EPA's proposed levels for PFAS in drinking water are approved.
No, that doesn’t mean you need to panic about your water safety.
On April 10, 2024, the Biden-Harris Administration officially approved the PFAS water maximum contaminant levels proposed by the US Environmental Protection Agency in March 2023. In order to ensure compliance and any potential remediation, the estimated cost will be about $1.5 billion annually. This regulation will apply to 6 specific PFAS chemicals. These maximum contaminant levels (MCLs) are set well below those associated with potential adverse health effects. The implementation will require routine monitoring, surveillance, and remediation if levels exceed any of these thresholds.
Do you need to panic about the safety of your drinking water?
The short answer is no. Let’s dig in.
What are PFAS and why are they called “forever chemicals”?
PFAS, or Per- and polyfluoroalkyl substances, are a class of thousands of different chemicals. Per-and polyfluoroalkyl substances (PFAS) are a group of thousands of different chemicals used in aerospace, automotive, construction, and electronics industries. These chemicals are used to treat clothes, plastics, & other goods, making them water and stain resistant.
PFAS all contain a carbon chain bonded to fluorine atoms. The strength of these bonds slows the biodegradation of PFAS compared to other substances. This is because fluorine is the most electronegative element, meaning that it can hold very tightly to other elements it is attached to in a chemical structure. This carbon:fluorine bond is what provides these chemicals their their advantageous properties, but also slows the rate at which PFAS break down in the environment (biodegrade).
Now, while they are colloquially called “forever chemicals”, this is a bit of a misnomer. They don’t last forever, but it does take about 8 years for PFAS to biodegrade.
Now, while PFAS are lumped into a catch-all, only a few PFAS have toxicity concerns to humans, animals, and the environment. Different PFAS may be found in soil, water, and air in varying quantities.
The majority of PFAS exposure is associated with food packaging and cosmetics, not drinking water. Most cosmetic companies have removed PFAS from their products.
High exposure levels of certain PFAS may be linked to adverse health effects, so surveillance & mitigation is of interest, however, these levels of exposure are limited to manufacturing and large disposal sites.
What are the limits set by EPA for drinking water?
The EPA has set both an enforceable maximum contaminant level (MCL) as well as a goal MCL (MCLG). The enforceable levels will be those that EPA and other regulatory agencies will be able to take action against, whereas the MCLG is the optimal target level.
PFOA and PFOS are the two most common PFAS. EPA set a MCL of 4 parts per trillion, with a target goal of zero.
For context, a part per trillion is is equivalent to 1 drop of water in 20 Olympic-size swimming pools, or one second of time in approximately 31,700 years.
For PFNA, PFHxS, and “GenX Chemicals” (HFPO-DA), EPA is setting the MCLGs and MCLs at 10 parts per trillion. In addition, since PFAS can often be found together in mixtures, and there may be synergistic impacts of combinations, there will also be a limit for combinations for any mixture of two or more of the following PFAS: PFNA, PFHxS, PFBS, and HFPO-DA.
Another important note: these regulations will not apply to individuals who have private well water.
Why do we care about PFAS levels?
There is some evidence that high exposure levels of certain PFAS may be linked to reproductive effects, developmental delays in children, increased cancer risk, increased risk of obesity, and decreased immune system function.
Research is ongoing to understand the full scope of PFAS impact on health, including individual PFAS of concern, exposure sources, and potential accumulation concerns.
It is important to note that drinking water is not a primary source of PFAS exposure, however, mitigating potential sources of exposure is a valid public health measure.
PFAS are often categorized as “endocrine disrupting chemicals” or EDCs. These can be any chemical, natural or synthetic, that can mimic hormones, which is why they are also referred to as hormonally active agents.
Hormones work by binding to specific receptors on cells, and EDCs can "trick" these receptors into activating or blocking them, leading to altered responses in the body. EDCs can interfere with different hormones and their corresponding receptors, leading to potential consequences on the biological processes that they control.
Endocrine disrupting chemicals are not inherently bad, it means that they alter endocrine (hormone) signaling. For example, intentional endocrine disrupting chemicals include hormone replacement therapies during menopause or after hysterectomy or hormonal contraception.
Genistein, a phytoestrogen found in soy milk and soy products (aka an isoflavone), seems to reduce the effects of type 2 diabetes at concentrations found in some products. Genistein works by reducing the concentration of blood glucose and increasing the sensitivity of the insulin receptor.
The challenge with studying potential EDCs like PFAS is that most of the data is based on observed adverse effects in animals. However, limited scientific evidence exists on potential health problems in humans. In addition, because many different chemicals, both natural and synthetic, can impact our endocrine system, it is very difficult to parse our individual chemicals and their contributions to public health.
Just like everything, the dose makes the poison.
"Toxic levels" of PFAS are not in 45% of our tap water.
Do you remember those headlines circulating last summer? They were wildly exaggerated and misinterpreted findings from a US Geological Survey study.
This study collected tap water samples from various water treatment plants, businesses, and residences across the US by volunteers. While diverse, the water sites sampled are not perfectly representative of the US water supply.
716 sites were included, 447 were regulated public supply and 269 were unregulated private well supply. Each sample was assessed for the detection of 32 different PFAS chemicals, changes in PFAS levels over time, and levels of PFAS if they were detected.
The results:
30% of sites had at least 1 PFAS detected.
Depending on the site, anywhere from 1 to 9 PFAS were detected. Cumulative PFAS concentrations in samples where PFAS were detected ranged from 0.348 parts per trillion (ppt) to 346 ppt.
Now, you can tell this is a VERY broad range. Many of these are well below those thresholds set by EPA, some exceeded it. PFAS and PFOA are of particular interest, as those are the most common and previously most widely used PFAS.
If you recall, those EPA MCLs are 4 PPT of PFOA and PFOS as water contaminants. Note: 4 PPT is a concentration equal to 0.0000000004%.
They also compared all of the detected levels of different PFAS to thresholds identified to cause adverse effects in research models.
This uses a method called Exposure-Activity Ratio (ΣEAR). ΣEAR assesses drinking-water exposure risk to potential contaminants. If ΣEAR is greater than 1, that means the levels detected in the sample exceed levels that have been shown to cause adverse effects.
None of the samples exceeded ΣEAR of 1. This means even in samples where PFAS were detected, the levels are lower than those identified to cause adverse events.
It is critically important to remember that we have the most sensitive analytical chemistry tools ever to exist. Detection can sound scary, but it does not automatically mean there is a health risk or even a clinical relevance. I discussed that in my pieces on chlormequat in Cheerios and the EWG’s Dirty Dozen.
So, if none of the samples exceeded the ΣEAR of 1, and 70% of water samples had NO detectable levels of PFAS….
How did headlines get this “45% of water is contaminated with toxic levels” of PFAS?
Well, because they only collected water from 716 sites around the country, the study authors used a mathematical model to predict where at least one PFAS might be detected in drinking water samples. This is where they estimate that 45% of drinking water may contain at least one PFAS.
This estimate does not mean that 45% of water samples actually DO have PFAS or that levels would be at a concentration that would be cause for concern.
What can you do if you want to reduce your PFAS exposure?
While these data should not cause alarm, some individuals in areas where there may be higher levels of PFAS may want to take measures to reduce potential exposure.
Water treatment options that can trap PFAS include activated charcoal and reverse osmosis (RO) filters.
PFAS are of concern because they biodegrade slowly, that is why EPA is setting more stringent regulation criteria. While some evidence suggests high levels of PFAS may be linked to certain adverse health effects, levels detected in these water surveillance studies should not cause alarm. Only a small percentage of samples exceeded thresholds proposed by EPA, and those levels are very conservative.
The best way to reduce your risk of PFAS exposure is to avoid cosmetic products that may contain PFAS, minimize occupational exposure if you work in an industry that utilizes them. You can also search the CompTox Chemicals dashboard to see what products you may own that may contain PFAS.
On a larger scale:
Recent research has actually determined straightforward ways to mediate PFAS levels. By heating PFAS in dimethyl sulfoxide along with with sodium hydroxide, many PFAS of interest can be degraded into fluoride ions (F-) and various carbon-containing byproducts. This might be a effective and utilitarian method to remediate areas with higher levels of PFAS in the environment.
Remember: misinformation about chemicals and their impact on us exploits a lack of science literacy.
Many activist organizations often make claims that are not aligned with our real risk, often using words that sound scary or mischaracterizing scientific evidence. Many also lobby for laws that are not based on reality. For example, in the PFAS discussion, an activist organization, PEER (Public Employees for Environmental Responsibility), has been pushing for the EPA to define PFAS simply based on the presence of a C-F bond in a molecule (like they do in Europe). We know European legislation is inherently based on chemophobia and uses a hazard-based approach, not a true risk assessment (which I discussed in my piece on the IARC and carcinogen classifications).
This would be a huge issue, because it would apply to a variety of chemicals that are NOT PFAS, that does not persist in the environment, and do not pose health risks. It would impede our ability to develop a myriad of technologies that benefit our health and lives, from medical devices, electronics, refrigerants, and more. All based on lack of knowledge of chemistry and fear-laden claims.
This is why it is essential that our legislators look to credible science that does not factor in hyperbolic statements made by activist groups that are promoting unfounded fears, but rather, form nuanced regulations that uphold the integrity of our scientific process.
So, do you need to panic about PFAS in your water?
The short answer is no. These regulations are a step toward improving monitoring and intervention as our understanding of science and health grow. However, try to limit how many people you listen to that share statements about PFAS that seem designed to elicit emotion. Those are exploiting the risk perception gap. In reality, most people’s risk should not even compare to a variety of other lifestyle factors that have far greater impact to our health today and over time.
Special thanks to Dr. Christopher Weis, former Senior Science Advisor and Toxicology Liaison to the Director of the National Institute of Environmental Health Sciences (NIEHS) and the National Toxicology Program (NTP) for reviewing my analysis of the USGS survey study.
Thanks for joining in the fight for science!
Thank you for supporting evidence-based science communication. With outbreaks of preventable diseases, refusal of evidence-based medical interventions, propagation of pseudoscience by prominent public “personalities”, it’s needed now more than ever.
Your local immunologist,
Andrea
What about PFAS in non stick cookware - would it be worth avoiding or do you feel there is sufficient evidence that it's safe? We stopped using non stick a few years ago but it's so much less convenient!
Slightly confusing typos: “ This is because fluorine is the most electronegative elements, meaning that it can hold very tightly only other elements is it attached to in a chemical structure.”