How do lead and cadmium get into chocolate products?

This infographic explains how lead and cadmium get into chocolate products in different ways. Most lead contamination happens where beans are exposed to soil and dust historically polluted with lead gasoline and paint. Cadmium occurs naturally in soils especially in South America, but can also be from industrial sources. Published in The Seattle Times: https://www.seattletimes.com/seattle-news/health/how-heavy-metals-get-into-dark-chocolate-bars/