“Trichomes are important because they store the CBD oil and the tetrahydrocannabinol (THC) consumers want,” says Bengyella. “This led us to wonder if these heavy metals are present at the trichome level, what can they do to humans?”
Next, the researchers examined the documented health effects of heavy metals. They found that the heavy metal contamination in cannabis can cause various health problems because the heavy metals are rarely metabolized and therefore accumulate in certain areas of the human body. The most common mechanism of heavy metal toxicity in the human body is through the production of reactive oxygen species and free radicals, which damage enzymes, proteins, lipids and nucleic acids and can cause cancer and neurological problems.
“Cannabis consumed in flammable form poses the greatest threat to human health as analysis of heavy metals in cannabis smoke revealed the presence of selenium, mercury, cadmium, lead, chromium, nickel and arsenic,” said Bengyella. “It is worrying to realize that the cannabis products consumed by consumers, especially cancer patients, can cause unnecessary harm to their bodies.”
The authors conclude that using good agricultural practices, such as choosing cannabis strains that were not bred to better absorb heavy metals and choosing arable land that is free of heavy metals, can mitigate heavy metal pollution. Specifically, the team offers farmers three recommendations for choosing farmland: Avoid abandoned industrial sites, conduct air quality analyzes before starting a farm, and conduct a soil pH test, as pH can affect the amount of heavy metals, that a plant absorbs.
“The problem is at the level of the consumer using cannabis products, but the solution has to come at the agricultural level,” said Bengyella. “We believe we should hammer hard here and solve the problem.”
Bengyella currently leads and teaches the Cannabis Production (Plant 240) course in the Department of Plant Science.
Other authors of the paper are Mohammed Kuddus, Professor, University of Hail, Saudi Arabia; Piyali Mukherjee, Research Associate, Burdwan University, India; Dobgima J. Fonmboh, lecturer, Bamenda University, Cameroon; and John E. Kaminski, Professor of Plant Science, Penn State.