Lead and Cadmium in Dark Chocolate: How Worried Should You Be?

In December 2022, Consumer Reports published a test of 28 dark chocolate bars and briefly ruined dessert for a lot of people. Lead and cadmium in all 28. For 23 of them, eating one ounce a day would push an adult past a level CR's experts consider potentially harmful for at least one of those metals. Five bars crossed the line on both.

The numbers are real, the lab work was real, and the headline was, in the strictest sense, accurate. It was also missing the piece that decides whether any of this matters to you: what that line represents.

The line they measured against is extraordinarily conservative

There's no federal limit for lead or cadmium in most foods, so Consumer Reports used California's Proposition 65 maximum allowable dose levels, which it described as the most protective standard available. Those are 0.5 micrograms a day for lead and 4.1 micrograms a day for cadmium.

Here's what a MADL is. For chemicals listed as reproductive toxicants, California takes the highest exposure at which no effect was observed and divides it by 1,000. The safety margin is baked in on purpose, and the resulting number is a warning-label trigger, not a health threshold. For scale, the FDA's interim reference level for lead is 2.2 micrograms a day for children and 8.8 for women of childbearing age. California's chocolate-relevant lead figure is a small fraction of that.

So "exceeds the MADL" means "would legally require a warning sticker in California." It does not mean "this dose has been shown to hurt people." Consumer Reports chose the strictest available benchmark, which is a defensible editorial decision. The headlines that followed mostly forgot to mention it was a choice.

The industry pushback was self-interested and partly correct

The National Confectioners Association, which represents the big chocolate makers, responded that the products tested comply with quality and safety requirements and that the levels Consumer Reports found sit well under the limits set by the trade group's own 2018 settlement with the advocacy group As You Sow.

Take that for what it is: a trade association defending its members with a standard its members negotiated. But the underlying complaint, that a Prop 65 warning level was being reported as a health finding, is the same objection independent toxicologists raised. A Johns Hopkins toxicologist quoted at the time made the point that MADLs are set to be very conservative by design.

Both things can be true. The chocolate industry has a genuine cadmium problem it's been slow to fix, and the coverage of that problem overstated the risk to any individual eater.

Then Tulane ran the numbers

In 2024, a Tulane University team led by Tewodros Godebo published an analysis in Food Research International of 155 dark and milk chocolates sold in the US, testing for 16 metals including lead, cadmium, and the essential ones like copper, iron, and zinc.

They modeled the risk of eating an ounce a day, which is more than two full bars a week. The finding: no adverse health risk for adults. Only one dark chocolate exceeded the international cadmium limit for bars above 50% cacao, and four of the 155 carried enough cadmium to be a concern for a child weighing 33 pounds or less. As Godebo put it, it's not common to see a three-year-old regularly eating more than two chocolate bars a week.

That's the dose-context answer to the 2022 headline, and it came from a university lab with no chocolate to sell.

Why the metals are in there at all

The two contaminants arrive by completely different routes, which is why no single fix handles both.

Cadmium comes up from the ground. Cacao trees pull it out of soil through their roots, so the amount in a bean tracks the soil it grew in. Latin American cacao soils are geologically younger and run higher in cadmium, and the difference in the beans is large: research pooling data across the cacao belt found South and Central American averages several times higher than West African ones. Farmers can't wash it off, because it was never on the outside.

Lead is a surface problem. It shows up after harvest, settling onto beans during outdoor drying, storage, and transport, largely from contaminated dust. That's the more fixable one, and it's why lead levels in US chocolate have drifted down as handling improved.

The other rule is arithmetic. Both metals live in the cacao solids, so the higher the cacao percentage, the more of both you get. A 90% bar is a bigger dose than a 55% bar of the same weight, and cocoa powder concentrates it further. Dark chocolate's health halo and its metal load come from exactly the same ingredient.

Who actually needs to be careful

Adults eating chocolate the way most adults eat chocolate, a square or two, a few times a week, are not the group these findings are about.

Young children are, because lead exposure in kids has no established safe level and small bodies get bigger doses per pound. Pregnancy is the other case, because cadmium and lead both cross into the tissue you're least willing to gamble on. Neither of those is a reason to ban chocolate in the house. Both are reasons to keep dark chocolate an occasional thing rather than a daily one, and to skip the very high cacao percentages for kids.

Ironically, milk chocolate is lower in metals, purely because it's mostly not cacao. It's also mostly sugar. It's not a health food, it's a lower-metal candy, and it's fine to treat it that way.

What we'd actually change

Rotate brands and origins. Since cadmium is a soil story, buying from a single producer with a single sourcing region every week for years is the one pattern worth breaking up. Alternating between a West African sourced bar and your favorite Latin American one is a real hedge and costs nothing.

If you want the tested names: Consumer Reports flagged five bars that stayed under both thresholds at an ounce a day, including Ghirardelli Intense Dark at 72% and 86%, Taza Chocolate Deliciously Dark 70%, Mast 80%, and Valrhona Abinao 85%. Worth knowing, with a caveat that matters: those were single bars tested at a single point in time, not a standing certification. Harvest lots vary, and none of these companies publishes ongoing per-batch metal testing.

And if you eat cocoa powder daily in smoothies or baking, that's the habit to look at before the bar. It's the most concentrated form of cacao in most kitchens.