We study the risks from these persistent pollutants in coastal environments as environmental analytical chemists at Florida International University’s Institute of the Environment.

Because PFAS can enter the food chain and accumulate in marine plants and animals, including fish that humans eat, the spread of these chemicals has ecological and human health implications.

In a new study, we traced the origins of PFAS contamination in Miami’s Biscayne Bay to help pinpoint ways to reduce the harm.

What are PFAS?

PFAS – perfluoroalkyl and polyfluoroalkyl substances – are a group of human-made contaminants that have been used for over 50 years. They’re found in personal care products, such as cosmetics and shampoo, and in water-repellent coatings for nonstick cookware and food packaging. They’re also used in adhesives and aqueous firefighting foams, among other products.

As those PFAS-containing products washed down drains and were thrown in landfills over the years, PFAS chemicals became widespread in the environment. Eventually, these chemicals found their way into aquatic ecosystems, including surface water, groundwater and coastal environments.

The same stability and resistance to degrading that makes these chemicals valuable for water- and stain-proof products also makes them nearly impossible to destroy. Hence, the nickname “forever chemicals.” They persist in the environment for decades to centuries.

That’s a problem, because PFAS have been linked to immunological disorders, endocrine, developmental, reproductive and neurological disruption and increased risk of bladder, liverkidney and testicular cancer. A drinking water study by the U.S. Geological Survey estimated these chemicals were in at least 45% of tap water across the U.S., and a large percentage of Americans are now believed to have PFAS detectable in their blood.

Studies have also found PFAS in a broad range of marine wildlife, including in the livers of otters and in gulls’ eggs, as well as in freshwater fish across the U.S. These chemicals have already been shown to affect the immune system and liver function of fish and marine mammals.

How PFAS get into the marine environment

When we began tracking the sources of PFAS in Biscayne Bay, we found hot spots of these chemicals around the exits of urban canals – especially the Miami River, Little River and Biscayne Canal. Each of these canals, we found, is a major point source contributing to the presence of PFAS in offshore areas of the Atlantic Ocean.

One major source of that PFAS is sewage contamination from failed septic systems and wastewater leaks in urban areas. This is evident by the presence of the types of PFAS – such as PFOS, PFOA, PFPeA, PFHxS, PFHxA, PFBA and PFBS – that are used as stain and grease repellents and in carpets, food packaging materials and household products.

Another major source is represented by the predominance of 6-2 FTS in the Miami River – 6-2 FTS is a fluorotelomer PFAS typically used in aqueous film-forming foam found at military and airport facilities. The Miami River flows past rail yards, industries and Miami International Airport on its way to Biscayne Bay…