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(11) | EP 0 086 638 A2 |
| (12) | EUROPEAN PATENT APPLICATION |
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| (54) | Tobacco smoke filter |
| (57) A tobacco smoke filter containing a deoxygen agent (at 2a) such as a sulfite, an
acid sulfite, a pyrosulfite, a hydrosulfite, iron powder, a ferrous compound, or a
reducing organic compound. This tobacco filter is capable of effectively inactivating
the mutagenicity of tobacco smoke. |
BACKGROUND OF THE INVENTION
Field of the Invention
[0001] The present invention relates to a tobacco smoke filter. More specifically, it relates to a tobacco smoke filter capable of effectively inactivating the mutagenicity of tobacco smoke.
Description of the Prior Art
[0002] Recently, the cause-and-effect relationship between smoking and carcinogenicity has been a subject of intense interest in a pathological field. Years of study by many researchers have as yet not proven a direct causal link between smoking and cancer, but it is now generally agreed, among other things, that smoking can trigger squamous cell carcinoma in lung.
[0003] Furthermore, it is a fact that tobacco smoke contains carcinogenic substances such as benzopyrene, although the amount thereof is very small, and also that tobacco smoke has mutagenicity against microorganisms. It has been verified that there is a high 70% to 80% correlation between mutagenicity and carcinogenicity.
[0004] Cancer is the number one killer in many advanced nation's. The number of deaths each year from lung cancer has been rising especially fast. Thus, regardless of the lack of complete proof of the carcinogenicity of tobacco smoke, the inactivation of the mutagenicity of tobacco smoke is of great importance in human health.
[0005] Various attempts have been made in the art to develop substances capable of removing or eliminating the mutagenicity of tobacco smoke. For instance, sugars, tannic acid, n-propyl gallate, pyrocatechol, rutin, crestin, BHT, catechol, pyrocatechuic acid, and cabbage extract have been reported as effective substances to decrease or eliminate the mutagenicity of tobacco smoke. However, these substances should be impregnated into, or should be mixed with, tobacco leaves. Furthermore, the effect of these substances to inactivate the mutagenicity of tobacco smoke is relatively small and the mutagenicity of tobacco smoke cannot be definitely inactivated according to the inventors' study.
SUMMARY OF THE INVENTION
[0006] Accordingly, the object of the present invention is to provide a tobacco smoke filter capable of at least partly inactivating the mutagenicity of tobacco smoke.
[0007] Another object of the present invention is to provide a tobacco smoke filter which optionally does not impair the flavoring taste of the tobacco smoke.
[0008] Other objects and advantages of the present invention will be apparent from the description set forth hereinbelow.
[0009] In accordance with the present invention, there is provided a tobacco smoke filter comprising a deoxygen agent (or free-oxygen absorber or free-oxygen scavenger).
BRIEF EXPLANATION OF DRAWINGS
[0010] The present invention will be better understood from the following description given in connection with the accompanying drawings in which:
Fig. 1 is a schematic partially broken front view of a cigarette to which an example of the tobacco smoke filter according to the present invention is applied; and
Fig. 2 is a schematic partially broken front view of a cigarette holder to which an example of the tobacco smoke filter according to the present invention is applied.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0011] The deoxygen agents usable in the present invention are those which are capable of absorbing or removing an oxygen molecule during an oxidation reaction of an inorganic or organic compound (i.e., readily oxidizable compounds). Example of such compounds are: iron powder; ferrous salts such as FeSO4 , FeCl2 , FeBr2 , Fe(N03)2 , Fe3(P04)2 ' ferrous oxalate, ferrous formate, and ferrous acetate; other iron compounds such as iron carbide, iron carbonyl, and ferrosilicon; sulfur-containing acid salts such as sulfites, bisulfites, pyrosulfites, and hydrosulfites (or dithionites); and reducing organic compounds such as erithorbic acid, ascorbates, and strong alkali treated lignin. Examples of the sulfur-containing acid salts are non-toxic metal salts such as alkaline metal salts (e.g., sodium salts, potassium salts), alkaline earth metal salts (e.g., calcium salts, magnesium salts), and aluminum salts; and ammonium salts. Typical examples of such salts are K2SO3 , KHSO3 . K2S2O6' Na2SO3 , NaHS03 , Na2S206 ,Na2S2O4 , CaS03 , Ca(HSO2)2 , MgSO3 , Al(HO)4SO3 , (NH4)25O3 , NH4HSO3 , (NH4)2S2Ob , and (NH4)2S204. Especially, the use of sodium and potassium salts is preferable from the viewpoints of water solubility, stability, and the allowability as a food additive. Accordingly, commercially available oxygen absorbents for food packaging such as Ageless (Trademark, manufactured by Mitsubishi Gas Chemical Co.), Tamotsu (Trademark, manufactured by Toyo Valve Co.), and Vitalon (Trademark manufactured by Toagosei Chemical Industry Co.) can also be used as a deoxygen agent in the present invention.
[0012] It has been found as shown in Table 1 below that various sulfites, which were ingredients of deoxygen agents, extremely effectively and completely inactivate the mutagenicity of cigarette smoke condensate against Salmonella typhimurium TA-100 strain in the absence of rat liver homogenate (S9 mix).
[0013] The present invention is based on this novel finding. According to the present invention, deoxygen agents are incorporated into a tobacco smoke filter. These deoxygen agents can be used generally in an amount of 0.1 g to 2 g, desirably 0.3 g to 1.2 g, based on a piece of the filter. The deoxygen agents do not adversely affect the flavoring taste of the tobacco smoke. Furthermore, as shown by the fact that these deoxygen agents are frequently used as food additives, no substantial harmful side-effect is caused.
[0014] The above-mentioned deoxygen agents can be applied to tobacco smoke filters in the following manners: (A) The deoxygen agent is impregnated into a support for tobacco filter; or (B) The deoxygen agent is directly, or after supported on a suitable carrier, packed inside a filter.
[0015] The first method (A) is suitable when water-soluble deoxygen agents (e.g., sulfur-containing acid salts) are used and is the simplest application method. On the other hand, the second method (B) can be applied whether or not the deoxygen agents are water-soluble. However, when metallic powder such as iron powder is used as the deoxygen agent, only the second method (B) can be adopted. Examples of the carriers usable in the second method (B) are activated carbon, alumina, silica gel, starch, dextrin, absorbent wadding, cellulose acetate, pulp, diatomaceous acid, gypsum powder, natural zeolite, and molecular sieve. The use of these carriers increases the efficiency of the deoxygen agents, as compared with simple use of the deoxygen agents, since the contact area of the deoxygen agents with tobacco smoke is increased due to the large specific surface area of the carriers. For instance, in the case of a metal such as iron, an extremely active deoxygen agent can be prepared by adsorbing the water-soluble salt thereof such as iron chloride in a carrier, followed by the reduction thereof. Furthermore, such a deoxygen agent can be suitably granulated and, therefore, the automatic production of tobacco smoke filter can be facilitated. Conventional filtering materials such as activated carbon and silica gel can be optionally included in the tobacco smoke filter, if desired.
[0016] The deoxygen agents used as a main constituent in the present tobacco smoke filter can be oxidized by oxygen present in the air. Furthermore, moisture in the air accelerates the above-mentioned oxidation in most cases. Accordingly, the tobacco smoke filter of the present invention and a tobacco, especially a cigarette provided with an assembled tobacco smoke filter according to the present invention are desirably wrapped with a wraping material having a high barrier property against oxygen and water vapor. Examples of such wrapping materials are polycellophane films lined with gas barrier plastics such as ionomer and poly(vinylidene chloride).
[0017] Fig. 1 illustrates one example of the tobacco smoke filter according to the present invention which is applied to a cigarette.
[0018] The rear filter portion 2 of a cigarette 1 is composed of two filter units 2a and 2b. Both filter units 2a and 2b are composed of compressed short fibers of'cellulose acetate. The front filter unit 2a is impregnated with a water-soluble sulfite and contains activated carbon particles 3. The rear filter unit 2b is composed of a conventional acetate filter. Thus, the tar contained in tobacco smoke, caused by the smoking, contacts with the sulfite for inactivation of the mutagenicity thereof and is also adsorbed into the activated carbon particles 3 in the filter unit 2a. If necessary, it should be noted that the length of the filter unit 2a can be extended or that the sulfite or other deoxygen agents can be impregnated into the acetate filter of the filter unit 2b. Typical lengths of the filter units 2a and 2b are 5 mm to 20 mm and 3 mm to 10 mm, respectively.
[0019] Fig. 2 illustrates another example of the tobacco smoke filter according to the present invention which is applied to a separate cigarette holder.
[0020] That is, activated alumina particles 6 impregnated with sulfite (or the other deoxygen agents) are packed through separators 5 and 5' provided with fine pores in the inside of a pipe body 4. The activated alumina gradually becomes brown upon use due to the tar captured from the tobacco smoke. Thus, the filter should be changed according to the coloration of the filter.
EXAMPLES
[0021] The present invention now will be further illustrated by, but is by no means limited to, the following examples. As shown in the following examples, various deoxygen agents or oxygen absorbing agents deactivate the mutagenicity of cigarette smoke condensate. The action of such deoxygen agents or oxygen absorbing agents during the deactivation is not clearly understood, but it would seem that the mutagenic substances contained in the tobacco smoke has a high reactivity to the deoxygen agents or oxygen absorbing agents. In the following Examples, the mutagenicity and the inhibitory effect against mutagenicity were determined according to a pre-incubation method disclosed in Sugimura and Nagao "Chemical-Mutagenes" Vol 6, pp 41 (1981).
Example
[0022] Filters were prepared by separately absorbing 0.4 ml each of a 2 M aqueous sodium sulfite solution, a 2 M aqueous sodium bisulfite solution, and a 1 M aqueous potassium pyrosulfite solution into absorbent wadding packed in hard plastic tubes of which one end was flattened.
[0023] The filter thus prepared was set in an automatic smoking machine. The smoking test was carried out by using a "Long-Piece" brand Japanese cigarette having a size of 8 mmØ x 80 mm under the conditions of the smoking rate of 2 sec / 1 min and the smoke intake amount of 35 ml per each smoke until the length of the cigarette end became 30 mm. The intake main stream was passed through the filter to be tested and, then, the tar contained therein was collected by a glass fiber filter. The tar was extracted from the glass fiber filter by dimethylsulfoxide. The mutagenicity of the collected tar was determined. The results are shown in Table 1 below. As is clear from the results shown in Table 1, the mutagenicity of the tar obtained through the above-mentioned filter completely disappeared.
Example 2
[0024] Mutagenicity tests were carried out in the same manner as in Example 1, except that three types of commercially available deoxygen agents and the other two agents were used. As filters, commercially available ".Aqua Filter" (manufactured by American Drug Co.) was used and the content of the filters were replaced with the test agents listed in Table 2 below. The results are shown in Table 2.
Example 3
1. A tobacco smoke filter comprising a deoxygen agent.
2. A tobacco smoke filter as claimed in claim 1, wherein said deoxygen agent is a
sulfite, bisulfite, pyrosulfite, or hydrosulfite.
3. A tobacco smoke filter as claimed in claim 1, wherein said deoxygen agent is iron
powder or a ferrous salt.
4. A tobacco smoke filter as claimed in claim 1, wherein said deoxygen agent is a
reducing organic compound.
5. A tobacco smoke filter as claimed in claim 1, wherein said deoxygen agent is supported
on a carrier of activated carbon, alumina, silica gel, starch, dextrin, absorbent
wadding, cellulose acetate, pulp, diatomaceous acid, gypsum powder, natural zeolite,
or molecular sieve.
6. A tobacco smoke filter as claimed in claim 1, wherein said tobacco smoke filter
is assembled in a cigarette or other tobacco-containing smoking material.
7. A tobacco smoke filter as claimed in claim 1, wherein said tobacco smoke filter
is formed separately from a cigarette or other tobacco-containing smoking material.