Blood Alcohol Testing

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The care of the blood sample once taken from the subject should be investigated. It is a common practice to let the blood specimen sit for days before analyzing it, due to delay in getting it to the laboratory, to a crowded schedule in the laboratory, or to simple neglect. But blood is an organic material and will decompose because of enzymes and bacterial action. One of the results of this decomposition is that alcohol is created in the blood. In a sample originally containing no alcohol, decomposition can cause a reading of .25 percent or even higher, depending on the stage of decay. Usually the specimen will be refrigerated to prevent this. However, refrigeration will only slow down the decomposition process, not prevent it. To stop this decaying of the blood and the resultant formation of alcohol, a preservative such as a sodium fluoride solution should be added. Failure to do this - and it is not at all uncommon - should provide defense counsel with sufficient material at least to discredit the test results, if not prevent their admission into evidence.

Most blood-alcohol kits used to collect blood samples for alcohol testing use tubes containing 20 mg of sodium fluoride to preserve the blood sample. The noted Swedish expert on blood-alcohol analysis, A. W. Jones, however, claims that this is an insufficient amount to prevent fermentation: at least 100 mg should be used. Salting-Out Effect of Sodium Fluoride and its Influence on the Analysis of Ethanol by Headspace Gas Chromatography, 18 Journal of Analytical Toxicology 292 (September 1994). Dr. Jones also found that using sodium fluoride to preserve a blood sample actually increased the amount of alcohol in the sample when gas chromatography was used to analyze it. According to his research, even 10 mg of sodium fluoride "increased the concentration of ethanol in the equilibrated (34 degrees centigrade) headspace by 8.9% when compared with heparinized blood" (i.e., blood treated with an anticoagulant). This was due to a "salting out" effect from the sodium fluoride.

Although many scientists believe that a preservative consisting of 1 percent of the sample is sufficient to stop the growth of microorganisms, many others feel that a 2 percent preservative such as sodium fluoride is required. See Dick and Stone, Alcohol Loss Arising from Microbial Contamination of Drivers' Blood Specimens, 34 Forensic Science International 17 (1987).

Clearly, the risk of fermentation will vary according to the amount of preservative used. However, it will also be directly affected by the length of time the sample is stored, and by the temperature at winch it is stored. Sodium fluoride of 1 percent or less concentration is stable for only about two days. Kaye, The Collection and Handling of the Blood Alcohol Specimen, 74 American journal of Clinical Pathology 743 (1980). And fluctuations from a storage temperature of 25 degrees centigrade will increase fermentation and production of alcohol. As toxicologist Anne ImObersteg of Park-Gilman Clinics in Burlingame, California, has observed:

Even in a blood tube containing sodium fluoride, Candida albicans, the most common microbial culprit of ethanol production in blood samples, can produce ethanol. See Blume, Bacterial Contamination on BAC Stability, 60 American journal of Clinical Pathology 700 (1973). Specimens stored at room temperature for more than five days showed significant alcohol formation (up to 0.08 percent maximum) in a study by Chang arid Kollman, The Effect of Temperature on the Formation of Ethyl Alcohol by Candida Aihacans in the Blood, 34(1) JFSCA 105 (Jan. 1989). Therefore, the third prong of sample integrity, storage temperature, is also crucial.

An anticoagulant such as potassium oxalate also should be added to the sample to prevent the blood from coagulating. However, defense counsel should insist that the prosecution establish exactly what chemicals were used as an anticoagulant as well as the possible side effects on the alcohol and blood.

Cross-Examining the Evidence in Texas

Once counsel has obtained the laboratory records through discovery, they should be reviewed for any notations concerning the condition of the blood sample when received. Quite often, the lab technician will enter an annotation such as "clotting" or "some coagulation." If so, this should be developed during cross-examination - and the inference made that if the anticoagulant was not working, then perhaps the preservative was similarly ineffective (resulting in fermentation and an elevated blood-alcohol concentration).

Assuming that preservatives and anticoagulants were in the vial when the blood sample was introduced, it should not be presumed that they were, in fact, mixed with the blood. In State v. Schwalk, 430 N.W.2d 319 (N.D. 1988), for example, the Supreme Court of North Dakota reversed a DUI conviction where a foundation had not been laid showing that the collecting officer mixed the blood and chemicals. The court refused to presume "compliance with step four, which requires that immediately upon placing the blood in the glass vial it must be inverted several times to dissolve the chemicals contained in the vial."

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