Environmental advocacy group As You Sow has some bad news for those of us who like to celebrate Easter by indulging in chocolate treats: In addition to cacao, some chocolate products have trace amounts of toxic heavy metals, like lead and cadmium.

The group tested 50 chocolate products manufactured by well-known companies, including Trader Joe’s, Hershey’s, Whole Foods, Ghirardelli, and Earth Circle Organic, for metals. Thirty-five of the products contained lead and cadmium, and levels that were higher than those set by California’s Safe Drinking Water and Toxic Enforcement Act.

Lead poisoning is a public health issue due to its damaging effects. Exposure to lead has been linked to learning disabilities, decreased IQ, and even schizophrenia. Lead can show up almost anywhere, but the most common places are dust and chips from old paint, according to the New York State Department of Health.

Cadmium exposure is also damaging. Previous studies have linked cadmium exposure to lower birth weight, neurobehavioral problems, and adverse outcomes on male reproduction. Exposure to both metals can lead to kidney, liver and bone damage.

"Lead and cadmium accumulate in the body, so avoiding exposure is important, especially for children," As You Sow President Danielle Fugere said in a statement. "Our goal is to work with chocolate manufacturers to find ways to avoid these metals in their products."

The chocolate companies, however, disagree. A Hershey's spokesman told The Washington Post that their products meet all of the necessary criteria, including the U.S. Food and Drug Administration's, and are safe for consumption.

"People have been eating cocoa and chocolate for centuries with no evidence of a single incident of concern regarding these naturally occurring minerals," he said.

The National Confectioners Association, a non-profit trade association of the confectionery industry, said these heavy metals are "naturally-occurring elements" that can be found in nearly all edible products, including fish, meats, grains, fruits and vegetables.

However, the National Institute of Environmental Health Sciences maintained that no amount of lead is safe. Furthermore, given the amount of chocolate products people consume each year — about 9.5 pounds per year — these levels are still cause for concern.

In fact, last month, As You Sow filed legal notices against these chocolate manufacturers because they failed to warn their customers of the dangerous amounts of metals in their products.

"As underscored by the Flint disaster, humans have contaminated our environment with lead, and now we must do everything in our power to protect ourselves and children, who are the most vulnerable of us, from every possible exposure," Dr. Sean Palfrey, a pediatrician and Professor of Pediatrics and Public Health at Boston University School of Medicine, said. "Young children and pregnant women especially should avoid exposure to lead."