PFAS General Information

What is PFAS?

PFAS (Per- and Polyfluoroalkyl Substances) is a class of chemical compounds that include over 3,000 synthetic organic chemicals used since 1940s that contain multiple Fluorine (F) atoms. The two most studied PFAS compounds are Perfluorooctanoic Acid (PFOA) and Perfluorooctane Sulfonate (PFOS).

PFOA molecule

PFOS molecule


Historical and Current Uses of PFAS

PFAS compounds have a wide range of commercial and industrial applications:

  • Polymers and coatings (Scotchgard®, Teflon®, Gore-Tex®,  STAINMASTER®)
  • Fire-fighting foams (AFFF - Aqueous Film Forming Foam)
  • Metal plating, cosmetics, food packaging, electronic and semiconductor applications, and oil/mining production

Products containing PFAS include, but are not limited to, firefighting foam, Chemguard, Gore-Tex, Simoniz, Stainmaster, and Teflon.


Chemical Properties of PFAS

Although these chemicals provide beneficial uses to society, there are several human health and environmental challenges due to the creation and use of PFOA and PFOS, including:

  • Water Solubility – spread in groundwater and surface water
  • Bioaccumulation – concentrations can increase 10,000 times in fish and aquatic organisms
  • Binds to proteins in blood – stays in circulation
  • High maternal transfer to fetus
  • Reabsorbed by human kidney – elimination is slow and has a half-life of 4-9 years in blood
  • Stable – resistant to biological and chemical degradation

Select Chemical Properties of PFAS and other Contaminants (PubChem and EPA)

Property

PFOA

PFOS

PFBS*

PCB 1260

TCE**

Water Solubility 25°C (mg/L)

9500

680

344

0.0027

1100

Soil Adsorption Factor (Log Koc)

2.0

2.5

1.5

6

2.4

Bioconcentration Factor (BCF)

3

1000

0.71

100,000

4

*Perfluorobutane sulfonate
**Trichloroethylene


How is PFAS measured and reported?

PFAS concentrations are reported in concentrations of “parts per trillion”, or “ppt”. A ppt is a measurement of the quantity of a substance in the air, water, or soil where there is one part of that substance for every one trillion parts of the medium it is contained in (a ratio of 1:1,000,000,000,000). One part per trillion is equivalent to one nanogram per liter of water.  A nanogram is a unit of measurement that is equal to one billionth of a gram. One way to visualize this amount is that a dollar bill weighs about 1 gram.  To get 1 nanogram, the dollar bill would be cut into 1,000 pieces.  Take one of those pieces and cut it into another 1,000 equal pieces. Then take one of those pieces and cut it into another 1,000 pieces. Each piece in this group will be a billionth of the original dollar and will weigh approximately 1 nanogram.  Other ways to conceptualize one ppt are one second in 32,000 years or one grain of sand in an Olympic-size swimming pool.

While this concentration appears to be very small, certain hormones and biomolecules have significant effects at this concentration.  Examples include:

Compound

Concentration in blood serum (ppt)

Aldosterone – regulates blood pressure

10-210

Estradiol – premenopausal female

15-350

Parathyroid hormone

10-65

Testosterone (free) – male

90-300

Corticotropin (ACTH) – pituitary hormone

10-60

Triiodothyronine (T3) (free)

2.4-4.2


Health Effects of PFAS

During 2005-2013, the C8 Science Panel carried out exposure and health studies in the Mid-Ohio Valley communities, which had been potentially affected by the releases of PFOA (or C8) emitted since the 1950s from the Washington Works plant in Parkersburg, West Virginia. They then assessed the links between C8 exposure and a number of diseases. The C8 Science Panel has completed its work and no longer exists; this website summarizes the results.

The Science Panel consisted of three epidemiologists: Tony Fletcher, David Savitz, and Kyle Steenland, who were chosen jointly by the parties to the legal settlement of a case between plaintiffs and DuPont regarding releases of C8 from the plant. The Panel, its research programme, and links to other sources of information can be found via the links below.

The main conclusions are in the form of Probable Link reports which summarize in each case whether the Science Panel found or did not find a link between exposure and disease. The detailed science behind the summaries in the Probable Link reports is published in articles in scientific journals. Many articles have been published and a few more are still in the process of publication. Follow the links at the left. For six disease categories, the Science Panel concluded that there was a Probable Link to C8 exposure: diagnosed high cholesterol, ulcerative colitis, thyroid disease, testicular cancer, kidney cancer, and pregnancy-induced hypertension.

The Environmental Protection Agency has recommended a lifetime exposure guideline for PFOS+PFOA of 70 ng/l (ppt). The state of Michigan has adopted this level as a cleanup standard.

Other states have adopted lower levels based on the desire to protect sensitive populations (fetus, infants)


Where can I read more about PFAS in Michigan?

Reports of the current PFAS investigation in Kent County and elsewhere in Michigan and the United States have been provided at the state and federal levels by the Michigan Department of Environmental Quality and the U.S. Environmental Protection Agency. Visit our PFAS news archive for links to media coverage at the regional, state, and federal level.



Page last modified June 25, 2018