With the holiday season in full swing, now is a great time to revisit that age-old topic of alcohol and pilots. Robert Louis Stevenson once famously said, “Wine is bottled poetry.”
Perhaps, still it hardly needs to be said to all of you out there that, poetry or not, alcohol has no place in the bloodstream of anyone operating any kind of dangerous equipment—especially high up in the sky. There are thousands of articles on the AOPA site and every other pilot publication on the topic but the problem never seems to go away. Driving and flying statistics according to the Department of Transportation are frightening. Every day, almost 40 people in the United States die in drunk-driving crashes; that’s about one person every half hour. In 2021, 13,384 people died in alcohol-impaired driving traffic deaths and that number represents a 14% increase from 2020. Alcohol use is cited as a factor in 40% of automobile accidents. The New England Journal of Medicine had a review on the use of alcohol in the cockpit and quoted similar numbers with 35.5% of fatal general aviation accidents linked to alcohol. Alcohol consumption around dangerous equipment is so risky because alcohol is a continuous depressant of brain function that impairs judgment, data interpretation, concentration, information processing, abstract reasoning, balance, and motor skills.
If the statistics are so well known and the risk of dying in an alcohol-related accident doesn’t seem to be enough to frighten some folks, maybe that post-celebration reminder of the “night before”—a few of those dreaded hangovers—would be a deterrent. A recent in-depth review lays out why and how our body reacts to alcohol intake that keeps us running to the bathroom on January 1. But first, to understand how we end up with that sick feeling after a night of partying we need to talk about how our body metabolizes alcohol. Although metabolism of alcohol varies in individuals, a 1.5 oz cocktail contains about 15g of alcohol (ethanol), and in the average 150-pounder that will cause a peak blood alcohol concentration (BAC) of about 0.02—0.04 percent. The negative effects of alcohol start to kick in when BAC reaches about 0.025%. That’s well within reach of even moderated drinking, and a couple of cocktails can push BAC well over the FAA legal limit to operate an aircraft of 0.04% and also the legal BAC for driving in most states of 0.08%. It takes a while for your body to metabolize even small amounts of alcohol, and that’s why the FAA has the “bottle to throttle“ rule of 8 hours.
Alcohol in the bloodstream passes through the liver where an enzyme, “alcohol dehydrogenase” (ADH), turns it into a poisonous metabolite called “acetaldehyde.” Not only is acetaldehyde a carcinogen (cancer cause), it’s used in the synthesis of a variety of organic compounds like perfumes, flavorings, aniline dyes, plastics, synthetic rubber, and other chemical compounds. That is not something any of us want floating around in our bloodstream, but if the liver systems work properly, this toxic chemical is quickly split up into an inert acetate byproduct that is safely excreted. If any of these chemical pathways to neutralize alcohol are overwhelmed by liver dysfunction or too much alcohol consumed over too short a time, the toxic stuff builds up, causing symptoms like dizziness, headache, nausea, and vomiting. If that sounds familiar, it is, and it’s known by another name—the dreaded “hangover.” Maybe that’s what Mark Twain was also talking about when he said, “At first you’re so sick you’re afraid you’ll die, then you’re so sick you’re afraid you won’t.”
Over time, if you put enough of the toxic metabolites of alcohol into your bloodstream, it can cause liver cancer or lead to liver failure (alcoholic cirrhosis), along with the breakdown of other systems in the body like the brain (Korsakoff’s syndrome), lungs, bones, heart, pancreas, and GI tract. The CDC publishes yearly reviews of “excessive deaths” from alcohol use and it’s no surprise that too much drinking can shorten individual life expectancy by a whopping quarter of a century (26 years to be exact)! In addition to alcohol-associated accident deaths, it also leads to 140,000 non-traumatic (illness) related deaths in the US per year. In our population, that adds up to almost 3.6 million years of potential life lost. The financial burdens to individuals and society in lost wages and income total in the trillions of dollars. Those are pretty sobering statistics (yeah, I know) considering alcohol is the most commonly used drug in our society.
The reason that some folks can drink more than others and not feel the same effect is that there are common mutations in the gene that makes the metabolizing enzyme, alcohol dehydrogenase. That means that there are wide individual variations in rate and efficiency of alcohol metabolism. Those enzyme variations lead to different levels and rates of accumulation of toxic acetaldehyde in the bloodstream and variation in all its side effects described above. There’s so much variation in individual ethanol metabolism that on the extreme end, there’s a rare condition appropriately called “auto-brewery syndrome” where ethanol is produced in the body endogenously without drinking anything. It’s usually associated with other diseases like Crohn’s disease and short bowel syndrome and is linked to the abnormal sugar fermentation by fungi or bacteria in the GI tract. Several strains of fermenting yeasts and rare bacteria are identified as pathogens. Patients who have auto-brewery syndrome will present with many of the signs and symptoms of alcohol intoxication without the intake of alcohol. There are cases of people with this syndrome who have been arrested for drunk driving after failure of field sobriety testing for a BAC that’s way above legal limits, and haven’t taken even one sip of alcohol (bummer).
The chemical process to clear alcohol from our blood system is applied to one of the treatments of alcohol addiction. It’s a medication called disulfiram (marketed with the catchy name “Antabuse”) that blocks the ADH enzyme medically and leads to the “mother of all” hangovers with alcohol use due to buildup of alcohol’s toxic byproducts. It’s tough love since the drug doesn’t prevent a user from drinking, but it sure makes the consequences of drinking incredibly unpleasant. Like I said at the start, maybe that’s what it takes to change the habits of some folks.
Don’t get me wrong, I’m not trying to throw shade on anyone’s holiday celebration, I’m just reminding everyone of one of life’s unavoidable lessons: pretty much anything in life taken in moderation is OK, but timing is everything. Don’t drink too much or too fast and give your system time to work its biochemical magic before you pick up a snow blower, chain saw, or car keys or grab the throttle. Happy holidays to all of you and as always, fly safe!