A pollution outbreak occurred subsequent to an accident involving a tanker lorry transporting 21 tonnes of thioglycolic acid. At about 7 am, the lorry missed a curve, rolled over and fell 30 m into a ditch. Nearly 12,000 litres of acid escaped from barrels and cans before spilling into the ILLOUVRE, a tributary of the VERNAZOBRE. As a preventive measure, water extraction and fishing were prohibited downstream of the accident. Information announcements advised residents of 4 neighbouring towns to avoid the watercourse. After initial analyses, the concentrations measured around the various water supply extraction points were below the 1 mg/litre detection threshold. It seems that all possible traces of product were trapped either by the production facilities or via the filtering mass of the alluvial fan. Consequently, pumping was authorised from both the ORB River and the groundwater. Water quality monitoring was upgraded in order to halt pumping as needed. Following their on-site response, 48 fire-fighters and 17 gendarme officers suffering from irritations and rashes were hospitalised out of precaution.