Citation:

Smoot, J., S. Padilla, Yong Ho Kim, B. Hill, B. Knapp, M. Lowery, W. Oshiro, M. Hazari, M. Hays, B. Preston, I. Jaspers, Ian Gilmour, AND A. Farraj. Plastic Dominates Developmental Toxicity Responses to Burn pit-related Smoke in Zebrafish: Role for PAHs. 2023 Annual meeting of the Society of Toxicology, Nashville, TN, March 19 - 23, 2023.

Impact/Purpose:

The combustion of mixed materials in open air burning of refuse and housefires produces emissions that worsen air quality and contaminate rivers and streams. Additionally, smoke from biomass burns, which often include emissions from structural fires, especially in the wildland urban interface, has been associated with mortality and poor health outcomes including developmental effects. Freshwater organisms are often exposed to smoke from watershed runoff, ash deposits, or other forms of contamination making the zebrafish, a freshwater fish, a useful model for quickly screening the toxicological and developmental effects of smoke in such species. Furthermore, zebrafish biological responses to chemical agents are often analogous to and predictive of responses to the same agents in mammalian models. Thus, the present findings may increase understanding of the ecotoxicological and biological impacts of a key contemporary air pollution source (i.e., mixed material burns) and shed light on the influence of material type and combustion chemistry on such responses.

Description:

Combustion of mixed materials in open air burning of refuse and housefires produces emissions that worsen air quality and are increasingly associated with adverse health effects. Although previous studies have linked air pollution exposure from other sources to congenital defects, 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 (EOM) derived from burn pit-related smoldering smoke condensates from 5 fuels: plywood, cardboard, plastic, mixture, and mixture plus diesel in zebrafish and relate responses to condensate chemistry, which was analyzed by gas chromatography-mass spectrometry. 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. Zebrafish larvae (n=28 per treatment) were exposed during that same developmental window to 0.4% dimethyl sulfoxide vehicle or sublethal concentrations (0.01-1.2 µg/ml) of all 5 condensates and assessed by measuring photoinduced locomotion at 5 dpf. 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. Developmental exposure to plastic condensates also altered locomotor responsiveness to stimuli to the greatest extent, although plywood condensates also modified responsiveness. Interestingly, some morphological and behavior responses strongly correlated with condensate concentrations of total and specific polyaromatic hydrocarbons. Taken together, these results suggest that material type and combustion chemistry impact the severity of burn pit-related smoke-induced developmental toxicity in zebrafish. (Abstract does not reflect U.S. E.P.A policy; DoD award #W811XWH-18-1-0731 (IJ)).

Record Details: