Fuel Type Influences Developmental Toxicity of Burn Pit-related Smoke in Zebrafish
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Exposure to smoke emitted from burn pits in military bases has been linked with adverse health effects. Earlier studies have linked air pollution exposure from other sources to congenital defects, but the 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 derived from burn pit-related smoldering smoke condensates of 5 fuels: plywood (representing ammunition boxes), cardboard (representing military spec boxes), plastic (a mixture of low-density polyethylene, high-density polyethylene, polyethylene terephthalate, and polystyrene pellets), mixture (mixt of plywood, plastic, and cardboard), and mixture plus diesel (mixture treated with diesel fuel, often used as an accelerant in burn pits), in zebrafish. We hypothesized that developmental toxicity is dependent on fuel type. To test this, zebrafish larvae (n = 8/treatment) were exposed from 6 hours post fertilization through 4 days post fertilization (dpf) to 0.4% dimethyl sulfoxide vehicle or extractable organic material from burn pit smoke (0.01-40 µg/ml; half-log intervals) from each of the 5 condensates in 96-well plates and assessed by a blinded researcher for malformations at 5 dpf using visual observation with light microscopy, a bioimager, and analysis software. 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 in the remaining treatment groups. Condensates from plastic and the mixture containing plastic caused a higher rate of deformities than other materials. Taken together, these results indicate that material type burned impacts the severity of burn pit smoke-induced developmental toxicity in zebrafish. (This abstract does not reflect U.S. E.P.A policy; DoD award #W811XWH-18-1-0731 (IJ)).