In response to recent concerns over toxic heavy metals in chocolate, Tulane University researchers have conducted a comprehensive study to assess the levels and risks of such metals in chocolates sold in the U.S., focusing on the origins of the cocoa beans used. The results indicate that nearly all chocolate samples have toxic heavy metal levels below recommended safe limits, with notable variations depending on the cocoa beans’ geographical origins.
Background and Methodology
Global health concerns about contaminants in cacao-derived products have risen, especially following findings by Consumer Reports in 2022 and 2023 about cadmium and lead in chocolates. The Tulane study aimed to clarify these concerns by analyzing 155 chocolate samples for 16 elements, including arsenic, cadmium, cobalt, copper, iron, lead, magnesium, manganese, molybdenum, nickel, selenium, strontium, thallium, thorium, uranium, and zinc.
Samples were sourced from major brands such as Alter Eco, Hershey, Lindt, and others, representing cocoa from West Africa (33 samples), South America (27 samples), Asia Pacific (10 samples), Central America (10 samples), East Africa (9 samples), and mixed-origin cacao (61 samples). Four samples had unknown origins.
The potential non-carcinogenic risk from long-term exposure to cadmium, lead, nickel, arsenic, and uranium was assessed using the hazard quotient (HQ) or hazard index (HI) proposed by the U.S. Environmental Protection Agency (EPA), assuming daily consumption of one ounce of chocolate.
Key Findings
Cadmium Levels:
Dark chocolates from Central and South America had the highest mean cadmium levels.
Cadmium levels ranged from 0.3–843 µg/kg, with the highest in Lok Dark Chocolate (100% cocoa) from Colombia (843 µg/kg).
West African and Asian chocolates showed lower cadmium levels.
Lead Levels:
Lead levels ranged from 1.9–632 µg/kg, with the highest in Napolitains Dark from Venezuela (632 µg/kg).
West African and Asian chocolates had lower lead levels compared to other regions.
Other Metals:
Higher cacao content correlated with increased levels of cadmium and nickel, and moderately with arsenic.
Weak associations with lead and uranium suggest post-harvest contamination.
Health Risks:
Most samples did not exceed EPA HQ/HI values for adults.
Four samples exceeded safe levels of cadmium for children weighing 15 kg (33 pounds) or less.
The HI for cumulative risk from cadmium, lead, nickel, arsenic, and uranium was exceeded in 33 dark chocolates, indicating potential non-carcinogenic risks for children.
Nutritional Benefits:
Dark chocolates were found to contain significant levels of copper, iron, magnesium, manganese, and zinc, which can limit the bioavailability of cadmium and lead.
Conclusion
The Tulane study provides a detailed assessment of toxic heavy metals in chocolates, revealing that West African and Asian cocoa sources generally have lower cadmium and lead levels. While most chocolate samples are safe for adult consumption, some dark chocolates pose potential risks for children due to elevated levels of specific toxic metals. The study underscores the importance of monitoring and regulating heavy metal content in chocolates to ensure consumer safety.