NCJ Number
77936
Journal
Journal of Forensic Sciences Volume: 21 Issue: 1 Dated: (1976) Pages: 9-41
Date Published
1976
Length
33 pages
Annotation
Modern uses of breath analysis are discussed, current methods of breath-alcohol analysis are explained, and forensic and technical problems inherent in breath-alcohol analyses are explored.
Abstract
Examinations of breath have been and are being used in studies establishing norms of health and alterations induced by disease and in studies monitoring the effect of toxic chemicals; however, most breath analyses are currently used for the determination of ethanol undertaken in connection with traffic law enforcement. There are a number of instruments developed for law enforcement use which calibrate, from a sample comprised of deep lung air substantially alveolar in composition, the existing arterial blood-ethanol concentration analyzed from reference standards. Those instruments meeting Federal standards for mobile evidential breath testers are the Alco-Limiter, the Mark II Gas Chromatograph, the Intoxilyzer model 4011, the Breathalyzer models 900A and 1000, and the Alcohol Screening Device. Despite the usefulness of such instruments, specific problems arise in the use of breath-alcohol analysis as trial evidence. These center on the variability of the effects of ethanol on assessable nervous system functions, skillful exploitation by defense attorneys of the complex nature of breath testing, questions concerning the necessity of retaining the reagents employed in individual tests, and the publication of studies showing discrepancies between the results of analyses for ethanol in nearly simultaneous blood and breath samples from the same subject. Forensic and technical questions arising in the use of breath analyses include the presumption of uncomplicated obedience to Henry's Law, difficulties in capturing alveolar air specimens, uncertainty of the exact values for the blood/breath ratio for alcohol, as well as the effects of temperature, of variations in the cellular composition of blood, and of ethanol absorption and distribution into the water of the tissues. However, it remains advisable that the offense of driving while under the influence of alcohol should be statutorily defined in terms of the concentration of ethanol found in the breath in jurisdictions employing breath analysis. A summary of regression analysis applications to data from blood breath measurements for ethanol and a list of 159 references are appended.