Donations can be in money, goods, blood, organs and bone marrow. But what happens when you mix heartfelt charity with a handful of self-gratification? Sperm donation.

And college students are taking a leading role in this field in China.

Nearly 10 percent of China's couples cannot conceive, with male infertility being the reason for one-third of them. Experts put the blame on pollution, work-related stress and unhealthy lifestyle.

College students, however, have come to the rescue of many such couples, even though sperm donations still fall short of the demand, said an official of Beijing's only sperm bank. The country has 10 such banks.

Myths such as "one drop of semen equals 10 drops of blood" prevent people from donating sperm, said Chen Zhenwen, director of the bank, affiliated to the National Population and Family Planning Commission of China.

Thankfully, college students don't share any such belief and "are more willing to help", Chen said. "Many of them are Beijing Olympic volunteers."

Several hundred volunteers, half of them college students, have approached the sperm bank since it opened in late 2005.

A donor's sperm can be used to impregnate five women, according to the Ministry of Health (MOH).

"We donate blood and bone marrow, then why can't we donate sperm. After all, it can help fulfill barren couples' dream of having a child," said Xiao Wang (name changed). But the Beijing college student hasn't told his girlfriend about the donation.

Most college student donors lead a comparatively healthy and orderly life, said experts, stressing that they are among the best donors.

Unlike what some people may think, sperm donation is not just about walking into a place, having a pleasant five minutes with yourself and handing over your happiness in a cup. One has to pass tests for STDs and genetic and infectious diseases. And the entire process can take a couple of months.

"It's a long and demanding process which requires great patience and commitment, and the schedules have to be largely flexible for the young donors," Chen said.

"A college student donor even paid his airfare to complete the donation process after graduating from a university," he said. Which means students don't donate only for money, even though they get 2,000 yuan ($260) for a successful donation.

Chen asked students to be wary of "sperm hunters" on the campus, however. Such people can take students for a ride. Students should always verify the identity of "agents" before agreeing to donate.

Sperm trade outside the 88 institutions approved by the MOH is banned in China. And only these institutions can offer IVF (in vitro fertilization).

Sperm donation should, however, be handled very carefully, said Qiao Jie, head of the reproduction center of Peking University Third Hospital, China's biggest fertility clinic.

"Evidently, it (sperm donation and IVF) helps complete a family... but ethical concerns and the setting up of a sound system to track the use of sperm should not be ignored. Or else, there could be a tragedy of biological siblings getting married," she said.