Tobacco and alcohol pose a greater threat to human health around the globe than the use of all other addictive, illicit drugs, scientists say. A study, published in the journal Addiction, showed that in 2015 alcohol and tobacco use between them cost the human population more than a quarter of a billion disability-adjusted life years, with illicit drugs costing a further tens of millions. Researchers including those from University of New South Wales in Australia and University of Bristol in the UK found that the largest health burden from substance use was attributable to tobacco smoking and the smallest was attributable to illicit drugs. Global estimates suggest that nearly one in seven adults (15.2 per cent) smoke tobacco and one in five adults report at least one occasion of heavy alcohol use in the past month. Compared with the rest of the world, Central, Eastern, and Western Europe recorded consistently higher alcohol consumption per capita (11.61, 11.98 and 11.09 litres, respectively) and a higher percentage of heavy consumption amongst drinkers (50.5 per cent, 48.2 per cent, and 40.2 per cent, respectively). The same European regions also recorded the highest prevalence of tobacco smoking (Eastern Europe 24.2 per cent, Central Europe 23.7 per cent, and Western Europe 20.9 per cent). In contrast, use of illicit drugs was far less common. Fewer than one in twenty people were estimated to use cannabis in the past year, and much lower estimates were observed for amphetamines, opioids and cocaine. Hotspots included the US, Canada, and Australasia. The US and Canada had one of the highest rates of cannabis, opioid, and cocaine dependence. Australasia had the highest prevalence of amphetamine dependence, as well as high rates of cannabis, opioid and cocaine use dependence (693.7, 509.9 , and 160.5 per 100,000 people, respectively). Some countries and regions (eg Africa, Caribbean and Latin America, Asia regions) have little or no data on substance use and associated health burden. These are typically low or middle income countries that frequently have punitive drug policies, and may experience serious political and social unrest. These countries need enhanced monitoring because they are at risk of rapid escalation in substance use and related health burden.