The study, published Wednesday in the Environmental Health Perspectives journal, found that marijuana users had higher levels of lead in their blood and urine compared to non-marijuana users. Conducted at Columbia University's Mailman School of Public Health, the study used data from the National Health and Nutrition Examination Survey and conducted the research with a group of more than 7,200 participants.
The researchers split participants into five groups: non-marijuana/non-tobacco, exclusive marijuana, exclusive tobacco, and dual marijuana and tobacco use. They measured five different metals in participants' blood and 16 in their urine.
"Because the cannabis plant is a known scavenger of metals, we had hypothesized that individuals who use marijuana will have higher metal biomarker levels compared to those who do not use," author Katlyn McGraw, postdoctoral researcher in Columbia Public Health's Department of Environmental Health Sciences, said in a press release.
"Our results therefore indicate marijuana is a source of cadmium and lead exposure," she added.
According to the World Health Organization, there is no healthy level of lead concentration, especially for children. Lead can cause permanent intellectual disabilities, behavioral disorders and even death. The organization also considers cadmium a human carcinogen that can create toxic effects on the kidneys, skeletal and respiratory systems.
"Going forward, research on cannabis use and cannabis contaminants, particularly metals, should be conducted to address public health concerns related to the growing number of cannabis users," senior author Tiffany R. Sanchez, assistant professor of environmental health sciences at Columbia Public Health, said in the press release.
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