FIVE-YEAR-OLD Billy lay in bed in his Hong Kong flat, eyes closed in peaceful sleep. But his mother, watching over him, was troubled. For two months her son had had a persistent cough. Medical specialists suspected asthma. But nothing the doctors suggested had relieved the boy of his coughing and wheezing. Billy's mother felt she should not worry too much. Her son was a lively boy and chest X-rays had shown his lungs and respiratory tract were clear. But paediatrician Dr Tseng (who prefers to remain anonymous) took a different line of questioning: had Billy swallowed anything unusual lately? And gradually the problem afflicting the child emerged, leading to a report in the latest issue of the New England Journal of Medicine and new questions on toy safety. Four months earlier, his father recalled, Billy had swallowed a Lego piece the size of a peanut. He did not choke or have difficulty breathing at the time so the parents thought the part had simply passed through his system. Dr Tseng thought otherwise: 'I suspected the child's condition might have something to do with the piece of Lego. I stuck pieces of Lego similar to the one he might have swallowed on his shoulder with celluloid tape and stood him against an X-ray machine. 'The X-ray shows no Lego pieces. It was then that we discovered Lego, like many other toys, does not show up on an X-ray. They are what we technically call radiolucent. 'All along, we thought the child had asthma, when in fact, he had had a piece of Lego lodged in his airway for four months.' Billy's condition has led doctors involved in the case to ask why manufacturers do not make toys that are detectable by X-ray. Professor Andrew van Hasselt, chief of ear, nose and throat surgery at Chinese University, who successfully removed a cylindrical 0.5-centimetre piece of Lego from Billy's left lung in a 45-minute procedure, said: 'There may be a number of children, not just in Hong Kong, but anywhere in the world, who are now being treated for asthma when in fact they have a piece of a toy in their airways. 'I know of no toy that is plastic that is actually detectable via X-ray. This means nobody can tell they are there unless manufacturers actually put a compound in their toys to make them detectable. 'This can be done very easily and should not be harmful. All medical tubing, such as feeding tubes, are detectable by X-ray. And you don't have to make all toys radio-opaque. 'It is only the little toys that can be swallowed or that can go into the airways that we need to deal with.' Toys sold in Hong Kong have to follow standards stipulated in the Toys and Children's Products Safety Ordinance. They must meet one of three accepted sets of criteria: the International Committee of Toy Industries standard, the American standard and the European Community standard. The ordinance, which came into effect in 1993, is presently under review. The Government is planning to introduce new regulations in the middle of this year. But the new proposals deal mainly with identification marking and bilingual safety labelling. Making toys detectable via X-ray is not considered. Sansan Ching, director of the Hong Kong Council of Early Childhood Education and Services, said there were still unsafe toys on the market despite the ordinance. 'Some toys give out too much noise, which can harm children's hearing,' she said. 'Neither the ordinance nor the new proposals cover this aspect.' The Lego group said in a statement that various tests have been conducted for some years but they 'have unfortunately not made plastic or Lego elements detectable via X-ray'. The group said it was currently working to find a solution, but 'it does not seem that these technical problems can be solved for the present'. Andrew Tang, general manager of Inchcape testing services for toys, said manufacturers had considered making toys detectable via X-ray about five years ago. But he said it was not a general practice to do so. This was because a special chemical, barium sulphate, had to be used. 'Industry grade barium sulphate is not pure and can be toxic,' he said. 'Medical and food grade barium sulphate can be used but it is very costly.' The Consumer Council's chief research and testing officer Connie Lau Yin-hing said the case showed further study was required to look at the need to make toys radio-opaque, but she added: 'Parents should read the instructions carefully and supervise the child. 'The new proposals require all safety labels be bilingual which will help parents. 'But parents have to read the instructions carefully. Some toys are designed for older children and they should not think, 'my child is smart so he can have this'.' Dr Tseng said there was certainly a lesson for parents to learn: 'Our experience has shown that Lego is immunologically inert. Mr Tseng said it had caused no ongoing symptoms except periodic coughing during the months that it had lodged in the child's airway. In this respect Lego is considered safe. 'But the father told me the Lego toy was not meant for children as young as his son,' he said. Professor van Hasselt said since sophisticated tests had confirmed obstruction in the boy's left lung and a procedure to remove it was carried out, the child had been in good health and his cough had disappeared. He said that if the Lego piece had been slightly bigger, it could have lodged in the child's trachea, blocking both his airways completely. The child might have managed to cough it out or could have choked to death in a matter of minutes. 'This particular piece of Lego is the size of a peanut,' he said. 'It was quite a good fit in the child's airway. 'When it lodged there, it allowed a little bit of air to go up and down. This gave his left lung minimal ventilation, hence the child did not develop pneumonia. 'That's also why doctors detected wheezing with a stethoscope and suspected asthma.' Professor van Hasselt said objects in the nose were commonly encountered in his practice. In a four-year period, doctors at the Prince of Wales Hospital's department of ear, nose and throat surgery had come across 147 children under 12 with objects such as plastic beads, buttons, detachable parts of dolls and teddy bears, or broken parts of toy cars, nuts and seeds up their nose. He said although the presence of such items was not life-threatening, as it was in the airways, it could still result in injury. Eighty-six per cent of the 147 cases presented to the hospital from 1989 to 1993 were children between the ages of two and five. The youngest was nine months old. Doctors observed a cluster of patients arriving during holiday periods suggesting a greater tendency during this time to leave children alone at play. Button batteries in the nose are especially dangerous, doctors say, because of the narrow aperture, moist and relatively large surface with which they make contact. These batteries can also cause chemical and electrical injury. A study by Chinese University doctors on the hazards posed by button batteries has revealed seven paediatric cases locally. In each case, it was noted that the battery had leaked and in all the children, aged between two and five, the surface in contact with the negative pole had suffered severe damage. The study warns injury resulting from button battery impaction can have life-long consequences, damaging the growth of the nose. Ingestion of an alkaline battery is potentially fatal and if it gets lodged in the oesophagus, can cause severe injury. Vegetable matter such as peanuts which can expand and block the airways completely are especially dangerous. 'A peanut that goes down the wrong way constitutes a medical emergency,' Professor van Hasselt said. 'It will absorb moisture from body tissues and grow in size. This makes it very difficult to remove.'