Chemicals used for carpets and anti-stain products have been found in water sources for 7.5 million people in California, detailing the extent of the problem as state regulators work to develop safety levels for the contaminants that have been linked to cancer.

A report released Wednesday by the Environmental Working Group found variants of the chemicals known as PFAS in 74 community water systems between 2013 and 2019, according to data from state and federal regulators. More than 40 percent of the systems had at least one sample that exceeded the health advisory level set by the U.S. Environmental Protection Agency.