Our commentary
This is a case where a viral health panic tracked real laboratory testing — and where the honest reading is more complicated than either "your chocolate is poisoned" or "nothing to see here."
What was actually found
Consumer Reports tested 28 dark chocolate bars and detected lead and cadmium in all of them. For 23 of the 28, eating one ounce a day would put an adult over CR's level of concern for at least one metal. Five exceeded for both.
Notably, five bars came in relatively low for both metals — which is the finding CR's own researcher emphasised, and the most actionable part of the story. Contamination at these levels is not an inherent property of dark chocolate.
The threshold is where it gets interesting
CR measured against California's Proposition 65 Maximum Allowable Dose Levels: 0.5 µg/day for lead, 4.1 µg/day for cadmium. CR was explicit about why — there are no federal limits for lead and cadmium in most foods, so a state warning-label standard is the only available yardstick.
But a MADL is a warning-label trigger, not a safety limit, and it is deliberately set at one one-thousandth of the level producing no observable effect. Exceeding it is not a finding that harm occurs.
The lead figure has a stranger history still. As documented in a California Court of Appeal opinion, the 0.5 µg/day lead MADL was derived by taking an occupational airborne exposure limit, multiplying by the air a worker breathes in a shift, and dividing by 1,000 — then applying the result as an oral daily dose. It was adopted in 1989. Whatever else it is, it is not a dietary no-effect threshold.
What later work found
A 2024 peer-reviewed analysis of 72 dark chocolate and cocoa products found 43% exceeded the Prop 65 lead MADL and 35% the cadmium MADL — but 97.2% fell below the FDA's Interim Reference Level for lead, and median concentrations sat below even the MADLs, indicating the totals are driven by outlier products. The authors described the MADLs as "conservative" and concluded contamination "may not pose any appreciable risk for the average person when consumed as a single serving."
Their lead author put it less formally: "there is no evidence that the consumption of dark chocolate is at all problematic," and "there's little sense in freaking out about it."
The same study found "organic" products were significantly more likely to show higher levels of both metals — an inversion of what most shoppers would assume.
Why lead and cadmium are different problems
Cadmium is taken up from soil by the cacao plant; it is in the beans at harvest. Lead is post-harvest contamination — beans pick it up from dust and dirt while drying in the open, near roads and industrial sites.
That distinction determines what can be fixed and how fast. Lead is a handling problem: dry beans on protective surfaces, away from traffic, and levels fall quickly. Cadmium requires soil surveying, regional blending, replanting, or breeding cadmium-tolerant varieties — a generational project.
Where we land
A toxicologist at Johns Hopkins offered the most useful framing: "The safety levels for lead and cadmium are set to be very protective, and going above them by a modest amount isn't something to be concerned about." He added that a diet with adequate calcium and iron reduces absorption of both metals.
The measurements are real and worth acting on at the margins — some bars are consistently lower, and choosing them costs nothing. The panic that "dark chocolate is poisoning you" is not supported by the same data it claims to rest on.
Since we criticise others for this: the widely-repeated claim that only two specific bars fell below the threshold for both metals does not appear in the Consumer Reports article. We checked. It is not there.