5.3 Tar, nicotine and carbon monoxide levels

Cigarettes

With growing concern about health problems caused by smoking, tobacco manufacturers, growers and scientists have combined efforts to reduce the quantities of noxious substances being delivered to smokers.(1,18) Although lower tar content and improved filtration have tended to bring about lowered yields of some other toxic compounds, carbon monoxide levels are subject to other variables (see Section 5.1 above), and nicotine levels may also vary independently. Despite falling tar levels, nicotine content in popular British and American low-yield brands has not been reduced at the same rate.(2) During 1994 strong evidence emerged that nicotine content has been independently manipulated by US tobacco manufacturers to create and sustain addiction among smokers.(19)

The amount of tar and nicotine in Australian made cigarettes has fallen substantially since the late 1960s, as a direct consequence of action taken by the Anti-Cancer Council of Victoria (ACCV) (Tables 5.2 and 5.3). The Council arranged for the first testing of a sample of popular Australian brands in 1967. The cigarettes were sent to the United States, as no appropriate measuring equipment existed in Australia. Viscount, with 40 mg, had the highest tar content measured.(21)

The results gained wide publicity, and in the following year Monash University in Victoria was commissioned by the ACCV to test all available brands. In the face of periodic testing and the accompanying publicity concerning the results, the tobacco industry rapidly reduced tar content.(21)

In August of 1982, when tar and nicotine labelling on cigarette packages was introduced (see Section 5.4 below), upper limits of 18 mg of Corrected Particulate Matter (CPM, or tar) and 1.6 mg of nicotine per cigarette were established as part of a voluntary agreement reached between the tobacco industry and the federal government.(22) The agreement was renegotiated in 1986 (enacted 1987) and extended to cover carbon monoxide content. Approved maximum yields were reduced to CPM 16 mg per cigarette; nicotine 1.5 mg per cigarette, and carbon monoxide 20 mg per cigarette.(23) In 1988 these were further reduced to 14 mg CPM and 1.4 mg nicotine per cigarette. The maximum carbon monoxide level permitted for new brands manufactured or imported since 1986 was reduced to 18 mg per cigarette, but brands first manufactured or imported prior to 1986 could continue to contain up to 20 mg of carbon monoxide per cigarette.(24) (Maximum permitted levels of tar, nicotine and CO have since been set by federal legislation (see Section 5.4)).

Routine testing by the Australian Government Analytical Laboratories (AGAL) of all brands and variants of cigarettes sold in Australia was suspended following the monitoring of tar, nicotine and carbon monoxide levels in 1991. Testing in the future will be on an ad hoc basis and may be similar in format to the data released in 1994 from the analysis of the 29 most commonly smoked cigarettes.(25) However the standard laboratory testing methods have been criticised as inadequate (see below).

Table 5.2 gives a summary of the AGAL findings, presenting the percentage of brands falling within specified tar bands.

Table 5.2 shows that tar content of Australian cigarettes has been falling. In 1991 85% of brands contained less than 12 mg of tar per cigarette, and of these, over a third (37%) contained 6 mg of tar per cigarette or less. No Australian manufactured cigarette contained more than 13 mg per cigarette of tar, 1.2 mg of nicotine, or 13 mg of carbon monoxide. However 40% of the 37 imported brands in 1991 contained 14 or more mg of tar per cigarette, and 13% of these brands contained 27 mg of tar per cigarette or more. The brand containing the highest levels of all three constituents measured was Gudang Garam King Size, a brand of kretek (clove cigarette) imported from Indonesia,(27) which contained 49 mg of tar, 2.3 mg of nicotine, and 22 mg of carbon monoxide per cigarette (thereby exceeding Australian limits set by voluntary agreement for imported brands).

Table 5.3 shows that average tar content (sales weighted) in Australian cigarettes has declined by 52.5% in the past 20 years.(28,29) Table 5.4 provides a breakdown of market share of cigarettes by tar level from 1989 to 1993, summarised into bands. The new 1 milligram brands are increasing their market share, and the highest yielding subgroup of cigarettes has become less popular. The majority of cigarettes smoked in Australia between 1989 and 1993 had tar levels lying between 4-12 mg. Market share of these brackets has remained stable.(30)

Limitations of laboratory testing for tar, nicotine and carbon monoxide levels in cigarettes

While the data on tar levels measured by the AGAL have provided a useful comparative index of tar, nicotine and CO content, published and actual levels attained under real smoking conditions may vary widely. This is because machines used to measure smoke content test the cigarettes in a uniform way, with a fixed puff volume, duration of puff and pause between puffs. Research has suggested that settings on smoke testing machines may seriously underestimate real exposure by failing to imitate a realistic smoking pattern.(31) Moreover, there is also considerable individual variation in smoking behaviour, with smokers adjusting intake to meet their own requirements.(4) They may inadvertently or deliberately alter smoke delivery by blocking with their fingers the perforation holes in filters and papers designed to dilute smoke.

Research led by a former AGAL scientist has confirmed that smoke yields measured by current smoking machine methodology are likely to produce results which vary widely from yields to which the smoker is exposed under normal smoking conditions.(32) A number of brands which use ventilation holes in the filter to reduce toxic yield were tested, first with half and then with all the filter holes blocked. Hole blocking caused a marked rise in smoke yield for all brands tested, with the lowest yield (1mg) brands showing an up to ninefold increase in tar content.

The report contends that low yield cigarettes have been carefully manufactured to produce the lowest possible measurements under machine test conditions, through deliberate placement of ventilation holes in relation to the standard positioning of the cigarette in the machine's specified cigarette holder. The authors of this study observe that cigarette testing methods endorsed by the International Standards Organization (ISO) have been developed in close collaboration with the tobacco industry, with the result that ISO requirements have served industry ends. In Australia, the tobacco industry has the right to veto the publication of AGAL test results which do not accord with their own. The outcome, according to the report, is that '... for fifteen years Australian Tar Tables have merely upheld industry findings', and have misled the public about the true nature of the cigarettes they smoke.(32)

Given that routine testing by AGAL of smoke yield levels for Australian brands has been discontinued, and that recently introduced federal regulations specify that ISO standard methods should remain the criteria by which Australian cigarettes are tested,(33) it is not immediately clear how the situation outlined by this study might be improved. See also Chapter 2, Section 7 for related discussion about mean daily exposure to tar, nicotine and carbon monoxide for Australian smokers, and Chapter 11, Section 4 for discussion about how the US tobacco manufacturers have manipulated nicotine content of cigarettes.

'Roll your own' (RYO) tobacco, pipes and cigars

There are currently no published data on the tar, nicotine and carbon monoxide content of RYO tobacco. The AGAL did not include these tobaccos in their routine cigarette testing because of the difficulty in formulating an 'average' cigarette, since RYO users make up their cigarette according to their own taste. Analysis of RYO tobacco would also need to take into account the paper and filter (if any) used by the smoker in making their cigarette, as Canadian research has shown that these variables have greatest effect on the ultimate yield delivered.(34) Pipe tobaccos were also excluded, on the basis of difficulty of standardising variables such as quantity, ventilation and density of tobacco in a typical pipeful of tobacco. Cigars were presumably excluded because of the wide product variation.

Health agencies urged the Department of Health to devise some suitable way of providing measurements for toxic content of RYO tobacco, as is now happening in Canada,(34) but this did not occur.(35) This may have led to confusion among smokers about the dangers of using RYO tobacco. All tobacco products pose health risks.


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