Results

1. Abstract Recently a heavy emphasis has been put on diminishing the amount of arsenic (As) present in food and water products in developing countries. Chocolate bars have been identified as source of arsenic that may pose a threat to the average consumer in recent studies, and this fact calls for a more thorough examination. Using previously dry-ashed samples of single-source origin chocolate bars coupled with analysis of bars from different manufacturers of the same region by means of ICP-MS, high levels of arsenic were identified and scrutinized. Arsenic was found at an average concentration of 429 ng/g (ppb), though results varied greatly amongst various regions and producers. Although some outliers had levels of arsenic bordering the PTWI, bioavailability in the bloodstream and the human body’s own metabolic processes most likely limits the amount of toxic arsenic present post-consumption. No correlation was found between arsenic uptake from soil and other dangerous heavy metals discovered in the shells of cacao pods, though raw cacao nibs and powder had highly elevated heavy metal levels in comparison to the finished chocolate product. Without direct knowledge of the mineral composition of the soil local to the Theobroma cacao trees, it is difficult to attribute the presence of these toxic chemicals to anything other than external environmental contaminants with close proximity to the site of cacao growth. Terminology: PTWI: Provisional Tolerable Weekly Intake ICP-MS: Inductively Coupled Plasma – Mass Spectroscopy Materials and Methods • Take previously ashed samples of single-source origin chocolate and dry-ash a new variety from similar countries that experience environmental turmoil. • Dry-ash the chocolate samples at 450o C and use Activation Labs ICP-MS to detect levels of arsenic in products by means of a laser ablation system.3 Discussion • Discussion • Arsenic levels were low enough in the majority of chocolate products to cause no significant toxic effects unless consumed in absurdly large quantities. • The amounts identified in the chocolate products in this study were much smaller, on average, than previous literature amounts indicated, though outliers produced comparable values. This can be mainly attributed to those studies taking samples from regions with previously identified areas of contamination. • The increase in arsenic concentration in direct response to an increase in cacao content points towards the contamination being a results of the cacao beans taking up arsenic from the soil either in the drying and fermenting process, or during the growth of the pods on Theobroma cacao trees.4 Introduction • Danger of High Levels of Arsenic: • Though present in trace quantities throughout most of the earth, ingestion of large amounts can over time lead chronic arsenic poisoning, which may induce negative health effects such as gastrointestinal symptoms, disturbances of cardiovascular and nervous system functions, and even death.1 • Metabolizing Arsenic: • While the PTWI of arsenic is 15 µg/kg, only bioavailable arsenic has a significant impact on toxic effects to the human body. Even amongst bioavailable arsenic, arsenic is much more potent in its inorganic form and organic arsenic is dangerous when demethylated.2 • Arsenic in Chocolate: • It is difficult to determine if arsenic present in chocolate comes from the bean itself, so chocolate using beans from a single location made by artisan specialists is useful to find a source of the contamination. Results Acknowledgements For all his help and support, I would like to graciously thank Dr. Donald McFarlane as well as for proposing this project as a senior thesis topic. Together with Dr. Andrew Zanella, they assisted me through all the experimental processes and aided in data interpretation and presentation. I am humbled by their expertise and professionalism in handling this project and showing me the ins and outs of the numerous procedures. I offer my sincerest thank you for all the time and effort put into this. I would also like to thank Matt Stjernholm for his data assistance and chocolate-buying guidelines which instructed me along the way. References Goals 1 ATSDR. 1993b. Toxicological Profile for Arsenic. U.S. Public Health Service. Agency for Toxic Substances and Disease Registry. Atlanta, GA. 2 Arsenic Exposure and Health Effects III, Proceedings of the Third International Conference on Arsenic Exposure and Health Effects, July 12–15, 1998, San Diego, California, 1999, Pages 267-279 [Accessed Oct 25, 2010] 3Activation Laboratories Ltd., http://www.actlabs.com, 1-888-228-5227, Ontario, Canada. 4 Lee, C.K., Low, K.S. and HOH, R. (1985) Determination of Cadmium, Lead, Copper and Arsenic in Raw Cocoa, Semifinished and Finished Chocolate Products. Pertanika 8(2) 1985, 243 - 248). 5,6,7,8,9 Image obtained from: http://www.grenadacocoa.com/ 10 Image obtained from: Hernandez-Zavala, A., Drobna, Z., Styblo, M. and Thomas, D. J. 2009. Analysis of Arsenical Metabolites in Biological Samples. Current Protocols in Toxicology. 42:4.33.1–4.33.17. • Use ICP-MS to determine arsenic levels in single-source origin chocolate bars from varying locations and amongst comparable manufacturers and address similarities and differences between these values and those of previous studies. • Analyze the data to decide if country of origin has a significant impact on arsenic contamination and if that can be traced to arsenic uptake from the soil. Arsenic Levels in Single-Source Origin Cacao Products Jeff Astor Claremont McKenna College, Joint Science Department Figure 1 Arsenic levels in single-source origin chocolate bars from varying regions and cacao content (D.R. = Dominican Republic). Results indicate a high variability associated with high standard deviation. Figure 2 Direct relationship between a rise in cacao percentage in chocolate and a rise in arsenic levels, indicating that the arsenic uptake comes from the cacao portion of the product. . Figure 3 As a control for arsenic uptake, other prominent heavy metal uptake is assessed in terms of the company that produces the chocolate, and where it originates from. No significant results are found based on manufacturer, pointing to soil as the main contaminant of chocolate products Image 6 Breakdown of arsenic methylation in mammals from pentavalent to trivalent form as well as conversion from inorganic to organic species of arsenic.10 Image 1 Cacao trees in full blossom5 Image 2 The pulp and beans composing the inside of a cacao pod6 Image 3 Storage facility for pre-processed cacao beans in preparation for shipment7 Image 5 Cacao farmer striding through a field of cacao beans at a local plantation in Grenada9 Image 4 Collective farmers of Grenada Cacao Association sifting through cacao beans8