Warning: Columbia University Uncovers High Metal Levels in Blood of Marijuana Users

Alert: Columbia University Discovers Elevated Metal Levels in Blood of Cannabis Consumers

A recent investigation has unveiled substantial quantities of metals present in the blood and urine of individuals who consume marijuana, suggesting that marijuana could potentially be an unacknowledged source of lead and cadmium exposure. This new research, one of the initial studies to establish a connection between self-reported marijuana usage and internal metal exposure, raises apprehensions about public well-being, particularly in the context of escalating marijuana consumption and the persisting irregularity of federal regulations.

The researchers at Columbia University have ascertained heightened metal concentrations in the blood and urine of marijuana consumers. This discovery underscores potential health risks and emphasizes the urgency for consistent regulatory measures.

A recent scientific inquiry conducted at Columbia University’s Mailman School of Public Health has detected significant metal levels in the blood and urine of individuals who consume marijuana. These outcomes propose that marijuana might constitute an imperative but underestimated source of exposure to lead and cadmium.

This study stands among the first of its kind to report biomarker metal levels in marijuana users. It is likely the most extensive investigation to date, establishing a link between self-reported marijuana consumption and internal indicators of metal exposure, rather than merely examining metal levels within the cannabis plant itself. The outcomes of this study were disseminated on August 30 in the journal Environmental Health Perspectives.

Crucial Discoveries

In comparing data reported by participants who exclusively use marijuana with those who do not use any form of marijuana or tobacco, the study revealed notably elevated lead levels in blood (1.27 ug/dL) and urine (1.21 ug/g creatinine).

“Due to the cannabis plant’s recognized ability to accumulate metals, our initial hypothesis was that individuals who use marijuana would exhibit higher levels of metal biomarkers compared to non-users,” articulated Katelyn McGraw, a postdoctoral researcher in the Department of Environmental Health Sciences at Columbia Public Health, and the study’s primary author. “Consequently, our results indicate that marijuana acts as a source of cadmium and lead exposure.”

Methodology of the Research

The researchers amalgamated data from the National Health and Nutrition Examination Survey spanning the years 2005 to 2018. Led by the National Center for Health Statistics (NCHS) at the CDC, this biannual program encompasses a series of studies designed to assess the health and nutritional status of both adults and children in the United States.

McGraw and her colleagues classified the 7,254 participants of the survey into four groups: non-marijuana/non-tobacco users, exclusive marijuana users, exclusive tobacco users, and individuals who used both marijuana and tobacco. The study examined five metals in blood samples and sixteen in urine samples.

To establish exclusive marijuana and tobacco usage, the researchers employed four NHANES variables: current cigarette smoking, serum cotinine levels, self-reported prior marijuana usage, and recent marijuana consumption. Exclusive tobacco usage was defined as individuals who either acknowledged current cigarette smoking or exhibited a serum cotinine level exceeding 10 ng/mL.

Prevalence and Regulation of Marijuana

After tobacco and alcohol, marijuana stands as the third most commonly used substance worldwide. By 2022, over half of the U.S. population, encompassing 21 states and Washington D.C., had legalized the recreational use of marijuana, and medical marijuana was lawful in 38 states along with Washington D.C. However, owing to its ongoing federal illegality, the regulation of contaminants within cannabis-containing products remains fragmented, with no guidance offered by federal regulatory bodies such as the FDA or EPA. As of 2019, approximately 18 percent of Americans, equating to 48.2 million individuals, reported using marijuana at least once within the preceding year.

While 28 states have regulations governing inorganic arsenic, cadmium, lead, and total mercury concentrations in marijuana products, the specific limitations vary both by metal type and by state.

Tiffany R. Sanchez, PhD, an assistant professor of environmental health sciences at Columbia Public Health and the senior author, underscored the necessity for forthcoming research to delve into cannabis use and the presence of contaminants, particularly metals. This research is imperative for addressing public health concerns in light of the escalating number of cannabis consumers.

Reference: “Blood and Urinary Metal Levels among Exclusive Marijuana Users in NHANES (2005–2018)” by Katlyn E. McGraw, Anne E. Nigra, Joshua Klett, Marisa Sobel, Elizabeth C. Oelsner, Ana Navas-Acien, Xin Hu, and Tiffany R. Sanchez, published on August 30, 2023, in Environmental Health Perspectives. DOI: 10.1289/EHP12074

Co-authors of the study include Anne E. Nigra, Joshua Klett, Marisa Sobel, and Ana Navas-Acien from Columbia Public Health; Elizabeth C. Oelsner from Columbia University Irving Medical Center; and Xin Hu from Emory University School of Medicine.

The research received support from the National Institutes of Health (NIH) National Institute of Environmental Health grants P30ES009089 and T32ES007322.

Frequently Asked Questions (FAQs) about Metal Exposure

More about Metal Exposure

• Environmental Health Perspectives: Link to the journal article detailing the Columbia University study on metal exposure in marijuana users.
• National Health and Nutrition Examination Survey (NHANES): NHANES is a comprehensive program that provides data on health and nutritional status, serving as the basis for the study’s data collection.
• Columbia University Mailman School of Public Health: Source of information about the institution where the research was conducted and the expertise involved.
• National Institutes of Health (NIH): The NIH provided support for the research through its National Institute of Environmental Health grants.
• [FDA and EPA Regulations](https://www.fda.gov/ and https://www.epa.gov/): Information on the regulatory bodies responsible for overseeing contaminants and safety standards in products, including cannabis-containing items.