Concentrations of heavy metals found in single servings of some chocolates and cocoa-based products are too low in most cases to pose a health risk to consumers, research set to be published on Thursday in the journal Frontiers shows.
Some consumer groups and independent test agencies have previously reported heavy metal contamination in cocoa products such as dark chocolate, with possible causes being the type of soil where cocoa is grown and industrial processing.
Yet researchers at the George Washington University School of Medicine and ConsumerLab.com found that 70 of the 72 cocoa-containing products they analyzed fell below limits set by the Food and Drug Administration (FDA) for lead contamination.
They said the findings of their study showed the products may not pose a health risk when consumed as single servings, though larger portions could exceed strict California limits set in a law known as Prop 65.
The recommended single serving for chocolate is about 1 oz to 2 oz (30 gm to 60 gm).
"If contaminated products as a whole are consumed in small amounts and infrequently by most, these contaminants may not be a public health concern," read the paper, which concluded with a call for more testing of consumer products.
"In contrast, if many such products are consumed fairly regularly by the average consumer, the additive exposure may be a public health concern."
US chocolate industry group the National Confectioners Association said the research confirms that "chocolate and cocoa are safe to eat and can be enjoyed as treats as they have been for centuries."
The long-running research analyzed 72 products for potential contamination with heavy metals such as lead, cadmium and arsenic in four different cohorts in 2014, 2016, 2019 and 2022.
"Median concentrations of each metal tested were lower than even the conservative Prop 65," they added, referring to the strict California legislation on food contamination used as a benchmark for the study.
"However, consuming some of the products tested, or more than one serving per day in combination with non-cocoa derived sources ... may add up to exposure that would exceed the Prop 65 (limits)."
The researchers used the California legislation because it sets limits on contamination for the three types of heavy metals tested, while the FDA regulation only sets limits for lead.
