Mexican environmental authority Profepa said it is investigating the possible environmental impact produced by a 50,000t tailings spillage at Grupo Frisco's [part of the Carso Group] Minera María copper mine in Sonora state…"What is clear is that the tailings are not corrosive or toxic, in other words they are not dangerous," Profepa said…A subcontracted worker was killed as a result of the spillage [said] Minera María's human resources director José Luis Ramírez…Frisco company officials were not immediately available for comment.