Smoking marijuana can alter a person’s DNA, accelerating aging and leading to birth defects in their future children.
The drug has boomed in popularity over the last decade. It is now recreationally legal in 24 US states and daily use of weed has surpassed that of alcohol.
But new findings have warned of the dangerous health implications, including faster aging, increased cancer risk and fertility problems.
Researchers from The University of Western Australia looked at more than 50 global studies investigating the effects of cannabis use on the body and said the startling statistics should ‘reframe the discussion of cannabis legalization.’
Co-author Dr Stuart Reece said: ‘This new research shows how genetic damage from cannabis use can be passed down the generations. This should reframe the discussion surrounding cannabis legalization from a personal choice to one that potentially involves multiple subsequent generations.’
They say premature aging is one of the most common effects of marijuana and a recent study found long-time users who were 30 years old showed they had a biological age of 30 percent higher.
The study involved 154 participants from a small city in the southeastern US, who provided blood samples that yielded two indices of epigenetic aging from age 13 to age 29 and at age 30
The blood tests, that measured chemical tags on DNA, showed any increased risk of chronic obstructive pulmonary disease (COPD), type 2 diabetes, ischemic heart disease, COPD and lung cancer.
Study authors say these age-related health issues are ‘extremely worrying,’ and even more so because other bodies of research have shown certain ailments can be passed on to future generations due to irreversible DNA damage.
Cannabis is now legal in 24 US states and the daily use of weed has surpassed that of alcohol across the country
They point to strong evidence – drawn from both comprehensive US and European studies – showing the link between cannabis and congenital anomalies.
Along with cardiovascular, limb, and gastrointestinal abnormalities, both human and rodent studies ‘show that adult cannabis exposure is linked with the incidence of autism and cerebral processing difficulties in children prenatally exposed.’
Additionally, childhood cancers have been linked to cannabis use among parents.
A study by Duke Health found prenatal cannabis use was associated with an increase of tumors of the central nervous system, while a rodent study found paternal consumption of marijuana prior to conception altered offspring brain development.
The University of Western Australia researchers also highlight a ‘high rate of known fetal loss’, with some studies suggesting marijuana use can trigger miscarriages and still births.
According to research funded by the National Institutes of Health, women who use marijuana during pregnancy face a 2.3 time greater risk of stillbirth.
In terms of cancer risk among smokers and their offspring, the authors say ‘historically, the cancer-cannabis link has been controversial.’
This is because ‘differing results in published studies may be attributed to various factors including multiple exposures (including tobacco), differences in study design and the rapid rise of cannabis potency.’
However, recent studies suggest using marijuana over a long period of time may increase the risk of cancer among adults, particularly cancers of the lung, head, and neck.
‘The literature on cannabis and testicular cancer is almost uniformly positive and has a relative risk of around 2.6-fold,’ the authors add.
Federal research has shown that cannabis use is growing, particularly in Americans under the age of 30
They say the effect of marijuana can be ‘quite fast since the median age of exposure may be about 20 years and the median age of testis cancer incidence is only 31 years.’
From the evidence, it is not clear how much cannabis use can cause long-lasting damage.
Summing up their report, which was published in Addiction Biology, the authors describe the ‘present time’ as a ‘watershed moment.’
They highlight that the ‘new profoundly insightful studies’ should serve as a ‘trigger’ for change.
As legal pot is more potent than ever and with little regulation, the authors say the health implications can be more catastrophic.
The findings come just months after the Drug Enforcement Agency (DEA) proposed to downgrade marijuana’s legal classification.
The plan is to move it from Schedule 1, which has the highest potential for abuse with drugs such as heroin and ecstasy, to Schedule 3, alongside the likes of ketamine and some anabolic steroids.
Schedule 3 drugs are still controlled substances and subject to rules and regulations, and people who traffic in them without permission could still face federal criminal prosecution.
Recreational marijuana is legal in 24 states, though others have legalized it only for medicinal purposes
When it is enforced this rescheduling, however, will not automatically legalize marijuana for the whole US.
Recreational marijuana is currently legal in 24 states, and 13 allow for limited medicinal use.
As the substance becomes legal in more states, use and addiction has also become more prevalent.
An NIH-funded study, for example, found that marijuana use among young adults reached an all-time high of one in 12 in 2021.
Rates surged the most in states like California, which legalized recreational cannabis in 2018.
