Marijuana users have high levels of toxic metals in their blood and urine, a study suggests.
Researchers from Columbia University in New York City found that cannabis smokers who don’t use nicotine had 27 and 21 percent more lead in their blood and urine, respectively, than non-users.
They also found that users had 22 and 18 percent higher levels of the metal cadmium in their blood and urine.
These toxic metals have been linked to several health problems, such as high blood pressure, kidney disease, and even cancer.
They are believed to find their way into cannabis through the soil during the farming process. Soil is increasingly becoming contaminated with metals due to pollution and pesticides.
The study authors say the issue has never been more important as marijuana use in the US skyrockets, with an estimated 42 million regular users in the US.
Marijuana use is on the rise, official data suggests. A 2019 study by the Substance Abuse and Mental Health Services Administration (SAMHSA) found that nearly 18 percent of Americans, more than 42 million, used marijuana in that year
Dr Tiffany R Sanchez, study author and professor at Columbia University, said: ‘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.’
The study, published Wednesday in the journal Environmental Health Perspectives, used data from the annual National Health and Nutrition Examination Survey (NHANES), which was collected between 2005 and 2018.
They examined blood and urine tests from 7,254 participants who had used marijuana within the last 30 days. Researchers measured five levels in the blood and 16 in the urine.
They found that marijuana users had 1.27 ug/dl (micrograms per deciliter) lead in their blood compared to 0.93 ug/dl in non-users. This is a 27 percent increase.
Marijuana users had 1.21 micrograms of lead in their urine, 21 percent more than the control group, which had 0.96.
The Environmental Protection Agency (EPA) says there is no safe level of lead in the body.
Lead poisoning is more common in children, particularly those under six years old, according to the Centers for Disease Control and Prevention (CDC).
However, exposure in adulthood has been linked to several health issues, including high blood pressure, kidney damage, and infertility.
Additionally, a study published last year by researchers at Florida State University found that lead poisoning, usually from gasoline, has robbed Americans of 2.6 IQ points each on average.
The researchers in the new study also tested levels of the metal cadmium. In marijuana users, cadmium levels were 22 and 18 percent higher in blood and urine than in non-users.
The International Agency for Research on Cancer (IARC) classifies cadmium as a known human carcinogen, meaning it can cause cancer.
According to the CDC, high levels of cadmium have been linked to lung issues, gastrointestinal problems like diarrhea and abdominal pain, kidney disease, and fragile bones.
Lead and cadmium get into cannabis plants through soil. Metals are naturally present here, though some soils have higher levels than others. This is because metals are sometimes present in pesticides and can be spread from construction and other industrialization.
Cannabis is a hyperaccumulator, which means it’s particularly good at absorbing heavy metals. Cannabis can be grown in several different environments since it has deep, wide roots, increasing the chance of being grown in high-metal soil.
The study comes as marijuana use is on the rise across the US.
A 2019 study by the Substance Abuse and Mental Health Services Administration (SAMHSA) found that nearly 18 percent of Americans, more than 42 million, used marijuana in that year.
The agency also estimates that one in 10 people who use marijuana become addicted to it.
A Gallup survey conducted last year also found that almost half of Americans (48 percent) have tried the drug for the first time, up from 45 percent in 2019 before the COVID-19 pandemic.
According to SAMHSA, marijuana has been linked to IQ loss, as well as mental health issues like depression and anxiety.