Environment/Climate Change
Association between early life traffic-related exposures and subsequent childhood asthma development in the Tennessee Medicaid population: A retrospective cohort study Akihiro Shiroshita* Akihiro Shiroshita Shiroshita Shiroshita Shiroshita Shiroshita Shiroshita Shiroshita Shiroshita Vanderbilt University
Traffic-related exposures during early life are associated with increased risk of childhood asthma. However, most studies have not accounted for residential relocation, and were conducted primarily in urban settings and in highly selected populations. In this study, we evaluated eight measures of traffic-related exposure among children enrolled in the Tennessee Medicaid program (TennCare), a vulnerable low-income population. We constructed three cohorts based on exposure windows: a dyad cohort (exposure during pregnancy), an infant cohort (exposure during the first year of life), and a childhood cohort (exposure during the first four years of life). Traffic-related exposures included road proximity, traffic density and road length within a 500-m buffer, and nitrogen dioxide and black carbon levels estimated using previously validated machine learning models. To account for residential relocation during the exposure window, exposures were weighted by the number of months each child resided at each address. The outcome was childhood asthma, defined using ICD-9/10 diagnosis codes and medication prescriptions between ages 4 and 6 years. Logistic regression models were fitted, adjusting for clinically meaningful covariates, and exposures were modeled using restricted cubic splines. A total of 455,116 (dyad), 552,080 (infant), and 489,360 (child) children were included in each cohort. About 10–15% of children had an asthma diagnosis across cohorts. Across all exposure windows, higher average black carbon levels during the exposure period were consistently associated with an increased risk of childhood asthma (Figure). In contrast, other traffic-related indicators did not capture biologically plausible dose-response relationships with asthma. These findings suggest that reducing black carbon exposure among pregnant women and children may be an effective strategy for mitigating childhood asthma risk.
