Long considered healthier than other sugary treats, some brands of dark chocolate contain potentially dangerous amounts of heavy metals, according to to research released Thursday by Consumer Reports.
Scientists at the nonprofit 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 of the bars, consuming just one ounce a day would put an adult above a level for at least one of the metals that could be harmful, CR said. Five of the bars were above these levels for cadmium and lead.
According to experts, long-term exposure to small amounts of heavy metals can lead to a host of health problems, including developmental problems and brain development in young children.
“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 lead exposure in adults can lead to nervous system problems, hypertension, immune system suppression, kidney damage and reproductive problems, he noted.
While most of the chocolate bars tested contained levels of lead, cadmium or both, five had relatively low levels of both metals, CR found.
“It shows that it’s possible for companies to make products with fewer heavy metals – and for consumers to find safer products that they value,” Akinleye said.
To determine the risks for the chocolate tested, CR used the maximum allowable dose of 0.5 micrograms for lead and 4.1 micrograms for cadmium in California, as there are no federal limits.
CR found that one ounce of Hershey’s Special Mild Dark Chocolate contained lead 265% above what California allows, and that Trader Joe’s 72% Cacao Dark Chocolate contained 192% more.
Trader Joe’s did not respond to a request for comment.
A spokesperson for Hershey referred to the National Confectioners Association for comment. In an emailed statement, the trade group objected to CR’s use of California-set levels, noting that the state does not set federal food safety standards.
“The products cited in this study comply with strict quality and safety requirements,” a spokesperson for the group said in an email to CBS Money Watch. “Food safety and product quality remain our top priorities and we remain committed to being transparent and socially responsible.”
The association of pastry chefs published in August to research show how to reduce lead and cadmium in chocolate, including asking cocoa farmers to plant new trees.
The study was conducted in partnership with As You Sow as part of a 2018 settlement between the nonprofit shareholder advocacy association and 32 trade group members over a California law requiring companies to warn people of significant exposure to chemicals that cause cancer, birth defects or other reproductive harm.
According to CR’s findings, the safest choices are:
- Mast Organic Dark Chocolate 80% Cocoa. CR found that one ounce contained 14% less lead and 40% less cadmium than California’s allowable limits.
- Taza Chocolate Organic Deliciously Dark Chocolate 70% Cacao contained 33% less lead and 74% less cadmium.
- Ghirardelli Intense Dark Chocolate 86% Cacao contained 36% less lead and 39% less cadmium.
- Twilight delight with intense dark chocolate Ghirardelli. The lead contained was 61% below the permitted level and the cadmium 96% below its permitted limit.
- Valrhona Abinao dark chocolate 85% Cocoa. Lead 63% and Cadmium 73% below.