Nearly 40% of nonorganic fruits and vegetables grown in California contain traces of pesticides that are also PFAS, or “forever chemicals,” according to a new investigation.

California supplies nearly half of the vegetables and more than three-quarters of the fruits and nuts eaten in the United States.

Perfluoroalkyl and polyfluoroalkyl substances, or PFAS, are called “forever chemicals” because their strong carbon to fluoride molecular bonds can take years to decades — even centuries— to completely break down in the environment. It’s estimated there are nearly 15,000 types of fluorinated chemicals, or PFAS, in existence today.

“The PFAS pesticide is the active ingredient in these products because it’s effective at killing things — which is the very reason why it’s so concerning to public health and the environment at large,” said Bernadette Del Chiaro, senior vice president for California operations for the Environmental Working Group, or EWG, a health advocacy organization that produced the report published Wednesday.