Developmental Toxicity of Burn Pit-related Smoke in Zebrafish is Influenced by Fuel Type
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Combustion of mixed materials in open air burning of refuse and housefires produces emissions that worsen air quality and are increasingly linked to adverse health effects. Although previous studies linked air pollution exposure from other sources to congenital defects, potential developmental toxicity of burn pit-related emissions remains unclear. The purpose of this study was to assess the developmental toxicity of extractable organic material (EOM) derived from burn pit-related smoke condensates from 5 fuels: plywood, cardboard, plastic, mixture, and mixture plus diesel in zebrafish. We hypothesized that morphological and behavioral toxicity following developmental exposure is dependent on fuel type. Zebrafish larvae (n = 8/treatment group) were exposed from 6 hours post fertilization (hpf) through 4 days post fertilization (dpf) to 0.4% dimethyl sulfoxide vehicle or EOM (0.01-40 µg/ml; half-log intervals) from each of the 5 condensates in 96-well plates and assessed for malformations at 5 dpf. Behavioral responses to sublethal concentrations of all 5 condensates were also assessed by measuring photoinduced locomotion in 5 dpf larvae (n=28 per treatment). Morphologically, all burn pit condensates caused mortality at the highest concentration and concentration-dependent effects including delayed swim bladder inflation, pericardial edema, scoliosis, tail kinks, and/or craniofacial deformities. Condensates from plastic and the mixture containing plastic caused a higher rate of deformities than other materials. The behavioral test yielded mixed results by fuel type, and it suggests that embryos developmentally exposed to plastic condensate had a greater response to stimuli. Taken together, these results suggest that material type burned impacts the severity of burn pit smoke-induced developmental toxicity in zebrafish (Abstract does not reflect U.S. E.P.A policy; DoD award #W811XWH-18-1-0731 (IJ)).