Drinking tapwater in the US could give you cancer, scientists warn

More than six million people in the US are drinking water that contains poisonous industrial chemicals linked with cancer and other health problems at levels higher than official safety limits, according to a major new study.

Researchers from Harvard University and other institutions used information about 36,000 water samples collected nationwide by the US Environmental Protection Agency (EPA) from 2013-2015.

They found that chemicals known as PFASs were present in 194 out of 4,864 public water supplies. And 66 water supplies had at least one sample that was above the EPA safety limit.

The highest concentration was found in Newark, Delaware, where the level of one kind of PFAS was 25 times higher than the safe limit. The worst problems were found in watersheds near industrial sites, military bases and wastewater treatment plants, the researchers reported in the journal Environmental Science & Technology Letters.

PFASs – polyfluoroalkyl and perfluoroalkyl substances – can be used in everything from food containers such as pizza boxes and non-stick cooking utensils to clothing, carpets and furniture. Only last year a group of scientists expressed concern about the increasing number of these kinds of chemicals in the environment, noting a "growing body" of evidence that they can cause cancer, obesity, low birth weight and even delay puberty.

Lead author of the paper, Xindi Hu, said: “For many years, chemicals with unknown toxicities, such as PFAS, were allowed to be used and released to the environment, and we now have to face the severe consequences.

“In addition, the actual number of people exposed may be even higher than our study found, because government data for levels of these compounds in drinking water is lacking for almost a third of the US population – about 100 million people.”

Some manufacturers have stopped using them amid rising concern over their health effects, but the chemicals have persisted in people, wildlife and in the natural environment.

PFASs are also widely used in fire-fighting foam and some industrial processes. Normal waste-water treatment plants are not able to remove them and sludge from these plants is often used as fertilizer on farms, which could lead to the contamination of groundwater.

Three-quarters of the samples of PFAS-polluted water were found in 13 states with the highest levels in California, followed by New Jersey, North Carolina, Alabama, Florida, Pennsylvania, Ohio, New York, Georgia, Minnesota, Arizona, Massachusetts, and Illinois.

Professor Elsie Sunderland, who worked on the study, said the problem could actually be significantly worse as other research had cast doubt on the safety of the current limits.

“These compounds are potent immunotoxicants in children and recent work suggests drinking water safety levels should be much lower than the provisional guidelines established by EPA,” she said.

Last year a group of scientists issued the "Madrid Statement on PFASs", in which they said they were "concerned about the production and release into the environment of an increasing number of poly- and perfluoroalkyl substances".

"PFASs are found in the indoor and outdoor environments, wildlife, and human tissue and bodily fluids all over the globe. They are emitted via industrial processes and military and firefighting operations, and they migrate out of consumer products into air, household dust, food, soil, ground and surface water, and make their way into drinking water," they wrote.

"In animal studies, some long-chain PFASs have been found to cause liver toxicity, disruption of lipid metabolism and the immune and endocrine systems, adverse neurobehavioral effects, neonatal toxicity and death, and tumors in multiple organ systems.

"In the growing body of epidemiological evidence, some of these effects are supported by significant or suggestive associations between specific long-chain PFASs and adverse outcomes, including associations with testicular and kidney cancers, liver malfunction, hypothyroidism, high cholesterol, ulcerative colitis, lower birth weight and size, obesity, decreased immune response to vaccines, and reduced hormone levels and delayed puberty."