A limit should be set on heavy metal contained in traditional medicines, experts said yesterday. Limits on heavy metals such as arsenate, lead and mercury would not only help patients but make it easier for the medicine to enter international markets, they said. Current regulations only stipulate the maximum concentration in solid and liquid food, not medicine. Mildred Yang Sze-ming, associate professor at the Hong Kong Baptist University's biology department, said latest studies on six Chinese drugs had found there were 168 micrograms in Lu Shen Wan - a traditional drug for sore throat - against the legal limit of 1.4 micrograms in solid food. 'It well exceeds the existing limit. But taking into consideration that the amount of Chinese medicine consumed is much smaller than that of food, the toxic metal contents of the medicine should not be evaluated by these standards,' she said. After taking dosage and body weight into account, it was found that the drug met the World Health Organisation's safety limits and local regulations. She said arsenate, lead and mercury were the top three in a list of 20 toxic and hazardous heavy metals in the US Agency for Toxic Substances and Disease Registry. 'Western countries would just simply ban importation whenever they see any of the three metals. 'But there is no such evaluation for Chinese drugs. Therefore setting a safety and quality standard is the most vital factor in developing Chinese medicine in Hong Kong,' said Professor Yang. The study, which was jointly conducted by Baptist University and the Xiamen University in Fujian, also found the concentration of heavy metals in the same drugs varied with different brands.