Per- and polyfluoroalkyl substances

The Social Discovery of a Class of Emerging Contaminants

Aqueous film-forming foam (AFFF)

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U.S. Air National Guard photo by Airman 1st Class Amber Powell

Since its development in the 1960s, AFFF foam has been used by branches of the U.S. armed forces, members of NATO, and by fire departments around the word. AFFF consists of fluorosurfactants (PFASs), hydrocarbon surfactants, solvents, inorganic salts, corrosion inhibitors, and water. The use of PFASs in foam gives these mixtures a low surface tension and ability to spread; this makes it particularly effective against flammable liquid fires when mixed with water.

foam agent at work
Image source: Vanguard IFP

The fluorosurfactants originally produced by the 3M Company were based on perfluorooctane sulphonate (PFOS) chemistry. This continued until 2001 when the manufacturer ceased production (in part due to the discovery of ubiquitous PFOS exposure in the blood of the U.S. population) and other companies began to produce non- PFOS containing formulations of AFFF. However, some new formulations of foam contain “telomers,” compounds that can break down into PFOA (also known as C8) and other PFASs.

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C8+S Perfluorooctane sulfonate (PFOS)

While the Air Force maintains large stockpiles of PFOS-containing foam — which is still permitted to fight petroleum fires — it established parameters for reducing its existing PFOS-based supply in 2010.

AFFF enters the environment in multiple ways: through fire or catastrophic events, system discharge or false activation, firefighter training, and system testing. In areas where PFASs are not manufactured, PFAS groundwater contamination is typically traced back to a military fire or crash training sites and airports where AFFFs have been consistently used.

The Department of Defense (DOD) is currently in the process of testing for PFAS contamination in 664 locations where the military has conducted fire or crash training. The list of sites being investigated by the DOD can be found hereSee a map locations here.

Sources:

http://www.health.state.mn.us/divs/eh/hazardous/topics/pfcs/afff.html

http://themilitaryengineer.com/index.php/tme-articles/tme-magazine-online/item/418-investigating-emerging-contaminants

http://www.solbergfoam.com/getattachment/678ee341-8f4c-4a2f-b527-993568c6b606/Firefighting-Foam-and-the-Environment.aspx

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