Recent cadmium (Cd) regulation in chocolate threatens the sustainability of cacao production in Southwest America. Cadmium contamination in cacao beans has not been assessed at a country level. A nationwide survey was conducted in Ecuador to identify the spatial distribution of Cd in cacao beans, as well as soil and agronomic factors involved. Paired soil and plant samples (pods and leaves) were collected at 560 locations. Information on agronomic practices was obtained through a prepared questionnaire for farmers. Total soil Cd averaged 0.44 mg kg which is typical for young and non-polluted soils. Mean Cd concentration in peeled beans was 0.90 mg kg and 45% of samples exceeded the 0.60 mg kg threshold. Bean Cd hotspots were identified in some areas in seven provinces. Multivariate regression analysis showed that bean Cd concentrations increased with increasing total soil Cd and with decreasing soil pH, oxalate-extractable manganese (Mn) and organic carbon (OC) (R = 0.65), suggesting that Cd solubility in soil mainly affects Cd uptake. Bean Cd concentration decreased a factor of 1.4 as the age of the orchard increased from 4 to 40 years. Bean Cd concentration was inconsistently affected by genotype (CCN-51 vs. Nacional), pruning or application of fertilizers. It is concluded that the relatively larger bean Cd concentrations in Ecuador are related to the high Cd uptake capacity of the plants combined with their cultivation on young soils, instead of Cd depleted weathered soils. Mitigation strategies should consider the application of amendments to modify such soil properties to lower soil Cd availability. There is scope for genetic mitigation strategy to reduce bean Cd, but this needs to be properly investigated.

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Phosphorus (P) bioavailability depends on its concentration and speciation in solution. Andisols and Oxisols have very low soil solution concentration of free orthophosphate, as they contain high concentrations of strongly P-sorbing minerals (Al/Fe oxyhydroxides, allophanes). Free orthophosphate is the form of P taken up by plants, but it is not the only P species present in the soil solution. Natural colloidal P (P associated with Al, Fe, and organic matter of sizes ranging from 1 to 1000 nm) constitutes an important fraction of soil solution P in these soils; however, its availability has not been considered. We measured the uptake of P by wheat (Triticum aestivum) from radiolabeled nonfiltered (colloid-containing) and 3-kDa filtered (nearly colloid-free) soil-water extracts from Andisols and Oxisols. In the Andisol extracts, P uptake was up to 5-fold higher from the nonfiltered solutions than the corresponding 3-kDa filtered solutions. In the Oxisol extract, no difference in P uptake between both solutions was observed. Also the diffusional flux of P as measured with the DGT technique was larger in the nonfiltered than in the 3-kDa filtered solutions. Our results suggest that colloidal P from Andisols is not chemically inert and contributes to plant uptake of P.

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Commercially available single origin chocolates (n=139) were analysed by ICP-MS to identify the potential of elemental fingerprinting for tracing cacao origin in chocolate and to compare chocolate composition relative to trace metal limits. Cadmium (Cd) concentrations exceeded the EU limit of 0.80 mg Cd kg -1 in 16 samples, all produced with cacao from South or Central America. Six samples contained lead (Pb) concentrations > 0.10 mg kg -1 , the limit of the Codex Alimentarius for edible fats. Increasing cacao content was associated with increased element concentrations for most elements, indicating cacao as the main source of minerals and trace elements. Significant differences in elemental composition between origins (P value ≤ 0.05) were found for Ba, Cd, Mo and Sr. Classification and regression tree analysis (CART) resulted in a decision tree that could effectively classify chocolate samples by cacao origin continent (overall misclassification rate 23%) based on the concentrations of five elements (Ba, Cd, Mo, Sr and Zn). Samples of South America were classified based on their Cd concentration, indicating the geogenic origin of Cd. 1.INTRODUCTIONChocolate is made from the seeds of the cacao tree (Theobroma cacao L.) through an extensive post-harvest process that includes fermentation, drying and roasting. Cacao is a perennial crop grown at low altitude in tropical climates (within 20° latitude from the equator). The plant originates from Central and South America where many cacao varieties can be found, and was exported to other suitable geographical areas such as Africa in the 19 th century (Beckett, 2008).Several health benefits have been attributed to moderate cacao consumption mainly due to its high polyphenol content, which has been related to cardiovascular health (Corti et al., 2009;Hooper et al., 2012;Lee et al., 2003). However, cacao-derived products may contain potentially toxic trace elements, such as cadmium (Cd), nickel (Ni) and lead (Pb).In 2014, the EU Commission approved Cd limits in chocolate that have been enforced since January 2019. These limits range from 0.10 mg Cd kg -1 dry weight in chocolates with < 30% cacao solids to 0.80 mg Cd kg -1 in cacao powder and chocolates with ≥ 50% cacao solids (European Commission, 2014). Recently, the Codex Alimentarius adopted similar limits for Cd in chocolate, ranging from 0.80 mg Cd kg -1 for chocolates that contain between 50% and 70% cacao solids to 0.90 mg Cd kg -1 for chocolates with ≥ 70% cacao solids (Codex Alimentarius Commission, 2018).The European Food Safety Authority reviewed the exposure of the European population to Ni in food. This study concluded that chronic dietary exposure to Ni is of concern for the general European population and proposed a tolerable daily intake level of 2.8 µg Ni kg -1 bodyweight (EFSA CONTAM Panel, 2015). In addition, the review highlighted that cacao based products are among the main food sources with high levels of Ni, e.g. some types of chocolate (average 3.8 mg Ni kg -1 ) and cacao beans and derived prod...