Many slimming pills and detoxifying treatments sold in Hong Kong contain an ingredient that can cause serious health problems, a Consumer Council survey has found. Twenty-two out of 35 such products tested contained a stimulant laxative that can prove dangerous if taken for a prolonged period. The formulas contained anthraquinone - a chemical that occurs naturally in plants such as rhubarb, aloe and senna. Four of the products did not carry a label to warn consumers about the presence of the laxative. Products with the highest concentrations of anthraquinone were Selfit, Beauty and Healthy, and ESC Slimming Formula. The tests were conducted with the assistance of Chinese University's Institute of Chinese Medicine. The institute's Professor Paul But said anthraquinone had been known to cause chemical-induced hepatitis and even death when taken over a long period of time. Long-term use of stimulant laxatives could cause nausea, vomiting, abdominal cramps and drug reliance. 'Without taking this product the patient will not be able to have normal bowel movements. In some cases it has caused hepatitis and even death,' Professor But said. 'There are even two documented cases of people contracting hepatitis in Hong Kong.' According to the council's latest Choice Magazine, the United States' Food and Drug Administration has required laxatives to be clearly labelled after four people died from a suspected overdose of slimming tea. The Consumer Council's publicity and community relations committee chairman, Dr Lo Chi-kin, called on the Government to introduce comprehensive labelling requirements on detoxifying and slimming products. The Chinese Medicine Ordinance was passed in July 1999, but subsidiary legislation on the registration of herbalists and labelling is still pending. Currently it is the manufacturers' responsibility to prove claims about product efficiency and safety. Dr Lo said some manufacturers even claimed their products were free of adverse side effects and most failed to provide warning labels. 'Many of the products were labelled inconsistently, resulting in great confusion to the consumer,' Dr Lo said. 'For instance, the Chinese and English lists of ingredients were different, and so were the ingredient lists on the box and the insert. 'In one case, even the recommended dosage in Chinese and English was not identical.' The council has referred 10 of the products tested to the Department of Health for further investigation. A department spokesman said that five manufacturers were issued with warning letters because their products contravened the Undesirable Medical Advertisements Ordinance. The breaches were rectified immediately. The other five had medicinal claims but were not registered. The manufacturers were also issued warnings and rectified the claims. Long Far Herbal Medicine Manufacturing, which produces Beauty and Healthy and was named in the Consumer Council report, said last night its products were safe. It said that its products contained just three to five per cent anthraquinone concentration, which would not cause harm.