Beachgoers on a wealthy Massachusetts island have been advised to avoid the shoreline because of toxic sea foam contaminated with dangerous ‘forever chemicals’.

Nantucket environmental officials have alerted that the waters might contain alarmingly high levels of PFAS, a class of thousands of long-lasting human-made chemicals known to cause numerous health issues.

Residents are urged to steer clear of the seafoam lurking on the millionaires’ island – and, above all, not to ingest it. 

“While PFAS are known to be present, and probably at these higher levels, we aren’t sure of the exact concentration,” Dr. Rebecca DeVries, vice president at Eastern Research Group, which is assisting in data analysis, informed the Nantucket Current.

“Some lab qualifiers suggest that results could be skewed high, so that is something to consider,” she noted.

Last week, residents who came into contact with the sea foam were advised to rinse off with fresh water immediately, as PFAS can significantly cling to the foam, reaching levels much higher than those in the nearby water.

‘Because of the chemical structure of PFAS, foam can contain higher levels of these chemicals than the water it floats on,’ the recent advisory read.

‘While there are no standards for PFAS foam, taking precautions to reduce contact is important,’ it added.

It comes after locals on the island, where a typical home costs $5 million, were warned about high levels of PFAs in drinking water. 

PFAS, or per- and polyfluoroalkyl substances, are long-lasting synthetic chemicals that persist in air, soil and water.

Commonly found in a wide range of consumer products and industrial applications, PFAS are made up of extremely strong carbon-fluorine bonds that allow them to accumulate in the bodies of both humans and animals. 

Its exposure in humans has been linked to certain cancers – including kidney and testicular cancer – as well as high cholesterol, liver damage, thyroid disease, and pregnancy complications, according to the CDC.

Friday’s advisory followed early tests that revealed the contamination to be far more widespread than environmental experts first believed.

Although water samples from Nantucket’s beaches and ponds showed little to no PFAS, seafoam collected from areas like Madaket Harbor and Sesachacha Pond revealed shockingly high levels.

In one case, levels soared to 30,000 parts per trillion – which, if accurate, would be the highest PFAS concentration ever recorded on the island. 

But the lab that did the testing warned many samples were unreliable due to low volumes, so these numbers might not tell the full story. 

‘Many of the results, in fact, all of the results from Sesachacha Pond, were qualified by the laboratory as not meeting their quality assurance criteria,’ Dr. DeVries told the Nantucket Current.

‘This was largely because there was not sufficient volume in the sample,’ she added.

Nantucket has been grappling with concerning levels of PFAS contamination for years, but experts have recently noticed the problem is more widespread than they thought. 

‘The more we test, the more we’re going to detect,’ Andrew Shapero, Nantucket’s new environmental contamination administrator, told the Boston Globe.

It was previously understood that tainted areas included Nantucket Memorial Airport and Toms Way, located mid-island.

But a recent Department of Environmental Protection investigation revealed private wells are also contaminated.

In May, Shapero warned that PFAS levels at one specific location – the intersection of Hummock Pond Road and Burnt Swamp Lane – had exceeded the ‘imminent hazard’ threshold, according to the Nantucket Current.

PFAS levels at the intersection measured 124 nanograms per liter – more than six times the state’s drinking water limit of 20 nanograms per liter. 

‘That is an extremely concerning concentration to see in drinking water,’ Shapero previously told the board. 

Then, in July, the town collected surface water samples from 21 sites, including coastal beaches, sheltered harbors, freshwater ponds, and two nearshore ‘background’ locations, according to the advisory.

Foam appeared at only two sites – Sesachacha Pond and Madaket Harbor – where samples sent for PFAS testing revealed high concentrations of the so-called ‘forever’ chemicals. 

Though the recent tests may not be entirely reliable, Nantucket plans more thorough sampling in late August 2025 to better understand what’s really in the foam washing up across Nantucket’s shore. 

Anywhere from 71 million to 95 million Americans rely on groundwater riddled with detectable levels of the substances, according to the US Geological Survey. 

But what makes Nantucket’s dilemma unique is the island’s dependency on groundwater.

‘One is that Nantucket is a sole source aquifer, so all of the water on Nantucket comes from the ground that residents live on top of, whether that’s private wells or the public water supply,’ Shapero told the Boston Globe.

‘So Nantucket really has no alternative options,’ he added.

Before experts realized their detrimental health and environmental impact, PFAS were used in various everyday products.

Starting around the 1940s, they were commonly present in non-stick cookware, cleaning supplies, dental floss, candy wrappers and firefighting foam – which easily makes its way into groundwater. 

While certain types of PFAS are no longer used in the US, other variations of the potentially poisoning man-made chemicals are actually FDA approved for limited use, according to the agency.