Global use of alcohol, drugs and tobacco.

Humans have always used drugs, probably as part of their evolutionary and nutritional heritage. However, this previous biological adaptation is unlikely to be so in the modern world, in which 2 billion adults (48% of the adult population) are current users of alcohol, 1.1 billion adults (29% of the adult population) are current smokers of cigarettes and 185 million adults (4.5% of the adult population) are current users of illicit drugs. The use of drugs is determined largely by market forces, with increases in affordability and availability increasing use. People with socio-economic deprivation, however measured, are at increased risk of harmful drug use, as are those with a disadvantaged family environment, and those who live in a community with higher levels of substance use. Substance use is on the increase in low-income countries which, in the coming decades, will bear a disproportionate burden of substance-related disability and premature death.