Candy lovers, take note: Nearly half of the popular chocolate bars on the US market have been found to contain toxic metals linked to serious diseases, including cancer.
Researchers in Washington DC purchased and analyzed 72 commercial cocoa products over eight years, testing them for heavy metals such as lead, cadmium and arsenic.
The values were then compared to the maximum thresholds set by California’s Proposition 65 (Prop 65), which sets the amount of toxic metal that can be found in food or beverages.
They found that all of the products contained traces of toxic metals, with nearly half to 20 percent containing lead above the maximum allowable level. More than a third exceeded the permitted levels of cadmium, which has been linked to cancer and kidney damage.
The George Washington University researchers did not disclose which chocolate was tested, though it is speculated that popular brands such as Hershey’s, Reese’s and Kit Kats were at least considered for evaluation.
An analysis in the journal Frontiers in Nutrition found that 72 chocolate samples contained toxic metals such as lead and cadmium, with more than half having levels higher than the maximum allowable daily amount.
The team also noted that while a single serving of the sweet would likely not cause health problems, eating multiple servings could carry dangers such as kidney problems, heart disease and cancer.
The findings fit with recent research showing that thousands of cancer cases each year are linked to foods high in lead, cadmium and arsenic.
Dr Leigh Frame, study author and director of integrative medicine at the George Washington University School of Medicine and Health Sciences, said: ‘We all love chocolate, but it’s important to do so in moderation, as with other foods that contain heavy metals, such as large fish like tuna and unwashed brown rice.
‘While it is not practical to completely avoid heavy metals in your diet, you do need to be careful about what you eat and how much.’
According to the American Academy of Pediatrics (AAP), heavy metals such as lead, cadmium and arsenic can enter foods through soil, air, water or during the manufacturing process.
The George Washington University team purchased 72 chocolate products from online retailers, stores like Whole Foods and distributor websites between 2014 and 2022.
It is unclear where the stores were located.
The maximum daily thresholds set by Prop 65 in California were 0.5 micrograms per day, 4.1 micrograms per day, and 10 micrograms per day for lead, cadmium, and arsenic, respectively.
This was an important caveat to the study, as California is known for having stricter limits on heavy metals than many other states and is leading the way in implementing restrictions.
All products tested positive for trace amounts of toxic metals. However, 43 percent of the chocolate exceeded the Prop 65 maximum daily exposure limit, and more than one in three chocolates had levels above this limit.
And surprisingly, chocolate labeled “organic” contained higher levels of lead and cadmium than their “non-organic” counterparts, averaging 3.2 micrograms per serving.
The chart above shows the 28 chocolate bars tested by the nonprofit Consumer Reports in New York in a study separate from the one conducted by GWU researchers. All were found to contain lead and cadmium
Toxic metals such as lead and cadmium have been linked to several brands of baby food in studies separate from those conducted by GWU researchers
Lead has long been linked to a range of health problems, including developmental delays and behavioral problems in children. Some evidence also suggests that autistic children have higher levels of lead in their blood, but the research is mixed.
In addition, the EPA has classified lead and cadmium as probable human carcinogens, meaning they can cause cancer. Chronic exposure to cadmium has also been linked to kidney damage.
According to the FDA and CDC, there is no safe level for lead consumption.
Additionally, none of the products in the sample exceeded safe levels of arsenic, a known carcinogen linked to lung, bladder and skin cancer, the American Cancer Society said.
The team also noted that the levels of all three metals in the samples decreased over the study period. This could be due to stricter measures in states like California to limit exposure to heavy metals.
The research is part of a growing body of research showing that chocolate, vegetables and even baby food contain high levels of toxic metals.
For example, a 2022 analysis by regulator Consumer Reports found that 28 chocolate products, including Hershey’s and Lindt, contained lead and cadmium last year.
The research was published Wednesday in the journal Limits in nutrition.
