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Lead in Dark Chocolate

While dark chocolate has more lead than other foods, it isn't something you should worry about.

Posted: Jan 7th, 2022

Consumer Reports published a story about the lead content in some brands of dark chocolate.1 For example, Consumer Reports’ testing found that an single ounce of Hershey’s dark chocolate has 2.65 times California’s maximum allowable dose level (MADL) for lead.

Oh my goodness! I love eating chocolate. I must be at risk for lead poisoning!

But wait a sec, are those levels actually dangerous? California is notorious for poorly designed chemical safety regulation.

Short answer: It’s just California being California. Dark chocolate is safe to eat, thank goodness.

For very small children, occasional chocolate consumption is completely safe. A diet consisting of literally nothing but dark chocolate would potentially push the child’s lead intake above the limits set by the FDA. But you probably don’t need me to tell you not to give your kid a diet of literally 100% candy. The risk of lead exposure doesn’t even make the top ten list of reasons that’s a terrible idea.

And if you’re an adult, the detected lead concentrations are so low that it isn’t even worth thinking about. You could eat literally nothing but dark chocolate and the lead intake still wouldn’t be a concern.

Read on for details.

Lead Limits in Chocolate

To start off with, what levels of lead in chocolate should be concerning?

Consumer Reports says they chose to use California’s MADL because

there are no federal limits for the amount of lead and cadmium most foods can contain, and CR’s scientists believe that California’s levels are the most protective available.

But this is about as close as you can get to lying without actually saying something technically untrue. While there may not be federal limits for the amount of lead “most foods” can contain, the FDA does have guidelines for the maximum amount of lead in candy specifically, and the guidelines go into detail about chocolate in particular.

The FDA’s recommended maximum lead level in candy, including chocolate, is 0.1 parts per million (ppm).

Does Dark Chocolate Stay Below This Limit?

The FDA’s article, (which is from 2006) mentions that

The chocolate industry data indicate that the mean lead level in 226 dark chocolate samples (consisting of 9 products) was 0.048 ppm, the standard deviation was 0.029 ppm, and the maximum lead level found was 0.275 ppm. Several dark chocolate samples had lead levels exceeding 0.1 ppm, and more dark chocolate than milk chocolate samples had lead levels approaching 0.1 ppm.

For comparison, the most lead-contaminated dark chocolate brand in Consumer Report’s article was Hershey’s Special Dark Mildly Sweet Chocolate, with a lead concentration of .047 ppm,2. This is less than half the limit set by the FDA, and slightly less than the 0.048 ppm average cited by the FDA.

So Consumer Report did not find unusually high levels of lead in chocolate. There hasn’t been any sort of catastrophic contamination event. The levels of lead measured by CR are pretty much exactly what the relevant regulatory authorities expect to find, and well below the limits these authorities consider to be dangerous.

But What if I Eat a LOT of Chocolate?

Let’s consider a worst case scenario for dark-chocolate based lead exposure. If you eat nothing but the worst brand of dark chocolate, would you be consuming a dangerously high amount of lead?

The brand with the highest lead content in Consumer Report’s article was Hershey’s Special Dark Mildly Sweet Chocolate.

Looking at the nutrition label on Amazon’s storepage, one serving of this chocolate weighs 1.45 oz and contains 200 Calories.

10 servings is 2000 Calories, making it a full day’s worth of food for the ‘typical’ person. That’s 14.5 oz of chocolate.

According to Consumer Reports, this brand has 1.325 micrograms of lead per ounce. So 10 servings would result in your ingesting 19.2 micrograms of lead.

Is that a dangerous amount of lead? Probably not if you’re an adult. The FDA’s provisional total tolerable intake level (PTTIL) for a non-pregnant adult is 75μg/day, well above the 20μg/day you’d get from a nothing-but-dark chocolate diet. The FDA calculates this limit like so: The lowest blood concentration of lead observed to have any measurable health impacts is 30μg lead per deciliter blood. It is estimated that this blood concentration would result from the consumption of 750μg/day of lead, which is divided by 10 to give a safety margin.3

A nothing-but-dark-chocolate diet is probably a terrible idea for a toddler, however. For small children the PTTIL is only 6μg/day, both because their health is affected by lead in the blood at lower concentrations, and because the same amount of lead consumed translates to a higher blood concentration (baby is small). Even 600 kcal of dark chocolate is enough to push them above that limit, and little kids typically eat above 1000 kcal. There are about a million other reasons that it’s a bad idea to feed your kid only candy, but hey, there’s another one.

For pregnant women, the PTTIL is 25μg/day. (Baby is sensitive but momma is large.) The nothing-but-dark-chocolate diet could push the limits of that limit. But again, that diet would be a bad idea even if chocolate was completely free of impurities.

So what’s the important takeaway from all these numbers?

Simple: Make sure your kids eat their vegetables, and don’t eat literal kilograms of cocoa powder each day if you are pregnant.

Otherwise, forget about it.

Some other bits of info

Actual sources of lead

So if even the worst brand of dark chocolate doesn’t contain high enough levels of lead to cause significant concern, are there any foods that do?

Probably not. Or at least, it isn’t the food itself that causes the problem.

But there are other ways for a person to consume dangerously high amounts of lead. I’m sure you’ve heard of the problems with lead pipes and leaded gasoline, but did you know we used to use lead solder in food cans until the 90s?

From this 1993 issue of the Federal Register:

The dietary lead intake from eating canned foods only packaged in lead-soldered cans would be 50 μg/day for 2-year-old children and 75 μg/day for women 25 to 30 years old.

50 micrograms! Remember that 6 is the limit, and 10 or so is what they’d get from eating nothing but the worst, most contaminated brand of dark chocolate every day. Fifty! From old cans!

Where Did the Limits in the Consumer Report Article Come From?

If you’re wondering where the California Maximum Allowable Dose Level limit comes from: They find the maximum daily exposure level which is known not to cause any reproductive health problems specifically, and then divide it by 1000.4 So the number is basically completely meaningless.

  1. The article also talks about high levels of cadmium. I have not read the research about cadmium exposure. This post focuses only on lead. My gut instinct is that CR has exagerated the cadmium concerns in exactly the same way they exagerated the lead concerns. But please let me know if the mentioned levels of Cadmium actually are dangerously high. 

  2. CR states that one ounce of this chocolate has 265% of California’s MADL (0.5 micrograms). This means that there are 1.325 micrograms of lead per ounce of chocolate. Doing the unit conversion, this works out to 0.047 ppm. 

  3. The FDA’s PTTILs for lead come from this paper: Carrington, C. D., & Bolger, P. M. (1992). An assessment of the hazards of lead in food. Regulatory toxicology and pharmacology, 16(3), 265-272. 

  4. The primary source for this definition seems to be this this bit of California legal code, but it’s written obtusely enough that I’m partially relying on secondary sources like this one for my interpretation. That paper, for example, cites that legal code and describes MADL as “the exposure level at which a chemical would have no observable reproductive effect, even if a person were exposed to 1000 times that level”. 

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