Effects of Fire-Retardant Chemical Products of Fathead Minnows in Experimental Streams

摘要

Each year large amounts of fire-retardant chemicals are applied to wildfires across the nation. The assessment of risk posed by the use of these chemicals includes understanding the toxicity of these materials relative to exposure concentrations that are likely to result from applications, the environmental persistence of the material, and surface runoff from treated watersheds. Recent laboratory studies with long-term fire retardant chemicals indicate a significant photo-enhanced toxicity of products containing sodium ferrocyanide corrosion inhibitors, with up to a 100-fold increase in toxicity to rainbow trout and a 10-fold increase in toxicity to southern leopard frogs in the presence of ultraviolet (UV) light. In contrast, compounds without this corrosion inhibitor were either unaffected in the presence of UV or exhibited a lesser additive toxicity than those containing the corrosion inhibitor. Toxicity data determined in laboratory studies of fireretardant chemicals may not accurately reflect toxicity in natural habitats because a variety of environmental variables can influence persistence as well as toxicity. Without information on toxicity in natural settings it is difficult to determine the ecological hazards and probability of injury resulting from exposure following field application of the fire-retardant chemicals. Aside from unintentional spills and overspray, stormwater runoff is a likely pathway of contamination to aquatic systems by fire-retardant chemicals. One might expect such exposures to be transient and of limited duration as the contaminated runoff is diluted and carried downstream by the water flow. In order to assess fire-chemical toxicity resulting from runoff, the fate and effects of two fire-retardant chemicals, Fire-Trol GTS-R (GTS-R) and Phos-Chek D75-R (D75-R) were tested over a 24-hour period in field tests using experimental streams.