To what extent does smoking cannabis expose humans to heavy metals, and what could that mean for our bodies? Researchers for the Center for Health, Work & Environment (CHWE) at the Colorado School of Public Health (ColoradoSPH) are looking to answer those questions and more after receiving funding from the Institute for Cannabis Research to study the topic.
According to a release from ColoradoSPH, the three-year study aims to evaluate the risk of health effects from consuming cannabis, through smoking or vaping, contaminated with heavy metals like arsenic, lead, nickel, cadmium, manganese and uranium. Cannabis plants inherently have the ability to absorb heavy metals from soil, which may make cannabis dangerous to consumers who ingest it.
This new new will be the first-known human health risk assessment to evaluate the large number of heavy metals that could be present in cannabis flower, concentrates and vape products.
The new study will answer public health and regulatory questions regarding cannabis usage, information of interest both nationally and globally. Inhaling heavy metals, even at low levels, has been associated with dangerous and harmful effects. In addition to metals present in soil, contaminated irrigation water or fertilizers and heavy metal leaching from vape hardware can also play into the problem.
ColoradoSPH notes that inhalation exposure to heavy metals can increase a user’s risk for cancer, alongside neurological, renal, cardiovascular and hepatic issues.
“We know that exposure to metals can have systemic health impacts and leading one of the first studies to evaluate the contribution of vaping cannabis is an important public health effort,” said Katherine James, PhD, MSPH, MSCE, project co-investigator and associate professor of environmental and occupational health at the ColoradoSPH.
As part of a separate project, James is currently researching in-utero exposure to heavy metal and adverse birth and pregnancy outcomes among people in the San Luis Valley of Colorado.
Ultimately, ColoradoSPH says the metal exposure from cannabis vaping poses a “serious public health concern,” as the percentage of people primarily vaping cannabis has increased by 50% between 2017 and 2019 in the U.S. Previous research has found chromium, lead, tin and nickel in cannabis vapors at higher concentrations than in tobacco smoke.
In a 2021 Penn State meta-analysis, Louis Bengyella, assistant research professor of plant science, noted, “The heavy-metal content of cannabis is not regulated; therefore, consumers could unknowingly be exposed to these toxic metals.”
Specifically, ColoradoSPH notes that cannabis is indeed regulated, but only for four heavy metals (lead, cadmium, arsenic and mercury), though there are known health effects from other heavy metals that are likely present within cannabis products. By comparison, pharmaceutical products are regulated for 24 heavy metal or elemental impurities.
Mike Van Dyke, PhD, project principal investigator and associate professor of environmental and occupational health at the ColoradoSPH and CHWE, expressed his excitement to for the opportunity to explore cannabis heavy metal contamination and exposures in a “systematic way,” adding, “This project should answer a number of long-standing questions and provide important information to consumers, medical users and the regulatory community.”
According to ColoradoSPH, the project will bring together a partnership between academic researchers, working extensively within heavy metal contamination and toxicology, and those with specific experience in cannabis regulations and policy. They will work with Kaycha Laboratories, a national cannabis testing laboratory with state-of-the-art testing facilities.
The school concludes, affirming that the study will give patients and consumers important information on the potential health risks surrounding heavy metal contamination in cannabis products. The school anticipates the results will have “direct and immediate impacts” on cannabis public health regulations, growing practices and specifications on vape devices around the country.
