Sperm counts dropped by 62 percent in under 50 years — a decades-long trend that is picking up pace.

A low sperm count can contribute to adverse men's health outcomes, including "testicular cancer, hormonal disruption and genital birth defects, as well as declines in female reproductive health."

Hagai Levine, lead author of the study, called the issue a "crisis," warning the steep decline could get to an irreversible point.

"We have a serious problem on our hands that, if not mitigated, could threaten humankind's survival," he added.

Since 2000, there has been a yearly 2.64 percent decline in the number of sperm per milliliter of semen, more than doubling the number found since 1978.

While this study does not address potential causes, other studies have linked low sperm counts to obesity, sedentary lifestyles, smoking, and exposure to certain chemicals and pesticides.

Many such chemicals are found in widely used, everyday items ranging from personal care products to food packaging, according to study co-author Shanna Swan.