British experts evaluated substances including alcohol, cocaine, heroin, ecstasy and marijuana, ranking them based on how destructive they are to the individual who takes them and to society as a whole.

Researchers analyzed how addictive a drug is and how it harms the human body, in addition to other criteria like environmental damage caused by the drug, its role in breaking up families and its economic costs, such as health care, social services, and prison.

Heroin, crack cocaine and methamphetamine, or crystal meth, were the most lethal to individuals. When considering their wider social effects, alcohol, heroin and crack cocaine were the deadliest. But overall, alcohol outranked all other substances, followed by heroin and crack cocaine. Marijuana, ecstasy and LSD scored far lower.