be independently associated with an excess leukemia risk. When we stratified the study population by age, the relative risk associated with benzene exposure was higher among children aged less than five years. Overall, these findings suggest that low levels of benzene exposure released from motorized traffic may increase the risk of childhood leukemia, and do not rule out an independent effect of PM10.