Part Seven
Technical Advisory Group
Technical Advisory Group - Work Programme
7.1 The Technical Advisory Group (TAG) has conducted a review of emissions from cigarettes (see below), and has played a major role in selecting a programme of research commisssioned by the Department of Health (DH) and carried out by the Laboratory of the Government Chemist (LGC). Members of the TAG have made toxicological assessments of proposed additives in order that they might be used or excluded from use in tobacco products. The TAG has prepared guidelines for a Voluntary Agreement with the tobacco industry on the approval and use of new additives, which are described in Part Eight. A full version is to be found at Annex K. A review of the procedures used by European and US bodies responsible for food and tobacco regulation was conducted. The group agreed that, although the approval of additives for use in food provided useful toxicological information, data on volatility and the products of pyrolysis were required before permission could be granted for use of an additive in tobacco products.
Laboratory of the Government Chemist
7.2 Yields of various harmful constituents of tobacco smoke have been measured by the LGC on behalf of the DH. Tar, nicotine and carbon monoxide (TNCO) yields are currently measured on a routine basis in accordance with section 9 of the Tobacco Products Labelling (Safety) Regulations, 1991. Yields of some other components of mainstream tobacco smoke which may be hazardous to health have also been determined by the LGC. Assessments of tobacco specific nitrosamines,115 benzene, nitric oxide (NO) and polycyclic aromatic hydrocarbons (PAHs) have been carried out since 1994. Papers on benzene, NO and PAHs are being be prepared for publication. The LGC have also carried out a study on yields of TNCO and other analytes from cigarettes made from hand-rolling tobacco116 and are currently determining yields of TNCO, PAHs and benzene from small cigars. Results of the research programme are regularly reported to TAG.
Review of Emissions
7.3 For more than 20 years the Government has taken action to encourage smokers to stop smoking and non-smokers not to start. At the same time a programme of product modification has allowed smokers, unable to give up, to smoke products with lower emissions of noxious substances. At the request of the Scientific Committee on Tobacco and Health, its Technical Advisory Group undertook a review of emissions in cigarette smoke, updating former work. The full text of this review forms Annex L.
Tar
7.4 The tar content of cigarette smoke is the single most important factor in terms of health risk. Tar yields of UK manufactured cigarettes have fallen over the past few decades, partly as a result of a programme of cigarette modification and partly in response to legislation. Manufacturers have tended to reduce tar yields in all brands - not just those at the top end of the tar range - and there is growing evidence of increasing consumer acceptance of this trend with more people than ever in 1994 smoking low tar brands.
7.5 Lower tar cigarettes still carry substantial health risks, and there is evidence that smokers largely compensate for lowered yields by increasing inhalation. There is, however, reasonably good evidence to show that lower tar cigarettes are associated with a reduced risk in some smoking related diseases, notably lung cancer. It remains true that tar reduction is no substitute for the avoidance of cigarettes. It is a cause for concern that benefits derived from the increasing popularity of low tar manufactured brands are partly off set by an increase in the smoking of hand-rolled tobaccos in which the tar content is high.
7.6 Yields of nicotine and carbon monoxide in hand rolling tobacco are also higher on average than those from manufactured cigarettes. The TAG recommends that the public should be made aware of the relatively high yields of hand rolling tobacco and of the potential impact of this on health.
7.7 The European Directive to reduce cigarette tar yields to 12 mg should be achieved by January 1998.
Nicotine
7.8 The role of nicotine in the pathogenesis of smoking related diseases is uncertain, although it is clearly implicated in the establishment and maintenance of the smoking habit.113 Nicotine yields in manufactured cigarettes are not currently controlled, but yields have tended to fall as tar levels have reduced and this trend needs to be maintained.
7.9 The TAG agreed that continuing information is required on the role of nicotine in relation to health and disease. Much work has been done on compensatory smoking.114
7.10 The TAG noted the recent settlement negotiated between the US tobacco companies and Attorneys General from forty states080 and the confirmation of the FDA's authority to regulate tobacco products under the Food, Drug and Cosmetic Act and to regulate the levels of nicotine in these products. The widespread concerns that the settlement undermines the FDA's authority to regulate nicotine were also noted. Nicotine could not be banned from tobacco for 12 years and nicotine levels could not be reduced until the FDA could show substantial evidence of a “substantial reduction on the health risks” and that the nicotine reduction would not create a black market for cigarettes with a high nicotine content.
Carbon Monoxide
7.11 The carbon monoxide (CO) yield from cigarettes has decreased over the past few years, but at a slower rate than tar. As further measures to reduce tar yields are likely to result in similar reductions in CO no specific action is required, although the ratio of yield of CO to tar should be kept under review. The health effects of CO, especially in relation to ischaemic heart disease, are less clear.
Nitrogen and Carbon Derived Noxa
7.12 Yields of nitrogen derived noxa (harmful compounds), such as nitric oxide (NO), relate to the type of tobacco and its nitrate content and are independent of tar yields. Yields of carbon derived noxa, such as polycyclic aromatic hydrocarbons (PAHs), follow those of tar reasonably closely. Tobacco blends containing air-cured tobacco are relatively rich in nitrates and are popular in the United States. Flue-cured tobacco, favoured in the UK, contains higher levels of carbon derived noxa.
7.13 Nitric oxide is produced by the decomposition of nitrates in tobacco and is inhaled by the smoker. Exhaled NO, and NO contained in side stream smoke, gradually oxidise to nitrogen dioxide. Nitrogen dioxide is a respiratory irritant; inhaled NO appears to have no direct toxic effect, although recent research suggests that smoking may adversely affect the physiological function of naturally occurring NO in the lung. Like CO, NO is reduced by increasing cigarette ventilation and paper porosity - measures which also help to reduce tar yield.
7.14 The inverse relationship between the nitrogen and carbon derived noxa from tobacco is well established. Experimental data show that tar from cigarettes made from nitrate rich tobacco, containing reduced yields of PAHs, may be less carcinogenic than tobacco rich in carbon and low in nitrate, suggesting a potential “health benefit” from smoking nitrate rich tobacco. However, the issue is not straightforward, as tobacco rich in nitrate yields higher levels of certain tobacco - specific N-nitroso compounds which are carcinogenic.
7.15 The issue is complex and the TAG concluded that the impact of tobacco type and blend on the genesis of smoking related disease would benefit from further evaluation, together with an examination of the behavioural differences noted in populations smoking cigarettes made from different tobacco blends, to determine what factors, if any, contribute to differences in the incidence and prevalence of smoking related disease.
7.16 Recent studies carried out by the LGC have indicated that yields of NO from cigarettes and hand-rolling tobacco have increased in the last decade. Further work is necessary to establish the reasons for this increase. Total levels of nitrates in tobacco are currently being determined by the LGC in order to assess whether this might be responsible.
Conclusions
7.17 Reduction in tar yields has contributed modestly to reduction in mortality from some diseases caused by smoking, particularly lung cancer.
7.18 Tar reduction is no substitute for not smoking since low tar cigarettes continue to carry important health risks.
7.19 The yields of tar, nicotine, some N-nitroso compounds and carbon monoxide from hand-rolling tobacco are higher on average than those from manufactured cigarettes.
7.20 Nicotine has been shown conclusively to be addictive.
Recommendations
7.21 A policy of further tar reduction in manufactured cigarettes should be pursued without compromising the message of the importance of not smoking.
7.22 As a consequence of potential tar reductions, and thus changes to the manufacturing processes, the monitoring of tar, nicotine and carbon monoxide levels should continue. There should also be investigation into changes in harmful compounds as manufacturing processes change.
7.23 The public should be made aware of the relatively high yields of harmful compounds in hand rolling tobacco and of their potential impact on health.
7.24 There is a continuing need for population studies, such as the Health Survey for England, which relate tobacco type and yield, smoking behaviour and intake and the incidence and prevalence of tobacco related diseases.
7.25 Consideration should be given to smoking status being recorded as part of the death registration process, to aid monitoring of the evolving epidemic of tobacco related diseases.
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