Heavy Metals in Kratom
Evaluating the FDA’s Warnings
A week after Thanksgiving in 2018, the FDA published a statement announcing that in their testing of dozens of Kratom products available across the US, results found “disturbingly high” concentrations of heavy metals, including lead. Since then they have maintained a table online of heavy metal concentrations in products from a variety of Kratom distributors. The results indicate that most products contain around 300–600 parts per billion (ppb) of lead and 2000–3000 ppb of Nickel. My own research indicates that these numbers are accurate in November 2020, with even the websites that market themselves as “ethically sourced” still reporting these levels of impurities. This leads me to wonder: what would these values need to look like for the FDA to consider them “safe”?
Answering that question requires a deeper understanding of how the FDA and other regulatory bodies evaluate the safety of a product. The reference generated by the FDA (which is also used globally) for evaluating the safety of heavy metals in drug products is the Guidance Document Q3D(R1) Elemental Impurities. The document identifies “Class 1” elemental impurities as arsenic (As), cadmium (Cd), mercury (Hg), and lead (Pb). These elements are singled out as not typically used in the manufacture of pharmaceuticals, but if found in them would present a significant risk to human life. The document lists nickel (Ni) as a “Class 2A” elemental impurity, which means it is a less-toxic impurity but it is often found in pharmaceuticals so large concentrations need to be controlled. These five elements have been found in noticeable concentrations in tests performed on Kratom products, and when evaluating a lab result of a Kratom product, the concentrations listed for these elements should be evaluated carefully.
So we know what we elements we are looking for, but how do we know what a safe concentration is? The answer to this is more difficult because dosage and frequency of use will also be factors in that answer. The document provides a table with “Permitted Daily Exposures” for impurities, which we can use as a reference for our evaluation for what is “safe” for a daily dosage of Kratom. We can keep in mind that these values are probably conservative for an adult, since they have considered children for these values as well, who can experience symptoms at lower concentrations and bear harsher negative effects of heavy metal poisoning.
According to Grassroots Harvest Kratom, the rule of thumb is a mild dose is 2g, a moderate dose is 4g, and a large dose is 6g for their kratom powder products. Let’s evaluate their Boost Kratom Blend product, which comes with a lab test from October 2020. Using the dosage information, the concentration information from the lab test, and the Oral PDE data in the FDA document, we can estimate what percent of our permitted daily exposure each dose will cost and the maximum amount of doses, if any, can be safely taken in a day without reaching this limit. Below is a table with these percentages:
It appears the biggest threat by far in the kratom products in general is the lead content. You can reach your permitted daily exposure of lead with two large doses of this kratom product. While this is certainly not ideal — and needs to be monitored carefully by any potential kratom user — it seems like a stretch to call these numbers disturbingly high. The FDA document later on even does a similar thought experiment here, where they said these numbers can be used for drug dosages up to 10g, and certainly by those criterion this kratom product would pass that rule of thumb.
Certainly not all the distributors would pass the rule of thumb. Mitragaia — a long-time distributor formerly branded as just Gaia, has many products with higher concentrations of heavy metals. It seems like in general, white and green veins tend to have higher concentrations of heavy metals than red veins. Sifting through their results, I see concentrations of lead up to 0.818 mg/kg.
You also need to keep in mind that there are other sources of lead in your life that you may not be aware of or be able to control. Heavy metals are present in the soil that grows produce and the food we eat can often contain noticeable concentrations of heavy metals. This article for example found subjects were intaking more than a hundred micrograms of lead every day and that more than 16% of it was from rice, which suggests that having a bowl of cheaply produced rice could give you three times your permitted daily exposure of lead (although this NIH article says if you wash it you can get a lot of the lead out).
The truth is that the FDA have become one of the most lenient regulatory bodies in the world of food and drug regulation. The Clean Label Project, for example, exposed concentrations of heavy metals in many protein powder products more than two years ago and the issue is only slow changing because of customer awareness, not regulation. This is why we need to be honest with how these heavy metals concentrations compare with the big picture — because customer awareness can lead to safer products on the market.
