Elemental impurities (heavy metals) in kratom products: an assessment of published individual product analyses.

Introduction: Kratom is commonly used by consumers, and the elemental impurity exposure that consumers would have at different kratom ingestion doses has been determined.

Methods: This assessment used original data from independent third-party laboratory testing of kratom products to identify the percentage of products that exceeded permissible daily exposure limits for lead (5 µg/day), nickel (200 µg/day), arsenic (15 µg/day), and cadmium (5 µg/day), the interim reference level for lead in adults (12.5 µg/day), and the tolerable upper intake level for manganese (11 mg/day) and nickel (1 mg/day). We assessed all products regardless of type and then evaluated non-extract products, extract products, and a soda preparation separately for elemental impurities.

Results: Three assessments of elemental impurities in kratom products have been published, totaling 68 products. Assessing all products and assuming a 3 g daily dose of kratom, 7.4% would exceed the permissible daily exposure limits for lead, 0% for nickel, 3.1% for arsenic, and 0% for cadmium. At a kratom dose of 25 g daily, 70.6% would exceed the permissible daily exposure limits for lead, 20.6% for nickel, 9.4% for arsenic, and 0% for cadmium. The interim reference level for lead would be exceeded by 1.5% of products at a kratom daily dose of 3 g and 33.8% of products at 25 g. The tolerable upper intake level for manganese would be exceeded by 12.5% of products at a kratom daily dose of 3 g and 41.7% of products at 25 g. Non-extract products generally contain greater concentrations of elemental impurities than extract products or the soda preparation.

Discussion: Apart from their concentrations in a gram of product, assessing the amount of exposure to elemental impurities at different kratom ingestion doses is also important. Elemental impurities exceeding regulatory permissible concentrations for many products, especially with greater daily kratom ingestion doses, may impact human health.

Conclusions: Some kratom products contain excessive concentrations of elemental impurities of toxicological concern, such as lead and arsenic. Non-extract products (powders, capsules, tablets) generally contain greater concentrations of elemental impurities than extract products or the soda preparation. Daily use of these products can result in exposures exceeding regulatory thresholds and adverse health effects.