Workers in factories that make flat screen televisions could suffer long-term health damage, say scientists.
Flat screen televisions are becoming hugely popular
A healthy 30-year-old man developed a serious lung disease after being exposed to a type of metal oxide used to coat the screens.
Doctors at Toranomon Hospital in Tokyo found tiny deposits of the compound in the man's lungs, according to a report in the European Respiratory Journal.
But British consumers have been assured buying the televisions poses no risk.
A spokeswoman for the Information, Technology, Telecommunications and Electronics Association, known as Intellect, said: "These screens are manufactured in the Far East and by the time they reach the UK, they are totally sealed.
"There is no health risk whatsoever to UK buyers."
Flat screen TVs are proving more popular than ever. Sony, the world's largest consumer-electronics group, recently announced it was struggling to meet demand in Europe, with sales doubling in the six months to September.
But now Japanese doctors have raised concerns about whether this boom is threatening the health of employees who make them.
They examined a man who had been working on flat screen TVs for four years, during which time he was repeatedly exposed to an aerosol containing indium-tin oxide (ITO).
He had become ill with a devastating respiratory condition called pulmonary fibrosis.
This is a disorder of the lung tissues that are involved in exchanging oxygen and carbon dioxide.
It leads to scarring and thickening of the lung tissue and kills half its victims within five years.
The young man also had emphysema, another potentially fatal lung disorder that leaves sufferers struggling for breath.
When doctors examined the employee's lungs, they discovered tiny particles of ITO.
This is a type of metal oxide used in liquid crystal displays or plasma display panels for TVs, computers and video monitors.
Only one previous incident of a fatality due to inhaling ITO has been documented.
But it was an employee who worked at the same production plant as the latest case.
Doctors who made the discovery called for more research on the possible toxic effects of ITO in order to protect industry workers against future health damage.
"As industrial consumption of ITO rises, the potential health hazard caused by occupational exposure to indium compounds has been attracting much more attention.
"Maximum measures should be taken to protect workers from the potential toxicities of indium compounds."
The Intellect spokeswoman said flat screen TVs used in Britain are also safe when they are finished with.
This is because disposal has to comply with an EU directive that governs the handling of potentially harmful materials in consumer goods.