In a story May 4, The Associated Press reported on research that found drilling fluids likely leaked into a drinking water supply in Pennsylvania. The story should have noted that one of the study's authors, Garth T. Llewellyn, was a consultant for affected homeowners who sued the driller. That information was not included on a pre-publication version of the study provided to reporters by the journal Proceedings of the National Academy of Sciences, but it was later added to the published version.