I’ve posted a number of times on the problem of non-specificity of breathalyzers — that is, their inability to distinguish ethyl alcohol from thousands of other chemical compounds. See ”When Alcohol is Not Alcohol”. I’ve also discussed specific situations that commonly recur, including the presence of acetone on the breath of diabetics and folks on low-carbohydrate diets. See “Drunk Driver?…or Diabetic?“ and ”Dieting Can Cause High Breathalyzer Results”.
In today’s news:
Diet Clears Drinking-Arrest Pilot
London, April 7 (BBC) – A pilot arrested on suspicion of being over the alcohol limit has been cleared after tests found heavy dieting had caused his breath to smell like drink.
The Virgin Atlantic employee – held at Heathrow on 31 March before a flight to New York – had failed a breathalyser.
But blood samples taken from the 47-year-old prove his blood-alcohol level was consistent with a non-drinker.
Scientists say low-carbohydrate diets can produce acetone in the body, which may fool breath test equipment.
The long-serving pilot was said to have been on a heavy diet for a long period.
Acetone is a substance produced by the body as it tries to make up the glucose absent from low-carbohydrate diets.
Wayne Jones, a professor in experimental alcohol research at the University of Linkoping in Sweden, told the BBC breathalysers can sometimes fail to distinguish acetone from drink.
“Then there’s a risk you get a false positive reading,” he said.
Of course, prosecutors in the U.S. routinely tell DUI juries that this is just another defense attorney’s smoke-and-mirrors trick.