Are Heavy Metals in Your Dark Chocolate Cause for Concern?

A Consumer Reports investigation found trace amounts of lead and cadmium in dark chocolate sold by brands like Hershey and Trader Joe's—but here's why experts say not to worry.

Squares of dark chocolate

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Pregnancy and parenting are two of the most beautiful experiences in life, but let's face it—they're some of the most challenging and stressful, too. Sometimes, you just want to put your feet up and enjoy a little luxury to take the edge off, and for many of us, that means biting into a lovely piece of dark chocolate. So when news broke that a study was raising the alarm that some popular brands of chocolate contain heavy metals, it didn't take long for social media to do its thing and panic. 

Should you swear off dark chocolate in light of news that it might contain trace heavy metals? Probably not. “I would advise expectant [parents] to follow the advice they do for other potential contaminant exposure (like high mercury-containing fish, for instance), which is to limit the total amount consumed each week to a serving or two, choose a dark chocolate product that has lower levels of lead/cadmium, and eat a varied diet to mitigate overall exposure to undesirable metals,” says Jill Castle, M.S., RDN, the pediatric dietitian behind the popular The Nourished Child website and podcast. 

Here's what you need to know about that study that shows heavy metals in different chocolate brands, including which brands were tested and what to do if you think you've been exposed to heavy metals.

What The Chocolate Study Says

Consumer Reports, a trusted nonprofit watchdog group that conducts independent product testing to educate the public on product safety, put 28 bars of dark chocolate to the test to see how much lead and cadmium they contained. Of the 28 bars, 23 had enough trace heavy metals that eating an ounce a day would exceed what public health authorities say is safe for one of the two metals. Five of the 28 bars had high levels of both lead and cadmium. 

The nonprofit measured the metals using California's standards for lead and cadmium. This standard is called the maximum allowable dose level (MADL), which is 0.5 micrograms (mcg) for lead and 4.1 mcg for cadmium. They state that since there are no federal legal safety limits for food production, California's regulations stand out as the most protective, so they used those. 

Jill Castle, pediatric dietitian

There are many proven benefits of dark chocolate on health, so the potential harm from the presence of lead and/or cadmium needs to be weighed against these benefits. Moderation is probably the best advice for dark chocolate lovers.

— Jill Castle, pediatric dietitian

What are Lead and Cadmium?

Lead and cadmium are heavy metals that are naturally found in many foods. Lead is found in peas, beans, sweet potatoes, chocolate, and even cannabis. And cadmium is commonly found in shellfish, mushrooms, grains, and root crops. You can safely eat these foods without worry of harm. Eating these foods may pick up some traces of these toxic heavy metals, but they are not likely enough to cause harm.

Scientists know relatively little about cadmium exposure from food sources, but a foundational study that sought to understand where our cadmium exposure comes from and how it affects people based on age and ethnicity is shedding some light on the matter. For example, the highest sources of cadmium exposure come from pasta and grains, followed by leafy greens and potatoes. But even if you eat these foods every single day, you won't get enough cadmium to harm you, according to the data published in the study. 

Lead, on the other hand, is well-studied, and we know that even the tiniest exposure can be dangerous, particularly for pregnant people and children. 

According to the Centers for Disease Control and Prevention (CDC), lead can harm a still-developing nervous system and lead to neurological problems, learning delays, difficulty learning, and negative behavior issues. These health issues can be both debilitating and permanent, so it is important to be aware of lead exposure. 

In 2021, the CDC updated the lead level in the blood, which is considered lead poisoning. This level is called the Blood Level Reference Value (BLRV) and was lowered from 5 µg/dL to 3.5 µg/dL. 

The CDC states that no level of lead is considered safe for children. That said, we are all exposed to trace amounts of lead from the food supply every day. The Food and Drug Administration (FDA) says that it would be impossible to remove lead entirely from our food supply; however, we can lower our exposure through good policy changes, which has been happening. For example, the FDA says that the average daily lead exposure in 1980 was 43 mcg, and in 2016, that number dropped to 1 mcg, which is a 97% decrease.

Which Chocolate Brands Are Affected?

So, which brands of chocolate did the Consumer Reports scientists test, and what were those test results? They broke up their findings into categories based on how the 28 brands measured up. Chocolate was either "above" or "below" the California standard MADL. The percentages listed next to each chocolate do not indicate if that chocolate is above the limit of what's safe, but rather a percentage of MADL per ounce. 

"To determine the risk posed by the chocolates in CR’s test, we used California's maximum allowable dose level (MADL) for lead (0.5 micrograms) and cadmium (4.1mcg)," says Consumer Reports. "Shown are the percentages of the MADL supplied in an ounce of each chocolate."

Here is what the report said:

Safest chocolate

The following chocolate brands tested "below" the MADL for both lead and cadmium.

  • Mast Organic Dark Chocolate 80% cocoa, 14% lead, 40% cadmium
  • Taza Chocolate Organic Deliciously Dark Chocolate, 70% Cacao, 33% lead, 74% cadmium
  • Ghiradelli Intense Dark Chocolate 86% Dark Chocolate, 36% lead, 39% cadmium
  • Ghiradelli Intense Dark Chocolate Twilight Delight 72% Cocoa, 61% lead, 96% cadmium
  • Valrhona Abinao Dark Chocolate 85% Cacao, 63% lead, 73% cadmium

High in cadmium

The following chocolate tested high for cadmium:

  • Beyond Good Organic Pure Dark Chocolate 70% Cocoa, 42% lead, 112% cadmium
  • Beyond Good Organic Pure Dark Chocolate 80% Cocoa, 42% lead, 138% cadmium
  • Equal Exchange Organic Extra Dark Chocolate 80% Cocoa, 45% lead, 120% cadmium
  • Lindt Excellence Dark Chocolate 70% Cocoa, 48% lead, 116% cadmium
  • Scharffen Berger Extra Dark Chocolate 82% Cocoa, 49% lead, 136% cadmium
  • Alter Eco Organic Dark Chocolate Classic Blackout 85% Cocoa, 49% lead, 204% cadmium
  • Pascha Organic Very Dark Chocolate 85% Cocoa, 68% lead, 253% cadmium
  • Dove Promises Deeper Dark Chocolate 70% Cocoa, 49% lead, 112% cadmium

High in lead

The following chocolate tested high for lead:

  • Tony's Chocolonely Dark Chocolate 70% Cocoa, 134% lead, 28% cadmium
  • Lily's Extra Dark Chocolate 70% Cocoa, 144% lead, 42% cadmium
  • Godiva Signature Dark Chocolate 72% Cocoa, 146% lead, 25% cadmium
  • Chocolove Strong Dark Chocolate 70% Cocoa, 152% lead, 60% cadmium
  • Lindt Excellence Dark Chocolate 85% Cocoa, 166% lead, 80% cadmium
  • Endangered Species Bold + Silky Dark Chocolate 72% Cocoa, 181% lead, 31% cadmium
  • Trader Joe's Dark Chocolate 72% Cocoa, 192% lead, 36% cadmium
  • Hu Organic Simple Dark Chocolate 70% Cocoa, 210% lead, 56% cadmium
  • Chocolove Extreme Dark Chocolate 88% Cocoa, 240% lead, 83% cadmium
  • Hershey Special Dark Mildly Sweet Chocolate, 265% lead, 30% cadmium

High in both lead and cadmium

The following chocolate tested high for both lead and cadmium:

  • Theo Organic Pure Dark 70% Cocoa, 120% lead, 142% cadmium
  • Trader Joe's The Dark Chocolate Lover's Chocolate 85% Cocoa, 127% lead, 181% cadmium
  • Theo Organic Extra Dark Pur Dark Chocolate 85% Cocoa, 140% lead, 180% cadmium
  • Lily's Extremely Dark Chocolate 85% Cocoa, 143% lead, 101% cadmium
  • Green & Black's Organic Dark Chocolate 70% Cocoa, 143% lead, 181% cadmium

Should You Throw Away Your Chocolate?

Probably not. You can safely eat dark chocolate from the brands mentioned that contain "below" MADL for both lead and cadmium. And if the number feels ick, you can always switch up to a bar of milk chocolate or a different treat altogether. 

“There are many proven benefits of dark chocolate on health, so the potential harm from the presence of lead and/or cadmium needs to be weighed against these benefits,” says Castle. “Moderation is probably the best advice for dark chocolate lovers. A varied diet with plenty of fiber and nutrients will also offer some protection.”

Remember, the Consumer Reports study numbers reflect the percentage of heavy metals found in one ounce of chocolate. You probably eat chocolate only a few times a week, and when you do, you are probably not eating an entire bar of chocolate. 

That said if you are pregnant or are caring for children under the age of 6, avoiding some of the chocolates listed with high amounts of lead or cadmium might not be a bad idea. 

What to Do If You're Exposed to Heavy Metals

Call your doctor to schedule lead and cadmium poisoning tests. Your doctor will take blood and urine samples to determine if you have lead or cadmium in your system and how much. 

Kids who test above the CDC's BLRV limit of 3.5 µg/dL are considered to have lead poisoning and will likely undergo treatment that includes iron and calcium supplements. Lead takes a long time to work its way out of your system, making lead poisoning particularly harmful. Note that lead poisoning has other causes besides food, such as lead paint used in older homes.

You can learn more about kids and lead poisoning at the CDC or talk to your child's pediatrician.

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