Factors affecting contamination of blood samples for ethanol determinations

Contamination of blood samples collected for alcohol analysis from swabbing with an ethanolic antiseptic is minimal (less than 0.6 mg/100 ml or 0.0006 percent ethanol) when routine clinical technique is followed. When technicians were told to be deliberately sloppy, considerable contamination (89 mg/100 ml or 0.09 percent ethanol) occurred. The incidence and extent of contamination from banked blood intended for transfusions are minimal. Two percent of the 1,450 samples analyzed contained alcohol. The average blood alcohol concentration was 26 mg/100 ml or 0.03 percent ethanol. One microliter of rubbing alcohol per milliliter of whole blood, or one-tenth of a drop of rubbing alcohol per milliliter of whole blood, increases the BAC 56.5 mg/100 ml (0.06 percent ethanol) and 67.5 mg/100 ml (0.07 percent ethanol), respectively.