US sets legal maximum PFAS limits for drinking water

In a move that has been heralded as a historic marker of what might follow in other countries, the US Environmental Protection Agency (EPA) has set legally enforceable standards for a set of six PFAS compounds – per- and polyfluoroalkyl substances, often dubbed forever chemicals, which are linked to a wide range of serious health conditions, including cancer.

Until 2022, the EPA set an advisory limit of 70 nanograms per litre (ng/l) for two of the most common chemicals, PFOS and PFOA. It reduced this to 0.004ng/l and 0.02ng/l respectively last year. Now it has set legally required maximum contaminant levels of 4ng/l each, which takes into account measurement reliability, feasibility and cost, as well as health considerations. The EPA also set a maximum level of 10ng/l for three other PFAS compounds as well as levels for PFAS mixtures (see table). Compliance is expected within five years. 

The cost of compliance has been estimated to be as high as $400bn. A number of US water firms, concerned about the cost and impact on customer bills, have taken out legal cases against major PFAS producers including DuPont and 3M. Some suits have been settled but others continue. 3M has said it plans to stop producing PFAS.

The EPA’s move has been widely welcomed. The Agency said it “expects that over many years the final rule will prevent PFAS exposure in drinking water for approximately 100 million people, prevent thousands of deaths, and reduce tens of thousands of serious PFAS-attributable illnesses.”

Some, however, say the move does not go far enough in tackling only a handful of the thousands of PFAS compounds, and applying limits to drinking water only, leaving food markets untouched.

The US action will increase the pressure on other countries, including the UK, to take more action to protect people against the health risks linked to PFAS consumption. Last year, the Royal Society of Chemistry called on the UK Government to overhaul its drinking water standards after new analysis revealed more than a third of water courses tested in England and Wales contained medium or high-risk levels of PFAS.

The Society pointed out that current standards in England and Wales allow concentrations of each individual PFAS at up to ten times the level considered ‘low risk’, which is 10ng/l, and there is no overarching limit on the total concentration when they are combined. It called for a 10ng/l limit on each individual forever chemical, and a 100ng/l limit on total concentrations in drinking water.