Dark chocolate and similar cocoa products contain lead and cadmium, two neurotoxic metals linked to cancer, chronic disease, and reproductive and developmental issues, particularly in children, according to a new study.
Lead and cadmium are naturally occurring elements found in the Earth’s crust, and they end up in the soil where crops grow. Consequently, they cannot be entirely avoided. However, some agricultural regions have higher toxic levels due to the overuse of metal-containing fertilizers and ongoing industrial pollution.
Interestingly, organic dark chocolate, despite being grown in areas with fewer pesticides and contaminants, was found to have some of the highest levels of these metals, as per the study published on Wednesday in *Frontiers in Nutrition*.
Dark chocolate is often praised for its rich content of flavonoids, antioxidants, and beneficial minerals, which have been linked to improved cardiovascular health, cognitive performance, and reduced chronic inflammation. The research focused exclusively on pure dark chocolate products, which contain the highest amounts of cacao—the raw, unprocessed part of the cacao bean. Products with other ingredients, like candies or baking chocolates, were not included in the study, and the names or manufacturers of the tested products were not disclosed.
“The average levels of lead and cadmium in cocoa-containing products in the new study are at or above the average amounts the U.S. Food and Drug Administration finds in the most highly contaminated foods they test,” said Jane Houlihan, the national director of science and health for Healthy Babies Bright Futures, a coalition dedicated to reducing babies’ exposure to neurotoxic chemicals. The FDA’s list of foods most contaminated with lead includes baby food sweet potatoes, teething biscuits, sandwich cookies, white wine, and ranch dressing. For cadmium, sunflower seeds, spinach, potato chips, leaf lettuce, and french fries top the list, Houlihan noted.
“If typical health risks from eating chocolate fall below the federal government’s official safe thresholds, it is because people usually consume it in fairly small amounts,” Houlihan added. “However, there may be heightened risks for young children, pregnant women, and regular consumers of dark chocolate.”
The National Confectioners Association, representing the chocolate industry, responded to the findings by stating that “chocolate and cocoa are safe to eat and can be enjoyed as treats, as they have been for centuries. Food safety and product quality remain our highest priorities, and we are committed to transparency and social responsibility.”
### Lead and Cadmium Found, but No Arsenic
The study analyzed 72 cocoa products for levels of lead, cadmium, and arsenic over an eight-year period, with testing done in 2014, 2016, 2018, and 2020. Consumer Labs, a nonprofit that provides third-party testing of health and nutrition products, conducted the testing, sending samples to various laboratories to ensure accuracy.
Of the 72 products tested, 43% exceeded the maximum allowable dose level for lead as established by California’s Proposition 65, and 35% exceeded the Prop 65 limit for cadmium. The study did not find significant levels of arsenic.
Proposition 65’s limits are stricter than those set by the federal government. For example, the FDA allows a maximum of 0.1 parts per million of lead in children’s candy, while Prop 65 sets a more stringent safety standard of 0.05 parts per million for chocolate.
“Prop 65 sets a protective level, allowing consumers to make informed decisions,” said Danielle Fugere, president and chief counsel for As You Sow, a nonprofit specializing in shareholder advocacy. “There are many sources of lead, such as water, vegetables, fruits, soil, dust, and air. Do I feel comfortable eating chocolate that might also contain lead? Each person must decide for themselves.”
Healthy adults who limit their intake to small amounts should not be overly concerned about consuming chocolate, said senior study author Leigh Frame, executive director of the Office of Integrative Medicine and Health at George Washington University.
“A typical serving of dark chocolate is 1 ounce, so consuming 1 ounce every day or so presents a relatively small risk in the grand scheme of things,” Frame said. “However, it’s important to be aware of this risk, especially if you’re exposed to other sources of lead, such as lead paint in older homes.”
### Should You Avoid Chocolate?
The risk of heavy metal exposure increases if a person is medically compromised, pregnant, or a small child, according to Tewodros Godebo, an assistant professor of environmental geochemistry at Tulane University School of Public Health and Tropical Medicine. Godebo conducted a July study that analyzed 155 chocolate samples and found higher levels of cadmium but less lead in dark chocolates.
Long-term consumption of low levels of cadmium can damage the kidneys, and the Environmental Protection Agency considers it a probable human carcinogen. “Medically compromised individuals, such as those with kidney disease who may not efficiently excrete metals, and pregnant women protecting their unborn child, are at greater risk,” Godebo said.
Children are particularly vulnerable, as they can absorb about 50% of ingested lead after a meal and up to 100% on an empty stomach. The World Health Organization states that there is no safe level of lead, especially for children, noting that lead exposure can negatively affect brain development, reduce IQ, and lead to behavioral changes and lower educational achievement.
For healthy adults, however, Godebo’s risk analysis suggests little cause for concern when indulging in 1 ounce of dark chocolate occasionally. “Ideally, we want to minimize exposure, but achieving zero exposure is impossible,” he said. “Everything we eat likely contains some level of contaminants, but it’s a relative risk.”
