Once, when analyzing what was suspected to be a counterfeit antimalarial pill, his team discovered traces of sildenafil, the main ingredient in the anti-impotency drug Viagra.
Increasing use of birth control pills is also contributing towards rising impotency, he said.
Chinese state media say U.S. drug maker Pfizer has won a court case in China against two companies which were copying its immensely popular male impotency treatment, Viagra.
Earthworms have been eaten to cure impotency.
