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Continued from page 1... University of Oklahoma blood-alcohol expert Dr. Kurt Dubowski has conducted extensive experiments and has found that peak blood-alcohol concentration varied among his subjects from 14 minutes after ingestion of alcohol to 138 minutes after ingestion. In other words, there were some subjects who would absorb alcohol and reach peak concentration ten times faster than other subjects! Dubowski, Absorption, Distribution and Elimination of Alcohol: Highway Safety Aspects, journal on Studies of Alcohol, Supp. No. 10 (July 1985); Mason and Dubowski, Breath Alcohol Analysis: Uses, Methods, and Some Forensic Problems - Review and Opinion, 21 Journal of Forensic Sciences 9 (1976). Just as the absorption rate can vary from individual to individual, so can it fluctuate within a given individual. One scientist has concluded that assuming a continuous, uniform rate of absorption can lead to grossly inaccurate blood-alcohol concentration readings: BAG levels fluctuate in short-term oscillations within individuals. Simpson, Medicolegal Alcohol Determination: Implications and Consequences of Irregularities in Blood Alcohol Concentration vs. Time Curves, l6Joiirnal of Analytical Toxicology (1992). Interestingly, Simpson went on to indicate that fear, pain, emotional disturbances, exercise, stimulants (such as coffee and nicotine), and shock can have the effect of decreasing absorption rates, thus throwing off any attempts to accurately extrapolate blood-alcohol levels to the time of driving. It would seem, then, that the circumstances of a Los Angeles DUI investigation and arrest, with the commonly associated fear and emotional disturbance in the suspect, would themselves trigger a physiological reaction directly affecting efforts to extrapolate. The elimination rate for alcohol in any DUI case has also been proven to vary widely from person to person. One of the variables determining the individual rate is the drinking habits or background of the individual. In Winek and Murphy's article, The Rate and Kinetic Order of Ethanol Elimination, 29 Forensic Science International, 159 (1984), scientists concluded that "non-drinkers" (defined as persons who consume less than 6 ounces of alcohol per month) eliminate ethyl alcohol at a rate of .012 gram percent/hour, while "social drinkers" (persons who consume between 6 and 30 ounces a month) have an average elimination rate of .015. Alcoholics, however, showed a .030 rate - double that of nonalcoholics! Certainly, such variations will drastically affect any attempts in a DUI case to use retrograde extrapolation to estimate blood alcohol level at the time of driving based on blood-alcohol level at the time of testing. In one study of ethanol elimination, the rate was observed to vary among individuals by a factor of four - that is, the individual observed to have the fastest rate eliminated alcohol four times faster than the one with the slowest rate. Jones, Disappearance Rate of Ethanol from the Blood of Human Subjects: Implications in Forensic Toxicology, 38(1) Journal of Forensics 103 (1993). Another study has shown that the elimination rate for alcohol in the human body can vary from .010 percent to as much as .064 percent, with an average rate of .022 percent. In other words, some individuals can eliminate alcohol at a rate six-and-one-half times faster than others. Such a wide variation would, of course, completely invalidate any attempts at retrograde extrapolation in any given Los Angeles DUI case. See Neuteboom and Jones; Disappearance Rate of Alcohol from the Blood of Drunk Drivers Calculated from Two Consecutive Samples: What Do the Results Really Mean?, 45 Forensic Science International 107 (1990). |
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