Heavy Metal Contamination in CBD Products – New Study

Written by Lydia Kariuki

A new study has found that heavy metal and phthalate contamination is prevalent in the cannabidiol (CBD) industry. The study also highlighted the widespread mislabeling of CBD products in the market which provides misleading information to consumers.

Demand for CBD products has increased exponentially over the last couple of years. Consumers are turning to CBD to find relief from pain, anxiety, fatigue, stress, and depression among other reasons.  On the business side of things, entrepreneurs and investors are looking to cash in on the high value CBD market.

The researchers tested over 500 CBD edibles and topicals and found that at least 42% were contaminated with lead as well as other heavy metals.  The study was led by Hannah Gardner from the Miami Miller School of Medicine and was sponsored by the Clean Label Project.

Hemp is a known bioaccumulator. This means that it readily absorbs chemicals from the environment, at a rate which is faster than the excretion rate. Over time, the chemicals accumulate in hemp and can easily reach toxic levels. It is critical to characterize  the level of contaminants in hemp so as to evaluate the potential benefits against potential health risks.

The researchers tested 512 different CBD products, including edibles and topicals. They tested the levels of lead, cadmium, mercury, arsenic, and four different phthalates (chemicals used to make plastics more durable). The researchers also considered labeling accuracy in all the products.

The researchers found the following levels of heavy metal contamination:

  • 42% of the CBD edibles (121) were contaminated with lead
  • 8% of the CBD edibles were contaminated with Cadmium
  • 28% of the CBD edibles were contaminated with Arsenic
  • 37% of the CBD edibles were contaminated with Mercury

Four CBD edibles exceeded the acceptable (California Proposition 65) limit for daily lead consumption. 13% to 80% of the CBD edibles had different levels of phthalate contamination. Lastly, only 42% of the CBD products were labeled accurately.

This is not the first time that CBD contamination and mislabeling has been highlighted. A study by John Hopkins University found gross mislabeling of over-the-counter CBD products. This study also found that  CBD manufactures, in a bid to bump up sales, make false and exaggerated claims on the health benefits of CBD. Such studies underscore the need for strict regulation of the cannabis industry to prevent consumer exploitation and to safeguard public health and safety.



Gardener, H., Wallin, C., & Bowen, J. (2022). Heavy metal and phthalate contamination and labeling integrity in a large sample of US commercially available cannabidiol (CBD) products. The Science of the total environment851(Pt 1), 158110.

PRNewswire: Global $13.4 Billion Cannabidiol Market to 2028 – Increasing Awareness CBD Health Benefits, Changing Consumer Opinion, and Attitude Toward CBD Products. Retrieved from—increasing-awareness-cbd-health-benefits-changing-consumer-opinion-and-attitude-toward-cbd-products-301254807.html

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Lydia Kariuki

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