Scotchgard strikes back
Long thought to be chemically so inert as to be biologically inactive, emerging studies combined with old data from industry files establish that perfluorooctane sulfonate (PFOS) is a persistent organic pollutant, with poorly understood but significant health risks to wildlife and people.
The PFOS story is likely to emerge as one of the apocryphal examples of 20th century experimentation with widespread chemical exposures: prolific use and almost no testing for safety, until unexpectedly and almost serendipitously, it is discovered as a contaminant virtually everywhere. And as is often the case in these stories, the company producing PFOS products possessed information hinting at its risks but chose not to share their data with regulators or the public for years.
[for a detailed exploration of this history, see The Chemical Industry Archives]
Extremely resistent to environmental breakdown, PFOS is now a ubiquitous contaminant, found in polar bears in the Arctic, dolphins in Florida, seals and otters in California, albatross in the mid-Pacific, and people world-wide. Traditional scans for persistent pollutants missed this exposure for a long time because unlike most POPs, PFOS doesn't accumulate in fatty tissue. Instead it binds to proteins.
Data accumulating on its toxicity provide as yet uncertain answer about its impacts. Long assumed by regulators to be inert and thus safe, evidence suggesting unsuspected risks lay largely unexamined in EPA and company files. They then became too ominous to ignore.
Used as the key ingredient in Scotchgard, the 3M-made fabric protector, PFOS has been part of consumer culture for over 40 years, valued for its ability to protect materials from stains because it repels both water and oil. It is widely used in a variety of industrial and consumer products, ranging from fire extinguishing foams to wrapping for microwave popcorn and other food products.
In spring 2000, Scotchgard's manufacture, 3M, surprised almost everybody by announcing they would eliminate their line of PFOS-related products by 2002.
When 3M announced it was removing Scotchgard and related chemicals from its product line the company was lauded for its environmental responsibility. According to 3M, it was eliminating a profitable part of its business--worth some $300 milliion per year--on the basis of precautionary concerns raised because PFOS was accumulating in a wide diversity of species, including people "at extremely low levels." 3M's press release disclaimed any health threats, asserting that over 700 studies established the chemical's safety.
As detailed by an EPA analysis (pdf file) of 3M's own documents, however, disturbing information had been accumulating for some time about PFOS toxicity.
For example:
- According to EPA's assessment of 3M data, PFOS caused postnatal deaths (and other developmental effects) in offspring in a 3M-run 2-generation reproductive effects rat study (NOAEL of 0.1 mg/kg/day and LOAEL of 0.4 mg/kg/day). At higher doses in this study, all progeny in first generation died while at the LOAEL many of the progeny from the second generation died. It is very unusual to see such second generation effects."
- A 3M study (pdf file) of the effect of PFOS on monkeys found that exposed individuals exhibited "low food consumption, excessive salivation, labored breathing, hypoactivity, ataxia, hepatic vacuolization and hepatocellular hypertrophy, significant reductions in serum cholesterol levels, and death."
EPA summarizes its assessment by observing: "PFOS accumulates to a high degree in humans and animals. It has an estimated half-life of 4 years in humans. It thus appears to combine Persistence, Bioaccumulation, and Toxicity properties to an extraordinary degree" (emphasis added).
This story is far from over. Research is now concentrating on characterizing the mechanisms of PFOS toxicity, identifying the full range of impacts, getting a fuller picture of contamination levels in people and wildlife, and examining related perfluorinated compounds, including perfluorooctanoic acid (PFOA), a chemical involved in the production of Teflon.