Your Favorite Dark Chocolate vs. Consumer Reports: The Heavy Metal Calculation
WELLNESS
If you love dark chocolate like me, you’ve probably seen news headlines about lead and cadmium contamination. Consumer Reports and the non-profit As You Sow have both raised awareness about these toxic metals in chocolates sold around the world. But how exactly do we calculate whether a chocolate bar is above or below safe levels? Let’s walk through it step by step.
Step 1: Understand the Safe Levels
Different organizations set different standards for heavy metals.
California Prop 65 (MADL): This is the strictest standard available, and the one used by Consumer Reports and As You Sow:
Lead: 0.5 µg/day
Cadmium: 4.1 µg/day
FSSAI (India): The Food Safety and Standards Authority of India sets maximum permissible limits for metals in foods. For chocolate and cocoa products:
Lead: 2.5 mg/kg
Cadmium: 1.5 mg/kg
As you can see, Prop 65 regulations are much stricter than FSSAI meaning many chocolates legal in India would still exceed California’s “most protective” guidelines.
Step 2: Check the Test Report
Let’s use Paul & Mike 87% Dark Chocolate as an example (not sponsored or paid). Their test report (publicly available on their website) shows:
Cadmium: 0.18 mg/kg
Lead: 0.013 mg/kg
Step 3: Convert to µg per Gram
1 mg/kg = 1 µg/g
So:
Cadmium: 0.18 mg/kg = 0.18 µg/g
Lead: 0.013 mg/kg = 0.013 µg/g
Step 4: Scale to Serving Size
A standard serving (used by Consumer Reports) is 1 oz (28.35 g) of chocolate.
Cadmium: 0.18 × 28.35 = 5.10 µg
Lead: 0.013 × 28.35 = 0.369 µg
Step 5: Compare to Consumer Reports Standards
Cadmium: 5.10 µg vs. limit of 4.1 µg → 124.5% of MADL (close, but above)
Lead: 0.369 µg vs. limit of 0.5 µg → 73.7% of MADL (below)
Step 6: Calculate max blocks/day
The whole chocolate bar is 68 g, it has 20 blocks which means each block is 3.4 g
According to Consumer Report values, you can have 4-6 blocks/ day of Paul & Mike 87% Dark Chocolate to be under the safe limits.
Why Serving Size Matters
We eat whole foods daily like rice, leafy greens, root vegetables, and nuts, and many of these naturally contain trace amounts of lead or cadmium from the soil and pollution. That means your total daily exposure might add up.
If you’re a chocolate lover like me and eat it daily, stick to smaller servings (a few squares instead of the whole bar). That way, you can enjoy your treat without worrying about heavy metal buildup.
Did you check your chocolate for heavy metals?
According to WHO, there is no safe level of lead intake. FDA limits daily lead intake from all foods combined to 2.2 µg/day for children and 8.8 µg/day for adults and pregnant women.
For nearly 60–100g of a chocolate bar, the brands listed above exceeded 100% of the daily limit for kids and reached nearly half of the limit for pregnant women, who are more sensitive and may sometimes eat larger portions than recommended.
Some big names didn't do so well. Lindt Excellence bars showed high levels, especially the 85% version. Hershey's Special Dark was even worse. Even fancy brands like Godiva had concerning amounts. Amul Bitter 90% had over 5 times the safe lead limit. Galaxy Fusions and The Whole Truth Chocolate weren't far behind. Most Indian chocolate brands actually comply with FSSAI standards. So technically, they're "fine" according to Indian regulations.
Industrial pollution and soil contamination mean even whole foods carry heavy metals. That’s precisely why mindful intake of foods like dark chocolate, where we actually have test results available, can help us keep overall exposure under control.
My post is not to discourage chocolate or single out any brand. At the end of the day, it's all about "moderation."
Check this blog post, where I have worked out the calculations and mentioned safe options along with the serving size for most popular chocolate brands.