Cannabis exposure can alter sperm: Study

Exposure to cannabis may trigger structural and regulatory changes in the DNA of users' sperm, a study warns.

Researchers from Duke University Medical Center in the US suggest men in their child-bearing years should consider how tetrahydrocannabinol (THC) could impact their sperm and possibly the children they conceive.

Like previous research that showed tobacco smoke, pesticides, flame retardants and even obesity can alter sperm, the study shows THC also affects epigenetics, triggering structural and regulatory changes in the DNA of users' sperm.

Experiments in rats and a study with 24 men found that THC appears to target genes in two major cellular pathways and alters DNA methylation, a process essential to normal development, according to the study published in the journal Epigenetics.

The researchers do not yet know whether DNA changes triggered by THC are passed to users' children and what effects that could have.

"What we have found is that the effects of cannabis use on males and their reproductive health are not completely null, in that there's something about cannabis use that affects the genetic profile in sperm," said Scott Kollins, a professor at Duke.

"We don't yet know what that means, but the fact that more and more young males of child-bearing age have legal access to cannabis is something we should be thinking about," Kollins said.

The study defined regular users as those who smoked marijuana at least weekly for the previous six months.

Their sperm were compared to those who had not used marijuana in the past six months and not more than 10 times in their lifetimes.

The higher the concentration of THC in the men's urine, the more pronounced the genetic changes to their sperm were, the researchers found.

THC appeared to impact hundreds of different genes in rats and humans, but many of the genes did have something in common -- they were associated with two of the same major cellular pathways, said Susan K Murphy, an associate professor at Duke.

One of the pathways is involved in helping bodily organs reach their full size; the other involves a large number of genes that regulate growth during development.

Both pathways can become dysregulated in some cancers, researchers said.