Long thought to be healthier than other sweet treats, some brands of dark chocolate contain potentially dangerous levels of heavy metals, according to a study published Thursday by Consumer Reports.
Scientists from the nonprofit advocacy group 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 of the bars, consuming just one ounce a day would put an adult above levels for at least one of the metals that could be harmful, CR said. Five of the bars were above these values for both 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 all ages,” Tunde Akinleye, the CR food safety researcher who led the tests, said in a statement. Frequent exposure to lead in adults can lead to nervous system problems, high blood pressure, immune system suppression, kidney damage and reproductive problems, he noted.
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While most of the candy bars tested contained lead, cadmium, or both, five had relatively low levels of both metals, CR noted.
“This shows that it’s possible for companies to make products with lower levels of heavy metals — and for consumers to find safer products they like,” Akinleye said.
In determining the risks for the chocolate tested, CR used the maximum allowable dose in California of 0.5 micrograms for lead and 4.1 micrograms for cadmium because there are no federal limits.
CR found that an ounce of Hershey’s Special Dark Mildly Sweet Chocolate contained 265% more lead than the California legal limit, and Trader Joe’s Dark Chocolate 72% Cacao contained 192% more.
Trader Joe’s did not respond to a request for comment.
A Hershey’s spokesman directed the National Confectioners Association for comment. In an emailed statement, the trade group disagreed with CR’s use of limits set by California, noting that the state does not set federal food safety standards.
“The products cited in this study meet stringent quality and safety requirements,” a spokesman for the group told CBS MoneyWatch in an email. “Food safety and product quality remain our highest priorities and we remain committed to being transparent and socially responsible.”
The Confectioners’ Association released research in August showing ways to reduce lead and cadmium in chocolate, including the planting of new stands of trees by cocoa farmers.
The study was conducted in partnership with As You Sow as part of an agreement reached in 2018 between the nonprofit shareholder representative and 32 members of the trade group over California law requiring companies to warn people about significant exposure to chemicals that cause cancer, birth defects or cause other reproductive harm.
Based on CR’s findings, the safer choices are:
- Mast organic dark chocolate 80% cocoa. CR found that an ounce contained 14% less lead and 40% less cadmium than California’s allowable limits.
- Taza Chocolate Organic Deliciously Dark Chocolate 70% cocoa contained 33% less lead and 74% less cadmium.
- Ghirardelli Intense Dark Chocolate 86% Cacao contained 36% less lead and 39% less cadmium.
- Ghirardelli Intense Dark Chocolate Twilight Delight. The lead contained 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.