Columbia University Mailman School of Health researchers have discovered elevated levels of metals in the blood and urine of marijuana users, suggesting a potential source of lead and cadmium poisoning previously unnoticed.
Recreational marijuana legalized in 21 states
Marijuana ranks as the third most popular drug globally, trailing only tobacco and alcohol. In 2022, 21 states and Washington D.C. permitted recreational marijuana use, with medical marijuana legalized in 38 states plus the District of Columbia. Federal law still prohibits marijuana, leading to minimal oversight on contaminants and a lack of guidance from federal agencies, including the US FDA.
Postdoctoral fellow in Columbia Public Health’s Department of Environmental Health Sciences Kately McGraw said that the study hypothesized that marijuana users would have elevated metal biomarker levels due to the cannabis plant’s metal-absorbing properties. These findings suggest that marijuana consumption is linked to increased exposure to lead and cadmium.
McGraw and the research team performed an analysis by amalgamating data extracted from the National Health and Nutrition Examination Survey (NHANES) spanning the years 2005 to 2018. They categorized a total of 7,254 respondents from the survey into four distinct groups based on their substance use habits: non-tobacco/non-marijuana users, exclusive cannabis users, exclusive tobacco users, and individuals engaging in both cannabis and tobacco consumption. The investigation entailed the assessment of the concentrations of five distinct metals within blood samples and sixteen metals within urine samples.
More studies on presence of metals in cannabis
To delineate the categories of exclusive marijuana and tobacco usage, the researchers employed four specific NHANES variables: current cigarette smoking status, self-reported marijuana utilization, serum cotinine levels, and recent marijuana engagement. Exclusive tobacco users encompassed those who responded affirmatively to the question “Do you currently smoke cigarettes?” or displayed serum cotinine levels exceeding 10ng/mL. Cotinine, a substance primarily derived from tobacco, serves as the principal metabolite of nicotine.
In the future, it is imperative to undertake further investigations into cannabis utilization and the presence of contaminants, specifically metals. This research is essential for mitigating public health apprehensions arising from the escalating population of cannabis consumers, as emphasized by Columbia Public Health environmental sciences’ Dr Tiffany Sanchez.
