Dark chocolate has long been seen as a healthy sweet — but a new report suggests that the treat might actually be harmful. A new investigation by Consumer Reports found that dark chocolate bars may contain two heavy metals that are linked to a wide range of health problems. The organization tested 28 dark chocolate bars from the following brands: Hershey’s, Ghirardelli, Lindt, Dove, Godiva, Trader Joe’s, Hu, Mast, Taza Chocolate, Valrhona, Beyond Good, Equal Exchange, Scharffen Berger, Alter Eco, Pascha, Tony’s, Lily’s, Chocolove’s, Endangered Species, Theo and Green & Black’s. Researchers have found that all 28 chocolate bars contain cadmium, a natural element found in the soil that ends up in cocoa beans; and lead, which contaminates the beans naturally through the environment. The heavy metals have been linked to a variety of health issues such as lung issues, memory problems, cancer and even early death. Lead specifically is well known to be dangerous to humans, with long-term exposure causing memory loss, high blood pressure, abdominal pain and low moods in adults, and brain damage and central nervous system damage leading to learning and behavioral problems in children. Even just low levels of cadmium are considered cancer-causing and have been linked to kidney cancer and fragile bones, according to the Centers for Disease Control and Prevention. The organization tested 28 dark chocolate bars. Shutterstock While the products didn’t contain extremely high levels of the metals, they still had high enough health levels for it to be a concern, James Rogers, the director of food safety and testing at Consumer Reports , said. For 23 of the 28 bars, eating just one ounce per day would put an adult over the level for at least one of the metals for harmful effects. Five of those bars were above those levels for both cadmium and lead. Five of the bars had relatively low levels of both. Consumer Reports used California’s maximum allowable dose level (MADL) of 0.5 micrograms of lead and 4.1 micrograms of cadmium to determine health risk levels. Many of the chocolate bars with concerning levels had the word “organic” on the label, which doesn’t guarantee that toxicity levels won’t be high. The Lindt Excellence Dark Chocolate 70% Cocoa bar contained high levels of cadmium.Shutterstock The bars that were listed as high in cadmium were: Beyond Good Organic Pure Dark Chocolate 70% Cocoa: with cadmium levels reaching 112% of California’s MADLBeyond Good Organic Pure Dark Chocolate 80% Cocoa: 138% Equal Exchange Organic Extra Dark Chocolate 80% Cacao: 120% Lindt Excellence Dark Chocolate 70% Cocoa: 116% Scharffen Berger Extra Dark Chocolate 82% Cacao: 136% Alter Eco Organic Dark Chocolate Classic Blackout 85% Cacao : 204%Pascha Organic Very Dark Dark Chocolate 85% Cacao: 253%Dove Promises Deeper Dark Chocolate 70% Cacao: 112% The Godiva Signature Dark Chocolate 72% Cacao Bar contained high levels of lead.Shutterstock The bars found to have high levels of lead included: Tony’s Chocolonely Dark Chocolate 70% Cocoa: with lead levels reaching 134% of the California’s MADLilily’s Extra Dark Chocolate 70% Cocoa: 144% Godiva Signature Dark Chocolate 72% Cacao: 146%Chocolove Strong Dark Choc olate 70% Cocoa: 152% Lindt Excellence Dark Chocolate 85% Cocoa: 166%Endangered Species Bold + Silky Dark Chocolate 72% Cocoa: 181% Trader Joe’s Dark Chocolate 72% Cacao: 192%Hu Organic Simple Dark Chocolate 70% Cacao: 210 %Chocolove Extreme Dark Chocolate 88% Cocoa: 240%Hershey’s Special Dark Mildly Sweet Chocolate: 265% Two Theo chocolate bars contained concerning levels of both lead and cadmium. Shutterstock The following chocolate bars had concerning levels of both lead and cadmium: Theo Organic Pure Dark 70% Cocoa: 120% of the MADL for lead, 142% for cadmium Trader Joe’s The Dark Chocolate Lover’s Chocolate 85% Cacao: 127% and 229% Theo Organic Extra Dark Pure Dark Chocolate 85% Cocoa: 140% and 189% Lily’s Extremely Dark Chocolate 85% Cocoa: 143% and 101% Green & Black’s Organic Dark Chocolate 70% Cacao: 143% and 181% Two Ghirardelli bars were listed as “safer choices.” Shutterstock The bars that had lower levels and five were listed as “ safer choices are: Mast Organic Dark Chocolate 80% Cocoa: 14% of the MADL for lead, 40% for cadmium Taza Chocolate Organic Deliciously Dark Chocolate 70% Cacao: 33% and 74% Ghirardelli Intense Dark Chocolate 85% Cacao: 36% and 39% Ghirardelli Intense Dark Chocolate Twilight Delight 72% Cacao : 61% and 96% Valrhona Abinao Dark Chocolate 85% Cacao: 63% and 73% The National Confectioners Association, the industry trade group, argued that chocolate and cocoa are safe to eat and told TODAY in a statement that dark chocolate “can be enjoyed as treats as they have been for centuries.” “The products cited in this study are in compliance with strict quality and safety requirements,” the statement continued.