Hamburg  - Many USB charging devices are actually a genuine threat to the user's safety, a recent study by the Hamburg-based Computer Bild magazine found.

The magazine tested 30 charging devices, primarily for use with MP3 players with a USB port. Nine of the models had significant safety issues, the test showed. A high-voltage test even sent sparks flying in five of the devices.

The best grades were achieved by the USB WorldTravel power supply by Haehnel, followed by Vivanco Universal's USB power adapter NL 701 USB. For iPod-compatible models, the USB Charger for iPhone and iPod from Belkin earned top honours. Apple's USB Power Adapter came second. For USB charging devices with a car adapter, the MP3 Charging Set USB from Hama was the test winner. Among iPod-ready car adapters, the Belkin Power Pack for iPod was the best of the pack. (dpa)