NCJ Number
212937
Journal
Journal of Forensic Sciences Volume: 51 Issue: 1 Dated: January 2006 Pages: 173-178
Date Published
January 2006
Length
6 pages
Annotation
This study determined blood alcohol concentrations (BAC) and corresponding breath alcohol concentrations (BrAC) for 21,582 drivers stopped by New Zealand police.
Abstract
Calculations were performed for single and duplicate breath samples that were obtained with the Intoxilyzer (groups I-1 and I-2) and Seres devices (groups S-1 and S-2). There were only small differences between the largest two groups (I-2 and S-2) regarding the distributions of BrAC and BAC values; however, group I-1 had significantly higher mean BrAC and BAC values compared with group S-1. The ratio of the respective legal limits for blood and breath alcohol in New Zealand is 2,000. The data from the current study suggest that the average BAC/BrAC ratio measured in the field is 19-26 percent higher than this. This means that for New Zealand drivers who are well in excess of the legal breath alcohol limit, there must be a long delay between the breath test and a subsequent blood test before they will gain any advantage by demanding a blood test. BAC was measured by using headspace gas chromatography, and BrAC was determined with Intoxilyzer 5000 or Seres Ethylometre infrared analyzers. The delay (DEL) between breath testing and blood sampling ranged from 0.03 to 5.4 hours. BAC/BrAC ratios were calculated before and after BAC values were corrected for DEL using 19 mg/dL/h as an estimate of the blood alcohol clearance rate. Before correction for DEL, BAC/BrAC ratios for groups I-1, I-2, S-1, and S-2 were 2320 plus or minus 260, 2180 plus or minus 242, 2330 plus or minus 276, and 2250 plus or minus 259, respectively. After BAC values were adjusted for DEL, BAC/BrAc ratios for these groups were 2510 plus or minus 256, 2370 plus or minus 240, 2520 plus or minus 280, and 2440 plus or minus 260, respectively. 3 tables, 2 figures, and 21 references