WSU study: Cannabis affects sperm counts in mice

PULLMAN, Wash. — A Washington State University study showed that intense but short-term exposure to cannabis vapor lowered sperm counts and slowed sperm movement not only in male mice that were directly exposed but also in their sons.

The study builds on other human and animal studies showing that cannabis can hamper male reproductive function.

“The current study uses more controlled circumstances than human studies, which often have to rely on surveys, and is the first known reproductive study to use vaporized whole cannabis in mice, which is the more common form humans use.

“Previous animal studies use other administration methods such as injections of THC,” a news release from the WSU School of Molecular Biosciences in the College of Veterinary Medicine said.

More research needs to be done, but the paper’s corresponding author, Kanako Hayashi, said the study’s findings should give male cannabis users who want to have children something to think about.

“This is a warning flag. You may take cannabis for some kind of momentary stress, but it could affect your offspring,” said Hayashi, who is an associate professor in WSU’s School of Molecular Biosciences.

According to some estimates, sperm counts in humans have declined by as much as 59% in recent decades.

Hayashi said there are probably many reasons for the decline, but the study adds to the evidence that using cannabis may negatively affect male reproductive function.

In the study, researchers studied 30 adult male mice and exposed half of them to cannabis vapor three times a day for ten days. Researchers said the intense amount mimics the intake of frequent cannabis users.

The researchers then compared sperm counts and sperm movements in those mice to the other half of mice that were not exposed.

They found that right after the exposure period, the mice’s sperm movements decreased, and after a month, sperm counts were lower.

Read the full study published in the journal Toxicological Sciences.