Experts warn that cannabis plants could absorb toxic heavy metals like lead, mercury, and cadmium from the soils.
Pennsylvania scientists have performed a meta-analysis on previous studies that examined the plant’s ability to absorb heavy Metals.
They report that some cannabis strains have been bred specifically for ‘phytoremediation’ – growing plants to remove pollutants from soils.
However, this could lead to heavy metals being absorbed into cannabis plants after they are harvested. This can potentially cause cancer or neurological issues.
Heavy metal contaminants could be dangerous for people who ingest them, the researchers say, including cancer patients who use medical marijuana.
New meta-analysis discusses cannabis’ ability to absorb heavy metals, and the health effects on users (stock photo).
The researchers, Penn State University, have therefore proposed strategies for cannabis growers to ensure they avoid heavy metals contaminating their cannabis crops.
Louis Bengyella (assistant research professor in plant science at Penn State University) stated, “Heavy metals like lead, mercury and cadmium are well-known to cause cancer.”
The heavy-metal contents of cannabis are not controlled; consumers may be unaware that they could be exposed.
This is bad news for all who smoke cannabis. It is even worse for those who are suffering from cancer and who use marijuana medically to manage their nausea and pain.
The cannabis plant is used amongst other purposes to make medical marijuana, industrial hemp, and cannabidiol oil (CBD).
Because they have the inherent capability to absorb heavy metals, these plants are useful in remediating soil contamination sites such as industrial activity.
However, cannabis may be dangerous to those who consume it because they can absorb harmful metals.
Bengyella explained that the problem lies in using these strains for phytoremediation, without taking into account why they were created. This could lead to consumers being exposed to heavy metals.
A schematic diagram illustrates the plant uptake, translocation and sequestration for heavy metals.
Bengyella and colleagues conducted a meta-analysis on research papers about heavy metal contamination of cannabis.
The researchers examined available information regarding the use of cannabis for phytoremediation, heavy metals in cannabis, and how they might affect medical outcomes.
Due to their special physical attributes, certain cannabis strains can be used as phytoremediation.
These characteristics include long stem length, fast growth, high root and leaf surface area, high photosynthetic activity and dependence on relatively few nutrients for survival – which facilitate the absorption of heavy metals.
Additionally, the team discovered that lead and cadmium can be transported up the stalk to the flowers and leaves of the plant.
The trichomes on flowers, which are hairlike structures that trap heavy metals in them, allow these elements to exit the plants.
Bengyella stated that trichomes were important as they contain the CBD oil (and the tetrahydrocannabinol [THC]) which are sought by customers.
“This led us question whether these heavy metals were present at the level that the trichome. What can they do to the people?”
The next step was to examine the known health effects of heavy metallics.
Researchers discovered that cannabis contamination can lead to various health issues. This is because heavy metals in cannabis are not metabolized and accumulate in certain areas in the body.
Reactive oxygen species, which are highly reactive chemicals that form from oxygen and free radicals, can cause heavy metal poisoning in the body.
They can cause damage to enzymes, proteins and lipids as well as neurological problems.
Bengyella said, “Cannabis in combustive forms represents the greatest risk to human health. As analysis of heavy metals contained in cannabis smoke showed the presence selenium mercury, cadmium and chromium as well as arsenic.”
Heavy metal contamination in cannabis can cause various health problems due to the fact that the heavy metals are rarely metabolised in the human body (stock image)
“It’s disturbing to realize that cannabis products used by patients with cancer may cause unnecessary harm.”
To mitigate heavy metal contamination, the authors advise growers to choose farmland that is free of heavy metals and cannabis varieties that are not bred to better absorb heavy metals.
When choosing farmland, growers should avoid abandoned industrial sites and perform air quality analyses.
You should conduct a pH test on your soil, since pH can affect the plant’s ability to absorb heavy metals.
Bengyella stated that the problem lies at the consumer’s level. However, the solution needs to come from the farm.
“We think that’s where we need to be hammering hard, and solving the problem.”
Toxin Reviews has published all the results.