Researchers at the University of North Carolina at Chapel Hill are working on a project they hope will provide a simpler method for male contraception. By exposing rat testicles to two 15-minute doses of ultrasound, they found that sperm counts dropped to levels that are usually associated with infertility in humans.
The research was performed with the help of a grant from The Bill and Melinda Gates Foundation, but is still far from ready for prime time. It’s still unclear, for example, if the effects are reversible, and whether there might be long-term damage from repeated doses. In addition, sperm must be killed completely rather than simply damaged, since damaged sperm could produce a child with birth defects.
"The last thing we want,” Allan Pacey, from the University of Sheffield told BBC News, “is a lingering damage to sperm."