Mobile Source Benzene Regulations and Risk of Childhood and Young Adult Hematologic Cancers in Alaska: A Quasi-experimental Study

Abstract

Background: We aimed to evaluate the impact of the EPA’s Mobile Source Air Toxics rules (MSAT), which targeted benzene emissions, on childhood and young adult leukemia and lymphoma incidence in Alaska. Methods: MSAT was implemented in 2011 and produced a dramatic decline in ambient benzene in Alaska. Due to previous benzene-related regulations enacted in the continental United States, MSAT had relatively modest impacts in other states. This created quasi-experimental conditions leveraged in this study. Using 2-year state-level incidence rates of childhood and young adult leukemia and lymphoma for each US state 2001–2018, we examined MSAT-attributable changes in incidence by applying a difference-in-differences approach. Results: We found evidence of a substantial reduction associated with MSAT in incidence of childhood and young adult lymphoma (–1.23 [–1.84, –0.62] cases per 100,000), but not in leukemia (–0.13 [–0.77, 0.51] cases per 100,000). Conclusions: Our findings are consistent with the hypothesis that MSAT, which reduced benzene levels in Alaska, led to a decline in lymphoma incidence in children and young adults.