Alcohol Interlock Curriculum: Legal Concerns

Alcohol and the human body  Offenders may challenge the accuracy of breath test readings captured by the alcohol interlock.  For this reason, it is important that program authorities have a good understanding of how alcohol is metabolized by the human body.  “Alcohol” is the name of a family of closely-related and naturally-occurring chemicals.

Alcohol and the human body  Ingestible alcohol is known as ethyl alcohol or ethanol.  Ethanol is a central nervous system depressant.  It does not affect a person until it reaches a person’s central nervous system (e.g., the brain, brain stem and spinal cord).  Ethanol reaches the brain through the blood.

Alcohol and the human body  Absorption of alcohol. Alcohol can be ingested in a variety of ways. In most cases, it is ingested orally. Drinking on an empty stomach creates an ideal circumstance for rapid absorption. When alcohol gets into an empty stomach, about 20% of it will make its way directly through the walls of the stomach. The remaining 80% will pass directly through the stomach into the lower intestine from where it is readily absorbed into the blood.

Alcohol and the human body  Absorption of alcohol. When the brain senses food in the stomach, it commands a small muscle at the base of the stomach (the pylorus or pyloric valve) to cut off the passage of the stomach contents to the small intestine. Food and any alcohol remain trapped in the stomach. Some of this alcohol will begin to break down chemically. For this reason, a drinker’s BAC will not climb as high as it would have if he or she had been drinking on an empty stomach.

Alcohol and the human body  Distribution. Alcohol has an affinity for water but is less soluble in fat. Once in the blood, alcohol is distributed throughout the body in proportion with water content. Research shows that there are some important differences in the way that alcohol is distributed in men and women. A Swedish pioneer in alcohol research, E.M.P. Widmark, determined that the typical male body is about 68% water; the typical female body has only about 55% water. As a result, when a man and a woman drink exactly the same amount of alcohol under the same circumstances, the woman’s BAC will be higher.

Alcohol and the human body  Elimination of alcohol. As soon as alcohol enters the bloodstream the body starts to rid itself of the alcohol. Some alcohol (about 2-10%) is expelled by the body in a person’s breath, urine, sweat, and tears. The majority of alcohol is eliminated through the process of metabolism. Alcohol reacts with oxygen in the body and changes into carbon dioxide and water both of which are directly expelled from the body.

Alcohol and the human body  Elimination of alcohol. Most of the metabolizing of the alcohol takes place in the liver. The speed of this reaction varies somewhat from person to person, and even from time to time for any given person. On average, a person’s BAC will drop by about per hour. There is nothing that can be done to speed up the metabolism or the process of elimination. Drinking coffee, exercise, deep breathing or a cold shower will NOT speed up the elimination process.