Abstract
The reliability of measurements of mainstream smoke analytes other than “tar”, nicotine and carbon monoxide (CO) is not known but is important in the current regulatory environment internationally. An appreciation of between laboratory variability is essential for companies contracting analytical work to outside suppliers.
Seven laboratories obtained data from three cigarette brands for as many as they could currently measure of the 44 smoke analytes, commonly referred to as the “Hoffmann list”. The brands, of “tar” yields 12 mg, 8 mg and 5 mg, were smoked under the International Organisation for Standardisation (ISO) smoking regime to obtain average yield values based on 5 replicates, each laboratory smoking their chosen number of cigarettes per replicate. In addition, laboratories used their preferred and internally validated methodology i.e. smoking machine type, trapping system, sample work-up and detection system. Around 3600 data points were obtained.
This study was based on one point in time measurements. It did not therefore include any components of longer-term variability that would be expected to further increase the measurement variability. No analytes had lower within-laboratory measurement variability than “tar” and 70% of the other analytes had significantly higher levels. All laboratories ranked the products in the same order for all analytes (except some metals) but there were as much as 10-fold differences in measured values between laboratories. The mean difference between highest and lowest yield measurements was 80% when the values for the three smoke analytes with differences in excess of 8-fold were excluded.
Given the lack of standardised methods, and the consequent high degree of inter-laboratory variability it is not currently possible to make meaningful comparisons between such data from several sources. Indeed, calculation of yields from benchmarking studies may prove no less reliable.