Jack C. Robinson

Yields of tar, nicotine, and carbon monoxide in the sidestream smoke from 15 brands of Canadian cigarettes.

Sidestream smoke yields for 15 brands of cigarettes were determined under conditions where mainstream yields were approximately equal to those used for determining the values which appear on packages of Canadian cigarettes. Sidestream yields of tar, nicotine, and carbon monoxide were much higher than mainstream yields for all brands tested. The average sidestream-to-mainstream ratios for the 15 brands were 3.5, 6.6, and 6.8 for tar, nicotine, and carbon monoxide, respectively. The highest yields of sidestream were obtained from the brands with the lowest mainstream yields.

The role of carbon monoxide in cigarette smoking. I. Carbon monoxide yield from cigarettes.

The carbon monoxide deliveries of 20 major Canadian brands of cigarettes, determined by gas chromatography and using standard smoking conditions, were estimated and found to vary by a factor of about two. The CO yields were found to increase with puff volume and tobacco moisture, decrease with increased paper porosity, but remain essentially constant with puff duration. The data suggest that reduced CO deliveries can be achieved by increasing the cigarette paper porosity. Combustion temperature presumably also influences CO deliveries, but the relative role ascribed to dilution and combustion is not clear. It may be concluded that smokers can lower their CO exposure by reducing their puff volume, smoking cigarettes manufactured from high porosity paper, by taking fewer puffs, and decreasing their tendency to inhale. Since CO and tar deliveries are correlated, these measures would also tend to decrease a smokers exposure to tar.

ESTIMATING THE HAZARDS OF "LESS HAZARDOUS" CIGARETTES. I. TAR, NICOTINE, CARBON MONOXIDE, ACROLEIN, HYDROGEN CYANIDE, AND TOTAL ALDEHYDE DELIVERIES OF CANADIAN CIGARETTES

The tar, nicotine, CO, HCN, total aldehyde, and acrolein deliveries of 102 brands of Canadian cigarettes have been determined. On the basis of these deliveries, 15 brands (9% of sales) were categorized as low hazard and 9 brands (10% of sales) as high hazards. All six constituents were used for the classification since for most brands tar was a poor indicator of gas-phase deliveries. As a result, smokers who indiscriminately switch to a brand with a lower tar delivery may inadvertently increase their exposure to gas-phase constituents such as CO and increase their risk of smoking-related pathology. With respect to Canadian cigarettes, the choice of a 30-mm standard butt length may result in omission of some of the available tobacco from the testing procedure, thus reducing the value of tar level as a guide to choosing a less harmful cigarette.

Characterization of tobacco products: a comparative study of the tar, nicotine, and carbon monoxide yields of cigars, manufactured cigarettes, and cigarettes made from fine-cut tobacco.

Yields of tar, nicotine, and carbon monoxide were compared in selected Canadian brands of manufactured and hand-rolled cigarettes, and small and large cigars. To control for varying volumes of smoke delivery per cigarette or cigar, standardized comparisons in milligrams of toxic substance per liter of smoke were made. The mean deliveries per liter of smoke and tar, nicotine, and carbon monoxide were highest for small cigars, followed by hand-rolled and manufactured cigarettes; large cigars had the lowest deliveries. Five out of six brands of cigarettes handmade from fine-cut tobacco delivered significantly more tar, nicotine, and carbon monoxide per cigarette or per liter than did the identically named manufactured brand.

How good are the numbers for cigarette tar at predicting deliveries of carbon monoxide, hydrogen cyanide, and acrolein?

Simple and multiple linear regression analyses were performed on the tar, nicotine, CO, HCN, and acrolein deliveries of 98 brands of commercially available Canadian cigarettes. Simple linear regressions of CO, HCN, and acrolein on tar and of acrolein on CO were not significant at the 5% level for plain cigarettes; all other regressions were very strongly significant (p less than 0.01). In addition there was strong statistical evidence that filter, vented filter, and plain cigarettes have different regression relations and different levels of precision associated with the regression parameters. With respect to CO, tar level could predict the corresponding CO value only within 3.9 mg (filter), 1.9 mg (vented filter), and 3.1 mg (plain). These results show that tar delivery alone is an inadequate predictor of gas-phase constituents such as CO. Information concerning these constituents is best conveyed by an analytically determined value for each component.

Estimates of maximum or average cigarette tar, nicotine, and carbon monoxide yields can be obtained from yields under standard conditions☆

Average yields of tar, nicotine, and carbon monoxide per liter of smoke and per cigarette were determined for 10 brands of cigarettes smoked under 27 different conditions (one standard and 26 nonstandard). Per cigarette yields were highly variable across smoking conditions due to differences in the total volume of smoke taken for analysis. The results of a simple linear regression analysis indicated that up to 95% of the variation in tar yield per cigarette could be explained by variations in the total volume of smoke produced per cigarette. Per liter yields for tar, nicotine, and carbon monoxide were almost constant over the conditions investigated. Since most smokers inhale less than this amount, yields per liter provide a rough estimate of the maximum amount to which a smoker might be exposed. Yields per liter, taken over all 26 conditions, are highly correlated with per cigarette yields under standard conditions. Consequently, values on one scale can be converted to the other, at least for the 10 brands investigated. The average conversion factor for tar, nicotine, and carbon monoxide is 2.5 when proceeding from milligrams per king-size cigarette under standard conditions to milligrams per liter. This relationship is true for both vented and nonvented cigarettes when ventilation holes are not blocked.

Yields of selected toxic agents in the smoke of Canadian cigarettes, 1969 and 1978. A decade of change?

Abstract Canadian sales-weighted averages of cigarette carbon monoxide (CO) and tar have been evaluated for the decade ending 1979. Virtually no change occurred up to 1976; between 1976 and 1979 the sales-weighted average CO dropped from 21 to 16 mg with a much smaller decrease in the corresponding values for tar (16.1 to 14.4 mg). Thus changes in CO deliveries did not take place at the same rate as changes in tar deliveries. If standardized smoking machine yields are related to the risk of smoking-related morbidity and mortality, the low correlation and the 8-year lag time in the curves describing the decrease in two of the major toxic constituents of cigarette smoke may be of importance in helping to explain a lower impact of less hazardous cigarettes on coronary heart disease (CHD) rates. Assuming that exposure to CO is a risk factor for CHD, the relatively recent reduction in sales-weighted CO yields might have the effect of decreasing CHD rates among smokers in the future. In addition to CO yields, HCN, acrolein, and total aldehyde yields of 25 brands of cigarettes manufactured in 1969 were compared with yields of the same cigarettes manufactured in 1978 in order to assess changes which may have occurred in other gas phase constituents. Significant decreases were noted in the yields of all constituents other than CO; the average decrease per brand was HCN, 69 μg; total aldehydes, 114 μg, and acrolein, 5.2 μg.