Abstract 2531: Childhood cancer and traffic-related air pollution exposure in pregnancy and early life.
Authors: Heck Julia E. , Wu Jun , Meyers Travis J. , Wilhelm Michelle , Cockburn Myles , Ritz Beate 
Published: August 2014

Background: The literature on traffic-related air pollution and childhood cancers presents a mixture of findings, likely due to variations in exposure assessment methods, differing time periods in the children's lives that were considered with regard to exposures, and often, small sample sizes which necessitated the grouping together of disparate cancer types. To date, few studies used a sophisticated emissions-based model to assess pollution exposures in pregnancy and early childhood.

Methods: The present study included children younger than age 6 identified in the California cancer registry (born 1998-2007) who could be linked to a California birth certificate (N=3590). Controls were selected at random from California birthrolls (N=80,224). 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. Model inputs were based on local traffic emissions of both gasoline vehicles and diesel trucks within a 1500m radius buffer, and included traffic volumes, roadway geometry, vehicle emission rates, and meteorology. Unconditional logistic regression was used to estimate cancer risk.

Results: A per interquartile range increase in exposure to traffic-related pollution from CALINE4 was associated with increases in acute lymphoblastic leukemia, germ cell tumors, and retinoblastoma, particularly bilateral. CALINE4 estimates were highly correlated across trimesters and the 1st year of life (r∼0.96-0.98), making it difficult to discern the most important period for exposure.

Cancer risk with one interquartile increase of CO (ppm) in the 2nd trimester Cancer N cases OR (95% CI) Acute lymphoblastic leukemia (ALL) 1280 1.04 (1.00, 1.09) Acute myeloid leukemia (AML) 229 0.91 (0.80, 1.04) Non Hodgkin lymphoma (NHL) 78 1.10 (0.95, 1.28) Ependymoma 125 1.08 (0.94, 1.24) Astrocytoma 282 0.95 (0.85, 1.06) Intracranial and intraspinal embryonal tumors 205 0.98 (0.86, 1.11) Neuroblastoma 417 0.99 (0.91, 1.09) Retinoblastoma 254 1.14 (1.04, 1.24) –Unilateral 165 1.11 (0.99, 1.24) –Bilateral 87 1.19 (1.05, 1.35) Wilms tumor 298 0.91 (0.81, 1.03) Hepatoblastoma 127 1.01 (0.86, 1.18) Rhabdomyosarcoma 144 0.90 (0.76, 1.07) Germ cell tumors 140 1.17 (1.05, 1.30)

Conclusions: Our findings support a relation between traffic pollution and several childhood cancers. As this is the first study to report upon traffic pollution in relation to retinoblastoma or germ cell tumors, and both are rare, these findings require replication in other studies.

Citation Format: Julia E. Heck, Jun Wu, Travis J. Meyers, Michelle Wilhelm, Myles Cockburn, Beate Ritz. Childhood cancer and traffic-related air pollution exposure in pregnancy and early life. [abstract]. In: Proceedings of the 104th Annual Meeting of the American Association for Cancer Research; 2013 Apr 6-10; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2013;73(8 Suppl):Abstract nr 2531. doi:10.1158/1538-7445.AM2013-2531