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As a society, we have created and become dependent on a class of chemicals that live forever in the environment and build up in our bodies for years, causing serious health problems. They have entered your food and water, and spread across the globe… This is the reality of contaminants called per- and polyfluoroalkyl substances (PFAS). These compounds are creating a modern-day “public health crisis”, and we are still discovering the full extent of their health effects.
This post is a one-stop-shop that includes what we know about PFAS and human health, how we know it, and whether industry claims that newer versions of PFAS don’t pose a threat are true.
What Are PFAS?
PFAS are a class of around 5,000 human-made chemicals widely used in industry for their oil, water, temperature, and friction resistance; the most widely known and researched PFAS chemicals are perfluorooctanoic acid (PFOA) and perfluorooctane sulfonate (PFOS). PFAS are used in non-stick pans, food wrappers, paper, waterproof fabrics, cleaning products, carpeting, construction, and electronics. Does it sound like PFAS are all around you? It turns out they are, and there’s a good chance they’re inside your body, too. PFAS were detected in the blood of an alarming 97% of Americans in a representative survey conducted in 2011-2012.
Concerning evidence suggests that PFAS have started building up in our bodies and the environment, which have garnered them the unfortunate moniker “forever chemicals.” People are exposed to PFAS through contaminated food, drinking water, and contact with consumer products . Once they enter the body, PFAS are known to cause serious toxic effects.
How Can PFAS Impact My Health?
There are three main ways that toxicologists determine the health effects of chemicals like PFAS: epidemiological studies, occupational studies, and animal studies.
When chemical exposure measurements are available in a particular area, researchers collect existing census data, birth and death certificates, and medical records on the surrounding population, looking for unusually high instances of a particular health problem. These are called epidemiological (epi) studies, and they typically rely on statistical models that evaluate health outcomes as a function of chemical exposures and other factors (e.g. those that might mediate or moderate the effect of a chemical on health). Epi studies can provide strong evidence of the adverse health effects of a substance for the general population.
Research can also be conducted in an occupational setting to evaluate workers’ health after exposure to high levels of a chemical at their jobs. These are called occupational studies, and usually look at the effects of very high exposures rare outside of the workplace.
Data is not always available about people’s health and their exposures. As such, scientists have historically turned to animal models and lab experiments to evaluate toxicity. In the lab, researchers purposefully expose animals to a substance and observe the effects. Health effects in animals are frequently used to identify a chemical’s toxicity to a particular organ or body system, but substances can affect laboratory animals very differently than humans. In determining health protective levels of exposure for a chemical based on animal toxicity studies, scientists include estimates of uncertainty to make the extrapolation between animal models and humans.
Now that you know how we determine health effects from contaminant exposures, let’s dive into what we know about PFAS based on the existing toxicological evidence. Research on the health effects of PFAS is ongoing, but the Agency for Toxic Substances and Disease Registry (ATSDR) has identified the following health effects:
Liver and Cholesterol Changes
Epidemiological studies have shown associations between certain PFAS (specifically: PFOA, PFOS, and some additional PFAS chemicals) and increased low-density lipoprotein cholesterol (LDL). LDL is also known as “bad” cholesterol. In addition to being used by toxicologists as an indicator of liver problems, increased LDL in the blood can eventually lead to the buildup of plaque in blood vessels, which is a precursor to heart attack or stroke.
Studies on animals have repeatedly shown increases in liver weight, cholesterol changes, and other adverse liver effects related to elevated levels of PFAS compounds, including PFOA and PFOS. ATSDR has determined that these effects provide significant evidence that PFAS are toxic to the liver.
Impaired Immune System
Epidemiological evidence shows decreased antibody response to vaccines in populations exposed to higher-than-normal PFAS levels (PFOA, PFOS, and some additional PFAS chemicals). In other words, PFAS exposure could mean that vaccines won’t protect people from disease as effectively as they should. This is a particularly threatening health effect amidst the Covid-19 pandemic. There is also suggestive epidemiological evidence that PFOA can lead to a heightened risk for ulcerative colitis, an immune disease that causes inflammation and ulcers in the digestive system. Immune problems including reduced antibody response have also been found in animal studies on PFOA and PFOS.
When fetuses or children exhibit delayed or abnormal development after exposure to a substance, this is a developmental effect. Mixed results have been found in epidemiological studies for developmental problems associated with PFAS in humans.
However, there is a large body of evidence from animal studies that a number of PFAS compounds can cause developmental problems. Effects observed in the fetuses of exposed animals include low birth weight, motor problems, and decreased survival, which are all common indicators of developmental toxicity. It is difficult to say how PFAS can impact developing humans, but animal studies provide strong evidence that these compounds are toxic to development.
Occupational and epidemiological studies show associations between PFOA exposure and an increased risk of testicular and kidney cancer. Human evidence is limited for other PFAS, but increased cancer risk has been observed in animals exposed to various PFAS compounds, notably liver tumors associated with PFOS exposure. The EPA has determined that there is “suggestive evidence of the carcinogenic potential of PFOA and PFOS in humans.”
There are other possible PFAS health effects that require more research because results are inconclusive. Hypertension in pregnant women, damage to the reproductive system, blood system changes, changes in thyroid hormones, and kidney problems have all been observed with increased PFAS exposure in either human or animal studies. However, these health effects are seen in some studies and not others, and may require more research.
Who Is Most Vulnerable?
Some populations are particularly vulnerable to PFAS exposure and their associated health effects. Babies and young children love to crawl around on all fours and put their fingers and toys in their mouth. These (perfectly natural and adorable) traits may result in greater exposures through ingesting dust contaminated by PFAS in carpeting, textiles, and other products. Additionally, their bodies are still developing, placing them at greater risk for PFAS health effects.
Pregnant adults, who tend to drink a lot of water, may experience greater PFAS exposure where water contamination is an issue. PFAS can pass through the umbilical cord to developing fetuses and lead to developmental effects. People with impaired immune systems, liver disease, or cancer may also be vulnerable populations to the health effects of PFAS compounds.
Are Some PFAS Worse Than Others?
As the significant harms of PFAS have come into the public eye, PFAS producers have responded, insisting on their commitment to making sure their “products are safe and do not harm the environment”.
Companies like 3M have phased out the use of certain “long-chain” PFAS with well-documented health effects and replaced them with “short-chain” PFAS compounds, like perfluorobutane sulfonic acid (PFBS) and GenX. The chain length refers to the number of carbons in the compound. Short-chain PFAS, usually defined as compounds with less than six carbons, have been shown to pass through the body more rapidly than their long-chain counterparts. In theory, this gives them less time to cause damage.
Unfortunately, researchers have found that these chemical replacements can still cause significant health problems. For example, PFBS has been linked to developmental, liver, kidney, and thyroid toxicity. Further, short-chain PFAS don’t break down in the environment either. So are some PFAS worse than others? Possibly, but the evidence suggests that replacing longer-chain PFAS with shorter-chain versions won’t be enough to protect the public from the harmful effects of these chemicals.
I’m Concerned About PFAS, What Should I Do?
If you’re concerned about your or your family’s exposure to PFAS, take a look at this blog article that discusses different ways to reduce your exposure. If your tap water contains PFAS chemicals, it is possible to remove them using various treatment technologies. However, it’s important to test your water first to determine whether it contains PFAS chemicals, if so, which ones, and which treatment system would be best for you. Our team of water quality engineers, treatment experts, and chemists are standing by to help figure out your next steps and answer any questions you may have about your water. Send them a message any time: firstname.lastname@example.org.
Sources and References▾
- The 'forever chemicals' fueling a public health crisis in drinking water
- 3M to share record on PFAS with House Oversight Subcommittee
- Serum Biomarkers of Exposure to Perfluoroalkyl Substances in Relation to Serum Testosterone and Measures of Thyroid Function among Adults and Adolescents from NHANES 2011–2012 - PMC
- PFAS Explained | US EPA
- PFAS chemical exposure | ATSDR
- Toxicological Profile for Perfluoroalkyls
- PFAS and Sensitive Populations
- Notification Level Recommendation for Perfluorobutane Sulfonic Acid in Drinking Water
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