Our Heavy Metal Manifesto

Our Heavy Metal Manifesto

We wrote this article to share our perspective on the topic of heavy metals in chocolate, to offer some research for further reading, and to help you feel confident in choosing chocolate for you and the people you care about.

A quick look at our standards:

  • Each shipment of cacao is tested so that we know what is in it
  • We look for cacao origins that consistently…
    • tests negative
    • test negative for arsenic OR has arsenic levels below FDA standards for baby food
    • has cadmium levels below European Union standards

We keep our standards high because we want to enjoy our chocolate – and share it – without any concerns. There’s enough things to worry about when running a chocolate factory, and we don’t want heavy metals to be one of them.

That’s the short story, and you can keep reading for the unabridged version that really drills into the two most important metals for chocolate lovers to be aware of: lead and cadmium. 

Don’t hesitate to reach out if you have any questions on what’s in here or want to share some new research you’ve found on this topic!

- Logan & Lauren

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Overview

Heavy metals are elements that have a density at least five times greater than water. These elements are found in the earth’s crust and are formed by volcanic activity, forest fires, or the weathering of rocks. Some heavy metals, like zinc and copper, are essential for the body to function, while others, like cadmium and lead, are toxic.

The VolcĂĄn de Fuego visible from Antigua, Guatemala making some heavy metals. Photo by Diego GirĂłn

Because heavy metals naturally occur in the earth’s crust – and the soils that sit on the crust – many plants absorb trace levels as they grow, which means most food staples contain trace levels of heavy metals. For example, a 2012 study in Europe showed that people get their dietary cadmium from the following sources:

  • 26.9% of dietary cadmium came from grains and grain products
  • 16.0% of dietary cadmium came from vegetables and vegetable products
  • 13.2% of dietary cadmium came from and starchy roots and tubers
  • 4.3% of dietary cadmium came from chocolate products

Heavy metals are a part of life, and our bodies are skilled at managing both the beneficial and toxic heavy metals effectively. From a health perspective, heavy metals become a problem when our diet provides more than just trace amounts. What follows is a detailed discussion about the two most important metals for chocolate lovers – lead and cadmium – and how we think about and manage these metals as chocolate makers.

Lead

While lead naturally occurs in the Earth’s crust, cacao trees do not pick up lead from the soil. This means that if there is lead in your cacao, it is almost certainly from an industrial pollution source. Common sources of lead contamination include cacao that is left to dry on a surface that has lead-containing dust or stored in containers with leaded paint on the interior walls.

From the perspective of a craft chocolate maker, cacao with lead contamination is a sign that the cacao may not have been well-cared-for during the post-harvest process. And because of that, lead is mostly found in commodity cacao and is less common in the specialty cacao that we buy.

I recently looked at lab reports from 20 of the most popular speciality cacao origins. Of those 20 origins, just 3 of the origins tested positive for lead. One origin had 17 parts per billion (PPB), one had 20 PPB, and one had 33 PPB. For context, the FDA says that baby food should not have more than 20 PPB lead.

So 3 out of the 20 origins were positive for lead (15%), and only 1 of those 3 had levels exceeding the standard for baby food. This tells me that, when looking at speciality cacao lead is both rare to find AND at very low levels when it is present.

BUT… We still don’t like lead, and zero lead is better than 20 parts per billion. So we’ve decided to seek out origins that consistently test negative for lead, for two key reasons.

  1. Lead in cacao can be a sign of a sloppy post-harvest handling process, and it makes us wonder if there are other things about the cacao that we don’t like: poor quality fermentations, inconsistent fermentations from year-to-year, poor shipping conditions, etc.
  2. We don’t tolerate lead in other areas of our life. Lauren used to volunteer for the Montana Raptor Center and learned that lead poisoning (from leaded bullet fragments in prairie-dog carcasses) is a huge driver of raptor hospitalizations and deaths each year in the Northern Rockies. We personally don’t want to eat chocolate with lead in it.

We consider cacao to be “lead free” if lead levels are below the limit of detection using an Inductively Coupled Plasma Mass Spectrometry (ICP-MS) test. The threshold for detection on this test is typically 0.005 mg/kg or 5 parts per billion. For context, 5 parts per billion is the same ratio as 5 days per 2.7 million years.

Cadmium

The issue of cadmium in chocolate is quite different than lead. Like lead, cadmium is a by-product of volcanic activity. Unlike lead, cacao trees do naturally pick up cadmium from the soil. This is because cadmium dissolves more easily in water and also because cadmium ions are similar in size and charge to zinc and calcium ions - two important metals that plants take up through their root systems.

Cadmium levels from a cacao origin will fluctuate from harvest-to-harvest, so each shipment needs to be tested. Factors like soil acidity and average tree age both impact how much cadmium cacao trees pick up from their soil. The European Union published cadmium limits in 2019 (which we follow), and because of that, there is a lot of research being down right now looking at how farmers can mitigate the amount of cadmium their trees pick up.

Because of the connection between recent volcanic activity and cadmium, cacao grown in Africa tends to have less cadmium in it than cacao grown in Colombia, Ecuador, or Peru – all places with recent - in geologic terms - volcanic activity. This also means that the cacao consumed by the Aztecs, Mayans, and Olmecs in 2,500 BC had trace levels of cadmium.

Cadmium levels from a cacao origin will fluctuate from harvest-to-harvest, so we need to test each shipment that we receive. Factors like soil acidity and average tree age both impact how much cadmium cacao trees pick up from the soil during a given harvest year. Photo by Franco Colomba

Before we go too far down the cadmium rabbit hole, let’s revisit the study from the beginning of this article that showed where our dietary cadmium comes from:

  • 26.9% of dietary cadmium came from grains and grain products
  • 16.0% of dietary cadmium came from vegetables and vegetable products
  • 13.2% of dietary cadmium came from and starchy roots and tubers
  • 4.3% of dietary cadmium came from chocolate products

And keep in mind that this was a study looking at Europeans, who consume more (and darker) chocolate that Americans do. So we would guess that Americans are getting less than 4% of their dietary cadmium from chocolate. BUT, like lead, there is no health benefit to having more cadmium in our diets, and we want to be mindful about how much cadmium is in our chocolate. This brings us to the question of figuring out how much is the right amount to tolerate.

In Montana and 48 other states, there are no laws or guidelines governing how much cadmium can be in chocolate. California has cadmium guidelines through Prop 65, but we don’t love the methodology they used to define their limit. That’s because their current guidelines are from a 2001 study that looked at a 1981 study on lab mice.

In that 1981 study, they fed pregnant mice cadmium until they started to see low birth rates in their offspring. The level of cadmium intake just prior to these low birth rates was assumed to be the amount that the mice could ingest without having any side affects. Next they translated this amount for a 135-pound pregnant woman. Lastly, they divided that amount by 1,000 to build in a factor of safety.

As someone who is interested in this topic, I have struggled to figure out how to use this information in my own life or the chocolate that we make. The 1,000-times factor of safety seems too big and all of the data is based on a lab mice study from 1981. For that reason, we don’t follow Prop 65 guidelines, but we DO follow guidelines from the European Union.

The European Union established new limits in 2019. Those guidelines allow 0.80 mg/kg cadmium in 70% dark chocolate. 0.80 mg/kg is equivalent to 8 parts per 10 million, and thinking back to our days-per-year analogy, this can be represented as 8 days per 27,300 years.

Like lead, these are really trace amounts we are talking about here and it can be hard to wrap our minds around these figures. We think even the European Union limits are extremely conservative, but we use them as a guide post so that we can enjoy our chocolate and share it with high-risk friends (pregnant women and young children) without having to worry about it.

where the rubber meets the road

Below is an e-mail that I recently sent to an import partner letting them know what we are looking for. Hopefully this provides from context on how this all works in practice.

Important to note when reading this: fair-trade certifications are kind of like minimum wage - it’s the bare minimum from an ethical perspective and we want to pay farmers better-than-fair-trade prices for exceptional cacao. This is why I say in the email below that the cacao doesn’t need to be fair-trade certified but that we do want to understand the economics for farmers growing cacao that we buy.

Email to import partner, 11/4/2024

We are looking for a Colombian and Mexican origin that:

1) is fairly traded — it doesn't need to be fair-trade certified, but we want to understand the supply chain and economics for the farmers involved to make sure it is ethically traded

2) consistently tests negative for lead

3) consistently comes in below 0.8 mg/kg for cadmium

Look forward to learning about your origins and how we might be able to work together!

- Logan

You might have noticed I used the word “consistently” in this message. As we noted, cadmium levels will fluctuate from harvest-to-harvest, so we want to work with origins that consistently come in below the E.U. standard. If one of our favorite cacao origins comes in above 0.8 mg/kg for a given harvest year we don’t want to reject that origin all together — we want to be thoughtful about how we use it that year and we can also blend it with lower cadmium origins to keep supporting those farmers.

As we noted in the section covering lead, the threshold for lead detection in these lab tests is 5 parts be BILLION. For context, 5 parts per billion is the equivalent to 5 days out of 2.7 million years. It’s hard to imagine how small these quantities are. So, for example, if a cacao origin that consistently tests negative for lead shows up one year with 10 parts per billion lead, we don’t want to reject that shipment or that origin. That’s because the FDA standard for baby food is 20 parts per billion lead, so in this example the cacao would have 50% of what’s safe for a baby with a developing brain to eat all day, every day.

Conclusion

We wrote this article to share our world view on the topic of heavy metals in chocolate, provide some research for further reading, and to help you determine if our chocolate is a good fit for you and your family.

Here’s a recap of where we stand:

  • Each shipment of cacao is tested so that we know what is in it
  • We look for cacao origins that consistently…
    • tests negative
    • test negative for arsenic OR has arsenic levels below FDA standards for baby food
    • has cadmium levels below European Union standards

Let us know if you have any questions about what’s covered here, or if you’d like to share some research you’ve found on these topics!

Take care,

Logan & Lauren

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