New data from George Washington University is pointing the finger at dozens of cocoa-based products for containing heavy metals — such as lead and cadmium — that surpass levels that the researchers consider safe.
The 72 dark chocolate products the research team analyzed were done over a span of eight years. They tested for lead, cadmium, and arsenic, which are heavy metals that pose a significant health hazard in sufficient amounts. Consuming excessive amounts of these metals have been linked to such things as neurological and development problems, kidney issues, and skin or lung cancers.
Though none of the tested products exceeded the maximum allowable dose level for arsenic, 43 percent of the products exceeded the maximum allowable dose level for lead, while 35 percent we in excess of cadmium. Organic-labeled products were found to have significantly higher levels of both metals when compared to conventionally grown cocoa products, and marketing labels such as “non-GMO” or “fair trade” did not yield any significantly different levels.
Lead in cocoa can come from many sources, including soil, dust and deposition from power plants around the world, according to the National Confectioners Association. It can adhere to the outer shells of cocoa beans after they are extracted from the pods. When they are harvested, cocoa beans are naturally covered with a sticky cacao pulp which allows lead to cling to the beans while they are being fermented and dried in the open in the tropical countries where cocoa is grown. Those shells, however, are removed at the beginning of the chocolate making process.
Cadmium, on the other hand, can be found in chocolate and cocoa due to its presence in tropical soils where crops are cultivated and harvested. Cocoa trees absorb cadmium from soils via their roots and deposit it in the nibs (center) of cocoa beans, the association explained.
“While it’s not practical to avoid heavy metals in your food entirely, you must be cautious of what you are eating and how much,” said Leigh Frame, director of integrative medicine at George Washington University. The research, titled, A multi-year heavy metal analysis of 72 dark chocolate and cocoa products in the USA, was published today in Frontiers in Nutrition.
The study said in its conclusion that “if contaminated products as a whole are consumed in small amounts and infrequently by most, these contaminants may not be a public health concern,” which fits how most Americans approach chocolate and cocoa products. A survey by the Centers for Disease Control and Prevention has found that U.S. residents eat candy two to three times per week on average.
“Chocolate and cocoa are safe to eat and can be enjoyed as treats as they have been for centuries,” the National Confectioners Association said in a statement in response to the study. “Food safety and product quality remain our highest priorities and we remain dedicated to being transparent and socially responsible.”
This is far from the first time that chocolate products have been connected to concerns about consuming heavy metals, though it’s usually dark chocolate specifically that gets the most media scrutiny. Consumer Reports, for example, which used to carry a substantial amount of credibility and information to consumers, just last year claimed that for 23 of the chocolate bars, eating just an ounce a day would put an adult over a level that public health authorities and the publication’s experts say may be harmful for at least one of those heavy metals. It also had said that five of the bars were above those levels for both cadmium and lead.
However, Consumer Reports intentionally didn’t provide the raw data for their findings, which led to a significant amount of speculation and skepticism as to what the “level” is that they’re referring to and where it came from. Safety levels under California’s Proposition 65 warning label, for example, are much lower than federal safety levels for many different chemicals, which is why you see a cancer warning almost everywhere in California, rendering the warning basically useless for consumers.
According to those Prop 65 guidelines, the threshold for heavy metals in foods is 0.5 micrograms a day. The scientists in the George Washington University study estimated the number of micrograms a day people would be exposed to if they ate the suggested serving amounts on the chocolate product labels. They found that the chocolate samples ranged from 0 to as high as 3.316 micrograms per daily serving. Levels of cadmium ranged from 0.29 to 14.12 micrograms, with the limit being 4.1 micrograms per day.
Andrew Stolbach, a toxicologist at Johns Hopkins Medicine, has previously told NPR, “When the chocolate is consumed in moderate amounts, the lead and cadmium levels are nothing to worry about.”
Still, potential solutions for reducing a heavy metal like cadmium could involve breeding or genetically engineering plants to take up less cadmium or replacing older cacao trees with younger ones, since cadmium levels tend to increase as the plants get older. There are also solutions that chocolate makers can implement in the more immediate future, such as blending low and high cadmium beans.
One AGDAILY columnist lamented in a piece in January 2023: “Unfortunately … what happens is that a legitimate concern, such as heavy metals in foods, gets reduced to a graphic with color coded designations that primarily serves to scare consumers regarding specific food items that aren’t unsafe when consumed in moderate amounts.”
