A study conducted by researchers at Columbia University (USA) showed that cannabis users had high levels of lead and cadmium in their blood and urine. This suggests that cannabis may be an important underestimated source of heavy metal contamination.
This study is the first to measure metal levels in the blood and urine of marijuana users. This is the largest study to date that establishes a link between cannabis use and an increased risk of exposure to heavy metals.
Cannabis, a source of lead exposure
Researchers surveyed over 7,000 people about their tobacco and cannabis use. The cohort was divided into four groups: non-smokers (neither tobacco nor cannabis), exclusive cannabis smokers, exclusive tobacco smokers and mixed smokers (tobacco and cannabis). The researchers then measured the levels of 5 metals in the blood and 16 metals in the urine of the participants.
They found that exclusive cannabis users had significantly higher blood (1.27 ug/dL) and urine (1.21 ug/g creatinine) lead levels than non-smokers.
“There is no safe concentration of lead in the blood”
Lead is a toxic substance that accumulates in the body and affects multiple organ systems. It is especially harmful to young children. “There is no safe concentration of lead in the blood”recalls the World Health Organization (WHO) on its website.
“We already know that cannabis is a plant known to accumulate metals in its leaves. Based on this finding, we hypothesized that people who use cannabis may have higher blood metal levels than those who do not., explained Katelyn McGraw, lead author of the study. A hypothesis that turned out to be true since the work of Katekyn McGraw and her team showed that cannabis is a source of exposure to cadmium and lead, two heavy metals.
Consumers who must be warned of the risks to their health
For the authors of the study, these results show the need for further research on cannabis consumption and on the pollutants present in cannabis in order to raise awareness among consumers (whose number is constantly increasing) about the possible risks to their health.
Cannabis is the third most widely used drug in the world after tobacco and alcohol.