PFAS, the “forever chemicals” that have caused health concerns across the country, aren’t just a problem in drinking water. As these chemicals leak from faulty septic systems and landfills and wash over airport runways and farmland, they can eventually find their way into streams into ocean ecosystems where fish, dolphins, manatees, sharks and other marine species live.
As environmental analytical chemists at Florida International University’s Environmental Institute, we study the risks from these persistent pollutants in coastal environments.
The release of these chemicals has ecological and human health impacts, as PFAS can enter the food chain and accumulate in marine plants and animals, including fish eaten by humans.
In a recent study, we traced the origins of PFAS contamination in Miami’s Biscayne Bay to help identify ways to reduce the harm.
What are PFAS?
PFAS – perfluoroalkyl and polyfluoroalkyl substances – are a group of man-made pollutants that have been used for more than 50 years. They are found in personal care products such as cosmetics and shampoos, and in waterproof coatings used in nonstick cookware and food packaging. They are also used in adhesives and aqueous firefighting foams, among other products.
Over the years, PFAS chemicals have become prevalent in the environment as products containing PFAS flow into sewers and are disposed of in landfills. Eventually, these chemicals found their way into aquatic ecosystems, including surface water, groundwater, and coastal environments.
The stability and resistance to degradation that make these chemicals valuable for water- and stain-resistant products also make them nearly impossible to destroy. Hence the nickname “forever chemicals”. They persist in the environment for decades to centuries.
This is a problem because PFAS are linked to immunological disorders, endocrine, developmental, reproductive and neurological disruption, and an increased risk of bladder, liver, kidney and testicular cancer. A drinking water study by the US Geological Survey estimates that these chemicals are found in at least 45% of tap water across the US, and a large percentage of Americans are now believed to have detectable PFAS in their blood. EPA finalized the first federal drinking water standards for PFAS on April 10, 2024.
Studies have also found PFAS in a wide range of marine creatures, including otter livers and seagull eggs, as well as freshwater fish throughout the United States. These chemicals have already been shown to affect the immune system and liver function of fish. and marine mammals.
How do PFAS enter the marine environment?
When we began tracking sources of PFAS in Biscayne Bay, we found hotspots of these chemicals at the outflows of urban canals, particularly the Miami River, Little River, and Biscayne Canal. Each of these channels we found is a significant point source contributing to the presence of PFAS in offshore areas of the Atlantic Ocean.
One of the main sources of these PFAS is sewage pollution from failing septic systems and wastewater leaks in urban areas. This is evident by the presence of PFAS species such as PFOS, PFOA, PFPeA, PFHxS, PFHxA, PFBA and PFBS, which are used as stain and oil repellents and in carpets, food packaging materials and household products.
Another significant source is represented by the predominance of 6-2 FTS in the Miami River – 6-2 FTS is a fluorotelomer PFAS used in aqueous film-forming foam typically found at military and airport facilities. The Miami River flows past railroads, industries, and Miami International Airport on its way to Biscayne Bay.
We also used a model to predict how ocean currents would distribute PFAS from these channels to coastal areas. We found that PFAS concentrations are highest near channels, decreasing throughout the bay and as ocean water becomes deeper and saltier, making PFAS less soluble in water.
Overall, PFAS concentrations were nearly six times higher in near-land surface waters compared to deep-water samples collected 13 to 33 feet (4 to 10 meters) below the surface in the Gulf and offshore. This indicates that the highest risk is for pelagic fish that live in surface waters, such as mackerel, tuna and mahi-mahi.
How are marine organisms at risk?
The levels of PFOS and PFOA in our study were below the Florida Department of Environmental Protection recommendation levels in surface water for human health exposure. However, advisory levels may not be protective of human and marine life.
They don’t take into account that these chemicals accumulate through the food chain. The higher concentration at the top of the food web means PFAS may pose a greater risk to dolphins, sharks and humans who consume fish.
Many PFAS species identified in our samples are not regulated and their potential toxicity is unknown. We believe there is a need for federal and state agencies to develop guidelines and implement action plans to protect people and aquatic life in Biscayne Bay.
What can you do about this?
Given the persistence and widespread use of PFAS, it is not surprising that these persistent chemicals are found in nearly every water system in South Florida and occur in coastal waters around the world.
While scientists are looking for effective and efficient ways to remove these chemicals from water, food, and the environment, people can limit the use of products containing PFAS to reduce the amount of these chemicals entering the marine environment.
Some common products containing PFAS to be aware of include: Teflon nonstick cookware; food packaging for fast food and popcorn; water-resistant clothing and cosmetics; and embroidered carpets.
This article was updated on April 10, 2024, when the EPA issued the first federal drinking water standards for PFAS.
This article is republished from The Conversation, an independent, nonprofit news organization providing facts and authoritative analysis to help you understand our complex world. Written by: Natalia Soares Quinete, Florida International University and Olutobi Daniel Ogunbiyi, Florida International University
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Natalia Soares Quinete receives funding from the National Science Foundation.
Olutobi Daniel Ogunbiyi receives funding from the National Science Foundation awarded through the FIU Institute for the Environment and the Center for Research and Excellence in Science and Technology.