Alcohol Facts by National Draeger
Routes
Alcohols are typically swallowed and the most common route of absorption is through the gastrointestinal tract. However, it may also be absorbed by inhalation, injection and direct insertion into the bladder or rectum. Whether or not absorption takes place by direct skin contact with alcohol is unknown.
Inhalation
Ethyl alcohol is readily absorbed by lung tissue, and both children and animals have become severely i8ntoxicated by breathing alcohol fumes in confined spaces. Approximately 62% of the inhaled alcohol will be absorbed into the blood regardless of the concentration in the air or the rate of ventilation. However, a concentration of alcohol high enough to produce a significant rise in blood levels is very irritating. Investigators have shown that inhalation of a 0.l9% alcohol-air mixture (about the highest tolerable limit) will produce a BAC of 0.045% only with forced respirations of 3 to 4 hours duration. Such conditions would not be obtained by industrial exposure to alcohol solvents.
Injection
Alcohol is detectable in the blood within 5 to 15 minutes after injection into a muscle or skin.
Insertion
When given as an enema, alcohol is readily absorbed by the large intestines (colon). Less than 10% of alcohol inserted in the bladder will be absorbed; alcohol passes more readily from the blood to the urine than from the urine to the blood.
Skin Contact
In experimental situations, no detectable blood levels have been obtained from alcohol rubs when care was taken that the subject did not inhale the alcohol. If absorbed via this route, apparently the rate of absorption is less than the rate of elimination.
Absorption from gastrointestinal tract
Alcohol is absorbed by various parts of the gastrointestinal tract as follows.
Mouth
Alcohol can be absorbed through the mouth lining; however, the amount is normally insignificant since fluid leaves the mouth rapidly. The mouth of a non-drinker rinsed with liquor will be free of alcoho9l after about 15 to 20 minutes.
Stomach
About 25% of the alcohol is absorbed directly into the blood stream through the stomach wall. The exact amount is variable and influenced by the emptying time of the stomach. In contrast, no other substances (even liquids) are absorbed from the stomach.
Small intestine
The remainder is absorbed from the small intestine; very little gets past the duodenum (the first 8 to 10 inches of the small intestines).
Rate
The rate of absorption varies somewhat from person to person and for the same person at different times depending on the condition of his body. However, alcohol begins to pass into the blood stream within 1 to 2 minutes after it is consumed, most alcohol is absorbed within 15 minutes, nearly 90% is absorbed within 1 hour, and nearly all is absorbed in 1.5 hours. Three hours may be required for complete absorption.
Factors that affect rate of absorption
Absorption through the stomach wall is slow and represents only a portion of total alcohol intake. Absorption through the small intestine is rapid. Therefore, anything that increases emptying time of the stomach increases absorption rate; anything that delays emptying time slows absorption rate. Both dilution of the alcoholic beverage and food in the stomach affect rate of absorption.
Dilution
Absorption is slow in dilute and strong beverages. It is fastest for a 20% water solution. Apparently very strong solutions irritate the gastrointestinal walls and inhibit absorption.
Food in the stomach
Food in the stomach delays absorption. Absorption is slowed since stomach emptying time is delayed. This applies to eating while drinking and to eating before drinking.
