SAO PAULO, March 28 (Reuters) - A Brazilian government-backed institute said on Wednesday that new testing confirmed elevated levels of heavy metals in waters near the world's largest alumina refinery, run by Norsk Hydro ASA , but the company for the first time questioned the validity of the scientific work.
Marcelo Lima, a public health researcher at the Evandro Chagas Institute, a research facility linked to Brazil's Health Ministry, told reporters the testing confirmed earlier findings of elevated levels of aluminum, lead and other contaminates in surface waters near populated areas around the Alunorte plant.
Hydro, in an emailed statement, pointed to "serious technical and methodological failings" by the institute and noted inconsistencies in the data on chemical levels found in surface water in a February study run by Lima.
The company, which has been forced to cut production following allegations of a toxic leak and could soon shut down three of seven alumina lines, also questioned the readiness of the Chagas Institute to carry out such testing.
Hydro said its own evaluations had found no evidence of pollution.
The Evandro Chagas Institute, in an emailed statement, acknowledged errors in its February report, which played a key role in a state court ruling that forced Alunorte to run at 50 percent of its capacity.
But the institute said that the errors were typographical, the testing itself was correct and conclusions drawn from their work remains valid.
A February thunderstorm dropped 200 millimeters (8 inches) of rain in 12 hours on the Alunorte plant, causing red water to flood streets, homes and areas of the Amazon rain forest near the plant, drawing the attention of authorities.
Hydro said it was "undertaking a detailed investigation into what happened in Alunorte during the extreme rainfall in February" and would release its own evaluation on April 9, based on the work of internal and outside expert groups.
Alunorte transforms bauxite into alumina, which is turned into aluminum at huge smelters. Hydro declared force majeure at the Alunorte unit in early March. (Reporting by Brad Brooks; Editing by Cynthia Osterman)