Study detects significant levels of metals in blood and urine in consumers
Researchers found that cannabis users had significantly higher levels of metals such as lead and cadmium in their blood and urine. The study, which is one of the largest of its kind, analyzed data from more than 7000 participants in the National Health and Nutrition Survey.
While it had been hypothesized that cannabis could cause exposure to metals due to its ability to capture metals from the ground, the study confirms that marijuana is indeed an unknown source of exposure. The findings call for further research into cannabis use and contaminants, especially as legalization of the plant continues in the United States.
Marijuana users have higher lead levels in blood (1,27 ug/dL) and urine (1,21 ug/g creatinine) than non-users. This study is the first to measure metal biomarker levels in marijuana users, making it one of the largest and most comprehensive studies on this topic to date.
As marijuana use becomes more common and more than half of the US population lives in areas where it is legal, the study raises concerns about the lack of federal guidelines on contaminants in the cannabis.
Research carried out at the Columbia University Mailman School of Public Health detected significant levels of metals in the blood and urine of marijuana users, concluding that marijuana may be a significant and underappreciated source of lead and cadmium exposure.
This is one of the first studies to report metal biomarker levels in marijuana users and quite possibly the largest study to date linking self-reported marijuana use to internal measures. exposure to metals, rather than just looking at the levels of metals present in the cannabis plant.
Participant-reported measures of exclusive marijuana use compared to non-marijuana-tobacco users showed significantly higher lead levels in blood (1,27 ug/dL) and urine (1,21 ug/dL). g of creatinine).
“Because the cannabis plant is a known metal scavenger, we hypothesized that people who use marijuana would have higher levels of metal biomarkers than those who don't”health, and first author of the study.Katelyn McGraw, postdoctoral researcher in the Department of Environmental Health Sciences Columbia Public Health, and first author
“Our results therefore indicate that marijuana is a source of exposure to cadmium and lead.
The researchers combined data from the National Health and Nutrition Examination Survey for the years 2005-2018. Led by the CDC's National Center for Health Statistics (NCHS), the NHANES is a semester-based degree program designed to assess the health and nutritional status of adults and children in the United States.
McGraw and his colleagues categorized the 7 survey participants based on their use: non-marijuana/non-tobacco, exclusive marijuana, exclusive tobacco, and dual use of marijuana and tobacco. Five metals were measured in blood and 254 in urine.
The researchers used four NHANES variables to define exclusive marijuana and tobacco use: current smoking, serum cotinine levels, self-reported marijuana use, and recent marijuana use. Exclusive tobacco use was defined by those who responded affirmatively to the question "Do you currently smoke cigarettes?" » or whose serum cotinine level was greater than 10 ng/ml.
Marijuana is the third most widely used drug in the world, after tobacco and alcohol. As of 2022, 21 states and Washington DC, covering more than 50% of the US population, have legalized the recreational use of marijuana; and medical marijuana is legal in 38 states and Washington, D.C. However, with marijuana still illegal at the federal level, regulation of contaminants in all cannabis products remains sketchy and there has been no guidance from federal regulatory agencies such as the FDA or EPA. In 2019, 48,2 million people, or 18% of Americans, reported using marijuana at least once in the past year.
While 28 states regulate the levels of inorganic arsenic, cadmium, lead, and total mercury in marijuana products, regulatory limits vary by metal and state.
“Future research on cannabis use and its contaminants, especially metals, should be conducted to address public health concerns related to the growing number of cannabis users,” said Tiffany R. Sanchez, PhD. , assistant professor of environmental health sciences at Columbia Public Health, and lead author of the study.