Archive for December, 2004

DUI, Field Sobriety Tests and “Circadian Rhythm”

Thursday, December 30th, 2004

Most drunk driving arrests take place at night, often after midnight. One reason for this is that many police officers engage in "cherry picking" — that is, the illegal practice of staking out bars and restaurants from about 10:00am to "closing time", pulling cars over on some pretext as patrons leave and drive away. It is during this period of time that the individual’s circadian rhythm is taking effect. The circadian rhythm is that 24-hour biological alarm clock in each of our bodies, most noticeable when we experience "jet lag".

Researchers have found that individuals will perform more poorly in tests during the low point of the circadian rhythm — that is, during the hours after midnight and into the early morning. It is just such tests — called "field sobriety tests" — that officers use to determine whether a driver is intoxicated or not. Specifically, British physicians and psychiatrists reported that "the same blood alcohol level is associated with a significantly greater impairment of different aspects of psychological funtioning when achieved in the morning." "Circadian Variation in Effects of Ethanol in Man", 18 (Supp. 1) Pharmacology, Biochemistry and Behavior 555. The researchers concluded that "the differences we have found…must be attributable to circadian change and susceptibility of the body to its effect."


Urinalysis: Unreliable for Blood-Alcohol

Tuesday, December 28th, 2004

In many states, a suspect’s blood-alcohol concentration can be determined with urinalysis. This is consistently the least accurate of the three available methods of analysis. The reasons for this are basically two.First, the test is completely dependent on the subject voiding his bladder and then waiting 20 minutes for fresh urine to be secreted into the bladder for a more representative sample. And it is virtually impossible for an individual to completely void his bladder: There will usually be about 10cc of old urine left. This urine will combine with approximately 20cc of fresh urine produced during the wait, resulting in a sample that is one-third old urine — a sample that will contain alcohol from many hours before the subject was driving.

Second, urine often contains a yeast called Candida albicans. This organism has an interesting characteristic: it manufactures alcohol in the urine (caused by the interaction with glucose). This "immaculate conception" of alcohol in the bladder has been confirmed by numerous scientific studies. See, for example, "Bladder Beer — A New Clinical Observation", 95 Transactions of the American Clinical Climatological Association 34. To make things more interesting, Candida albicans is also unaffected by preservatives added by the police to urine specimens. In other words, alcohol will continue to be produced inside the evidence vial for days until it is finally analyzed at the crime lab.


How Not to Beat the Breathalyzer

Tuesday, December 21st, 2004

Item from the Red Deer (Alberta, Canada) Advocate:


STETTLER — An 18-year old Stettler man tried to eat his underwear in the hope that the cotton fabric would absorb alcohol before he took a breathalyzer test, provincial court heard this week.

David Zurfluh was subsequently acquitted of a charge of impaired driving because he blew .08, the legal limit. But the testimony broke up people in Judge David MacNaughton’s provincial court here Thursday afternoon.

Mr. Zurfluh was collared by RCMP Const. Bill Robinson after he ran from his vehicle, which had been seen weaving down the highway. While sitting in the back of the patrol car, Mr. Zurfluh tried to eat his shorts, Const. Robinson told the court.

Mr. Zurfluh said he ripped the crotch out of his shorts, stuffed the fabric in his mouth and then spit it out. A class of law students from William E. Hay Composite High, in court as observers, was removed by the teacher when testimony enlivened the proceedings.

The Grade 11 and 12 students had difficulty maintaining composure. "People were leaving the courtroom with tears in their eyes, trying not to laugh," said RCMP Const. Peter McFarlane.


“Slurred Speech”: Evidence of DUI?

Sunday, December 19th, 2004

As with the odor of alcohol on the breath, few police reports will fail to include an observation by the arresting officer that the arrestee exhibited "slurred speech". (See my earlier post, "Alcohol on the Breath: Evidence of DUI?"). The officer fully expects to hear slurred speech in a person he suspects is intoxicated, particularly after smelling alcohol on the breath, and we tend to "hear" what we expect to hear. And hearing it supplies the officer with corroboration of his suspicions.

Even assuming the honesty of the officer that the defendant’s speech was slurred, there is little evidence that this is symptomatic of intoxication. Impairment of speech is, for example, a common — and sober — reaction to the stress, fear and nervousness that a police investigation would be expected to engender; fatigue is another well-known cause. However, consider the following excerpt from Discover magazine:

"Bartenders, police officers and hospital workers routinely identify drunks by their slurred speech. Several investigative groups judged the captain of the Exxon Valdez oil tanker to be intoxicated based solely on the sound of his voice in his radio transmissions. But a team led by Harry Holien, a phonetician at the University of Florida, has found that even self-proclaimed experts are pretty bad at estimating people’s alcohol levels by the way they talk."

Hollien asked clinicians who treat chemical dependency, along with a group of everyday people, to listen to recordings made by volunteers when they were sober, then mildly intoxicated, legally impaired, and finally, completely smashed. Listeners consistently overestimated the drunkeness of mildly intoxicated subjects. Conversely, they underestimated the alcohol levels of those who were most inebriated. Professionals were little better at perceiving the truth than the ordinary Joes…. "

He thinks his research could encourage police to be more wary of making snap judgments: Mild drinkers might come under needless suspicion…" Saunders, "News of Science, Medicine and Technology: Straight Talk", 21(1) Discover (Oct. 2000).


Asthma Inhalers Cause High Breathalyzer Results

Thursday, December 16th, 2004

If you use asthma inhalers and are ever arrested for DUI, you should perhaps think twice about taking a breath test. Most inhalers operate primarily by injecting a mist containing a substantial quantity of alcohol into the lungs. As an example, one of the most commonly used inhalers, Primatene Mist, contains 34 percent alcohol. This alcohol does not pass into the blood stream, but remains in the alveolar lining of the lungs — from where it will be exhaled into the breath machine.

The problem is that "breathalyzers" are designed to assume that the breath sample contains alcohol which has been swallowed and then metabolized by the body before being diffused into the lungs. As I mentioned in an earlier post ("Breathalyzers — and Why They Don’t Work"), they are further designed to assume that there are 2100 units of alcohol in the blood for every unit measured on the breath. So the breathalyzer’s computer mistakenly multiplies the alcohol measured from the asthma inhaler 2100 times. In other words, a very tiny amount of alcohol in the lungs from the inhaler mist can have a very large effect on the machine’s reading.

Just to make things worse, scientists have found that some asthma inhalers can cause high readings on breath machines due, apparently, to the propellent gasses used in the aerosols, in particular, chlorofluorocarbons. See "Using Asthma Inhalers Can Give False Positive Results in Breath Tests", 324 British Medical Journal 756 (March, 2002). As I mentioned in another earlier post ("Why Breathalyzers Don’t Measure Alcohol"), one of the many design defects in breath machines is that they are non-specific — that is, they will falsely report thousands of different chemical compounds as being alcohol.