pollution liability: Several oil majors in the US have agreed to pay up US $423 million in what is billed as the largest settlement over drinking-water contamination involving 153 public water utilities in the country.

The water utilities from 17 states filed a class-action lawsuit in 2003 complaining that a petrol additive, methyl tertiary butyl ether (MTBE), used by oil refining companies was contaminating the groundwater. Experts say much of the MTBE found in groundwater and public drinking-water supplies stemmed from leaks in underground storage tanks of these companies.

The settlement requires about a dozen of oil refiners to make a cash payment to the water utilities and bear treatment costs for contaminated wells and other water sources over the next 30 years. The US Environmental Protection Agency classifies MTBE as a "known animal carcinogen' and a "possible human carcinogen'. Many US state governments banned the chemical in 2007 as it can affect the taste and odour of drinking water even at extremely deep levels.