Thursday, September 29, 2005

PBT'S: Reliability? (part 2)

As discussed in part 1 breath analysis machines are non-specific.Intoxilyzers,Ignition Interlocks,and SCRAM are all subject to outside influences.The actual machines multiply the amount of alcohol in a subjects breath 2100 times to calculate a BAC.This is under the assumption that a person has 2100 units of alcohol in his/her blood for every unit of alcohol in his/her breath.This is referred to as the partition ratio.This ratio of 2100:1 is not always exact in fact,a ratio can vary from as low as 900:1 to 3500:1.Patition ratio's can vary through out the day as well,your ratio at this moment will probably not be the same in 12 hours.MADD and prosecutor's became uneasy that the scientific reliability of such devices was scrutinized and juries returned with "not guilty" verdicts.The laws then became "Percent,by weight of alcohol in a persons breath based on grams of alcohol per 210 liters of breath".Basically,the law was not concerned with facts or actual amount of alcohol in the blood,it then became legally (not scientifically) assumed to be 2100 times what was in your breath.Defense attorneys are now prohibited from mentioning anything about partition ratios in court,obfuscating facts from juries that only blood can tell.
Electromagnetic interference (EMI) can also pose a problem,also known as radio-frequency interference (RFI).Police stations,cars and the officers themselves have radio-transmitters,walkie-talkies,cell phones,and computer cathode ray tubes that can cause EMI.Breathylizers are composed of sensitive circuitry that has to compute tiny amounts of alcohol in breath to an accuracy of one tenth a percent.This may sound as if I am going over the edge so I located this report to varify my concerns(*NOTE-EBT stands for Evidential Breath Tests):
"The Washington D.C. Metropolitan Police Department reported to NHTSA that EBTs were found to display erroneous BAC [blood-alcohol content] readings in the presence of electromagnetic fields from radio transmission....Representatives of NHTSA and NBS were given a demonstration by police officers who routinely conduct breath testing using an EBT in a mobile van. One police officer operated his handheld radio within 1 foot of the EBT and demonstrated that the electromagnetic field could severely affect the analysis of alcohol samples." The National Bureau of Standards subsequently conducted the testing and subsequently reported that "These results show that EMI is a potential problem with many of the EBT units currently in use....The states may have to take interim measures to determine the extent of their individual problems with EMI affecting EBTs."The government attempted to bury the report but was later ressurected by a Minneapolis DUI firm's"Freedom of Information Act"lawsuit. These machines also discriminate:Researchers at the University School of Medicine in Trieste, Italy, found that the stomach lining contains an enzyme called gastric alcohol dehydrogenase that breaks down alcohol, and that women have less 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; with weight differences taken into account, they found that women reached BAC levels illegal in a DUI case after drinking 20 to 30 percent less alcohol than men. Breathing patterns can also alter the results.Holding your breath for 30 seconds before exhaling can produce readings 15.7% higher,and hyperventilating for 20 seconds before the test can decrease it by over 10%.One study found a 14% decrease after running up and down stairs and 25% decrease after doing it twice,and any physical activity can decrease readings up to 15%.Aware of this,many police officers tell the arrestee to blow into the machine’s mouthpiece, they’ll yell at him, "Keep breathing! Breathe harder! Harder!" As Professor Hlastala has found, this ensures that the breath captured by the machine will be from the bottom of the lungs, near the alveolar sacs, which will be richest in alcohol. With the higher alcohol concentration, the machine will give a higher, but inaccurate reading. Now you can see the reason I put this study in parts,the many ways these devices prove to be less than reliable.I will end this part with one more concern........EQUILIBRIUM.It takes the human body approximately one hour to absorb alcohol,this is refered to by toxicologists as "absorptive stage analysis".Food in the stomach can retard this for as many as four hours,during this period alcohol is passed from the stomach and intestines into the blood but has not reached the stage of equilibrium.Alcohol at this time is being passed into the arteries,so the arterial BAC will be much higher than the venuous BAC.What does this have to do with breath?Arterial blood bathes the alveolar sacs of the lungs,where the alcohol diffuses into the lung air.A PBT will produce increased readings up to twice as high the actual BAC less than an hour after the last drink.Results,a person has a BAC of .05 and driving home,can be arrested an charged with an EBT of .10. MADD's intent to relieve our roads of drunk driving has become more of a neo-prohibition movement prosecuting people without reliable evidence,obfuscating the facts of,re-writing the Bill of Rights,and producing over zealous law enforcement officers.


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5 Comments:

Anonymous Clean Breath said...

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10:14 PM  
Blogger No Hassle Loans said...

This comment has been removed by a blog administrator.

3:36 AM  
Blogger COZ6650 said...

I really appreciated reading your article. I was looking for a site that could give me more stats on the unreliability of the Guardian Interlock since my son is using one and it had an electrical failure causing him to miss work and now he has to have someone take the handset of the unit to a place 60 miles away to have it fixed.

8:16 PM  
Anonymous Anonymous said...

someone please reply
i have a scram on me but nextel 1615 radio has never been turned on can this system work????????

6:39 PM  
Anonymous Anonymous said...

It doesn't work if you don't turn it on. Unfamiliar with your system, mine had lights, you may need to call the administrator to ensure they are receiving the reads.

2:43 AM  

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