(ChemotherapyAdvisor) – Increased exposure to traffic-related air pollution during pregnancy and early life was associated with a higher incidence of acute lymphoblastic leukemia (ALL), retinoblastoma, and germ cell tumors, according to a study presented at the American Association for Cancer Research (AACR) Annual Meeting 2013 in Washington, DC.

“This is the first study that’s ever been reported on air pollution as it relates to rarer pediatric cancers, so it needs to be replicated in other states or in other countries,” said Julia Heck, PhD, MPH, an assistant researcher in the Department of Epidemiology at the UCLA School of Public Health. “It would be interesting to determine if there are specific pollutants like benzene or polycyclic aromatic hydrocarbons that are driving these associations.”

Dr. Heck and colleagues identified 3,590 children younger than 6 years of age (born 1998-2007) from the California Cancer Registry who could be linked to a California birth certificate. Children were 5 years of age or younger at diagnosis. The 80,224 controls were selected at random from California birth rolls.

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“CAlifornia LINE Source Dispersion Modeling, version 4 (CALINE4) was used to generate estimates of local traffic exposures at the child’s residence during each trimester of pregnancy and in the first year of life,” the investigators reported. “Model inputs were based on local traffic emissions of both gasoline vehicles and diesel trucks within a 1,500-meter radius buffer, and included traffic volumes, roadway geometry, vehicle emission rates, and meteorology.”

Cancer risk with one interquartile increase of carbon monoxide (PPM) in the second trimester was determined for ALL (n=1,280 new cases), acute myeloid leukemia (n=229), non-Hodgkin lymphoma (n=78), ependymoma (n=125), astrocytoma (n=282), intracranial and intraspinal embryonal tumors (n=205), neuroblastoma (n=417), retinoblastoma (n=254; unilateral, n=165 and bilateral, n=87), Wilms tumor (n=298), hepatoblastoma (n=127), rhabdomyosarcoma (n=144), and germ cell tumors (n=140).

Each interquartile range increase in exposure to traffic-related pollution was associated with an increased risk for developing ALL (4%), retinoblastoma (14% for all cases; 11% for unilateral and 19% for bilateral) and germ cell tumors (17%).

“CALINE4 estimates were highly correlated across trimesters and the first year of life (r~ 0.96-0.98), making it difficult to discern the most important period for exposure,” they concluded.

Link to abstract: