Recent news articles on PFAS (Per- and Polyfluoroalkyl Substances) have been highlighting the exposures that many people in the United States may have been exposed to the compound. PFAS are often called “forever chemicals” due to how long they survive in the environment. Could you be harmed by a chemical that could survive “forever”? We can evaluate what PFAS exposure means in terms of how dangerous it may be for you.
When making the determination, it is important to understand how people can be exposed to PFAS in everyday life. We likely have had exposures without even realizing we used PFAS-containing products. Personal exposures can include use of products intended to prevent food sticking (e.g., food packaging or cooking surfaces), ingestion of products from areas where PFAS may exist in the environment (e.g., drinking water or fish), or indirect exposure to PFAS that is contained within soil or settled dust that may exist inside the indoor environment.
Drinking water appears to me a major exposure pathway for the general population. A recent article in the Los Angeles Times highlighted the concern for PFAS exposures in urban areas based on a newly released study. Additionally, a recent finding by the University of Florida identify PFAS in drinking water where residents of a Florida county are being exposed. Are these exposures that you should be concerned about? We will explore this question within this article.
PFAS (Per- and Polyfluoroalkyl Substances) are a category of chemicals with at least one active chemical group. These active groups break down very slowly under typical conditions, making this category of chemicals useful for everyday products. PFAS function in many different capacities like surfactants, friction reducers, firefighting foams, and repellents of water, dirt, and oil. Many people think that all PFAS chemicals are the same because they have similar properties. However, there are actually different groups and subclasses within the PFAS umbrella.
While it may sound daunting, it is important to understand that PFAS is not one chemical but a group of chemicals. PFAS are generally categorized into six main groups: perfluorooctanoic acid (PFOA), perfluorooctanesulfonic acid (PFOS), perfluorobutanesulfonic acid (PFBS), perfluoroheptanoic acid (PFHpA), perfluorohexanesulfonic acid (PFHxS), and perfluorononanoic acid (PFNA). Within these groups, there are over 50 classes of PFAS, comprised of several individual similarly structured compounds.
While there are a number of known exposure routes, there is a general lack of agreement regarding the exact danger these chemicals may present. This is largely due to the many varieties and types of PFAS. There is insufficient information about the potential effects of inhaling PFAS. Exposure pathways such as aerosolization of PFAS-containing products and PFAS entrained in settled dust have been theorized, but there is still much to be explored.
Important questions to consider are, “is PFAS a human health risk and, if so, at what dose?” Unfortunately, the answer is not so clear. Although several studies have examined PFAS exposure by directly measuring PFAS levels in human samples, there is a limited number of studies that assess general population exposure using passive dosimetry. Studies on metabolism have demonstrated that the chemical structure of PFAS can affect how it interacts with the human body. This makes it challenging to categorize all PFAS as a single entity. Based on the particular PFAS structure, there are differences in how to interact with the body. These differences can impact half-life, which affects how long the substance will stay in the body.
This brings up the next question, “what will PFAS do to me”? That is, what are the toxic endpoints for PFAS? Again, there is no straightforward answer. The varying structures of PFAS makes general evaluation difficult. Different endpoints have been evaluated in different categories of PFAS. There have been studies that associate liver toxicity with PFOA, PFNA, PFBA, and GenX exposure. Developmental effects have been associated with PFOA, PFOS, and PFNA. Thyroid effects have been evaluated in relation to PFHxS and PFBS. Immunotoxicity, reproductive effects, and kidney issues have been linked to PFOS, PFHxS, and PFBS exposure respectively. These varying effects illustrate the difficulty in evaluating these PFAS substances as a single category.
Beyond the toxic endpoints there is also a concern among some regulators and others that PFAS exposure will cause cancer. The International Agency for Research on Cancer (IARC) performed a hazard assessment and identified that PFOA is possibly carcinogenic to humans at some hypothetical dose (Group 2B). Furthermore, the Environmental Protection Agency (EPA) has conducted a recent evaluation of PFOA and PFOS under the Safe Water Drinking Act. The findings have led to the identification of these two PFAS categories as having clear indications of being potentially carcinogenic. In the assessment, the EPA affirms that PFOA and PFOS have a high probability of causing cancer, specifically kidney and liver cancer. They further stress that there is no minimum dose that is considered safe for exposure to these substances. chemical is considered safe” and that “there is suggestive evidence of carcinogenic potential of oral exposure to HFPO–DA in humans, but the available data are insufficient to derive a cancer risk concentration”. There has been criticism of the EPA risk assessment because of the low threshold established based on the limited available data, especially considering that the latest epidemiological studies have yielded inconsistent findings to link cancer outcomes to PFAS exposure.
Limited assessments have been done on other PFAS compounds, including the short-chain variety, which creates information gaps in the PFAS umbrella category. Additionally, studies in humans and animals have been variable and inconclusive. It is unclear if the differences in health effects are species specific or related to dose differences. Inconsistencies in the epidemiological evidence are primarily due to generally limited information regarding PFAS exposure. There are several consistent reports of several biological effects associated with PFAS exposure; however, a direct causal relationship between PFAS exposure and critical health outcomes has not been defined.
In scientific circles, it is important to identify both the exposure and whether the exposure actually causes a health issue. In this scenario, are there enough data published to support a general causal relationship with PFAS and human disease?. That is a question that was likely evaluated in a recent settlement decision for PFAS in water supplies. Many scientists believe that the available data on causation are inconclusive, although the scientific evaluations done in these lawsuits currently remain unknown to this author.
There are approximately 500 PFAS substances registered with the Chemical Abstract Service (CAS). Because there are so many PFAS chemicals, it is important to understand: what risk does PFAS exposure mean for the general population? There is mixed information on how dangerous PFAS is as a category. If there is a concern about exposure, it is advisable to conduct a risk assessment to determine whether anyone may be at a higher risk for health issues. Who should be initiating these types of assessments? If someone under your care (e.g., building tenants, employees, etc.) is being exposed to PFAS then it is recommended that their exposure be understood and quantified to understand the health risk. It is better to be proactive in this scenario than attempt to play catch-up when reacting to a PFAS risk situation.
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