Studies have shown that the use of oral contraceptive steroids eliminate alcohol more efficiently than women who aren't using them. They reach their peak BAC's faster and return to lower levels more rapidly. This is a problem when the breath test used to estimate the BAC at the time of driving is not administered until 1-2 hours later. Also, pregnant women or ones using birth control pills had higher levels of acetylaldehyde on their breath because of a decreased ability to metabolize the enzyme as as their level of sex steroids increases. (Birth control pills work by increasing the level of sex steroid hormones to simulate pregnancy).
Since the breathalyzer machines measure the amount of acetylaldehyde in the breath and use it to calculate the BAC, this presents a problem. The machines actually measure those chemical compounds with a methyl group in their molecular structure. Both ethyl alcohol and acetylaldehyde have that same group. See O.C.S." Papple, "The Effects of Oral Contraceptive Steroids on the Rate of Post-Absorptive Phase Decline of Blood Alcohol Concentration in the Adult Woman, 15(1) Canadian Society of Forensic Science Journal 17 (1982), Jeavons and Zeiner, "Effects of Elevated Female Sex Steroids on Ethanol and Acetaldehyde Metabolism in Humans", 8(4) Alcoholism: Clinical and Experimental Research 352 (1984).
Friday, June 5, 2009
Breathalyzers Discriminate Against Women -Part 3
Breathalyzer machines work by measuring the amount of alcohol in a breath sample. They then multiply that amount by 2100 and report that as the blood alcohol volume. This number is called the partition ratio. It assumes that for every gram of alcohol in a breath sample, there are 2100 grams in that person's blood.
Here's the problem. Studies have shown that the actual ratio of breath alcohol to blood alcohol varies from person to person. It varies from around a low of around 1100:1 up to a high of 3500:1. State v. McCarty 434 N.W.2d 67 (S.D. 1988). This means that the lower a person's actual partition ratio, the higher their blood alcohol reading.
Lets take three people, each with .06% true BAC. One with a partition ratio of 2100:1 will have a breath test of .06%. Another person with a low ratio of 1100:1 will report a result 53.26% lower than their true result. Finally one with a high ratio of 3500:1 will report a result 126% higher than the true result. According to a study, women have higher partition ratios than men and will have higher breath test results. Jones, "Determination of Liquid/Air Partition Coefficients for Dilute Solutions of Ethanol in Water, Whole Blood and Plasma", Analytical Toxicology 193 (July/August 1983)
Here's the problem. Studies have shown that the actual ratio of breath alcohol to blood alcohol varies from person to person. It varies from around a low of around 1100:1 up to a high of 3500:1. State v. McCarty 434 N.W.2d 67 (S.D. 1988). This means that the lower a person's actual partition ratio, the higher their blood alcohol reading.
Lets take three people, each with .06% true BAC. One with a partition ratio of 2100:1 will have a breath test of .06%. Another person with a low ratio of 1100:1 will report a result 53.26% lower than their true result. Finally one with a high ratio of 3500:1 will report a result 126% higher than the true result. According to a study, women have higher partition ratios than men and will have higher breath test results. Jones, "Determination of Liquid/Air Partition Coefficients for Dilute Solutions of Ethanol in Water, Whole Blood and Plasma", Analytical Toxicology 193 (July/August 1983)
Breathalyzers Discriminate Against Women - Part 2
We have all heard and probably noticed that women tend to become more intoxicated than men when they drink the same amount of alcohol. Many driver's education classes, alcohol education and therapy classes and other department of motor vehicles claim that it is because of their generally smaller size and lower body weights than men. There is a lot more to it than simply size and weight. Because not every driver is a 150 pound man, the law should consider gender differences when determining safe levels of drinking. Here's why:
Italian researchers found that the stomach lining contains an enzyme called gastric alcohol dehydrogenase that breaks down alcohol. Women have less of that enzyme than men. To determine the relative effects of the enzyme, they gave alcohol both orally and intravenously to groups of alcoholic and non-alcoholic men and women. They found that women reached the same levels of blood alcohol as men after drinking only half as much.
When they factored in the test's subjects' weight they found that women reached BAC levels illegal in a DUI case after drinking 20 to 30 percent less alcohol than men. See. Frezza and Lieber, "High Blood Alcohol Levels in Women: The Role of Decreased Gastric Alcohol Dehydrogenase Activity and First-Pass Metabolism", 322(2) New England Journal of Medicine 95 (1990).
Italian researchers found that the stomach lining contains an enzyme called gastric alcohol dehydrogenase that breaks down alcohol. Women have less of that enzyme than men. To determine the relative effects of the enzyme, they gave alcohol both orally and intravenously to groups of alcoholic and non-alcoholic men and women. They found that women reached the same levels of blood alcohol as men after drinking only half as much.
When they factored in the test's subjects' weight they found that women reached BAC levels illegal in a DUI case after drinking 20 to 30 percent less alcohol than men. See. Frezza and Lieber, "High Blood Alcohol Levels in Women: The Role of Decreased Gastric Alcohol Dehydrogenase Activity and First-Pass Metabolism", 322(2) New England Journal of Medicine 95 (1990).
Breathalyzers Discriminate Against Women -- Part 1
If you have a BAC above .08 in Colorado, you are guilty of drunk driving. Your age, race, and gender do not matter. Perhaps they should. Several scientific studies have indicated that Breathalyzer machines discriminate against women.
In Colorado, if you refuse to take a breath test, you automatically lose your driving privelige. Also, the fact that you refused the test can be used as evidence of your guilt. Trying and failing to blow enough air into the machine is also treated as a refusal. Women have a higher rate of "refusals" reported by the machines than do men.
Breathalyzer machines do not directly measure the amount of air blown by a suspect. They measure the pressure of the suspects breath using a pressure sensor and the amount of time that the pressure is present. As air flows faster, its pressure increases. Mathematically, volume is the quotient of air flow and time. The machine makes assumptions about how hard the suspect is blowing and calculate the volume based on those assumptions. When those assumptions are incorrect, so are the results.
In a study of Breathalyzer test results in Florida, on average, women produced samples that were 20% to 40% lower than men. Women with lower lung capacities are not able to produce the minimum volume of air that the machine needs to complete its analysis. When it doesn't get enough air, the machine reports a refusal. In that same Florida study, women in every age group are twice as likely to be penalized for failing to produce a sufficient breath sample as men.
An equally troubling problem occurs when the machine reports an result, which has been inaccurately calculated. Because the machines computer software does not consider the subject's age, gender or the presence of medical conditions. The machines are inherently inaccurate.
Studies have shown that a 1 degree Centigrade change in body temperature can produce a 7.5% change in the reported BAC. Suspects with higher body temperatures have higher readings while those with lower body temperatures have lower readings.
In Colorado, if you refuse to take a breath test, you automatically lose your driving privelige. Also, the fact that you refused the test can be used as evidence of your guilt. Trying and failing to blow enough air into the machine is also treated as a refusal. Women have a higher rate of "refusals" reported by the machines than do men.
Breathalyzer machines do not directly measure the amount of air blown by a suspect. They measure the pressure of the suspects breath using a pressure sensor and the amount of time that the pressure is present. As air flows faster, its pressure increases. Mathematically, volume is the quotient of air flow and time. The machine makes assumptions about how hard the suspect is blowing and calculate the volume based on those assumptions. When those assumptions are incorrect, so are the results.
In a study of Breathalyzer test results in Florida, on average, women produced samples that were 20% to 40% lower than men. Women with lower lung capacities are not able to produce the minimum volume of air that the machine needs to complete its analysis. When it doesn't get enough air, the machine reports a refusal. In that same Florida study, women in every age group are twice as likely to be penalized for failing to produce a sufficient breath sample as men.
An equally troubling problem occurs when the machine reports an result, which has been inaccurately calculated. Because the machines computer software does not consider the subject's age, gender or the presence of medical conditions. The machines are inherently inaccurate.
Studies have shown that a 1 degree Centigrade change in body temperature can produce a 7.5% change in the reported BAC. Suspects with higher body temperatures have higher readings while those with lower body temperatures have lower readings.
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