PFAS substances can enter the food chain through plants and marine animals, affecting human health. Our team of environmental analytical chemists at the Institute of Environment at Florida International University is studying the risks posed by these persistent pollutants in coastal environments.
What are PFAS substances?
PFAS – per- and polyfluoroalkyl substances – are a group of manufactured contaminants that have been used for over 50 years. They are found in personal care products like cosmetics and shampoos, in water-repellent coatings for non-stick cookware, and food packaging. They are also used in adhesives, water-based fire-fighting foams, and other products.
Over time, PFAS substances have become prevalent in the environment due to the washing of these PFAS-containing products down drains and their disposal in landfills. As a result, these substances have found their way into aquatic ecosystems, including surface waters, groundwater, and coastal environments.
The stability and resistance to degradation that make these substances valuable for water and stain-resistant products also make them nearly impossible to destroy. Hence, the label “forever chemicals.” They persist in the environment for decades to centuries.
This is a problem because PFAS substances have been linked to immune disorders, hormonal, developmental, reproductive, and neurological disorders, and an increased risk of bladder, liver, kidney, and testicular cancer. A study of drinking water by the U.S. Geological Survey estimates that these substances are found in at least 45% of tap water across the United States, and a significant number of Americans are now believed to have detectable levels of PFAS in their blood.
PFAS substances have also been found in a wide array of marine life, including in the livers of whales and seagull eggs, as well as in freshwater fish across the United States. These substances have already been shown to affect the immune system and liver function in fish and marine mammals.
How do PFAS substances enter the marine environment?
When we began tracking sources of PFAS in Biscayne Bay, we found hotspots of these substances around urban canal outfalls – particularly the Miami River, Little River, and Biscayne Canal. We found that each of these canals serves as a major contributing point to the presence of PFAS in the marine areas of the Atlantic Ocean.
One major source of PFAS is sewage pollution from failing sewage systems and wastewater leaks in urban areas. This is evident from the presence of PFAS types – such as PFOS, PFOA, PFPeA, PFHxS, PFHxA, PFBA, and PFBS – that are used as stain and grease-resistant materials in carpets, food packaging, and household products.
Another major source is the dominance of 6-2 FTS in the Miami River – 6-2 FTS is a PFAS compound commonly used in aqueous film-forming foam found at military installations and airports. The Miami River flows past rail yards, industries, and Miami International Airport on its way to Biscayne Bay.
We also used a model to predict how ocean currents disperse PFAS substances exiting those canals and entering the coastal areas. We found that the concentrations of PFAS were higher near the canals, declining along the bay and decreasing as ocean waters became deeper and more saline, making PFAS less soluble in water.
Overall, PFAS concentrations were nearly six times higher in surface waters near shore compared to deep water samples collected at depths of 13 to 33 feet (4 to 10 meters) below the surface in the bay and marine areas. This indicates that the highest risk exists for marine fish living in surface waters, such as mackerel, tuna, and mahi-mahi.
How
Are Marine Organisms at Risk?
PFOS and PFOA levels in our study were below the advisory levels set by the Florida Department of Environmental Protection for surface waters for human health exposure. However, the advisory levels may not protect marine life and humans.
They do not take into account that these substances accumulate through the food chain. Higher concentrations at the top of the food web mean that PFAS substances could pose a greater risk to dolphins, fish, and humans who consume fish.
Many specific types of PFAS identified in our samples are unregulated, and their potential toxicity is unknown. We believe that there is a need for state and federal agencies to establish guidelines and implement action plans to protect people and marine life in Biscayne Bay.
What You Can Do About It?
Given the persistence of PFAS and their widespread use, it is not surprising that these everlasting substances are found in all water systems in South Florida and are showing up in coastal waters around the world.
While scientists seek effective and efficient ways to eliminate these substances and remove them from water, food, and the environment, individuals can reduce their use of products containing PFAS to limit the amount of these substances that enter the marine environment.
Here are some common products that contain PFAS and should be monitored: non-stick Teflon cookware; food packaging for fast food and popcorn; water-resistant clothing and cosmetics; and treated carpets.
This article was originally published on The Conversation. Read the original article.
Copyright and Permissions: Olutobi Daniel Ogunbi is a Ph.D. student in chemistry at Florida International University. More by Olutobi Daniel Ogunbi. Natalia Suarez Kenney is an assistant professor of chemistry at Florida International University. More by Natalia Suarez Kenney. Edited by professional editors, The Conversation provides informed commentary and discussion on the issues affecting our world. More by The Conversation US.
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