High-speed optical CD-Rom drives can be dangerous when used with CDs containing small cracks, according to research.

Because of the high speeds of modern drives, the CDs can shatter and, in certain circumstances, blow fragments of sharp plastic through the front of the drive at a speed that could cause serious injury.

Research Machines, an integrator in the academic sector, has warned that drives from many manufacturers are susceptible to this phenomenon, especially as a majority of them now run at 48x or faster.

Fiona McLean, spokeswoman for Research Machines, said that it would take an incident where someone is injured before PC manufacturers took action.

"We deal with schools where CD drives are generally set at the eye-level of children. Our lab tests have shown sharp pieces of plastic being ejected at force from the CD drives. It's only a matter of time before someone is blinded," she said.

As a result, Research Machines have developed a safety policy that includes fitting metal shields to CD drive trays, moving them away from head height and downgrading the firmware on the drives so they cannot spin faster than 42x.

St Andrews University, Edinburgh, has also reported at least one case where a user "has experienced the front of his CD-Rom drive being blown off by a disintegrating CD".

"Don't laugh - it has happened," the university warned. CD-Rom drive manufacturers have been made aware of the problem and some are already taking steps to reduce the likelihood of disintegration and to limit the resultant damage if it does occur.

CD drive manufacturer Viglen has released an advisory on the phenomenon, acknowledging that although there is an issue, "there is an exceptionally small risk of this happening. The standard speed for CD-Rom drives has been 48x for over two years, with millions of drives sold," the company said.

Viglen said that modern drives, spinning faster than 10,000RPM, exert extreme forces on the disc and, in rare cases, the use of poor quality, cracked media can result in the CD splitting or shattering inside the drive.

There is also a possibility that such fragments may penetrate the CD-Rom drive front panel. The company added, however: "it is important to understand that the problem will only occur when a defective CD is used in the CD-Rom drive."

Other researchers have suggested that the prevalence of cheaper media, particularly on the CD-R and CD-RW market, may be escalating the potential for disaster because of the thinner plastic that manufacturers tend to use in their construction.

But Viglen said that "although 'cheap' CDs may be more susceptible to damage, any CD may become defective".