A new study has found numerous dark chocolate products are contaminated with lead and cadmium, two highly toxic metals.
The study by researchers at George Washington University was published in the peer-reviewed journal Frontiers in Nutrition.
More than 70 dark chocolate products sold at stores such as Amazon, GNC and Whole Foods were purchased to test for toxic metal contamination, though the names of the products or manufacturers were not disclosed in the study. The samplings were conducted over a period of eight years from 2014 to 2022.
The study found that 43% of the products tested had exceeded acceptable levels of lead contamination, and 35% exceeded cadmium levels, based on California legal limits for heavy metals in food.
Researchers found lead levels in chocolate samples ranging from zero to as high as 3.316 micrograms per daily serving, with 0.5 micrograms a day the maximum allowed according to California guidelines, and cadmium levels in the samples ranged from 0.29 to 14.12 micrograms per daily serving, with 4.1 micrograms a day the maximum allowed.
No amount of lead exposure is safe. Cadmium is a highly toxic metal with exposure linked to cancer, and targeting the cardiovascular, renal, gastrointestinal, neurological, reproductive and respiratory systems.
The products were also tested for arsenic, but none tested above the maximum contamination level. The researchers also found organic products contained higher contamination levels, but they did not determine how the metal contaminations were introduced into the chocolate products.
Cadmium is suspected as a soil contaminant, while lead is suspected to be introduced to the products through drying, processing or packaging.
The researchers concluded in their study that the heavy metal contamination found in the products may not pose a risk to the average person by themselves, but could pose a risk for consumers of more than one serving per day or in combination with other sources of heavy metal contamination.
“The results of our analysis suggest that many products contain [lead] and [cadmium] in amounts that may exceed certain, stringent regulatory requirements,” wrote the researchers in the study.
“Therefore, enhanced surveillance may be warranted. Further, additional research into cumulative heavy metal exposure from the diet as a whole would help put this work into context to best inform public health policy and interventions.”
Christopher Gindlesperger, senior vice-president of public affairs and communications for the National Confectioners Association, said in a statement to the Guardian: “Chocolate and cocoa are safe to eat and can be enjoyed as treats as they have been for centuries. Food safety and product quality remain our highest priorities and we remain dedicated to being transparent and socially responsible.”
A spokesperson for the Food and Drug Administration said the agency did not generally comment on specific studies.
They stated :“the FDA monitors for environmental contaminants, including lead and cadmium, in chocolate and chocolate products. Cadmium and lead levels in chocolate depend on the growing area and the percentage of cocoa solids in the chocolate product. While the presence of cadmium and lead in chocolate has been the subject of considerable media attention, experts from around the world have found that chocolate is a minor source of exposure to these contaminants internationally.”
