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Kristina W. Whitworth,¹ Elaine Symanski,¹ and Ann L. Coker²

¹Division of Epidemiology and Disease Control, University of Texas School of Public Health, Houston, Texas, USA; ²Department of Obstetrics and Gynecology, University of Kentucky, Lexington, Kentucky, USA

Abstract
Background: Cancer is the second leading cause of death among U.S. children with few known risk factors. There is increasing interest in the role of air pollutants, including benzene and 1,3-butadiene, in the etiology of childhood cancers.

Objective: Our goal was to assess whether census tracts with the highest benzene or 1,3-butadiene ambient air levels have increased childhood lymphohematopoietic cancer incidence.

Methods: Our ecologic analysis included 977 cases of childhood lymphohematopoietic cancer diagnosed from 1995–2004. We obtained the U.S. Environmental Protection Agency's 1999 modeled estimates of benzene and 1,3-butadiene for 886 census tracts surrounding Houston, Texas. We ran Poisson regression models by pollutant to explore the associations between pollutant levels and census-tract cancer rates. We adjusted models for age, sex, race/ethnicity, and community-level socioeconomic status (cSES) .

Results: Census tracts with the highest benzene levels had elevated rates of all leukemia [rate ratio (RR) = 1.37 ; 95% confidence interval (CI) , 1.05, 1.78]. This association was higher for acute myeloid leukemia (AML) (RR = 2.02 ; 95% CI, 1.03–3.96) than for acute lymphocytic leukemia (ALL) (RR = 1.24 ; 95% CI, 0.92–1.66) . Among census tracts with the highest 1,3-butadiene levels, we observed RRs of 1.40 (95% CI, 1.07–1.81) , 1.68 (95% CI, 0.84–3.35) , and 1.32 (95% CI, 0.98–1.77) for all leukemia, AML, and ALL, respectively. We detected no associations between benzene or 1,3-butadiene levels and lymphoma incidence. Results that examined joint exposure to benzene and 1,3-butadiene were similar to those that examined each pollutant separately.

Conclusions: Our ecologic analysis suggests an association between childhood leukemia and hazardous air pollution ; further research using more sophisticated methodology is warranted.

Key words: 1, 3-butadiene, air toxics, benzene, childhood cancer, epidemiology, hazardous air pollution. Environ Health Perspect 116:1576–1580 (2008) .  doi:10.1289/ehp.11593 available via http://dx.doi.org/ [Online 25 August 2008]

Address correspondence to E. Symanski, University of Texas School of Public Health, 1200 Herman Pressler Dr., RAS 643, Houston, TX 77030 USA. Telephone: (713) 500-9238. Fax: (713) 500-9264. E-mail: Elaine.Symanski@uth.tmc.edu

We acknowledge the support and contributions from the Texas Department of State Health Services, Texas Cancer Registry.

This research was funded in part with federal funds from the National Cancer Institute, National Institutes of Health, Department of Health and Human Services through grant 1 R03 CA128106-01A1.

The authors declare they have no competing financial interests.

Received 18 April 2008 ; accepted 25 August 2008.