WATER with arsenic in it may be the most poisonous drink for us, but for two strains of bacteria, discovered by French researchers, it is the daily means of sustenance. A stream flowing through the abandoned Carnoules lead and zinc mine in the Cevennes mountains in southern France was found to be the home of these bacteria.

Researchers led by Michel Leblanc from the French national research agency, CNRs, at the University of Montpellier, believe that the bacteria could belong to the Thiobaciiius and Leptothrix strains. These convert the soluble form of arsenic into a less toxic precipitate. Said John Fawell, chief toxicologist at the Water Research Centre in Medmenham, Buckinghamshire, "it would be extremely exciting if these bacteria could be used for treatment of drinking water".