Asthma Associations with Multiple Environmental Exposures, Income & Systemic Products of Oxidative Stress

Diesel exhaust particles (DEP) and secondhand smoke (SHS) exposures induce and exacerbate asthma, likely in part because they lead to greater levels of oxidative stress. We therefore sought to determine whether fluorescent oxidation products (FLOP) in plasma are biologically relevant measures of exposure-derived oxidative stress. FLOP result from simultaneous activation of multiple pathways in vivo and are stable, easy to measure, and reproducible with persons over time.  We hypothesized that their measurement would better predict asthma risk and morbidity, particularly as children can be exposed to equal levels of measured pollutants, but experience very different biologic consequences.  We recruited 294 asthmatics and 98 non-asthmatic/non-allergic controls as part of our NIEHS-funded Pediatric Environmental Exposure Study (PEES).  DEP exposure was determined by estimating elemental carbon attributable to traffic using a land-use regression model from current and early-life home-address coordinates. SHS exposure was determined by questionnaire and serum cotinine ELISA. In addition, overweight status was based on the CDC’s age/sex-adjusted body mass indices (≥85^th %). We determined that SHS exposure alone (not DEP exposure, overweight status) was associated with FLOP (OR=1.6, p=0.05). FLOP was marginally associated with asthma (OR=1.6, p=0.06) and significantly associated with poorer asthma control (OR=1.9, p=0.02). FLOP did not better predict asthma over estimation/reporting of exposures. Importantly, children with higher DEP at birth that were also SHS-exposed and overweight were at greatest risk of asthma (OR=6.3; p=0.001) compared to unexposed, lower weight children; and these children were predominantly living in low-income households (<40K/year; OR=7.9; p=0.00005).  Additional analysis (e.g. multiple regression, factor analysis, etc.) are underway to assess the independent and combined roles of each of these factors. Further, from these studies, we are also pursuing mixed-methods/CBPR studies that will strongly consider economic/neighborhood context in order to better inform our studies' results and further examine how the environment and income modify asthma risk and morbidity.