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Many people believe
that breath testing is an accurate method of determining the amount
of alcohol in a person's blood. In fact, breath testing is far from
accurate and as currently used is fraught with error which can lead
to false high readings that are significantly higher than a person's
true blood alcohol content at the time of the test or at the time of
operation based upon a number of variables not taken into account by
the machine.
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Breath
to Blood Partition Ratios
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Breath testing is
based upon the principal that there is a direct relationship between
the amount of alcohol in a person's expired air sample and the
amount of alcohol in the person's blood. All breath testing
equipment currently used in the United States assumes this ratio to
be 2100 to 1. In other words; the amount of alcohol in one milliliter
(ml)
of our blood when consuming alcohol is 2100 times greater than the
amount of alcohol found in 1 cubic centimeter of our expired air
sample. According to the theory, if one took 2100 cubic centimeters
of our deep lung air and analyzed the amount of alcohol in that
sample, the amount of alcohol in that sample would be equal to the
amount of alcohol in one milliliter of our blood.
Consequently, the machines are calibrated on the assumption that
everyone has a 2100 to 1 ratio. However, not everyone has a 2100
breath to blood ratio. In fact, recent research shows this ratio to
vary from 990 to 1 to 3005 to 1. If a person has a ratio lower than
2100 to 1 then the corresponding breath test result will be
artificially high. On the other hand, if a persons ratio is higher
than 2100 to 1, then a persons breath test sample will be
artificially low. For example, if a person took a breath test and
produced a .10 and had a breath to blood partition ratio of 1000 to
1, the persons true blood alcohol content would be .05. Because the
machine does not have the capability to determine what a person's
actual ratio is, it has no way of detecting the error it has made.
Moreover, a person's breath to blood partition ratio varies from
person to person and even varies within the person over time, making
it almost impossible to classify the breath tests results as
accurate.
In the absorptive phase, the average mean for a healthy white male
is 1776 to 1. Through the use of statistical analysis this
translates into 75% of the people submitting to the test being
overestimated and 25% being underestimated based upon this factor
alone. The absorptive phase can last up to 5 hours after a persons
last drink on a full stomach and 2 on an empty stomach.
On the other hand, if a person is in the post absorptive phase, 25%
will be overestimated and 75% will be underestimated based upon this
factor alone. Current breath testing equipment assumes that a person
is in the post-absorptive phase when in fact many people arrested
for DWI are in the absorptive phase. Even the leading proponents of
breath testing concede that it is virtually impossible to determine
at which stage a person is in at the time of the test and therefore
impossible to determine whether or not the person is overestimated
or underestimated.
A person's breathing
technique (the way a person blows into a breath testing machine)
will effect the accuracy of the reading produced on the machine. To
produce a .10 on a Intoxilyzer 5000, the machine actually detects
less than 1 millionth of a fluid ounce of alcohol in the breath
sample. This amount is smaller than a pin head. If a person blows
into the machine for a long period over 10 seconds, the resulting
reading can be higher than the person's actual true blood alcohol
content by to 150%. In a recent lecture at Harvard University, Dr.
Michael Hlastala of the University of Washington Department of
Medicine confirmed that breathing technique can significantly impact
on a person's true BAC.
If a person holds their breath, or is a shallow breather, that can
cause the reading to be over 20% higher than the true BAC. Given
that the breathing pattern is not controlled, it is impossible to
determine whether or not a person's result on the breath test is
artificially high and to what degree.
Many of today's
breath testing equipment rely on infrared analysis to determine how
much alcohol is in a person's expired breath sample. A major flaw in
the analysis is that many of these instruments are non-specific for
alcohol. That is, they are not designed to detect the molecule of
ethyl alcohol, but rather only a part of that molecule - the methyl
group. These machines are based on the Baer-Lambert theory which
states that all organic substances absorb infrared energy at
different wave lengths. Alcohol absorbs at over 8 wave lengths
however, the great majority of the Intoxilyzer 5000's currently
being employed only test at two wave lengths 3.39 and 3.48 microns.
This creates a potential problem because there are several other
compounds or substances that absorb at these wave lengths that may
be present in a person's air sample. When these other substances are
present, the machines read them as being alcohol molecules when in
fact they are not. This can lead to a situation where a person is
charged with DWI based upon a breath test when in fact he has no
alcohol at all in his blood. One study conducted recently revealed a
case where a cabinet maker produced a reading of .24 when a
simultaneous blood test showed that he had no alcohol in his blood.
The reading was obviously attributable to the cabinet maker's
inhalation of chemicals contained in the paint he was applying which
have a similar chemical structure of alcohol.
If a person belches, or has false teeth, this can also produce false
high readings.
The temperature of
the person's breath sample is also of importance. If the temperature
of a person's breath sample is 1 degree above 34 C, then the
person's reading will be about 7% higher than the person's true BAC.
Temperature is an important variable that should be measured and
controlled when evaluating the accuracy of any breath test however,
to date no machine has been designed to make sure the subject's
breath sample is of the proper temperature.
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