For the final month of our year long exploration of water quality, we are going to focus on another contaminant of concern, perfluoroalkyl and polyfluoroalkyl substances which are known as PFAS. These are forever chemicals, similar to PCBs which we discussed in October. Being classified as a forever chemical means they stick around for a very long time in the environment which has led to them being found in food around the world, along with the blood of people and animals.
Unfortunately, there are thousands of different chemicals that fall into the category of PFAS, which means it’s hard to determine if they have negative human health consequences as each chemical is different and may have different effects [1].
Originally discovered in the 1930’s, PFAS are resistant to heat, water, and oil and last a very long time, making them useful for a variety of materials and making them fireproof, waterproof, and stainproof [2]. We tend to see higher concentrations of these chemicals around areas where they were used heavily, such as factories and military bases.
In the early 2000’s, we began to see an increase in concern on the impact of these compounds on human health. The Center for Disease Control estimated that 98% of the US population had PFAS chemicals in their blood at detectable levels. This work helped encourage companies to discontinue use of some compounds, however, these chemicals are still detectable in most Americans [2]. Animal studies suggest that high levels of these chemicals in the blood can lead to high cholesterol, thyroid problems, ulcerative colitis, and some cancers. However, regulations on the use of PFAS are still mostly voluntary and relatively new. Earlier in 2024, the Environmental Protection Agency published recommendations for exposure levels of 10 different PFAS compounds for aquatic life and Maximum Contaminant Levels (MCL) for 6 different PFAS compounds in drinking water [3,4]. In addition, earlier this week, the Environmental Protection Agency published new requirements for chemical review processes for all new chemicals being proposed for use in US commerce. These new requirements prevent PFAS and other Persistent, Bioaccumulative, and Toxic (PBTs) substances from being eligible for exemptions of the full review process [5]
These recommendations for drinking water require public water systems to begin monitoring PFAS and they have until 2027 to complete their initial monitoring and after that they must report PFAS levels to the public [4]. Water systems found out of compliance with the new regulations have until 2029 to reduce PFAS levels, though these MCLs are non-enforceable. According to the EPA, they expect “that over many years the final rule will prevent PFAS exposure in drinking water for approximately 100 million people, prevent thousands of deaths, and reduce tens of thousands of serious PFAS-attributable illnesses.”
As for exposure levels for aquatic life, the EPA breaks down exposure for freshwater and saltwater though it’s unclear how estuaries like the Chesapeake Bay fit into these exposure levels. These levels are also not enforceable and are simple recommendations for local managers to consider adopting into their water management plans. These recommendations are the exposure levels at or above which aquatic organisms may be harmed or killed. This is at least a starting point for updates to the Chesapeake Bay Watershed Agreement as there is currently no mention of PFAS, just toxic chemicals like PCBs. However, the Agreement goes until 2025 so there’s a lot of work to update the plan moving forward and PFAS will likely be added. The current Agreement lists the following goals for the broad category of toxic contaminants:
Continually increase our understanding of the impacts and mitigation options for toxic contaminants. Develop a research agenda and further characterize the occurrence, concentrations, sources and effects of mercury, PCBs and other contaminants of emerging and widespread concern. In addition, identify which best management practices might provide multiple benefits of reducing nutrient and sediment pollution as well as toxic contaminants in waterways.
Continually improve practices and controls that reduce and prevent the effects of toxic contaminants below levels that harm aquatic systems and humans. Build on existing programs to reduce the amount and effects of PCBs in the Bay and watershed. Use research findings to evaluate the implementation of additional policies, programs and practices for other contaminants that need to be further reduced or eliminated.
According to Chesapeake Progress, there is a Scientific and Technical Advisory Committee working on PFAS in the Chesapeake Bay and making recommendations to improve monitoring and recommendations based on PFAS has been a goal of the Toxic Contaminants Workgroup [6].
In 2020, the Maryland Department of the Environment added sampling for PFAS to its fish tissue sampling program and issued its first consumption advisory for PFAS in 2021 [7]. There are currently Fish Consumption Advisories for PFAS in the following species and tributaries on the Eastern Shore [8];
- Striped bass < 28”, Choptank River
- White Perch, Choptank River
- White Perch, Chester River
- White Perch, Wicomico River
- Blue Catfish 15” to 24”, Choptank River
- Sunfish, Upper Choptank River, Greensboro Branch
- Yellow Perch, Upper Choptank River, Greensboro Branch
- Large and Smallmouth Bass, Nanticoke River, Marshyhope Creek
- Spot, Lower Chesapeake Bay and Tributaries
- Black Sea Bass, Lower Chesapeake Bay and Tributaries
- Spot, Upper Chesapeake Bay and Tributaries
- Striped Bass >28”, Upper Chesapeake Bay and Tributaries
Now that was a lot of information about the lack of regulation and the presence of PFAS in our environment but how do we know what PFAS are present and at what concentration? The desire to quantify PFAS in different substances, such as blood or tissue, soil, and water, is still relatively new so analytical processes are still being developed. Currently, there are two categories of tests, targeted and non-targeted. As you can probably figure out, targeted analysis means you are looking for a specific compound, such as one of the 6 compounds now regulated in drinking water. Non-targeted means the use of a method like high resolution mass spectrometry (HRMS), which breaks down chemicals by their mass to identify all chemicals in a sample. Using this method, you can then identify known chemicals but unknown chemicals require further analysis. The major thing to understand is that none of the current methods allow for rapid, in-situ (on-site; like the YSI instrument mentioned in other posts) measuring of PFAS. All of these methods require skilled laboratory technicians, expensive equipment, and time.
While our goal with this year-long learning experience was not intended to be political, it is important to understand that regulations are vital to protecting human health and the environment. The fact that it took decades, during which these toxic, long-lasting chemicals were being freely used and released into the environment, before any impacts to human health were disclosed/discovered, is a reminder that we cannot rely on manufacturers to do what is right. The newly released rule regarding review of new chemicals is a step in the right direction but it does nothing to protect us from the last 150 years of chemical production and subsequent release into the environment. While chemicals can serve a vital role in advancing industry, cleaning them up after they’ve made their way into biological systems is like cleaning up glitter after an 80’s themed party; time-consuming, potentially expensive, and damn near impossible to get every last bit. It might be time-consuming and slow the process of innovation, but understanding the full impact of each and every chemical that comes to market is the best way to keep us all safe and healthy.
References:
[1] https://www.epa.gov/pfas/pfas-explained
[2] https://pmc.ncbi.nlm.nih.gov/articles/PMC8536021/
[3] https://www.epa.gov/system/files/documents/2024-09/pfoa-pfos-pfas-final-factsheet-2024.pdf
[4] https://www.epa.gov/sdwa/and-polyfluoroalkyl-substances-pfas
[6] https://www.chesapeakeprogress.com/clean-water/toxic-contaminants-research
[7] https://www.epa.gov/system/files/documents/2021-11/fish-news-november2021.pdf