Plastic Dominates Developmental Toxicity Responses to Burn pit-related Smoke in Zebrafish: Role for Polycyclic Aromatic Hydrocarbons

Combustion of mixed materials during open air burning of refuse and housefires produces emissions that worsen air and water quality and cause adverse health effects. Although previous studies have linked air pollution exposure from other sources to congenital defects, the potential developmental toxicity of mixed material combustion emissions remains uncertain. The purpose of this study was to compare the developmental toxicity of smoke derived from the combustion of 5 different material types (plywood, cardboard, plastic, mixture, and mixture plus diesel) in zebrafish larvae, a model often used to assess the behavioral and developmental effects of chemicals. Zebrafish have been shown to have similar physiological and biochemical responses to smoke exposure as other vertebrates and absorb chemicals such as polyaromatic hydrocarboons through their epidermis from their surroundings. Larvae were exposed to organic extracts of each smoke at various concentrations and assessed for morphological and behavioral toxicity at 5 days post fertilization. All extracts caused concentration-dependent effects, including mortality, delayed swim bladder inflation, pericardial edema, scoliosis, tail kinks, and craniofacial deformities, although plastic and the mixture caused the most pronounced effects. Plastic also altered locomotor responsiveness to light changes to the greatest extent. Interestingly, some morphological and behavioral responses correlated strongly with total and specific polycyclic aromatic hydrocarbons concentrations in the smoke extracts. Overall, the findings suggest that material type and combustion chemistry impact the severity of developmental toxicity of mixed material smoke in zebrafish. (Abstract does not reflect U.S. EPA policy; DoD award #W811XWH-18-1-0731(IJ)).

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, have 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.

Citation

Smoot, J., S. Padilla, Y. Kim, B. Hill, B. Knapp, M. Lowery, A. Tennant, 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 Polycyclic Aromatic Hydrocarbons. The 18th Meeting of the International Neurotoxicology Association, Durham, NC, May 21 - 25, 2023.