3M Co., a chemical manufacturer, has agreed to pay at least $10.3 billion to settle lawsuits over the contamination of US public drinking water systems with per- and polyfluorinated substances (PFAS), used in firefighting foam and various consumer products. PFAS, referred to as “forever chemicals” due to their longevity in the environment, have been linked to health issues such as liver damage, immune-system damage, and some cancers. The compounds have been found in varying concentrations in drinking water across the country.
WHAT ARE PFAS?
Per- and polyfluoroalkyl substances (PFAS) are a group of man-made chemicals that have been in widespread use since the mid-20th century. Due to their unique properties of resisting heat, water, and oil, PFAS have found their way into a broad spectrum of products. They are used in non-stick cookware, providing the surface that prevents food from sticking. Many fabrics and carpets are treated with PFAS to make them resistant to stains, and outdoor clothing often incorporates these chemicals to provide resistance to rain.
In the food industry, certain types of packaging such as microwave popcorn bags and pizza boxes use PFAS to resist oil and grease. They also play a crucial role in a type of firefighting foam known as aqueous film-forming foam (AFFF), which is effective in quelling petroleum fires, and is commonly used in both military and civilian airports. Furthermore, PFAS are used in various industrial processes due to their resilience against heat and chemical degradation.
The primary concern with PFAS is their stability; these compounds do not break down easily in the environment or the human body, earning them the moniker ‘forever chemicals’. Over time, they can accumulate and have been associated with a range of potential health issues, including cancer, hormone disruption, liver damage, and negative effects on the immune system.
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THE C-Fl BOND SAYS IT ALL
So-called forever chemicals are a group of synthetic compounds characterized by a carbon-fluorine bond, one of the strongest bonds in organic chemistry. This bond provides the unique properties that make these compounds so durable and resistant to heat, water, oil, and chemical reactions.
The carbon-fluorine bond in PFAS is both very strong and very short, which contributes to the chemical’s overall stability. Because of this bond, PFAS are resistant to breaking down in the environment or in biological systems, which leads to their persistence, or “forever” status.
PFAS are usually classified into two categories: perfluoroalkyl substances (PFAS) and polyfluoroalkyl substances. The main difference between the two types is that the former contains only carbon and fluorine atoms, while the latter also includes hydrogen atoms, making it slightly less stable.
The most well-known PFAS are perfluorooctanoic acid (PFOA) and perfluorooctanesulfonic acid (PFOS), both of which contain a chain of eight carbon atoms, fully substituted with fluorine atoms, and ending in a carboxylic acid group (PFOA) or a sulfonic acid group (PFOS).
EFFECT ON BODY
Once PFAS enter the human body, they can remain and accumulate over time due to their resistance to breakdown. This property, known as bioaccumulation, means that even low-level exposure over a long period can lead to significant concentrations in the body.
Upon ingestion or inhalation, PFAS are absorbed by the gastrointestinal tract or lungs into the bloodstream. They are lipophobic (meaning they do not dissolve in fat) but are proteinophilic (bind to proteins). This means that they can travel through the bloodstream and reach various organs and tissues, including the liver and kidneys.
In the body, PFAS bind to blood proteins such as albumin rather than being stored in fat tissue. This unusual characteristic contributes to their long half-lives in humans; they can remain in the body for years before being eliminated.
The elimination of PFAS from the body primarily occurs through urine. However, this process is slow due to the strength of the carbon-fluorine bonds that characterize these compounds. This slow elimination rate, coupled with the potential for ongoing exposure, can lead to bioaccumulation of PFAS in the body.
PFAS can also cross the placenta, meaning that they can be passed from a pregnant person to the developing fetus. They are also found in breast milk, so they can be passed to nursing infants.
The health effects of PFAS in humans are still being studied, but exposure has been associated with a variety of adverse health outcomes, including liver damage, immune dysfunction, high cholesterol, obesity, endocrine disruption, developmental problems in children, and increased risk of certain cancers. It is important to note that the relationship between PFAS exposure and these health effects is complex, and other factors, such as the duration and intensity of exposure, as well as individual health and genetic factors, can influence these outcomes.
The Environmental Protection Agency has proposed stringent limits on two common types, PFOA and PFOS, and plans to regulate four others. This settlement would resolve a case involving Stuart, Florida, one of around 300 communities with similar suits against PFAS manufacturers.
The settlement, to be paid over 13 years, could rise to $12.5 billion, based on the detection of PFAS in public water systems during mandated testing over the next three years. The settlement would help cover the costs of filtering PFAS from water systems and testing others. Earlier this month, DuPont de Nemours Inc., Chemours Co., and Corteva Inc. reached a $1.18 billion deal to resolve similar PFAS complaints.