When 3M stopped the production of their Class B foam in 2000 they had 50% of the market share. Their announcement sent shock waves throughout the fire community with fire chiefs wondering, 1) what they would use for foam, 2) if they should use ANY foam, and 3) where they stood with respect to the possible harmful effects, if any, on their firefighters and the public.
Here is an excerpt from the announcement that was part of a very interesting article in the May-June 2000 issue of Fireworld:
ST. PAUL, Minnesota—May 16–3M today announced it is phasing out of the perfluorooctanyl chemistry used to produce certain repellents and surfactant products. The affected product lines represent about two percent of 3M’s nearly $16 billion in annual sales. These include Scotchgard products, such as soil, oil and water repellent products; coatings used for oil and grease resistance on paper packaging; fire-fighting foams; and specialty components of other products.Class B foam is designed to be used on flammable liquid fires and was developed by 3M with the U.S. Navy in the 1960s. It covers burning petroleum with a thin film which smothers the fire.
Many wildland and structure fire organizations use Class A foam on vegetation and structure fires. Class A foam has not been identified in the probe of contaminated water in Minnesota.
The U.S. Forest Service tests and approves the Class A foam that is used by the federal land management agencies. One of the specifications they test for is the biodegradability. Foam concentrates must be "biodegradable" or "readily biodegradable". Other characteristics they test for include mammalian toxicity, fish toxicity, flash point, fire point, physical properties, exposure protection, corrosion, and surface tension. HERE is the list of Class A foam products that are currently approved. The Material Safety Data Sheets (MSDS) are listed HERE.
In the late 1970s when I worked for the U.S. Forest Service in California we occasionally used Class B foam on vehicle fires and even some wildland fires, especially on deep-seated fires such as hay stacks or deep duff. But when Class A foam became available we switched completely over, using Class A foam on vehicle and wildland fires.
Some of the early Class B foam was known as "protein foam". Conventional wisdom was that it was made from fish guts, and that's what it smelled like. NASTY stuff. Somehow I doubt if that crap contained the perfluorochemicals that 3M later used.
Even though in 2000 3M stopped making the foam currently being investigated, many fire departments probably still have 5-gallon pails of the stuff stored at their fire houses. In 2000 National Foam, Ansul, Chemguard and Angus pointed out that their foam products contained no PFOS and that electro-fluroination which produces the perfluorochemicals is unique to 3M.
More information about the contaminated water is at the Star Tribune.