Some dark chocolates have high levels of the toxic chemcials Cadmium and Lead, a major investigation has found.

A California-based NGO called As You Sow started looking into the dangerously high levels of these two chemicals in chocolate in 2014. After some tests showed that many chocolates had high concentrations, the NGO informed the companies. In California a law was passed in 1986 saying that food products must carry warning labels if there are toxic chemicals.

Fortunately, the companies decided against going to court and agreed to an investigation. Four experts were asked to analyse the entire food chain to determine at what point Cadmium and Lead were entering the manufacturing process to end up in chocolate. They issued a 371-page report, ‘Expert Investigation Related to Cocoa and Chocolate Products’ which has been distilled by Consumer Reports.

Cadmium is a known carcinogen or cancer-causing element, which can also cause trouble for your kidneys. Lead exposure may cause anemia, weakness, and kidney and brain damage. Pregnant women can expose their unborn child and Lead can damage a baby’s nervous system.

Cadmium is found in the soil where cocoa beans grow. The soils in Latin America and Caribbean regions have the highest levels. West African cocoa beans have less. The cadmium enters soil in areas where there have been factories and industrial activity.

The only way to reduce levels of Cadmium in chocolate is to blend high Cadmium carrying cocoa beans with ones which have lower levels. This is how the level can be kept under the product warning triggers.

Chocolate makers use “fine flavor” and “bulk or common” cocoa beans. The fine flavor ones go into luxury chocolates and while these beans are just 15% of world exports, they mostly come from the Latin American and Caribbean areas.

Lead and Cadmium do not enter chocolate at the processing and manufacturing stages. Makers of chocolate avoid these chemicals entering at these stages by processing water, production equipment, packaging, and environmental dust. The non-cocoa bean ingredients are also not to blame.

The experts found that Cadmium was found in the cocoa beans pre-harvest. The significant source of Cadmium is chocolate liquor that is produced from the deshelled portion of a cocoa bean (milled cocoa nibs). It is the same with Lead. The nib obtains approximately 70% of its Lead concentration because of contact with materials that contain the toxic chemical (i.e., shell, soil, light and fine material) during bean breaking.

Unlike with Cadmium, Lead enters the chocolate at the post-harvest stage because of how wet cocoa beans are handled. They are kept on the ground or on surfaces that are open air (roadsides, concrete patio, drying tables, plastic tarps, plastic bags, containers).

The California NGO sent notices to 20 companies, including Trader Joe’s, Hershey’s, Mondelēz, Lindt, Whole Foods, Kroger, Godiva, See’s Candies, Mars, Theo Chocolate, Equal Exchange, Ghirardelli, and Chocolove for failing to warn consumers that their chocolate products contained cadmium or lead, or both.

“For 23 of the bars, eating just an ounce a day would put an adult over a level that public health authorities … say may be harmful,” Consumer Reports said.

The majority of brands are not available in Pakistan. The ones that are include: Lindt and Hershey’s and Green and Black’s. Milk chocolates have less cacao than dark chocolate and may have less of the toxic chemicals. People prefer dark chocolate because it has less sugar and has flavanols, which are antioxidants linked to blood vessel function, reduced inflammation, and lower cholesterol.