DISPENSARIES illegally selling potentially lethal drugs to children should be blacklisted and have their licences cancelled, some district board members said yesterday. Shamshuipo District Board members Mervyn Cheung Man-ping and Lam Kin-lai, said one reason why the number of young drug addicts was increasing was the ease with which they could buy cough medicine, tranquilisers and sleeping pills from medicine stores. The members, who met Narcotics Commissioner Alasdair Sinclair yesterday, said penalties for unscrupulous dispensaries were far too low. The maximum penalty for selling potentially lethal drugs illegally is a $30,000 fine plus a 12-month jail term and cancellation of the licence. But no one had been jailed or had their licence cancelled and the fine usually ranged from $500 to $5,000 only, Mr Cheung said. ''We suggest any dispensary or drug store operators who sell drugs illegally should have their licence cancelled and be banned from operating the same kind of business again,'' he said. The pair called for more inspectors to carry out raids on the dispensaries and medicine companies. There were now only 10. ''Although there will be two extra inspectors soon, it is not possible for them to carry out sufficient checks on the several thousand dispensaries and medicine companies in Hong Kong,'' Mr Cheung said. Latest figures show there were 1,529 new drug addicts under 21 in the first nine months last year, compared with 983 in the same period in 1992. Mr Sinclair denied the problem was becoming very serious. He said legislation was tough enough, but there had to be more anti-drug education for youngsters, which would soon be included in teacher training at the two universities.