Pressure is mounting on UK ministers to tighten regulations on PFAS “perpetual chemicals” as studies show vast numbers of people are drinking water at levels that would be banned in the US.

On Tuesday, U.S. President Joe Biden announced plans to lower legal limits for drinking water to four nanograms per liter (4 ng/L) for two types of per- and polyfluoroalkyl substances (PFOS and PFOA), and announced proposals to regulate four more – PFNA, PFHxS, PFBS and GenX Chemicals – as a mixture.

In England and Wales, Drinking Water Inspectorate (DWI) guidelines allow levels of PFOS and PFOA in drinking water to be 25 times higher, up to 100 ng/l, and until 2021 the limit was 5,000 ng/l for PFOA and 10,000 ng/l. for PFOS.

“I think the Americans are quite right and we’re out of step,” said Baroness Bakewell, the Liberal Democrats’ environmental representative in the House of Lords. “It seems nonsense that we are determined to poison the population. The government believes that it is at the forefront of everything, but … it is not, and the government is not willing to move forward with regard to the environment.”

Former Green Party leader Caroline Lucas agreed. “A cocktail of toxic persistent chemicals is polluting our rivers and seas, poisoning our water sources and posing a serious threat to human health, marine life and animal life. However, UK chemical pollution limits shamefully lag behind international standards. The government urgently needs to get this chemical crisis under control and put in place much stricter regulations.”

PFAS is a group of approximately 10,000 substances used in a wide variety of consumer products and industrial processes due to their non-stick properties. They are widely distributed in the environment and are known as “timeless chemicals” because they do not break down in the environment, can accumulate in the body, and some of them can be toxic.

“Communities through [the US] have suffered for far too long from the constant threat of PFAS contamination. That’s why President Biden has initiated a whole-of-government approach to aggressively tackle these harmful chemicals, and the Environmental Protection Agency (EPA) is leading the way,” said Michael S. Reagan, U.S. Environmental Protection Agency (EPA) Administrator.

The new limit “has the potential to prevent tens of thousands of PFAS-related illnesses and marks an important step towards protecting all of our communities from these dangerous pollutants,” Reagan added.

Data from water companies and the Environmental Protection Agency analyzed by Guardian and Watershed Investigations show that around 1,900 samples of drinking water sources from across the country contain PFOS or PFOA above the proposed US limit of 4 ng/L. The total is likely to be higher as many samples are in ranges such as “less than 10 ng/L”.

“Some of the data collected on detection limits for PFOS and PFOA far exceed the regulatory detection limit set by the US Environmental Protection Agency,” says Dr. Cecilia Macleod, program manager for wastewater treatment and environmental protection at the University of Greenwich. “Given the findings of the Environmental Protection Agency regarding these PFAS compounds for human health, is the UK DWI approach suitable for this purpose?”

Tony Fletcher, an epidemiologist at the London School of Hygiene and Tropical Medicine who studies the health effects of PFAS, said the US proposals “reflect a long-awaited trend towards more stringent regulation. Many regulators in the US and Europe have stricter limits than the old 100 ng/L limit currently in place in the UK.

“Recently, data has been collected across the UK on the impact of PFAS on all sources of drinking water. With that in hand, as well as restrictions such as the EPA restrictions, I expect the UK to follow suit and lower the allowed levels for these two, but we also need restrictions on the large family of PFAS as new connections continue to emerge.”

Green Party member Natalie Bennett said the government “claims to be following the ‘Proactive Protection Principle’ and we regularly hear empty boasts about being the ‘world leader’ in environmental standards, but this is clearly not the reality.

“These persistent chemicals represent a rapidly growing area for human health and the environment associated with reduced fertility, elevated cholesterol levels, and developmental problems in children. The US is reacting with a serious tightening of standards. The UK should follow.”

According to Stephanie Metzger, advisor to the Royal Society of Chemistry, “the new US regulations indicate that the UK should review its current recommendations for PFAS in drinking water to ensure they are in line with the latest scientific evidence.”

A spokesperson for the Department for the Environment, Food and Rural Affairs said: “UK drinking water standards are among the best in the world and water companies are required to conduct regular risk assessments and PFAS sampling to ensure that drinking water remains safe. Since the 2000s, we have increased the monitoring of PFAS and the measures taken to support the ban or severe restriction of specific PFAS both domestically and abroad. We are closely monitoring developments in international policy, including EPA proposals for PFAS in drinking water, and continue to work across the government to assess environmental levels of PFAS. We will publish an analysis in the spring that will examine the risks and make recommendations for future PFAS policy.”

Water UK did not respond to requests for comment.