Dark chocolate: Does it contain cadmium or lead?

But there’s a darker side to dark chocolate. Overseas testing has found that some brands contain unsafe levels of the heavy metals cadmium and lead. We’re regularly contacted by consumers asking us whether there’s any problem with dark chocolate sold in New Zealand.

The good news is we tested eight dark chocolate bars and found none had levels high enough to be worried about.

The issue

In 2022, the United States’ consumer advocacy organisation Consumer Reports tested 28 dark chocolate bars and detected cadmium and lead in all samples. It found 23 of the 28 bars contained amounts of at least one heavy metal that would be harmful for an adult eating 1oz a day (about 28g or just over half a small chocolate bar). Five of the bars had high levels of both cadmium and lead.

Another study published in 2024 in the international journal Frontiers in Nutrition also raised red flags about heavy metals in dark chocolate and cocoa products in the US. From 2014 to 2022, researchers tested 72 products and found that 43% of samples exceeded the maximum allowable dose level for lead and 35% exceeded it for cadmium. The report concluded that, while consuming a single serving of these products may not pose a significant health risk, eating multiple servings, together with other foods containing heavy metals, could lead to higher than safe levels.

Heavy metals, such as lead and cadmium, occur naturally in the environment. But it’s the level of heavy metals that can be a safety concern.

Frequent exposure to even small amounts of heavy metals, particularly lead, can be dangerous. It’s difficult for the body to excrete them and, over time, exposure to heavy metals can lead to build-up of toxic levels in the body and harm health.

In children, lead can affect brain development and increase the risk of behavioural problems and lower IQ. In adults, it can contribute to health issues such as central nervous system problems, hypertension, kidney damage and immune system dysfunction. The World Health Organization has stated there is currently no known safe dose of lead.

What we found

We tested eight dark chocolate blocks for levels of cadmium and lead – the heavy metals of most concern in overseas testing.

All the products had detectable levels of cadmium and lead, which isn’t unexpected. These metals are commonly found in soils around the world so are often found in trace amounts in a wide range of foods.

In chocolate, the lead and cadmium are concentrated in the cocoa (or cacao), the ingredient that gives chocolate its distinctive flavour. Dark chocolate has higher levels of cocoa than milk chocolate and therefore contains higher levels of lead and cadmium.

The Australia New Zealand Food Standards Code sets a maximum level for cadmium of 0.5mg/kg of chocolate and cocoa products. It does not specify a maximum level for lead in chocolate. However, the European Union has a maximum level of 0.1mg/kg. All the products we tested were below these levels.

We sent our results to New Zealand Food Safety (NZFS) at the Ministry for Primary Industries and consultant toxicologist John Reeve and asked whether the levels we found posed a health concern to New Zealanders.

Deputy director-general of NZFS Vincent Arbuckle said the agency is aware of the international studies and associated media but reassures people chocolate sold here is safe to eat. He said Consumer NZ’s results confirm this.

“The cadmium levels found in Consumer NZ’s tests are well below the maximum limits set by the Food Standards Code and other international food standards, so we consider there to be no health concern. Similarly, there’s no concern with the lead levels found, which are all low and within the typical range we’d expect for these types of products.”

Reeve told us plant-based foods, like cocoa, generally have measurable levels of substances such as lead and cadmium. He agrees that there is no safety concern with the Consumer NZ test results and notes the results comply with maximum levels set in credible overseas jurisdictions and are lower than the US results for dark chocolate.

“The potential exposure to consumers of heavy metals from cocoa-containing products, assuming a normal dietary intake, is very low,” he said.

About our test

We tested one sample of eight products in an accredited laboratory for the presence of cadmium and lead. None of the products had levels that were a safety concern.

The products we tested

• Cadbury Old Gold Dark Chocolate 70% Cocoa
• Guylian Tablets Intense Dark 84% Cocoa
• Lindt Excellence Dark 70% Cocoa
• Lindt Excellence Extra Dark 85% Cocoa
• Wellington Chocolate Factory Pacific Dark Chocolate 70% Cocoa
• Well Naturally No Sugar Added Dark Chocolate 70% Cocoa
• Whittaker’s Cocoa Lovers Collection Ghana Extra Dark Chocolate 86% Cocoa
• Whittaker's Dark Ghana 72% Cocoa

Who monitors our food supply?

NZFS conducts the New Zealand Total Diet Study about every five years. The survey tests a range of foods consumed in a typical diet. It is used to assess our exposure to chemicals, environmental contaminants and nutrients and identify food safety risks.

The most recent survey in 2016 tested more than 4,300 food samples for 301 agricultural chemicals (insecticides, fungicides and herbicides), six contaminant elements (aluminium, arsenic, cadmium, lead, mercury and tin) and four nutrients (iodine, selenium, sodium and zinc). Food samples are taken from several regions and prepared as they would be eaten. For example, bananas are peeled, and meat is cooked.

The survey then estimates the intake of these chemicals based on what people eat for 10 different age and gender groups. This information is used to identify if certain chemicals or nutrients are a concern in the New Zealand diet.

Arbuckle said the 2016 survey shows a continued decline in dietary lead, corresponding with World Health Organization research, and that cadmium has not significantly increased across the total diet.

The latest survey is currently underway, with a focus on infant and toddler diets. It is testing milk chocolate, rather than dark, for both lead and cadmium.

Arbuckle said the milk chocolate results can be used to estimate what levels could be in dark chocolate.

A full dietary exposure assessment will be carried out at the end of the survey. Final results are expected to be published in mid-2026.