Sigh...
Drugs users generally don’t know when their heroin is laced with fentanyl, so it's easy for them to inadvertently take a deadly dose of the substance.
www.statnews.com
Since 1979, the potent narcotic analgesic fentanyl and its analogs have been synthesized in clandestine laboratories and sold as heroin substitutes. At least 112 overdose deaths have been associated with their use. In this study, toxicology data, autopsy findings, and coroners' investigative...
pubmed.ncbi.nlm.nih.gov
"Although most of the fentanyl victims had a prior history of intravenous drug use, morphine or codeine were not commonly found, which suggests that the victims had little or no opiate tolerance. Ethanol was present in 38% of the cases and is thought to be a significant risk factor. Mean fentanyl concentrations in the body fluids were quite low: 3.0 +/- 3.1 ng/mL (0.3 +/- 0.31 micrograms/dL) in blood and 3.9 +/- 4.3 ng/mL (0.39 +/- 0.43 micrograms/dL) in urine, measured by radioimmunoassay."
"Clinical analgesic doses produce plasma levels of 0.3–0.7ng/mL; doses greater than 3 ng/mL cause loss of protective airway reflexes and CNS depression."
George Floyd's fentanyl blood concentration:
11 ng/ml
"
Fentanyl at 11 ng/ml — this is higher than chronic pain patient. If he were found dead at home alone & no other apparent cause, this could be acceptable to call an OD.
Deaths have been certified w/ levels of 3"
For anyone who doesn't math very well, 11/3 = 3.6, which I rounded up to 4 for brevity. Assuming that Floyd had some opiate tolerance, and adjusting for his size, you could reasonably estimate that he had at least 2x the amount of Fentanyl in his system necessary to kill him.