Cadmium and lead in Cocoa is a serious problem which we have written about before when the ICCO planned research, and when the IAEA became involved in helping to track the movement of heavy metals through the plant.
Now a detailed scientific report funded through a California Proposition 65 settlement was released today by As You Sow, and the National Confectioners Association is available. It’s quite a technical read but contains solid findings beyond which we can report here without duplicating the report. We strongly suggest reading the full report.
The investigation was multi-disciplinary, involved four experts, and involved a three-year effort. The investigation found that the sources of lead and cadmium in cocoa and chocolate are largely the same and that potential for reducing levels in the future may be possible.
A new report by As You Sow and the National Confectioners Association has produced a list of recommended cadmium and lead reduction measures that the industry should consider implementing. Significant lead reductions can be expected within the first year of introducing the new handling practices.
Cadmium reductions beyond those achieved through blending and potential changes in farming practices, including soil treatment and planting new tree stock, will take longer.
Industry members plan to continue to work with As You Sow, cocoa farmers, scientists, and their own quality teams to further reduce cadmium and lead levels in chocolate products as feasible.
Section 1, paragraphs , , , 
Section 9, paragraph ; Section 335, paragraph ; Section 336, paragraph 
Expert Investigation Related to Cocoa and Chocolate Products
A panel of four experts looked at sources of lead and cadmium in cocoa and chocolate. The experts were asked to provide “affirmative conclusions” on their report. The report was divided into 3 phases: root cause, reductions recommendations and trigger levels. The final report was reviewed by the entire expert committee, who submitted their own affirmative conclusions.
- The individual affirmative conclusions appear on pages 7-12, with minor formatting changes to make the consensus more consistent. They are shown in alphabetical order of the Experts.
- Anthropogenic Cd input is often linked to atmospheric pollution (e.g., from coal combustion or metal smelters), erosion from industrial activity (including mine tailings), and fertilizer applications. In addition, Cd concentration in phosphate-containing fertilizers can reach 300 ppm; thus, these materials may contribute significantly to Cd accumulation in agricultural land.
- Cocoa litter may contribute to the topsoil’s mineral composition. The composted leaves are a source of the heavy isotope Cd. Allowing cocoa leaves to form part of the tree’s litter may account for the higher accumulation of heavy isotope Cd in the topsoil. An investigation by CGD/TTR in Trinidad and Tobago showed that per-colony Cd levels in the litter were strongly correlated to and generally higher than Cd levels in underlying topsoils. Further studies done in Honduras by Gramlich and in Colombia by Albarrin showed that litter was a significant source of Cd to upper surface soils in cocoa plantations. Due to the ubiquitous occurrence of Cd-containing recycled materials in cocoa plantations, it can be viewed as a common source.
- The majority of Pb contamination may be from “post-harvest” contamination, which Section 6 in the report describes further. Only two publications reported cocoa pods at levels suggesting that Pb was coming from cocoa pods. Table 15b in the report summarizes SD testing data for Pb contamination in 118 cocoa nib samples. Pb was detected in 34 per cent of these samples.
- Harvesting and opening cocoa pods are generally the same across all cocoa-growing countries. There is a possibility of contamination from tools used, but those tools rarely come into direct contact with cocoa beans. The Expert Committee did not find any existing research evaluating Cd or Pb.
- Contamination can still occur when removing the beans from the pods if the vessels are not cleaned. Contamination from these vessels can affect newly-harvested beans.
- Unwashed used bags left over from the cocoa bean harvesting process had significant Cd compared to washed ones. However, the likelihood of these bags contaminating the whole bean mass is minimal. In some cases, beans may inadvertently come into contact with Cd-containing soil or Pb-containing soil, but the likelihood of significantly contaminating the whole bean mass is minor.
Photo source: GeovannyPenaloza, CC BY-SA 4.0 https://creativecommons.org/licenses/by-sa/4.0, via Wikimedia Commons