Blood alcohol is the alcohol that has not been metabolized by the stomach, pancreas and liver and which makes it to the bloodstream. When a driver is pulled over, his or her breathalyzer result will give the officer an indication of how much alcohol is in the blood.
Every state in the US has a law that says blood alcohol levels above 8% will result in that driver being detained. Some states use the number 8% but other states represent the number more accurately as .08%. The correct number is .08%, or 8% of 1%.
The decimal conversion of .08% is .0008.
The average human body has about 9 pints of blood, or 144 ounces. Multiplying .0008 times 144 equals .1152 ounces. We can round that up to .12 ounces of unmetabolized alcohol in the blood which will show a blood alcohol level of .08%.
A teaspoon holds .17 ounces.
The human brain is responsive to very small volumes of what the blood delivers to it, as evidenced by this illustration of blood alcohol levels.
Less than a teaspoon of alcohol affects brain function.