Almost them half of US tap water samples contain toxic ‘permanent chemicals’substances used in hundreds of household items, from cleaners to pizza boxes, to which long exposure can cause serious health problemsaccording to new research.

The US Geological Survey (USGS) tested samples from more than 700 homes, businesses and water treatment plants across the country for the presence of perfluorinated alkylated substances (PFAS).

At least one such synthetic chemical was identified in 45% of samples at levels above the permissible, based on the rules proposed by the American authorities, the researchers pointed out.

The PFAS they are water resistant, which means they do not break down in the environment and stay in the human body for years. They were developed in the 1940s, with the creation of Teflon, the non-stick material in cookware, and are now used in a huge range of products.

Previous studies have measured the levels of PFAS in groundwater, reservoirs and water treatment plants.

But analyzing tap water allows for a more accurate estimate of what people are drinking, said USGS hydrologist Kelly Smalling, who led the research.

Exposure to large amounts of PFAS can cause hormonal disorders, affect liver function, increase the risk of kidney and testicular cancer, cause low birth weight and affect the health of pregnant women, according to the US Centers for Disease Control and Prevention (CDC).

Currently there are tests to detect very few of them 12,000 known types of PFAS. The samples, taken in the period 2016-2021 from private wells and public water reservoirs, were tested for 32 types.

Smalling said there was no difference in the rates of PFAS detected in the private and public sources, which she called “strange.”

Public waters are subject to federal Environmental Protection Agency (EPA) regulations, which private sources are not.

Also, compared to people who live in the countryside, those who live in large urban centers are more exposed to PFAS in drinking water, according to the research.