On December 1, the Tennessee Division of Forestry reported that ongoing wildfires in the state have devastated more than 26-thousand acres this autumn. This includes the 17-thousand acre fire that forced the evacuation of Gatlinburg, destroyed over fifteen-hundred structures, and killed 14 so far. During this time the Tennessee Poison Center has received calls about smoke inhalation, carbon monoxide, and other environmental concerns. One of the topics of interest has been the types of fire retardant that are sprayed to control the spread of wildfires and their potential health hazards.
Fire retardants used in wildfire suppression are mixtures designed to wet the area and chemically impede the fire’s progression through vegetation. Borate salts were used in the past to fight wildfires but have since been found to sterilize the soil and be highly toxic to animals. Newer fire retardants are typically phosphate compounds such as diammonium phosphate (DAP) or ammonium polyphosphate (AAP) with a thickener and colored red with either ferric oxide or fugitive color to mark where they have been dropped. These are not only less toxic but act as fertilizers to promote forest regrowth.