Battlefield (Doctor Who)

After two hundred years of trying, the Earth finally had an age. His main work done, Patterson now turned his attention to the nagging question of all that lead in the atmosphere. He was astounded to find that what little was known about the effects of lead on humans was almost invariably wrong or misleading-and not surprisingly, he discovered, since for forty years every study of leadБЂ™s effects had been funded exclusively by manufacturers of lead additives. In one such study, a doctor who had no specialized training in chemical pathology undertook a five-year program in which volunteers were asked to breathe in or swallow lead in elevated quantities. Then their urine and feces were tested. Unfortunately, as the doctor appears not to have known, lead is not excreted as a waste product. Rather, it accumulates in the bones and blood-thatБЂ™s what makes it so dangerous-and neither bone nor blood was tested. In consequence, lead was given a clean bill of health. Patterson quickly established that we had a lot of lead in the atmosphere-still do, in fact, since lead never goes away-and that about 90 percent of it appeared to come from automobile exhaust pipes, but he couldnБЂ™t prove it ...»