Lead is even deadlier than we feared as the full extent of its toxic effects are revealed. Now the full effects of using lead in petrol – surely the greatest ever mass poisoning experiment. Last week, a massive new study concluded that lead is 10 times more dangerous than thought, and that past exposure now hastens one in every five US deaths. A similar effect is expected in Britain and other industrialised countries. The study found that deaths, especially from cardiovascular disease, increased markedly with exposure, even at the lowest levels. It concluded that lead kills 412,000 people a year – accounting for 18% of all US mortality, not much less than the 483,000 who perish as a result of smoking.