WE are truly sorry to learn that the nine-year-old son of Dr B. W. Darvell, was injured in his foot by a satay stick while playing in the sand at Shek O Beach on Easter Monday (South China Morning Post, April 21). We fully support Dr Darvell's remarks about the ''callous, selfish stupidity of the kind of people who throw away such rubbish on beaches''. As a parent, I can fully appreciate his feelings about his son's injury but, it is unfair of him to accuse the Urban Services Department of ''superficial cosmetic cleaning of the beach''. Our staff work very hard to keep our beaches clean. We have placed 34 plastic litter bins on the sand-covered area of Shek O Beach. These are emptied once a day on weekdays and at least three times on weekends and public holidays. Our records show that during the Easter period about 130 baskets of rubbish (equivalent to 10 cubic metres) were collected from the beach on a weekday, and about 380 baskets (equivalent to 29 cubic metres) on a public holiday. All the rubbish collected is removed from the beach once a day. In addition, we also have a beach cleansing machine which cleans the sand-covered part of the beach early in the day when the beach is not so crowded. This mechanised cleaning is supplemented by manual picking of rubbish by our staff as the situation warrants. We hope that Dr Darvell and other readers will appreciate the fact that, no matter how much effort we put into cleaning our beaches, accidents like the one he complained of, will happen if beach goers do not heed our call to put rubbish where they belong- in the litter bins provided. As for dogs on beaches, we presume Dr Darvell is referring to stray dogs, as most beach goers know that they are not allowed to bring their dogs with them. If they do, they will not be permitted on our beaches. We will be asking the Agricultural and Fisheries Department to help us with the problem of stray dogs on our beaches. T. K. LAM Regional Leisure Manager (Hongkong West) for Director of Urban Services