NAPLES, ITALY — It may not be an appealing thought, but hydrogen sulfide — the gas responsible for the stench of rotten eggs and automobiles’ catalytic converters — may hold a key to curing impotence.Researchers at the University of Naples Federico II in Italy have determined hydrogen sulfide plays a role in erections. They hope the revelation will lead to a safer alternative to Viagra.

Unlike Viagra, which is a vasodilator and can be dangerous for men with cardiovascular issues, hydrogen sulfide stimulates blood flow in the penis by relaxing hyperactive nerve cells, the Italian researchers noted in the journal Proceedings of the National Academy of Science.

“This may help to unravel the complex mechanisms underlying the physiology of human penile erection and may lead to the development of therapeutic approaches in the treatment of erectile dysfunction and sexual arousal disorders,” lead researcher Giuseppe Cirino wrote.

One in 10 men reportedly suffers from erectile dysfunction.

“There is certainly a need for an alternative to Viagra,” Dr. Graham Jackson, chairman of the Sexual Dysfunction Association, told BBC News. “It is only about 60-percent effective in people with diabetes and 80-85-percent effective for the general population.”