Researchers say chemicals in cannabis alter DNA, which can cause gene mutations that raise the risk of cancer and other diseases.

Cannabis - also referred to as marijuana - is the most commonly used illicit drug in the United States, though legalization of the drug for medical or recreational use is increasing across the country.

According to the National Institute on Drug Abuse (NIDA), around 22.2 million people in the U.S. have used marijuana in the past month, and studies have suggested that use of the drug has increased significantly in recent years.

Given the high number of individuals using cannabis, it is important to establish its effects on health.

Study authors Albert Stuart Reece and Gary Hulse - both of the School of Psychiatry and Clinical Sciences at the University of Western Australia - note that previous research has suggested a link between cannabis use and increased risk of severe illnesses.

The mechanisms underlying this association, however, have been unclear. And researchers have had little insight into how cannabis use may affect future generations.

Cannabis-related DNA damage can be passed to future generations

To investigate further, the team conducted an in-depth analysis of previous studies and literary material assessing the effect of cannabis use on cells and how this might relate to disease risk.

The researchers recently published their findings in the journal Mutation Research/Fundamental and Molecular Mechanisms of Mutagenesis.

They found that the chemical properties of cannabis - including tetrahydrocannabinol (THC), the active ingredient of the drug - interact with and alter users' DNA, which can lead to gene mutations that increase the risk of disease.

"With cannabis use increasing globally in recent years, this has a concerning impact for the population," says Reece.

The researchers point out that even if a user does not develop an illness as a result of such mutations, the "unseen" damage can be passed to their children, and even their grandchildren, increasing their risk of disease.

"Even if a mother has never used cannabis in her life, the mutations passed on by a father's sperm can cause serious and fatal illnesses in their children.

The parents may not realize that they are carrying these mutations, which can lie dormant and may only affect generations down the track, which is the most alarming aspect."

Albert Stuart Reece

Reece explains that when cannabis chemicals alter a person's DNA, this can slow the growth of cells. This may have severe consequences for fetal growth, causing underdeveloped organs or limbs, and it can spur childhood cancers.

"The worst cancers are reported in the first few years of life in children exposed in utero to cannabis effects," notes Reece.

The authors conclude that their findings may have important implication for researchers, healthcare professionals, and policymakers when it comes to regulating cannabis use, and there should be focus on protecting individuals who are most vulnerable to the negative health implications of the drug.