Lowering of the Alcohol Limits for Drivers in Ireland and the Analytical Impact Helen Kearns, Pauline Leavy, David Reynolds, Denis Cusack. Medical Bureau of Road Safety, University College Dublin. Abstract Context The Road Traffic Act (RTA) 2010 1 was enacted on 28th October 2011 in the Republic of Ireland. This introduced two lower alcohol limits while retaining three higher penalty limits resulting in a total of five graded penalty levels. The two lower limits of 20 and 50 in blood are related to driver status; that is specified driver or non-specified driver respectively. Specified drivers are defined as learners, newly qualified drivers and professional drivers. This offered challenges in the areas of calibration, quality assurance and measurement of uncertainty for the Medical Bureau of Road Safety (Bureau) which is the national statutory body responsible for chemical testing of intoxicants in driving in Ireland. Objectives In preparation for the introduction of the new alcohol limits the Bureau aimed to introduce a method of calibration that would enable accurate analysis and reporting at the lower levels for both evidential breath testing instruments and blood and urine specimens. Key Outcomes Calibration and testing schemes including measurement of uncertainty budgets for evidential breath testing, breath screening and alcohol in blood or urine programmes were devised, validated and implemented to ensure accurate analysis and reporting of alcohol in specimens at all levels. Accredited status for the three testing schemes was maintained under the ISO 17025 standard. Discussion and conclusions Before the introduction of the RTA 2010 a % deduction had been subtracted from all analytical results prior to issue. Calculated uncertainty budgets demonstrated that this approach was not appropriate for all limits included in the RTA 2010. A % deduction remains in place over part of the measurement range while appropriate absolute deductions are made at lower limits. Introduction The responsibility for chemical testing of intoxicants in driving in Ireland rests with the Medical Bureau of Road Safety. The functions of the Bureau are laid down in the Road Traffic Acts 1968-2010 and their regulations. They include the receipt and analysis of specimens of blood and urine for intoxicants, the issue of certificates of analysis, the provision of equipment for the taking of specimens of blood and urine, the approval, supply and testing of apparatus for indicating the presence of alcohol in breath and the approval, supply and testing of apparatus for determining the concentration of alcohol in breath. The Road Traffic Acts include defined alcohol limits for blood, urine and breath and since 1995 graded penalties were applied depending on alcohol concentration found in the specimen provided. In October 2011, the 2010 RTA 1 was enacted and this included an additional two lower limits for each specimen type. Table 1 shows the original limits along with the current limits. 1
Table 1 Alcohol limits set out in the Irish Road Traffic Acts. Blood Urine Breath µg/100ml Added in Oct 2011 20 27 9 Added in Oct 2011 50 67 22 Pre Oct 2011 80 107 35 Pre Oct 2011 100 135 44 Pre Oct 2011 150 200 66 Blood and Urine Alcohol The addition of the lower limits required a review of the laboratory s testing, calibration and reporting protocols for alcohol analysis in blood and urine specimens. Procedure for Analysis of Alcohol in Blood and Urine Analysis of blood and urine specimens for ethanol was carried out using headspace gas chromatography (HS-GCFID) systems. Propan-1-ol was used as an internal standard and used to dilute the sample at a 1:10 ratio. The laboratory used packed columns for alcohol analysis, 5% Carbowax 20M on 60/80 Carbopack B and 0.2% Carbowax 1500 on 80/100 Carbopack C. Using the two types of column with different separation characteristics enables identification of ethanol based on retention times and ensures other possible interfering volatiles will be detected. Each specimen was analysed once on two different systems which included the different column types, different HS-GCFID systems, different diluters and different scientists. Initial analysis was carried out using single point calibration at 80 level and a further duplicate analysis was carried out using a three point calibration using 80,107 and 200 standards when the initial results fell within defined critical ranges. The critical ranges are defined as an analytical range just above the legal alcohol limit, where a result will be issued that could lead to prosecution and the result issued would determine the penalty imposed. Table 2 details the critical ranges used in the laboratory. Table 2 s for Alcohol in Blood and Urine pre 2010 RTA Limits Blood limit Urine Limit 80 87-100 107 115-128 100 108-121 135 145-158 150 161-174 200 214-227 In light of the lowering of the limit, new critical ranges were identified. Table 3 outlines the additional critical ranges adopted. Table 3 s for Alcohol in Blood and Urine post 2010 RTA Limits Blood limit Urine Limit 2
20 25-38 27 32-45 50 55-68 67 73-86 A review of the calibration standards was carried out. Table 4 outlines the different standard curves investigated. Both three point and four point curves were examined. Table 4 Standard Values for Multipoint Calibration 20 20 50 50 80 80 100 100 107 150 200 200 200 200 R 2 values were used to determine the closeness of the calibration curve to unity. We found no significant difference between the three point curves and the four point curves. We found no significant difference between curves produced using ERM standards or in house Bureau standards. All curves examined had R 2 values of 0.9999 and intercept values close to 0. Controls in the range 0 to 600 prepared in-house and/or purchased were analysed using the different calibration curves as in Table 4 above and single point calibrations using either 20, 50 or 80 standards were also examined. All results obtained, using the different calibrations were within the laboratories operating specification as outlined and all calibrations were fit for purpose. At this stage it was decided that the original protocol for analysis would be retained with different standard levels for calibration; for single point calibration a 50 standard was selected and for multipoint it was decided that a three point curve using 20, 80 and 200 would be used. Check standards are included across the measuring range throughout the analytical runs. Reporting Alcohol in Blood and Urine and Application of Measurement of Uncertainty The reported result was calculated by averaging the analytical results, truncating the result and applying a subtraction of 6% to determine the reported result in. The 6% subtraction was based on an historical maximum precision allowance of 2% multiplied by 3. However the laboratory typically attains precision of under 0.5% for relative standard deviations (RSD) and the new measurement of uncertainty was calculated using the specification laid out by the laboratory. Table 5. MBRS Alcohol in Blood and Urine Linearity Specification for Single Point Analysis Nominal Concentration Maximum Permissible Error of the certified value Repeatability Std. Dev mg 20 2 0.5 50 2 0.5 80 2 0.4 3
107 2% (2.14 0.535 200 2% (4.0) 1.0 The significant contributors to uncertainty of this method were identified as the maximum permissible error (MPE), the maximum precision (standard deviation) and the uncertainty of the calibrator. The uncertainty of the ERM calibrators is typically 0.6 (k=2) which is equivalent to a standard deviation of 0.3. Using the formula: Uc= ((MPE/ 3)² +(std dev)² + (uncertainty of calibrator)² Where Uc is the combined uncertainty and the MPE was assumed to have a rectangular distribution, the uncertainty of the measurement was calculated across the range of 20 to 200. An expanded uncertainty using a coverage factor of 3 was calculated for each level. The expanded uncertainties were plotted against the standard values. The equation of the line was then used to calculate the uncertainty for each analytical value. The relative expanded uncertainty was shown to be greater at the lower levels. A similar approach was used for calculating the uncertainty using the multipoint analysis. It was shown to be appropriate to continue deducting 6% from the mean of the rounded down analytical value for values above 50 and to deduct 4 from values equal to and below 50. Alcohol in Blood and Urine and Accreditation The Medical Bureau of Road Safety maintains accreditation to ISO17025 standard 8 for alcohol in blood and urine analysis. The changes to calibration and reporting procedures were notified to the Irish National Accreditation Board (INAB) prior to their implementation, and on their review no extension to scope was required as the range of alcohol measurement was within the scope of the current accreditation which remains at 10 to 600. Evidential Breath Testing Procedure for calibration and testing of instruments Evidential breath testing was introduced to Ireland in 1999 and the lion intoxilyzer6000irl instruments were chosen following an EU procurement process and installed in Garda Síochána (Police) Stations nationwide. The protocol was that the calibration was the responsibility of the manufacturer and it was carried out in their laboratory using wet bath standards. Post installation the instruments were tested on a six monthly basis on site using wet bath standards at 35, 44, 66 and 200µg/100ml levels. These tests were included as part of the full performance testing protocol. Certified dry gas ethanol standards at 35µg/100ml level were used for time of test validation during an evidential breath test. With the introduction of the lower breath alcohol limits the performance of the breath test instruments was reviewed. While the lion intoxilyzer6000irl was accurate at the lower levels it was not possible to adapt them to include mouth alcohol detection at the lower breath alcohol limits. As the instruments were also over 10 years old it was decided that new 4
instruments would be purchased. Following an EU procurement procedure the Evidenzer IRL was selected. These instruments included the required safeguards at the lower breath alcohol levels. The manufacturer,(nanopuls AB) is responsible for the calibration of the instrument. The EvidenzerIRL is wet bath calibrated. The calibration is verified using either wet bath or dry gas standards. The calibration and verification results must comply with the OIML R126: 1998 2 recommendation as follows. The MPE is 2.0µg/100ml for levels below 40µg/100ml and 5% of the reference value of mass concentration for levels between 40µg/100ml and 200µg/100ml. Post installation the instrument is tested on a six monthly basis on site using wet bath standards at 9, 22, 35, 190µg/100ml levels. During the provision of an evidential breath test, each set of 2 breaths specimens provided by the arrested person is now bracketed with dry gas standards, one at a level of 9µg/100ml and the other at a level of 22µg/100ml. EBT Reporting and application of uncertainty The Bureau had calculated the uncertainty budget for breath testing using the lion intoxilyzer 6000IRL based on test specifications and found it to be 17.5% with a coverage factor of 3. The evidential breath testing procedure requires a driver to provide two breath specimens. The lower of the two results is reduced by 17.5% and the resultant figure is reported as the breath alcohol concentration. This approach to reporting was retained when the new limits were introduced, however the measurement of uncertainty budget was reviewed to ensure that an appropriate deduction was being subtracted at all levels. The calculation was carried out across the measuring range using a different approach than previously used with breath variability, instrumental components and traceability of dry and wet standards as the major contributors. 3,4,5,6 Table 6. MBRS Evidential Breath Testing Linearity Specification. Nominal Concentration g/100ml 3% Maximum Permissible Error of the certified value Repeatability Std. Dev 0 0 to +2 g/100ml 9.0 2 g/100ml 0.7µg /100ml. 22.0 2 g/100ml 0.7µg /100ml. 35.0 5% 0.6µg /100ml. 190.0 5% 3.2µg /100ml. It was confirmed that 17.5% is an appropriate deduction for all concentrations above 22 g/100ml, however for alcohol concentrations of 22 g/100ml and below a deduction of 5 g/100ml was required. The performance tests should comply with OIML 2012 7 specifications as shown in Table 6. EBT and Accreditation The Medical Bureau of Road Safety maintains accreditation to ISO17025 standard 8 for onsite testing of the evidential breath instruments. The changes to the EBT test method required an extension of scope of accreditation application as the test item had changed from one instrument type to another. The Bureau submitted and was granted extension to scope after a full review of the new test method. 5
Conclusion The lowering of the alcohol limits provided a valuable opportunity for the Bureau to review the methods used and the uncertainty applied to reporting alcohol levels. Uncertainties were calculated across the range for alcohol in blood and urine and breath. The Bureau has shown that above 50 for alcohol in blood and urine and above 22 g/100ml in the case of EBT that a percentage deduction remains appropriate and below this level greater deductions are required to account for uncertainty associated with the test. This approach complies with ISO 17025 standard 8. References 1. Road Traffic Act 2010. http://www.irishstatutebook.ie/2010/en/act/pub/0025/indx.html 2. Evidential breath analysers International Recommendation OIML R 126 Edition 1998 3. Gullberg,R.G. (2006) Accreditation and Quality Assurance 11:562-568 Estimating the measurement uncertainty in forensic breath-alcohol analysis. DOI 10.1007/s00769-006-0176- y 4. Gullberg, R.G., Polissar, N.L. (2011) Journal of Breath Research. 5 Factors contributing to the variability observed in duplicate forensic breath alcohol measurement. DOI:10.1088/1752-7155/5/1/016004 5. Gullberg,R.G. (2003) Forensic Science International 131 30-35 Breath alcohol measurement variability associated with different instrumentation and protocols. 6. Gullberg,R.G. (2009) Private communication with Reynolds,D. MBRS. Breath alcohol testing uncertainty estimation. 7. Evidential breath analysers International Recommendation OIML R 126 Edition 2012 http://www.oiml.org/publications/r/r126-e12.pdf 8. General requirements for competency of testing laboratories ISO/IEC17025:2005 6