Arsenic-contaminated water can now be disinfected by exposing it to sunlight and air, according to scientists working with the Cooperative Research Centre for Waste Management and Pollution Control in Sydney, Australia. The ultra-violet radiation in sunlight helps the dissolved oxygen to oxidise arsenic to a less toxic form, which can then be precipitated as iron-arsenate using iron. This can then be disposed in landfills since it does not leach into groundwater. Purification of highly contaminated water using this method takes just a few hours ( New Scientist , Vol 152, No 2060).