Long viewed as healthier than other sugary treats, some brands of dark chocolate contain potentially dangerous amounts of heavy metals, according to research published Thursday by Consumer Reports.
Scientists at a nonprofit advocacy organization recently measured the amount of heavy metals in 28 popular brands of dark chocolate bars and found cadmium and lead in all of them. For 23 ingots, consuming just one ounce per day would put an adult over the level for at least one of the potentially harmful metals, CR said. Five bars were above those levels for cadmium and lead.
Long-term exposure to even small amounts of heavy metals can lead to a range of health problems, including developmental problems and brain development in young children, experts say.
“But there are risks for people of any age,” said Tunde Akinleie, a CR food safety researcher who led the testing. Frequent exposure to lead in adults can lead to nervous system problems, hypertension, immune system suppression, kidney damage and reproductive problems, he noted.
While most chocolate bars tested contained levels of lead, cadmium or both, five had relatively low levels of both metals, CR found.
“It shows that it is possible for companies to make products with lower amounts of heavy metals – and for consumers to find safer products that they enjoy,” Akinleye said.
In determining the risk for the chocolate it tested, CR used California’s maximum allowable dose of 0.5 micrograms for lead and 4.1 micrograms for cadmium, since there are no federal limits.
CR found that an ounce of Hershey’s Special Dark Mildly Sweet Chocolate contains 265% more lead than California allows, and Trader Joe’s Dark Chocolate 72% Cocoa contains 192% more.
Trader Joe’s did not respond to a request for comment.
A spokesperson for Hershey’s reached out to the National Confectioners Association for comment. In an emailed statement, the trade group objected to CR using levels set by California, noting that the state does not set federal food safety standards.
“The products listed in this study comply with strict quality and safety requirements,” a spokesperson for the group said in an email to CBS MoneyWatch. “Food safety and product quality remain our highest priorities and we remain committed to transparency and social responsibility.”
In August, the Confectioners Association released research showing ways lead and cadmium in chocolate could be reduced, including planting new trees.
The study was conducted in partnership with As You Sow as part of a 2018 settlement between the nonprofit shareholder advocacy organization and 32 trade group members over a California law requiring businesses to warn people about significant exposure to chemicals that cause cancer, birth defects or other reproductive harm .
According to CR’s findings, the safer choices are:
- Mast organic dark chocolate 80% cocoa. CR found that the ounce contained 14% less lead and 40% less cadmium than California’s legal limits.
- Taza Chocolate Organic delicious dark chocolate with 70% cocoa contains 33% less lead and 74% less cadmium.
- Ghirardelli Intense Dark Chocolate 86% Cacao contains 36% less lead and 39% less cadmium.
- Ghirardelli Intense Dark Chocolate Twilight Delight. The content of lead was 61% below the permitted level, and cadmium was 96% below the permitted limit.
- Valrhona Abinao dark chocolate 85% cocoa. Lead 63% and cadmium 73% below.