Heavy metals found in some dark chocolate, not 'cause for alarm’: Experts

A study published earlier this week found several dark chocolate products may be contaminated with heavy metals, setting off concerns about overexposure.

For the analysis, published in the journal Frontiers, researchers purchased and tested 72 different dark chocolate products for heavy metal contamination between 2014 and 2022.

The team looked for levels of lead, cadmium and arsenic and examined if they exceeded those allowed by California's Proposition 65. Researchers found that 43% of products had higher concentrations of lead than allowed by Prop. 65 and 35% had higher levels of cadmium than allowed by the law. Additionally, organic dark chocolate products had higher levels of metal contamination than non-organic products.

Both lead and cadmium can be harmful and have been linked to a range of health issues at high doses. However, levels were not high enough that it should cause worry for the average dark chocolate eater, said Brian Pavilonis, an associate professor in the department of environmental, occupational and geospatial health sciences at CUNY Graduate School of Public Health and Health Policy, in New York.

"To me, I don't think this is a massive cause for alarm," Pavilonis, who was not involved in the study, told ABC News. Low levels of heavy metals are found in many everyday foods.

Pavilonis explained that lead, for example, is a naturally occurring element, so it is bound to appear in the soil where food -- including cocoa beans -- grows. It would be ideal for levels to be zero in dark chocolate products, but studies have shown over the years that the amount of lead levels in blood have fallen, he said.

"We still have some ways to go; no children should be exposed to lead, but we've done a great job through removing lead from products like gasoline, lead-based paint, doing remediation … so to me, lead's a success story," Pavilonis said. "If this was a big concern, you wouldn't see the lead levels declining over time."

To be harmed by the levels of heavy metal contamination in dark chocolate, a person would need to eat an extremely large amount, said Elad Tako, an associate professor in the department of food science at Cornell University's College of Agriculture and Life Sciences.

We are "recognizing we need to be more conscious about these heavy metals and their presence in our food products … but also recognizing the fact that, at least in the concentrations that were identified in this study, it's not a concern unless we're talking about the person that eats pounds and pounds of dark chocolate every day," Tako, who was not involved in the study, told ABC News.

Study co-author Leigh Frame, executive director of the office of integrative medicine and health at George Washington University School of Medicine and co-director of the Frame Corr Labs, said health risks of trace amounts of heavy metals in certain foods are low with a varied diet.

"Particularly during the week, we can often get into a rut and just eat the same thing over and over again, but then you're increasing your risk … it also potentially could be putting [you at] risk for nutritional deficiencies," she said. "So, if you have a lot of different foods, you're sort of hedging your bets, right? You're lowering your risk of insufficient nutrients or too much nutrients."

Frame and the other experts added that moderation is key -- suggesting a one-ounce serving size of dark chocolate.

"The reason that we're really pushing that is because that's typically what's been shown in the literature as being beneficial for health," Frame said. "I did not stop eating chocolate. I'm still eating chocolate, and I will be eating chocolate later today. So, there's nothing wrong with that."