"Sunoco's use of deadly hydrofluoric acid at its Philadelphia refinery has come under scrutiny after a March accident that sent 13 contract workers to the hospital.
The Occupational Safety and Health Administration last month cited Sunoco Inc. for four "serious" violations related to the March 11 incident. Sunoco said the 13 workers had received "precautionary" medical treatment after a 22-pound release of hydrogen fluoride, the gaseous form of hydrofluoric acid.
The U.S. Chemical Safety Board last month announced it was investigating two other hydrogen fluoride releases during the summer at refineries in Illinois and Texas.
'Because of its high toxicity, any loss of primary containment for hydrogen fluoride is a serious matter,' said John Bresland, chairman of the board, an independent federal advisory panel."