Look up the work of a doctor called David Nutt. He has talks on youtube. Here is one of his studies. Copy paste url/doi or pmid into sci hub for full article https://www.ncbi.nlm.nih.gov/pubmed/21036393
FINDINGS:
MCDA modelling showed that heroin, crack cocaine, and metamfetamine were the most harmful drugs to individuals (part scores 34, 37, and 32, respectively), whereas alcohol, heroin, and crack cocaine were the most harmful to others (46, 21, and 17, respectively). Overall, alcohol was the most harmful drug (overall harm score 72), with heroin (55) and crack cocaine (54) in second and third places.