Academics wanting to make a point of how careless people are with their personal data have uncovered what they suspect could be pornographic images involving children.
They also discovered details of a US defence contract along with personal information about a defence contractor that could be used for blackmail.
About 300 second hand computer hard disks were bought by researchers wanting to find out how well people protected sensitive data when they got rid of their old hardware.
Two of the drives were suspected of containing "potential paedophile" material, said Andy Jones, head of technology research at BT's security research centre. The drives, one found in Australia and one in Britain, were handed over to the police.
The point of the research was to find out if people were taking care to erase legitimate personal data when they got rid of their old computers; and whether it was possible to steal identities from old hard disks bought down the car boot sale.
Of the readable drives, 49 per cent contained sensitive personal information, found researchers from BT, the Universities of Glamorgan, Wales, and Edith Cowen, Australia and data wiping specialist LifecycleServices.
Jon Godfrey, of Lifecycleservices, said 95 per cent of people fail to properly erase their old hard disks before they throw them out.
"Every hard drive contains so much information about you [criminals] would be able to profile you as a person, your tastes, your habits," he said.
They were encouraged that more than twice the hard disks had been properly wiped compared to those they rifled through when they did the same survey last year. But 60 per cent of the disks were still stuffed with readable data, the research will reveal in the Autumn edition of the Journal of Digital Forensics Security and Law.
Commercial data appeared on 47 per cent, including the complete customer database of a telecoms firm. Another included a bid for a contract to build a US Navy Destroyer - along with embarrassing personal information about the contractor.
"For corporates, it's nothing short of negligence," said Jones. "They've a responsibility of care under the Data Protection Act and responsibility to their shareholders."
Most companies take care to wipe their data from old machines, he said. But some contracted the job out and never checked to see if their recyclers were doing a proper job.
The same topic was tackled from a similar angle by a BBC documentary on Monday. BBC Journalists discovered that computers being thrown into municipal tips were being sorted by councils and sold for reuse in India and Nigeria.
Drives unearthed in markets in such places as Lagos contained enough personal information about people in suburban Britain for their identities to be snatched quite confidently, said the report.®