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.