Long considered healthier than other sweets, some types of dark chocolate contain potentially dangerous amounts of heavy metals, according to research published Thursday by Consumer Reports.
Scientists from the nonprofit advocacy organization recently measured the amount of heavy metals in 28 popular brands of dark chocolate bars, finding cadmium and lead in all of them. For 23 of the bars, consuming just one ounce a day would put an adult above the level of at least one of the metals that could be harmful, CR said. Five of the bars were above those levels for both cadmium and lead.
Long-term exposure to even trace amounts of heavy metals can lead to a host of health problems, including developmental problems and brain development in young children, experts say.
“But there are risks for people of any age,” Tunde Akinleye, the CR food safety researcher who led the trial, said in a statement. Frequent lead exposure in adults can cause nervous system problems, high blood pressure, immune system suppression, kidney damage and reproductive problems, he noted.
While most of the chocolate bars tested contained concerning levels of lead, cadmium, or both, five had relatively low levels of both metals, CR found.
“This 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.
To determine the risks of the chocolate it tested, CR used California’s maximum allowable dose level of 0.5 micrograms for lead and 4.1 micrograms for cadmium, as there are no federal limits.
CR found that one ounce of Hershey’s slightly sweet specialty dark chocolate contained 265% more lead than California allows, and Trader Joe’s 72% cocoa dark chocolate contained 192% more.
The Hershey Company and Trader Joe’s did not immediately respond to a request for comment.
Based on CR’s findings, the safest options are:
- Mast Organic Dark Chocolate 80% Cocoa. CR found that one ounce contained 14% less lead and 40% less cadmium than California allowable limits.
- Taza Chocolate Organic Deliciously Dark Chocolate 70% Cacao contains 33% less lead and 74% less cadmium.
- Ghirardelli Intense Dark Chocolate 86% Cocoa contained 36% less lead and 39% less cadmium.
- Ghirardelli Intense Dark Chocolate Twilight Delight. The contained lead was 61% below the permitted level and the cadmium was 96% below its permitted limit.
- Valrhona Abinao Dark Chocolate 85% Cocoa. Lead 63% and cadmium 73% below.
The National Association of Pastry Chefs in August launched research showing ways lead and cadmium in chocolate could be reduced, including by having cocoa farmers plant new trees.
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