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.
Lockheed Neptune (N443NA) dropping fire retardant ahead of a fire in Leona Valley, California
(Photo by Thomas Hays – July 2010)
DAP produces an irritant/corrosive effect on contact with moist tissues such as the eyes and upper respiratory tract. Mild to moderate inhalation exposures produce headache, cough, bronchospasm, nausea, vomiting, pharyngeal and retrosternal pain, and conjunctivitis. Severe inhalation produces laryngospasm, signs of upper airway obstruction (i.e. stridor, hoarseness, dysphonia) and, in excessively high doses, pulmonary edema. Warm humidified air may sooth bronchial irritation. All patients with conjunctival irritation should be decontaminated with water and tested for corneal abrasion. Dyspneic patients should receive a chest X-ray and arterial blood gases to detect pulmonary edema. Exposure to aqueous DAP solutions can also cause severe corrosive injury to the skin. In contrast, AAP is relatively inert, but may pose a mild eye irritation risk to those exposed to aerosolized particles.
The Tennessee Poison Center recommends the following to those encountering fire retardants:
- If skin contact occurs, immediately remove all contaminated clothing. Flush skin and hair with running water (and soap if available). Seek medical attention in event of irritation.
- If an eye exposure occurs, wash out immediately with fresh running water for at least 5-10 minutes. Seek medical attention without delay to assess for any corrosive injury.
- If vapor or combustion products are inhaled, remove the patient from the exposure area immediately, and give supplemental oxygen if available. Transport to hospital without delay.
- Residents who live under the flight path of aircraft performing retardant drops should limit outdoor activities to prevent incidental exposure to any potential runoff.
This question prepared by: Justin Loden, PharmD, CSPI (Certified Specialist in Poison Information) Tennessee Poison Center
References
- Albright Wilson. (2013 January 1). Ammonium Polyphosphate [ChemWatch Review Safety Data Sheet]. Retrieved from: https://jr.chemwatch.net/chemwatch.web/account/login
- Albright Wilson. (2013 January 1). Diammonium Phosphate [ChemWatch Review Safety Data Sheet]. Retrieved from: https://jr.chemwatch.net/chemwatch.web/account/login
- TEMA Headlines. (2016 December 2) Retrieved from: http://www.tnema.org/news/tema/
I am interested in any questions you would like answered in the Question of the Week. Please email me with any suggestion at donna.seger@vanderbilt.edu
Donna Seger, MD
Medical Director
Tennessee Poison Center
Poison Help Hotline: 1-800-222-1222