The drug is made from natural herbs and is not toxic, said Ye Wenhu, one of the main developers of the drug and a former professor at the Medical Center of Fudan University.

Ye said the drug can restrain male mice's sexuality for at least three months -- long enough to prevent them from breeding since they usually live for only 12 to 14 months.

The center?s anti-mouse office is conducting tests on the drug's potential risks to the local environment before it can be put into use.

Results of the drug's effect in test cases will be made public by the year's end, center officials said.

They would not say what the odds are that the drug would be mass produced in the city so as to keep the mice population in check.

Other contraceptive drugs for mice have been designed in the past, but all were harmful to the environment, center officials said.

The new drug, if approved by the Shanghai municipal government and the Ministry of Science and Technology, may also be used in the country's northern grasslands, where rats have become one of the main contributors to desertification, land developers said.

Shanghai Xincheng Technology Co Ltd, a private pharmaceutical company, will mass produce the drug if officials give the green light.

(China Daily July 10, 2002)