Scientists say marijuana alters DNA of sperm and 'may pose a risk' to smokers' fertility or even their future children
The study found that the drug alters the DNA of the sperm of the smoker and might affect his ability to conceive a child.
Scientists warn that men who are planning to have children with their partners must stop smoking marijuana at least six months before attempting to conceive the child. A study conducted at Duke University and published in the journal Epigenetics (a monthly peer-reviewed scientific journal covering research pertaining to epigenetics) shows that the drug alters the DNA of the sperm of the smoker. The Daily Mail reports that the study, led by Dr. Susan Murphy, was the first of its kind and used samples obtained from healthy men aged between 18 and 40 who admitted to smoking cannabis at least once a week for the past six months.
These samples were then compared against those of 12 men who had not used cannabis in the last six months and who had, at most, smoked the drug a maximum of 10 times over the course of their lives. Urine tests were administered to ensure the sanctity of the samples. Results showed that not only did cannabis users have significantly lower sperm concentrations than non-users — something that previous research had similarly proved — but more concerningly, also that the drug altered DNA responsible for growth and organ development.
Scientists also found a direct and proportional correlation between the amount of THC in the participant's urine and the extent of the changes in the DNA. Besides being responsible for organ development and growth, the genes that were affected by cannabis smoking were also associated with certain forms of cancer.
The study was inconclusive on whether the changes affected the smoker's fertility or would go on to have a negative impact on their future children, though the scientists said they were concerned about whether the sperm would even be strong enough to fertilize an egg.
They said they were planning to carry out a larger trial where they hoped to test the umbilical cord blood of babies born to fathers who smoke the drug to confirm whether any of the DNA changes are passed down from one generation to the next.
They also revealed they wanted to test if the effects of marijuana on sperm get reversed if the user stopped taking the drug, adding that while smoking affected the sperm, it could also have been influenced by other factors like nutrition, sleep, and alcohol.
Speaking about the study and its results, Dr. Murphy was quoted saying, "We know that there are effects of cannabis use on the regulatory mechanisms in sperm DNA but we don't know whether they can be transmitted to the next generation. In the absence of a larger, definitive study, the best advice would be to assume these changes are going to be there. We don't know whether they are going to be permanent. I would say, as a precaution, stop using cannabis for at least six months before trying to conceive."