Traffic-related air pollution exposure and childhood central nervous system tumors
There is a growing concern over the impact of exposure to traffic-related air pollutants and childhood central nervous system (CNS) tumors. The objective of this project was to assess exposure to high levels of traffic-related air pollution as a risk factor for childhood CNS tumors overall, as well as the specific CNS tumor histologic types (e.g., astrocytoma and medulloblastoma). In addition, we assessed the impact of residential mobility of CNS tumor cases between birth and diagnosis on air pollution exposure assessment. Data from the Texas Cancer Registry were used to: 1) conduct an ecologic study assessing the associations between area-level concentrations of traffic-related hazardous air pollutants (HAP) and the incidence of CNS tumors in children < 15 years of age; 2) conduct a case-control study assessing maternal residential proximity to major roadways at delivery and risk of having offspring who develop a CNS tumor at < 5 years of age; and 3) assess the extent to which change of residence may result is differential HAP exposure classification when based on maternal residence at birth compared to when based on the child's residence at diagnosis. We found that census tracts with medium and medium-high 1,3-butadiene concentrations had higher astrocytoma incidence rates (IRR [95% CI]: 1.5 [1.1, 2.0] and 1.7 [1.2, 2.3], respectively) compared with census tracts with low concentrations. Census tracts with medium diesel particulate matter concentrations had higher astrocytoma (IRR [95% CI]: 1.4 [1.1, 1.9]) and medulloblastoma (IRR [95% CI]: 1.5 [1.0, 2.1]) incidence rates compared with census tracts with low concentrations. Furthermore, mothers who lived in areas with high roadway density were 1.5-times more likely (95% CI: 1.1, 2.1) and 4.2-times more likely (95% CI: 1.2, 14.9) to have offspring with any CNS tumor and an ependymoma, respectively, when compared to mothers living in areas with low roadway density. On the question of differential exposure classification based on residential mobility, we found that HAP exposures assessed using the child's residence at diagnosis may be a reasonable proxy for exposures at birth for tumors diagnosed in early childhood (0-4 years old) (p = 0.277). In contrast, HAP exposure at birth may not be an accurate measure of HAP exposure at diagnosis, and vice versa, for tumors diagnosed in older children (5-14 years old) (p < 0.001). This project is the first to report statistically significant associations between exposure to traffic-related air pollutants and astrocytoma, ependymoma, and medulloblastoma in children. Our results contribute to the growing body of evidence regarding air pollutant exposure and childhood cancers.
Environmental Health|Public health|Epidemiology
Danysh, Heather E, "Traffic-related air pollution exposure and childhood central nervous system tumors" (2015). Texas Medical Center Dissertations (via ProQuest). AAI3720077.