NCJ Number
100089
Journal
Forensic Science International Volume: 28 Issue: 3-4 Dated: (August 1985) Pages: 157-165
Date Published
1985
Length
9 pages
Annotation
This paper reports results from a field trial with a breath-alcohol screening device -- Alcolmeter pocket model.
Abstract
Breath tests were made with drivers apprehended during routine controls (road-blocks), for traffic violations and those involved in traffic accidents. Of 908 roadside breath tests made with chemical reagent tubes, 343 showed zero alcohol (no color change) and these results were confirmed by the Alcolmeter. Alcohol was detected in 191 tests but the level was judged as being below the legal limit of 0.50 mg/ml. The Alcolmeter results, however, ranged from 0 to 1.22 mg/ml (mean 0.21 mg/ml) and 15 individuals (7.81 percent) were above the legal limit. There were 373 positive chemical tube breath screening tests whereas in 5 cases (1.3 percent) Alcolmeter indicated a blood-alcohol level below 0.50 mg/ml. Duplicate determinations with the Alcolmeter device were highly correlated r = 0.93 plus or minus 0.02 (plus or minus S.E.), P less than 0.001. The standard deviations of a single breath-alcohol analysis under field conditions was plus or minus 0.10 mg/ml which corresponds to a coefficient variation of 10 percent. The time interval between positive roadside breath test and blood-sampling ranged from 5 to 220 min (median 62 min). The results were therefore adjusted by 0.15 mg/ml per hour to compensate for ethanol metabolized between the time of sampling blood and breath. The corrected blood and breath values were well correlated r = 0.84 plus or minus 0.03, P less than 0.001 but the predictive power of the regression relationship was poor. The regression equation was y = 0.27 plus or minus 0.65x and the standard error estimate was plus or minus 0.21 mg/ml at the mean concentration of ethanol of 1.0 mg/ml. (Publisher abstract)