Chapter 1 0 
j Standardization has produced a remarkably reproducible procedure 
I given that the process involves the combustion of highly processed and 
I packaged plant material. This is illustrated by the data shown in Table 1. 
I Individual laboratories typically generate results with a precision of 
i ±5 percent (relative standard deviation) or better for tar, nicotine, and 
I carbon monoxide yields of high-tar products. Interlaboratory agreement 
j is generally within 4 and 8 percent of the mean, depending on the 
constituents and number of cigarettes considered. Precision and 
interlaboratory agreement as a percentage of the mean are poorer for 
very-low-delivery (e.g., 1 mg tar) products, but the absolute error is similar. 
The procedure is sufficiently reproducible to allow rounding of FTC results 
for tar and carbon monoxide to the nearest whole milligram based on a 
] difference between brands of only 0.1 mg (0.4 mg or less reported as <1 mg 
or below detection limit of the method, 0.5 mg or more rounded up to 1 mg, 
I 1.04 mg rounded down to 1 mg, etc.). Results for nicotine are rounded to 
the nearest tenth mg. Those with 0.05 mg or greater are rounded up, 
whereas those with 0.04 mg or less are rounded down, as above. 
INFLUENCE Each parameter specified in the FTC testing procedure influences 
OF SMOKING the yields of tar, nicotine, and carbon monoxide. Restrictive 
I PARAMETERS tolerances specified for acceptable puff volume, puff duration, and 
so forth are required to allow comparison of similar products and to allow 
interlaboratory comparability. Parameters such as cigarette conditioning 
prior to smoking are specified to accommodate the realities of laboratory 
measurements: in this case, that the cigarettes are likely to be analyzed after 
long periods of cold storage. Minor variations in any of these parameters can 
result in detectable differences in yields. Realistic (comparable with human 
smoking practices) variations also can result in large differences in yields. 
Darrall (1988) has reported a systematic study of the influence of smoking 
parameters on yields of tar, nicotine, and carbon monoxide. Puff durations 
of 1.6 seconds and 2.3 seconds produced essentially the same yields for very- 
low-tar (^4 mg) cigarettes and almost indistinguishable yields for higher tar 
products (Table 2). No clear trend toward increasing or decreasing yields 
was noted. Changing puff volume from 35 to 40 mL produced a small but 
generally consistent increase in tar and nicotine (Table 3). Low-tar products 
I yielded 1 to 3 mg more tar and 0.1 to 0.3 mg more nicotine at 40-mL puff 
j volumes than at 35-mL puff volumes. Higher tar products increased yield 
by 2 to 5 mg of tar and 0.1 to 0.5 mg of nicotine. The increases, although 
small, still may be larger than would be found using the standard FTC 
method because the investigator in Darrall's study (1988) smoked at 2 puffs 
per minute, thus increasing the number of puffs per cigarette. Larger changes 
in puff volume produce larger changes in yields. Browne and colleagues 
(1980) reported that particulate matter yield increased from 29 mg to 55 mg 
for a U.S. blend experimental cigarette when the puff volume was changed 
I from 17.5 mL to 50 mL under otherwise standard conditions. Carbon 
monoxide yields were 9 mg and 20 mg for puff volumes of 17.5 mL and 
: 50 mL, respectively. 
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