A major percentage of black tar heroin contains contaminants and additives that are toxic that can easily block blood vessels and significantly increase the risk of damaging the liver, brain, lungs, and kidneys. Other health risks of using black tar heroin include venous sclerosis, tetanus, wound botulism, abscesses, necrotizing fasciitis, overdose, and death.
https://recoverypartnernetwork.com/drug/illicit/black-tar-heroin