Attention, chocolate lovers: There may be lead, heavy metals in your favorite candy

Attention chocoholics: Your favorite candies may be contaminated with lead and other heavy metals known to cause long-term health problems.

A new study found dozens of popular chocolates made in the U.S. and Europe contain more heavy metals than the limit set by a California law, according to a report published Wednesday in the peer-reviewed journal Frontiers in Nature.

The 1986 California law, Proposition 65, requires businesses to inform state residents about products with chemicals known to cause cancer, birth defects and reproductive harm.

While the elevated levels of metals in chocolate are concerning, consumers needn't cut this delicious staple from their diet, said study co-author Leigh Frame, director of integrative medicine and associate professor at George Washington University.

“I’m a chocolate lover myself so you’ll be glad to hear that chocolate isn’t going to kill us,” she said. But like all things, moderation is key.

How heavy metals get into your chocolate

Lead and cadmium are naturally occurring elements that can affect every tissue in the body by inserting themselves into cellular processes involved in major bodily functions.

Children are especially vulnerable if they ingest heavy metals, particularly in terms of their neurological development. Exposure can damage the brain and nervous system, slow growth and development and trigger learning and behavior problems.

In Wednesday's study, researchers from George Washington University studied samples of more than 70 treats over eight years, from 2014 to 2022. They found 43% of the chocolate products studied exceeded the maximum allowable dose of lead and 35% exceeded the amount for cadmium.

These heavy metals make their way into your chocolate through the cacao bean, said Danielle Fugere, president and chief counsel at As You Sow, a nonprofit that worked with the chocolate industry to produce an investigative report on heavy metals in chocolate in 2022.

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The report found cacao trees absorb cadmium from the soil and deposit it in the cacao bean.

“It’s a naturally occurring metal,” said Ana M. Rule, assistant professor and director of the Exposure Assessment Laboratories at Johns Hopkins Bloomberg School of Public Health, who was not affiliated with either study. “But just because they’re naturally occurring, doesn’t mean they’re safe.”

Lead contamination occurs at various stages of chocolate production, – during the harvesting, drying and fermenting the cacao bean.

The beans can accumulate lead from the environment on their sticky surfaces as they’re drying on contaminated ground or on the side of the road in a place with heavy metals from car pollution. Lead can also be introduced during the manufacturing process, Fugere said.

“We added (heavy metals) to products and now they’re in the soil and pollution,” said Frame, from George Washington University. “As they start to accumulate in the environment, they become a problem.”

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What's the deal with dark and organic chocolate

Heavy metals are more of a glaring problem in some chocolate products than others. For example, samples of dark chocolate contained higher levels of lead and cadmium , according to the George Washington study.

Experts say dark chocolate is more concentrated with cacao than milk chocolate, which helps explain why it has more heavy metals.

Study authors were surprised to find organic products also contained higher levels of cadmium and lead compared with more processed chocolate. Frame suggested this could be due to less processing in the making of organic chocolate.

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Another explanation for the difference, Fugere said, is that organic chocolate producers tend to operate in a single area, and single-origin chocolate is likelier to have higher levels of heavy metals than chocolate products in which the cacao beans have been harvested from various places around the world.

Single-origin producers who harvest from an area high in cadmium or lead don't have beans from other regions to mix into the chocolate and dilute the concentration of heavy metals, she said.

What the chocolate industry can do

Mixing beans from different areas of the world is one of many ways chocolate producers can reduce the level of heavy metals in their products.

As You Sow determined from the 2022 report exporters can stop purchasing beans from regions high in heavy metals and farmers can stop planting new orchards in those regions.

Experts also recommend increasing the soil pH and establishing clean practices to prevent lead contamination, which Fugere said includes changing the type of equipment they’re using to allow less lead introduction.

Christopher Gindlesperger, spokesperson for the National Confectioners Association, said food safety and product quality are a top priority for the industry and the association remains “dedicated to being transparent and socially responsible.”

Rule, from Johns Hopkins, said it's also important to continue testing chocolate products to gauge areas of improvement.

“Every time we look for metals, we’re finding them,” she said. “It’s good to keep monitoring these consumer products to be able to identify sources and inform.”

What you can do as a consumer

Of course, chocolate isn’t all bad. Research has shown that this addicting treat can carry health benefits, too.

Chocolate is rich in flavonoids, which contain anti-inflammatory, antioxidant and anti-carcinogenic properties. Flavonoids are also associated with heart and brain benefits, such as reducing high blood pressure and improving cognitive function .

To get the health benefits from chocolate but reduce heavy metal exposure, experts recommend limiting chocolate consumption to 1 ounce per day. Frame says she's been able to curb her chocolate habit by limiting her intake to once every other day.

“Chocolate and cocoa are safe to eat and can be enjoyed as treats as they have been for centuries,” said Gindlesperger, from the confectioners association.

Health experts also urge consumers to research other foods that contain high levels of heavy metals to avoid pairing them in a meal with chocolate.

"These days, what we consume is so processed that we lose track of all the places where it can get contaminated," Rule said. "It’s important to be vigilant."

Adrianna Rodriguez can be reached at adrodriguez@usatoday.com.

This article originally appeared on USA TODAY: Attention, chocolate lovers: There may be lead, heavy metals in your favorite candy