The US government has proposed its first-ever restrictions on six harmful chemicals found in drinking water.

Research has suggested over 200 million Americans likely drink water contaminated with PFAS chemicals, which have been linked to a host of health issues, including cancer.

But up until now, the pollutants have only been regulated by some US states.

The US on Tuesday issued a rule that would require communities to test and treat water for six of the chemicals.

Once implemented, it will "prevent thousands of deaths and reduce tens of thousands of serious PFAS-attributable illnesses", the Environmental Protection Agency said.

Dubbed "forever chemicals", PFAS persist for years in the environment.

What are PFAS chemicals and how dangerous are they?

PFAS, which stands for per- and polyfluoroalkyl substances, are a class of thousands of chemicals. The pollutants, which repel water, oil and grease, are used in hundreds of everyday products from dental floss to cookware to firefighting foams.

Though most US companies have phased out manufacturing of the most well-studied types of PFAS chemicals, PFOS and PFOA, they remain widespread in the environment due to their lack of degradation.

In 2022, the EPA found the pollutants could cause harm at levels "much lower than previously understood" and that almost no level of exposure was safe, as the chemicals have been linked to a host of health conditions, including reproductive issues, decreased immune function, thyroid disease and asthma.

Research is ongoing to determine how different levels of exposure can lead to various health effects.

The new US regulations come as countries around the world are reckoning with how to regulate the forever chemicals. Both Canada and the European Union are in the process of proposing and adapting new universal limits on PFAS levels in drinking water.

What will the EPA rules do?

The new federal limits will help close large gaps in existing PFAS drinking water regulations, which are currently imposed by only 10 states, according to Sarah Doll, the national director of Safer States, which tracks regulations of the chemicals.

Specifically, the new rule - which experts said would be finalised after a 60-day period of public comment - will require communities to test for two of the "forever chemicals", PFOA and PFOS, and treat for them if they are found at levels higher than four parts per trillion. The rule also requires communities to monitor four other PFAS chemicals- PFNA, PFHxS, PFBS and HFPO-DA - as a mixture.

The EPA limits will likely have a wider impact on public drinking water quality as the thorough testing and treatment process required for PFAS will allow utilities to rid water of other contaminants besides PFAS, said Dr Lee Ferguson, a professor of environmental chemistry at Duke University.

But the new rules could also cause some communities to worry about the safety of their drinking water, as PFAS is widespread, and the new treatment systems could take time to put into place, said Dr Carol Kwiatkowski of the Green Science Policy Institute, an environmental advocacy organisation.

"Wherever you test for it, you find it," said Phil Brown, a co-director of the PFAS Project Lab at Northeastern University.

Who will pay to treat the water?

The restrictions could help reduce health inequalities in the US, protecting Americans who are unknowingly being exposed to PFAS and other contaminants, experts told the BBC.

Communities with poorer-quality drinking water systems stand to reap the largest benefits from the new EPA limits, but could also struggle the most to implement the new systems, which could cost as much as $5m (£4.11m) outright for a smaller town, according to Dr Brown.

Alissa Cordner, the co-director of the PFAS Project Lab, which researches the chemicals, said it will help boost municipal water protections in states currently without PFAS rules.

"This is an important step in bringing up the floor of health protections."

Through its infrastructure law, the Biden administration has dedicated $5b to address water contaminants like PFAS, $2b of which is designated for disadvantaged communities. Still, that may not be enough, experts said.

As a result, states are looking to the polluters themselves to help foot the bill. More than a dozen states have sued companies they allege are responsible for PFAS contamination, including Minnesota, where manufacturing company 3M settled in 2018 with the state for $850m, which had sued the firm claiming it had damaged drinking water. The company has it will stop making and using "forever chemicals".

But while cleaning up the chemicals marks an important first step to protecting Americans' health, the most safe and cost-effective method would be to limit the manufacturing of the chemicals, experts said.

"You have to turn it off at the source," said Dr Kwiatkowski. "It doesn't make any sense to keep cleaning them out of the water if we keep putting them back in."

Copied From bbc.com