Dr. Sanjay Gupta and I have been traveling for the upcoming documentary “Planet in Peril: Battle Lines.” We visited the small town of La Oroya, Peru a couple of times...home to the Doe Run Peru [part of Renco] smelting complex...It is a place where the air irritates the eyes, befouls the mouth, stings the nostrils and heavies the chest. In this town of 35,000 people, 99 percent of children living in and around La Oroya have blood lead levels that exceed acceptable limits...Lead poisoning is insidious...We interviewed Doe Run Peru’s president, Juan Carlos Huayhua. While his company is making major technological improvements and sponsoring community health programs, it recognizes that more needs to be done.