Learn About PFAS

Per- and polyfluoroalkyl substances (PFAS) are a large group of man-made chemicals that have been used in a variety of industrial and consumer products since the 1940s. These substances are known for their resistance to water, grease, and stains, which makes them useful in products such as non-stick cookware, water-repellent clothing, stain-resistant fabrics and carpets, some cosmetics, firefighting foams, and products that resist grease, water, and oil.

Key Characteristics of PFAS:

  1. Chemical Structure: PFAS contain fluorine atoms bonded to carbon chains, creating one of the strongest bonds in organic chemistry. This makes them extremely persistent in the environment and resistant to degradation.
  2. Persistence: Often referred to as “forever chemicals,” PFAS do not break down easily and can remain in the environment and in the human body for a long time.
  3. Bioaccumulation: PFAS can accumulate in the blood, liver, and kidneys of humans and animals, leading to potential health risks.

Health Concerns:

Research has linked PFAS exposure to a range of health issues, including:
  • Cancer: Certain PFAS have been associated with an increased risk of cancer.
  • Immune System Effects: PFAS may affect the immune system, reducing the body’s ability to fight infections.
  • Thyroid Hormone Disruption: PFAS can interfere with thyroid hormone production and regulation.
  • Liver Damage: High levels of PFAS exposure may lead to liver damage.
  • Developmental Issues: In utero and early childhood exposure to PFAS can potentially affect growth, learning, and behavior.

Environmental Impact:

  • Contamination: PFAS can contaminate soil, water sources, and air. They are often found near industrial sites, military bases, and areas where firefighting foam has been used.
  • Wildlife: Animals exposed to PFAS can experience similar health effects as humans, leading to concerns about the impact on ecosystems and biodiversity.

Regulatory Actions:

Due to the health and environmental risks associated with PFAS, many countries and regions are taking regulatory actions to limit their use and to clean up contaminated sites. This includes setting maximum allowable levels in drinking water, banning or restricting certain PFAS in products, and promoting research into safer alternatives.

Chemical Structure

The chemical structure of PFAS is characterized by a chain of carbon atoms fully or partially fluorinated. The strong carbon-fluorine bonds are what make PFAS so stable and resistant to degradation. Here are the key features:

General Structure:

  • Perfluoroalkyl Substances: These have a fully fluorinated carbon chain, meaning all hydrogen atoms in the alkyl chain have been replaced by fluorine. The general formula is Cn​F2n+1​. Example: Perfluorooctanoic acid (PFOA), one of the most well-known PFAS, has the formula C7​F15​COOH.
  • Polyfluoroalkyl Substances: These have a partially fluorinated carbon chain, meaning some hydrogen atoms remain in the alkyl chain, but many are replaced by fluorine.

Specific Examples:

Perfluorooctanoic Acid (PFOA):

  • Formula: C7​F15​COOH
  • Structure: CF3​−(CF2​)6​−COOH

Perfluorooctane Sulfonate (PFOS):

  • Formula: C8​F17​SO3−​​
  • Structure: CF3​−(CF2​)7​−SO3−​

GenX (Hexafluoropropylene oxide dimer acid):

  • Formula: C6​H4​F1​1O3
  • Structure: CF3​−CF2​−CF2​−O−CF2​−CF(OCF3​)−COOH