HOW LEAD AND CADMIUM GET INTO CHOCOLATE

In a three-article series, I collaborated with reporter Vonnai Phair to visualize how traces of lead and cadmium end up in consumer chocolate products. Most cadmium exposure is from soil, whereas lead exposure often happens during the process of drying the beans (likely from dust containing traces of lead from leaded gasoline and paints).

View the original story published by The Seattle Times on Feb. 10, 2023.

I also created visualizations of contamination data compared to regulation thresholds, and a comparison of chocolate bars to see which brands might be a safer choice.

Background

To fact-check this story, I reached out to environmental toxicology professor Russ Flegal at the UC Santa Cruz, who has an extensive background studying lead contamination. He reminded us that no amount of lead is safe, and tends to accumulate in the human body over time.

This was not just a toxicology story but also an environmental justice story. While cadmium comes from soils, lead contamination is mostly human-caused and preventable. In poorer countries where workers are paid less than a liveable wage and beans are left drying on tarps along roadsides, the sticky beans attract dust historically contaminated from lead gasoline and lead paints. Then, the lead comes in contact with the nibs during processing. I’m interested in doing follow-up stories on working conditions, and if fair trade practices might lead to better quality, cleaner chocolate.