Of all the legal substances ingested by Australians, tobacco and cigarettes alone have no legal maximums on the amount of toxic residues they can contain. Because tobacco is not categorised as either a food or a drug,(54,55) no existing Australian standards have been applied to them. No regular government testing is carried out on Australian or imported tobacco and cigarettes for substances other than tar, nicotine and carbon monoxide.(56) Levels of these three components have been restricted by voluntary agreement with the tobacco industry, but are now covered by Federal Government Regulations(33) (see Section 5.3 above).
A wide range of chemicals including herbicides, fungicides, insecticides and desuckering agents are routinely used in tobacco growing(54) in order to ensure maximum commercial production.
There is evidence that pesticide residues in mainstream smoke (the smoke inhaled by the smoker) may be retained by the smoker. Animal studies suggest that pesticide residues inhaled in smoke are metabolised in a similar way as if they were ingested.(54) Pesticide residues and other soil pollutants found in tobacco may also contribute to the accumulation of heavy metals in the body.(57)
In 1981 the Australian Government Analytical Laboratories (AGAL) determined that Australian cigarettes contained 43 times more DDT and 30 times more dieldrin than samples of British or American cigarettes.(56) In its 92nd session in October 1981, the National Health and Medical Research Council made the following observations:(58)
The Council noted that certain pesticide residues in Australian manufactured cigarettes were at levels appreciably higher than in overseas brands ...It considered that pesticide residues in tobacco were likely to increase the known adverse effects of inhaling tobacco smoke. Mean levels of dieldrin and DDT residues in particular had been determined at 0.09 parts per million (ppm) and 7.3 ppm respectively which, because of the amount absorbed from the smoke, constituted cause for concern. Significant proportions of the tolerable daily intakes of these chemicals were likely to be attributable to this source in smokers.
Council directed its Pesticides and Agricultural Chemicals Committee to undertake a scientific investigation into the levels of potentially harmful residues in cigarettes. Meanwhile, it considered that public health authorities should encourage awareness of the hazards of cigarette smoking, and recommended that to avoid such risks altogether people should not smoke.
Although the Department of Primary Industry suggested in 1985 that appropriate upper limits for agricultural chemical content in tobacco be set,(54) this has not occurred. In press reports, spokespeople for the National Health and Medical Research Council have stated the informal view that as tobacco is already known to contain large numbers of carcinogens and other toxins, and in view of the pronouncements which the NH & MRC has already issued about the dangers of smoking to health, there is no imperative to spend time and resources on measuring pesticide residues.(59)
Organochlorines (such as DDT and dieldrin) are characterised by persistence and hence their ability to accumulate. This means that continued low exposures can, over time, become toxically significant. DDT and dieldrin were extensively used on tobacco crops prior to their restriction in 1981, but their residues were still evident in soils in the tobacco producing areas of the Ovens and King region in Victoria during 1988-1989, and were detected in sediment in the Ovens and King Rivers at levels exceeding the threshold values for safe drinking water. These residues were considered likely to cause current and future harm to the aquatic ecosystem.(60)
It is not known whether Australian cigarettes still contain organochlorine residues. However, recent Canadian research has shown that minor residues of several organochlorine insecticides were present in cured tobacco leaf, although these chemicals had not been used on crops for up to twenty years.(61)
Some countries, for example Germany, Switzerland, the USA and the former Yugoslavia, set uppermost limits on the amount of toxic agricultural chemicals allowed in cigarettes.(56)
Research funded by the National Campaign Against Drug Abuse has found that the majority of smokers are not aware that cigarettes may contain pesticides and other chemicals (apart from 'tar' and nicotine), and that provision of specific information about tobacco content through pack labelling or on a pack insert would induce cutting down or quitting smoking(39) (see also Section 5.5 above).
As tar and nicotine content of cigarettes is being reduced, flavour additives are increasingly being relied upon by manufacturers to simulate full-bodied tobacco flavour.(62) Judicious use of flavourings can also disguise the shortcomings of less than premium tobacco leaf.(63) Flavour enhancers may comprise extracts from particularly flavoursome tobaccos or other plants, or synthetic agents.(12) Other chemicals added to the cigarette in the manufacturing process include chemicals to maintain combustion.(1)
In the United Kingdom, additives to tobacco products are assessed for safety and lists of permitted compounds published, with maximum levels of inclusion.(64) The (then) Federal Republic of Germany introduced strict regulations in 1977.(12) Canadian legislation introduced in 1989 requires cigarette manufacturers to disclose all constituents in their products to the Canadian government. Rather than abide by this disclosure, Philip Morris, a major international manufacturer based in the United States (and manufacturer of Peter Jackson, Marlboro and Alpine in Australia), has withdrawn its brands from the Canadian market. RJ Reynolds, another major manufacturer, has modified its products for the Canadian market. The reason given for these activities is the fear that the ingredients lists, regarded as trade secrets, might somehow become public.(65) However the tobacco industry also fears adverse publicity about the quantity and nature of its additives.(62)
The Government of New Zealand introduced legislation in 1990 which requires tobacco manufacturers and importers operating in that country to provide the Health Department annually with a list of approved additives and the quantity (by weight) of additives used. According to WD & HO Wills (New Zealand), in 1991 there were more than 2000 compounds approved as additives in New Zealand and some European countries. Included were known carcinogens, or compounds capable of producing carcinogenic compounds following combustion. One-third of the weight of pipe tobacco sold in New Zealand in 1991 was attributable to additives, compared to almost a quarter of the weight of loose tobacco for roll-your-own cigarettes. Additives made up 0.2% of the weight of ready-made cigarettes.(66)
It is not currently known which flavourings or additives are used by manufacturers of Australian cigarettes and tobaccos. The Department of Human Services and Health has signalled that the National Health and Medical Research Council may reconsider its policy in this regard.(66)