Marijuana users have high levels of toxic metals in their blood and urine, a study suggests.
Researchers at Columbia University in New York City found that non-nicotine cannabis smokers had 27 and 21 percent more lead in their blood and urine, respectively, than nonusers.
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 various health problems, such as high blood pressure, kidney disease and even cancer.
It is believed that they enter cannabis through the soil during the breeding process. The soil is becoming increasingly polluted 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, according to official data. A 2019 survey by the Substance Abuse and Mental Health Services Administration (SAMHSA) found that nearly 18 percent of Americans, more than 42 million, used marijuana that year
Dr. Tiffany R Sanchez, author of the study and a professor at Columbia University, said: “In the future, research on cannabis use and cannabis contaminants, especially metals, should be conducted to address the public health problems associated with the growing number of cannabis users.”
The study, published Wednesday in the journal Environmental Health Perspectivesused 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 in the past 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) of lead in their blood, compared to 0.93 ug/dl in nonusers. This is an increase of 27 percent.
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, especially those under the age of six, according to the Centers for Disease Control and Prevention (CDC).
However, exposure in adulthood has been linked to several health problems, including high blood pressure, kidney damage and infertility.
In addition, one study published last year Florida State University researchers have found that lead poisoning, mostly from gasoline, robbed Americans of an average of 2.6 IQ points.
The researchers in the new study also tested metal cadmium levels. In marijuana users, cadmium levels in blood and urine were 22 and 18 percent higher 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 problems, gastrointestinal problems such as diarrhea and abdominal pain, kidney disease and fragile bones.
Lead and cadmium enter cannabis plants through the soil. Metals are naturally present here, although 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, meaning it is particularly good at absorbing heavy metals. Cannabis can be grown in a variety of environments as it has deep, broad roots, making it more likely to grow in soil with a high metal content.
The study comes at a time when marijuana use is on the rise in the US.
A 2019 survey by the Substance Abuse and Mental Health Services Administration (SAMHSA) found that nearly 18 percent of Americans, more than 42 million, used marijuana that year.
The agency also estimates that one in ten people who use marijuana become addicted to it.
A Gallup survey last year also found that nearly 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 problems such as depression and anxiety.