Buying dark chocolate for Valentine's Day? It likely includes lead and cadmium, study finds

Check your cupboards. A new study by Consumer Reports has found that much of the dark chocolate we eat contains lead and cadmium.

Of 28 dark chocolate bars tested, all contained both metals, the study found. Of those, 18 were considered high in either lead or cadmium while five were high in both.

No amount of either metal is considered safe to ingest.

Eating just one ounce a day of the 23 bars containing high levels of lead and cadmium would put an adult over limits that public health officials say may be harmful for at least one of the heavy metals, the study found.

While dark chocolate lovers may be fretting over the news, it's not all bad.

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Here's everything you need to know about the latest research, what's being done about heavy metals in dark chocolate and how you can make safer choices in the meantime:

What chocolate was tested?

Consumer Reports tested big-name brands like Trader Joe's, Lindt, and Dove, as well as smaller ones like Alter Eco and Mast.

The organization used California's maximum allowable dose levels of lead and cadmium because they're believed to be the most protective.

The safest choices of the 28 bars tested were by brands including:

• Mast

• Taza Chocolate

• Ghirardelli

• Valrhona

All contained the smallest amounts of lead and cadmium among the chocolates tested.

The chocolates that were high in both lead and cadmium include bars from:

• Trader Joe's

• Theo

• Lily's

• Green & Blacks

The levels of the metals in those bars were often well over 100% of California's maximum allowable doses.

Another 18 were high in either lead or cadmium.

Check out the complete study to see how much lead or cadmium your favorite dark chocolate might contain.

Why are lead and cadmium harmful?

Experts have identified cadmium as a known carcinogen and lead as a probable one.

Consistent exposure to even small amounts of heavy metals over a long time period can lead to hypertension, immune system suppression, kidney damage and reproductive issues, according to Tunde Akinleye, the food safety researcher at Consumer Reports who led the chocolate-testing project.

The danger is greater for young children and pregnant people because heavy metals can affect brain development and lead to lower IQs, Akinleye said.

Why is there lead and cadmium in dark chocolate?

The chocolate industry and its watchdogs have been looking for solutions since a corporate accountability group called As You Sow began finding lead and cadmium in dark chocolate in 2014.

After years of litigation, As you Sow and the industry agreed to conduct a study to understand how metals are getting into chocolate and how to fix it.

That study found that lead gets into chocolate at various stages of cacao production, like when beans are removed from their pods. Cadmium is in the soil itself and levels can vary heavily.

Solutions to lead contamination include keeping sticky cacao beans off the ground to protect them from dust laden with lead. Manufacturers can address the cadmium problem by avoiding land with high levels of cadmium, for instance.

As You Sow is working with the industry to implement changes.

Meanwhile, at least two lawsuits have been filed over the issue since Consumer Reports' findings came out last month. Both Trader Joe's and The Hershey Company were sued last month over lead and cadmium in their products. The companies have declined to comment.

What can you do?

Until the chocolate industry fixes the problem, the experts at Consumer Reports say that people can do a few things to mitigate their risks. They include:

• Don't give dark chocolate to children.

• Pregnant women should eliminate dark chocolate consumption or greatly reduce it.

• Try to limit consumption to dark chocolate to a couple times a week, and choose chocolates with lower levels of cacao.

• Sweet tooth killing you? Milk chocolate has lower levels of cacao and therefore much lower levels of lead and cadmium.

This article originally appeared on USA TODAY: Lead and cadmium in dark chocolate frequently, Consumer Reports finds