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Are there dangerous levels of heavy metals in dark chocolate?


Consumer Reports has us fearing food once again with their December 2022 Lead and Cadmium Could Be in Your Dark Chocolate report. Is there really a dark side to this “healthier” chocolate as they claim, or can you continue to enjoy your dark chocolate in peace?

Let’s take a look at the report and determine whether this is a real concern or if it’s yet another alarmist take like CR’s Your Herbs and Spices Might Contain Arsenic, Cadmium, and Lead report that I discussed in early 2022.

@foodsciencebabe It’d be nice to see the actual data too 🤷🏼‍♀️ #spices #heavymetals #nutrition #foodtok ♬ original sound – Food Science Babe

CR tested a mix of brands, including smaller ones, such as Alter Eco and Mast, and more familiar ones, like Dove and Ghirardelli. They claim 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 CR’s experts say may be harmful for at least one of those heavy metals and that five of the bars were above those levels for both cadmium and lead.

Immediately, you should be wondering what the “level” is that they’re referring to and where it came from. Safety levels under Proposition 65, 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. I’ve discussed Prop 65 in further detail here.

Just like the spice situation that I referenced above, CR doesn’t provide the raw data in their report.

To determine the risk posed by the chocolates in CR’s test, they used California’s maximum allowable dose levels (MADL) set by Prop 65 for lead and cadmium, which are 0.5 micrograms (µg) and 4.1 µg per day, respectively. California’s MADL for lead is much lower than the U.S. Food and Drug Administration’s interim reference levels (IRL), which are 2.2 µg per day for children and 8.8 µg per day for females of childbearing age. The FDA’s IRLs include a 10x safety factor, which means that it is nearly 10 times less than the actual amount of lead intake from food that would be required to reach the Centers for Disease Control and Preventions’s blood reference level. In addition, a 2018 settlement between The National Confectioners Association and As You Sow, a group that advocates enforcement of Proposition 65, established concentration levels for both lead and cadmium that require warning labels if surpassed.

These levels are as follows for an ounce of chocolate with:

Up to 65% cacao content: 2.8 µg lead and 11.3 µg cadmium
Greater than 65% and up to 95% cacao content: 4.3 µg lead and 12.8 µg cadmium
More than 95% cacao content: 6.4 µg lead and 27.2 µg cadmium

The association maintains that the industry has adhered to the levels established by the settlement, and according to the CR report, it looks as though all of the chocolate bars tested are well below these levels. The CR report also states, “Our results indicate which products had comparatively higher levels and are not assessments of whether a product exceeds a legal standard.” However, they communicated their findings by reporting the results as percentages of the MADL supplied in an ounce of chocolate and a red color coded designation for anything that exceeds 100 percent of CR’s levels, so that is misleading.

The implication to consumers is that the products exceeding 100 percent are unsafe, when that’s not necessarily the case.

“MADLs are set to be very conservative to account for people with higher risk due to their age and other medical conditions,” Johns Hopkins Medicine toxicologist Andrew Stolbach told NPR. “When the chocolate is consumed in moderate amounts, the lead and cadmium levels are nothing to worry about.

“The safety levels for lead and cadmium are set to be very protective, and going above them by a modest amount isn’t something to be concerned about,” he said. “If you make sure that the rest of your diet is good and sufficient in calcium and iron, you protect yourself even more by preventing absorption of some lead and cadmium in your diet.”

Image by Brett Hondow, Shutterstock

Dark chocolate tends to be higher in heavy metals than milk chocolate, likely because of its higher cacao content. Similar to how heavy metals contaminate other foods, researchers found that cacao plants take up cadmium from the soil, with the metal accumulating in cacao beans as the tree grows. Researchers found that lead was typically on the outer shell of the cocoa bean, not in the bean itself, leading them to believe that it gets into cacao after beans are harvested. So, in order to reduce lead, that would likely mean changes to harvesting and manufacturing processes such as minimizing soil contact with beans as they lie in the sun, drying beans away from roads or with protective covers and/or finding ways to remove metal contaminants when beans are cleaned at factories.

Potential solutions for reducing 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.

Unfortunately, just like previous CR reports on other food items, 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. It’s unfortunate, because there seems to be some great research and progress being made in terms of reducing heavy metals in chocolate, but that gets lost among the fear-based messaging and alarmist reporting.

Food Science Babe is the pseudonym of an agvocate and writer who focuses specifically on the science behind our food. She has a degree in chemical engineering and has worked in the food industry for more than decade, both in the conventional and in the natural/organic sectors.

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The views or opinions expressed in this article are those of the author and may not reflect those of AGDAILY.