Electronic anti-theft devices used by retailers to detect and de-activate magnetic security tags hidden in items of clothing may be exposing children to harmful levels of radiation scientists have warned. And the onus is on the manufacturers of this equipment will have to demonstrate that their appliances are safe. 

A study carried led by Om Ghandi, professor of electrical engineering at the University of Utah, found that the sensors used at checkouts and in door guards produced electro-magnetic field levels at or exceeding the maximum safety standards prescribed by the International Commission on Non-Ionising Radiation Protection (ICNIRP). For five-year-olds they were more than double the limit.

The report in 'Physics in Medicine and Biology' showed that the amount of electric current in tissues such as the brain and the spinal cord were increasingly larger the smaller the person, since the level of radiation from both devices was greater at a child's height than an adult's.

"Our results show that limits must be put on the magnetic fields used in these devices if they are to comply with the safety regulations," said Professor Gandhi.

His concerns were echoed by Dr Michael Clark, spokesman for the UK National Radiological Protection Board, who said that the results should be a cautious warning to parents and manufacturers.