Alcohol Concentration Definitions

• For blood # of grams per 100 Milliters

• For Breath # of grams per 210 liters

• For Urine # of grams per 67 milliters

.08 per 210 liters

.008 per 21 liters

.0008 per 2.1 liters

.00008 per .21 liters

08/100,000 of one gram in vapor form of alcohol

08/100,000 of one gram in vapor form of alcohol

Acceptable .07

1st reading .140

Acceptable .120

2nd reading

Acceptable.160

2nd readingRange: 0.04

Predicted .08

If the device was correct

Amount of alcohol for 190 person who had a real .140

(based on 1 ounce alcohol)

5-6 drinks if consumed in last hour6-7 drinks if consumed in last two hours7-9 drinks if consumed in 3 hours

The software process for the CMI 5000

Is a Secret

• In Intoxication Test Evidence 2d (Clark, Boardman, Callaghan, 1995), Fitzgerald noted that Kurt M. Dubowski and others have found the normal range in test populations to vary from 1100:1 to 3000:1. These variances can be profound; as Fitzgerald notes: "All breath test devices, for example, will report a 0.10% for a subject who has a true BAC of 0.07% if he or she has a partition ratio of 1500:1 (instead of 2100:1), and conversely, a 0.10% for a subject who has a true 0.14%, if he or she has a partition ratio of 3000:1."

Table 11: Response of Intoxilyzer 5000 to Volatile Organic Compound Found in Human Breath at Non-Lethal Reported Blood Concentration ConcentrationBrAC on Calibration BrAC on Sampling g/L Solutionmode g/210Lmode g/210L0.4g/L acetoneInterferentInterferent0.0044 g/L acetonitrile0.0000.0000.011 g/L isoprene0.0000.0000.04 g/L methanol0.0070.0000.4g methanol0.0320.0360.0044 g/L acetaldehyde0.0000.0000.02gAcetaldehyde0.0090.01

Requirements: Closed system

Known and constant pressure Known and constant temperature

Dilute solution Reaches equilibrium

• A.W. Jones observed that the blood/breath partition ratio varies not only between individuals but within specific individuals across a one hour period. In a study conducted upon 21 males aged 30-55, Jones observed blood/breath partition coefficients ranging between 1837 to 2666. More importantly, individual subjects disclosed coefficient variations ranging from .95 percent to 12.56 percent.

For that reason, the conversion (extrapolation) of the directly measured concentration of alcohol in the expired air to obtain its concentration in the blood has been the subject of much litigation. Understandably, this conversion is fraught with problems of variability (uncertainties) introduced by the theoretical assumptions underlying the method. As was pointed out by one of the leading researchers in this area, The most trying forensic difficulties were consequent to what now appears to some to be an error in policy made by the pioneers in breath testing. This was in deciding to calculate the blood concentration from a quantity of alcohol found in the breath. Mason & Dubowski, Traffic & Chemical Testing in the United States: a Resume & Some Remaining Problems, 20 Clinical Chemistry 126, 128 (1974). The following section will present the scientific basis for the statutory decision to select a partition ratio of 2100 and the variability, both inter-subject and intra-subject, to be expected in this ratio.

Person A 1/1900

BLOOD ALCOHOL OVERESTIMATED BY 10 %

Person B 1/2300

BLOOD ALCOHOL UNDERESTIMATED BY 10 %

100 MILLITERS TO 210 LITERS

1/2100 RATIO

Person C 1/1700BLOOD ALCOHOL OVERESTIMATED BY 20 %

Person D 1/2500

BLOOD ALCOHOL UNDERESTIMATED BY 20 %

Person E 1/1500BLOOD ALCOHOL OVERESTIMATED BY 30 %

Person F 1/1300BLOOD ALCOHOL OVERESTIMATED BY 40 %

Percentage of Normal Personswho are 1/2100

NOT EVERYONE IS

• Effect of Temperature: The widely used partition blood-to-air partition ratio of 2100 is based on a normal body temperature of 98.6 0F. A higher body temperature of the individual will overestimate the actual BAC because of the higher volatility (or vapor pressure) of liquids like alcohol at a higher temperature. An elevation in body temperature of 1 0C (1.8 0F) results in a 7% higher value in the result. Therefore, a person with a body temperature of 100.4 0F and with an actual blood alcohol of 0.0935 % will register a value of 0.10 % by the breath test. As can be seen from this hypothetical example, a small difference in body temperature can make the difference of guilt or innocence of drunk driving in defendants with a BAC close to the legal limit. This widely accepted ratio is also based on the assumption that the average temperature of exhaled air is 93.20 F.

Srikumaran K. Melethil, Ph.D.Professor of PharmacologyUniversity of Missouri at Kansas City