Tobacco comes from plants that are native to the Americas around Peru and Ecuador, where it has been found since prehistoric times. It was brought back to Europe by early explorers where it was adopted by society and re-exported to the rest of the world as European colonization took place. Smoking tobacco in pipes of one sort or other gave way to handmade and then manufactured cigarettes, especially during the First World War. Smoking rates increased dramatically during the 20th century in developed countries until recently and rates are still increasing in underdeveloped countries. An epidemic of smoking-related diseases has followed the prevalence of smoking. Scientific knowledge of the harmful effects of active tobacco smoking has accumulated during the past 60 years since early descriptions of the increasing prevalence of lung cancer. The first epidemiological studies showing an association between smoking and lung cancer were published in 1950. In 1990 the US Surgeon General concluded that smoking was the most extensively documented cause of disease ever investigated but governments worldwide have been ambivalent and slow in taking action to reduce smoking. Tobacco smoking is now agreed to be a major cause of a vast number of diseases and other adverse effects. Since the 1980s passive smoking including exposure in utero has also been implicated as a significant cause of numerous diseases. In response, the tobacco industry has managed to forestall and prevent efforts to control this major health problem.