Campaigners have reacted with dismay after the Obama administration refused to stop classifying marijuana as a dangerous drug with no medical use - even though government research has shown it can kill cancer cells. The Drug Enforcement Administration (DEA) said it would continue to list marijuana as a co-called “Schedule I” drug, placing it on par with heroin. The government has repeatedly rejected appeals for reclassification. (See also: What Congress is saying about the DEA’s refusal to change course on pot | The DEA’s marijuana decision is more important than rescheduling)