Parents are paying an average of 5 per cent more for textbooks this year, a Consumer Council survey showed. More than half the schools surveyed received discounts of only 5 per cent from book stores this year. They had a 10 per cent discount last year. Two schools secured better bargains because they placed mass orders on behalf of their pupils. The 5 per cent increase was higher than the consumer price index, which rose 4.1 per cent in the year to July. "Parents have the burden of paying more for textbooks than the rate of inflation," said Professor Michael Hui King-man, chairman of the council's publicity and community relations committee. The finding came from a survey of the textbook lists of 47 primary and 42 secondary schools in the city last month, the council says in the latest issue of its Choice magazine. Other than the actual prices, textbook expenditure also varied with the number and kinds of books the schools chose. Primary school children spent an average of HK$2,399 on books, while those at secondary schools spent HK$2,489. Also in Choice is a report on home-use LED devices that claim to heal acne. Different models emit different-coloured light. The blue-light ones are of some value, while the rest - those emitting red, yellow or green light - are not, skin experts told the council. Even so, the effectiveness of blue-light devices varies, dermatologists say. "These devices are mostly safe, but their effectiveness is subject to further studies," Hui said. Professional use of the blue-light treatment is usually meant for patients who do not respond well to traditional acne medication. The light can kill acne-causing bacteria. The dermatologists warn the home-use devices might eventually darken the skin and worsen freckles in Asians. The energy output is much lower than in professional machines. The specialists doubt they can deliver the results as claimed. In some cases, the acne was healed but later came back.