You are here:
Zebrafish locomotor responses reveal that irritant effects of biomass are influenced by fuel type, burn conditions, and byproduct chemistry.
Citation:
Martin, W., S. Padilla, Y. Kim, M. Hays, D. Hunter, M. Hazari, D. DeMarini, Ian Gilmour, AND A. Farraj. Zebrafish locomotor responses reveal that irritant effects of biomass are influenced by fuel type, burn conditions, and byproduct chemistry. Society of Toxicology Annual Meeting 2019, Baltimore, Maryland, March 10 - 14, 2019.
Impact/Purpose:
This work demonstrates the utility of a rapid biologically relevant screening assay with which to quickly assess the toxicity of different sources of air pollution, including wildland fire-related biomass emissions. Furthermore, this assay, when combined with chemical speciation and engineering measures to mimic various burns, can be used to identify the most potent chemical classes, and facilitate targeting of air pollution sources of greatest concern.
Description:
Human exposures to wildfire-derived particulate matter (PM) have been linked to increased incidences of adverse heart and lung health outcomes. However, little is known about the influences of biomass fuel type and burn conditions on toxicity. The purpose of this study was to assess the irritant potential of extractable organic material (EOM) of PM derived from biomass smoke condensates from 5 fuels (Eucalyptus, Pine, Pine Needle, Peat, or Red Oak), representing various fire-prone regions of the USA, burned at 2 temperatures each (flaming at ~640 oC or smoldering at ~500 oC) in a locomotor assay in 6-day post-fertilization (dpf) zebrafish. We hypothesized that locomotor responses, measures of irritant effects, are dependent on fuel type and burn conditions and that these differences would relate to combustion byproduct chemistry. To test this, locomotor activity was tracked for 60 minutes in the dark in 6-dpf zebrafish embryos (28-32/group) exposed acutely to 0.4% DMSO vehicle or EOM from biomass smoke (0.3-30 µg EOM/ml; half-log intervals) from each of the 10 condensates in 96-well plates. All condensates elicited concentration-dependent responses. Linear regression analysis (of the first 20 minutes of concentration-response data) to derive rank order potency indicated that on a µg PM basis, flaming Pine and Eucalyptus demonstrated the greatest irritant effects. By contrast, on an emission-factor basis, which normalizes responses to the amount of PM produced/kg of fuel burned, smoldering smoke condensates showed a much greater capacity (~100-fold) to elicit irritant responses than flaming condensates, with smoldering Pine being the most potent. Importantly, irritant responses strongly correlated with polycyclic aromatic hydrocarbons (PAH) content (r=0.95, r2=0.90, p<0.0001), but not organic carbon or methoxyphenols. These results indicate that fuel type and burn conditions impact toxicity, and differences in responsiveness are likely determined by the quantity and chemical composition of PM. Furthermore, the results corroborate findings in mouse lung toxicity and PAH-sensitive Salmonella mutagenicity assays. [This abstract does not reflect USEPA policy.]