By Marco Torres

Levels of a widely used class of industrial chemicals linked with liver toxicity, developmental problems, tumour growth and hormonal disruptions exceed federally recommended safety levels in public drinking-water supplies for 33 states in the U.S. according to a new study led by researchers at the Harvard John A. Paulson School of Engineering and Applied Sciences (SEAS).

The chemical contaminants that infest city water supplies in industrialized nations are abundant, including fluoride, chlorine and many others. What’s worse is that many of these chemicals are added intentionally under faulty and misguided science. To top that off, city officials are increasingly being caught for falsifying documents and submitting fraudulent water tests.

Only 91 contaminants are regulated by the Safe Drinking Water Act, yet more than 80,000 chemicals are used within the United States, according to EPA estimates. Government and independent scientists have scrutinized thousands of those chemicals in recent decades, and identified hundreds associated with a risk of cancer and other diseases at small concentrations in drinking water.

While there is a paucity of data on some of the contaminants, regulated chemicals such as atrazine, metolachlor, triclosan found in drinking water samples have been demonstrably linked to serious human and environmental health problems. Atrazine, for example, is used nationwide to kill broadleaf and grassy weeds, primarily in corn crops. It has been shown to be harmful to humans, mammals, and amphibians even when the amount used is less than the government allows. Atrazine is also associated with infertility, low birth weight, and abnormal infant development in humans. The chemical’s use is widespread, but for agriculture its use in concentrated in the Midwest farmbelt.

Levels of a widely used class of industrial chemicals linked with cancer and other health problems — polyfluoroalkyl and perfluoroalkyl substances (PFASs) — exceed federally recommended safety levels in public drinking-water supplies.

“For many years, chemicals with unknown toxicities, such as PFASs, were allowed to be used and released to the environment, and we now have to face the severe consequences,” said lead author Xindi Hu, a doctoral student in the Department of Environmental Health at Harvard Chan School, Environmental Science and Engineering at SEAS, and Graduate School of Arts and Sciences. “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 U.S. population — about 100 million people.”

PFASs have been used over the past 60 years in industrial and commercial products ranging from food wrappers to clothing to pots and pans. They have been linked with cancer, hormone disruption, high cholesterol, and obesity. Although several major manufacturers have discontinued the use of some PFASs, the chemicals continue to persist in people and wildlife. Drinking water is one of the main routes through which people can be exposed.

The researchers looked at concentrations of six types of PFASs in drinking-water supplies, using data from more than 36,000 water samples collected nationwide by the U.S. Environmental Protection Agency (EPA) from 2013 to 2015. T