Health impact of "reduced yield" cigarettes: a critical assessment of the epidemiological evidence.
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Cigarettes with lower machine measured "tar" and nicotine yields have been marketed as "safer" than high tar products over the last four decades, but there is conflicting evidence about the impact of these products on the disease burden caused by smoking. This paper critically examines the epidemiological evidence relevant to the health consequences of "reduced yield" cigarettes. Some epidemiological studies have found attenuated risk of lung cancer but not other diseases, among people who smoke "reduced yield" cigarettes compared to smokers of unfiltered, high yield products. These studies probably overestimate the magnitude of any association with lung cancer by over adjusting for the number of cigarettes smoked per day (one aspect of compensatory smoking), and by not fully considering other differences between smokers of "high yield" and "low yield" cigarettes. Selected cohort studies in the USA and UK show that lung cancer risk continued to increase among older smokers from the 1950s to the 1980s, despite the widespread adoption of lower yield cigarettes. The change to filter tip products did not prevent a progressive increase in lung cancer risk among male smokers who began smoking during and after the second world war compared to the first world war era smokers. National trends in vital statistics data show declining lung cancer death rates in young adults, especially males, in many countries, but the extent to which this is attributable to "reduced yield" cigarettes remains unclear. No studies have adequately assessed whether health claims used to market "reduced yield" cigarettes delay cessation among smokers who might otherwise quit, or increase initiation among non-smokers. There is no convincing evidence that past changes in cigarette design have resulted in an important health benefit to either smokers or the whole population. Tobacco control policies should not allow changes in cigarette design to subvert or distract from interventions proven to reduce the prevalence, intensity, and duration of smoking. (+info)
Smokers' beliefs about "Light" and "Ultra Light" cigarettes.
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OBJECTIVE: To assess beliefs about the tar and nicotine delivery characteristics and health benefits of Light and Ultra Light cigarettes among cigarette smokers. DESIGN: Random digit dialed telephone survey conducted in September 1999. SUBJECTS: Daily smokers (n = 2120) of Regular (46%), Light (39%), and Ultra Light (15%) cigarettes in the USA. The sample was weighted to match the US smoker population on age, sex, and ethnicity. MAIN OUTCOME MEASURES: Beliefs about Light and Ultra Light cigarettes were summarised on three dimensions: Safety (reduced health risk), Delivery (lowered tar and nicotine delivery), and Sensation (less harsh). RESULTS: Most smokers believed Lights and Ultra Lights were less harsh and delivered less tar and nicotine. On average, smokers believed that Lights afforded a 25% reduction in risk, and Ultra Lights a 33% reduction in risk. Light and Ultra Light cigarette smokers evaluated the risks of their own cigarette types more favourably. Light smokers had greater interest in quitting than Ultra Light smokers. Quitting intention was modestly related to beliefs about these cigarettes. Believing that Lights and Ultra Lights delivered less tar and nicotine and that they were less harsh each independently contributed to the belief that these cigarettes were safer. CONCLUSIONS: Many Light and Ultra Light smokers believe that smoking these cigarettes impart a substantial health benefit, due in part to their experience that these cigarettes are less harsh and the belief that these cigarettes deliver less tar. (+info)
Effect of health messages about "Light" and "Ultra Light" cigarettes on beliefs and quitting intent.
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OBJECTIVE: To test the impact of three health messages focusing on vent holes, sensory effects of Light and Ultra Light cigarettes, or health consequences of smoking, respectively, on beliefs and quitting intentions. DESIGN: In the course of a random digit dialed telephone survey, subjects were randomised to hear one of three messages. To test the effects of the messages, beliefs and quitting intentions were assessed both pre- and post-message. PARTICIPANTS: Daily smokers (n = 2120) of Regular (46%), Light (39%), and Ultra Light (15%) cigarettes in the USA. The sample was weighted to match the US smoker population on age, sex, and ethnicity. MAIN OUTCOME MEASURES: Beliefs were summarised on three dimensions: Safety (reduced health risk), Delivery (lower tar and nicotine delivery), and Sensation (less harsh). Quitting interest was captured by the "quit index", an aggregate measure of quitting interest and intent. RESULTS: The message focusing on smokers' sensory perceptions of Light and Ultra Light cigarettes resulted in the most positive change in beliefs about safety, delivery, and intent to quit, and was particularly effective among those who believed that these cigarettes were less harsh. The effect was most pronounced among young adults, and among smokers of Light and Ultra Light brands who most endorsed their sensory benefits. CONCLUSIONS: Addressing smokers' sensory experience that Light and Ultra Light cigarettes feel less harsh may be a promising strategy for changing their misconceptions about these cigarettes and enhancing their interest in quitting. Media counter-advertising on Lights and Ultra Lights, focusing on sensory aspects of these cigarettes, may be an important part of tobacco control efforts. (+info)
Test of "Light" cigarette counter-advertising using a standard test of advertising effectiveness.
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OBJECTIVE: To evaluate systematically the effectiveness of six advertising strategies (two message strategies presented in three different contexts) designed to promote smoking cessation by addressing smokers' misperceptions about Light cigarettes. DESIGN: Smokers viewed one of six, 30 second test television concept advertisements, which varied by message (one emphasising how the sensory effects of Lights can be deceptive, the other describing the effects of vent blocking) and by ad context (non-commercial public service announcement (PSA), promotion of unbranded nicotine replacement therapy (NRT), or promotion of branded NRT). The effectiveness of each advertisement was determined using a validated advertising testing system in which ads were viewed in the context of reviewing a pilot television programme. Response to ads is assessed through shifts in subject choices of products offered as prizes before and after viewing the test advertisements. Included among the possible prizes were cigarettes and various pharmacotherapies for smoking cessation. SUBJECTS: Daily smokers (n = 1890) of Regular (34%), Light (47%), and Ultra Light (19%) cigarettes recruited from eight US cities. MAIN OUTCOMES MEASURES: The primary outcome of interest was the shift away from cigarettes as the selected prize following exposure to the test advertisements. Secondary outcomes of interest included movement away from Light cigarettes and movement towards assisted quitting products. RESULTS: Smokers who saw the advertisement emphasising the sensory characteristics of Light cigarettes were more likely than subjects who saw the advertisement emphasising the effect of vent blocking to move away from cigarettes (OR = 1.97, 95% confidence interval CI 1.25 to 3.09; chi(2)(1) = 8.69, p = 0.003). Similarly, subjects who saw the advertisement framed as a PSA, rather than as a promotion for either a branded or unbranded NRT product, were also somewhat more likely to move away from cigarettes (OR = 1.51, 95% CI 0.94 to 2.40; chi(2)(1) = 2.97, p = 0.085). The effect was observed regardless of sex, age, or type of cigarette smoked. CONCLUSIONS: Addressing smokers' sensory perceptions of Light cigarettes and presenting this information in an impartial way is likely to be an effective communication strategy for counter-marketing Light cigarettes. (+info)
Synergistic mechanisms in carcinogenesis by polycyclic aromatic hydrocarbons and by tobacco smoke: a bio-historical perspective with updates.
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B[a]P (benzo[a]pyrene) has been used as a prototype carcinogenic PAH since its isolation from coal tar in the 1930's. One of its diol epoxides, BPDE-2, is considered its ultimate carcinogen on the basis of its binding to DNA, mutagenicity and extreme pulmonary carcinogenicity in newborn mice. However, BPDE-1 has a similar binding to DNA and mutagenicity but it is not carcinogenic. In addition, BPDE-2 is a weak carcinogen relative to B[a]P when repeatedly applied to mouse skin, the conventional assay site. Its carcinogenicity is increased when applied once as an initiator followed repeatedly by a promoter. This indicates a major role for promotion in carcinogenesis by PAHs. Promotion itself is a 2-stage process, the second of which is selective propagation of the initiated cells. Persistent hyperplasia underlies selection by promoters. The non-carcinogenicity of BPDE-1 has yet to be resolved. PAHs have long been considered the main carcinogens of cigarette smoke but their concentration in the condensate is far too low to account by themselves for the production of skin tumors. The phenolic fraction does however have strong promotional activity when repeatedly applied to initiated mouse skin. Several constituents of cigarette smoke are co-carcinogenic when applied simultaneously with repeated applications of PAHs. Catechol is co-carcinogenic at concentrations found in the condensate. Since cigarette smoking involves protracted exposure to all the smoke constituents, co-carcinogenesis simulates its effects. Both procedures, however, indicate a major role for selection in carcinogenesis by cigarette smoke. That selection may operate on endogenous mutations as well as those induced by PAHs. There are indications that the nicotine-derived NNK which is a specific pulmonary carcinogen in animals contributes to smoking-induced lung cancer in man. Lung adenoma development by inhalation has been induced in mice by the gas phase of cigarette smoke. The role of selection has not been evaluated in either of these cases. (+info)
Health effects of subchronic exposure to low levels of wood smoke in rats.
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Wood smoke is a significant source of air pollution in many parts of the United States, and epidemiological data suggest a causal relationship between elevated wood smoke levels and health effects. The present study was designed to provide information on the potential respiratory health responses to subchronic wood smoke exposures in a Native American community in New Mexico. Therefore, this study used the same type of wood under similar burning conditions and wood smoke particle concentrations to mimic the conditions observed in this community. Brown Norway rats were exposed 3 h/day, 5 days/week for 4 or 12 weeks to air as control, or to 1 or 10 mg/m3 concentrations of wood smoke particles from pinus edulis. The wood smoke consisted of fine particles (< 1 microm) that formed larger chains and aggregates having a size distribution of 63-74% in the < 1-microm fraction and 26-37% in the > 1-microm fraction. The particle-bound material was primarily composed of carbon, and the majority of identified organic compounds consisted of sugar and lignin derivatives. Pulmonary function, specifically carbon monoxide-diffusing capacity and pulmonary resistance, was somewhat affected in the high-exposure group. Mild chronic inflammation and squamous metaplasia were observed in the larynx of the exposed groups. The severity of alveolar macrophage hyperplasia and pigmentation increased with smoke concentration and length of exposure, and the alveolar septae were slightly thickened. The content of mucous cells lining the airways changed from Periodic Acid Schiff- to Alcian Blue-positive material in the low-exposure group after 90 days. Together, these observations suggest that exposure to wood smoke caused minor but significant changes in Brown Norway rats. Further studies are needed to establish whether exposure to wood smoke exacerbates asthmalike symptoms that resemble those described for children living in homes using wood stoves for heating and cooking. (+info)
Birth weight and exposure to kitchen wood smoke during pregnancy in rural Guatemala.
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In this study, we aimed to establish whether domestic use of wood fuel is associated with reduced birth weight, independent of key maternal, social, and economic confounding factors. We studied 1,717 women and newborn children in rural and urban communities in rural Guatemala. We identified subjects through home births reported by traditional birth attendants in six rural districts (n = 572) and all public hospital births in Quetzaltenango city during the study period (n = 1,145). All were seen within 72 hr of delivery, and data were collected on the type of household fuel used, fire type, and socioeconomic and other confounding factors. Smoking among women in the study community was negligible. Children born to mothers habitually cooking on open fires (n = 861) had the lowest mean birth weight of 2,819 g [95% confidence interval (CI), 2,790-2,848]; those using a chimney stove (n = 490) had an intermediate mean of 2,863 g (95% CI, 2,824-2,902); and those using the cleanest fuels (electricity or gas, n = 365) had the highest mean of 2,948 g (95% CI, 2,898-2,998) (p< 0.0001). The percentage of low birth weights (< 500 g) in these three groups was 19.9% (open fire), 16.8% (chimney stove), and 16.0% (electricity/gas), (trend (p = 0.08). Confounding factors were strongly associated with fuel type, but after adjustment wood users still had a birth weight 63 g lower (p = 0.05; 95% CI, 0.4-126). This is the first report of an association between biofuel use and reduced birth weight in a human population. Although there is potential for residual confounding despite adjustment, the better-documented evidence on passive smoking and a feasible mechanism through carbon monoxide exposure suggest this association may be real. Because two-thirds of households in developing countries still rely on biofuels and women of childbearing age perform most cooking tasks, the attributable risk arising from this association, if confirmed, could be substantial. (+info)
Relationship between the electrical activity of the oviduct and the uterus of the rabbit in vivo.
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The electrical activity of the whole genital tract of the rabbit was recorded by means of chronically implanted electrodes after section of the uterotubal junction on one side. When the junction was intact, the activity of the isthmus and that of the proximal uterine horn occurred almost simultaneously, but uterine activity decreased after the junction was cut. During the preovulatory phase and also after administration of HCG, synchronos activity due to adrenergic drugs, smoke or oxytocin persisted on both sides of the uterotubal junction. Hypersensitivity of the isthmus and the proximal segment of the uterine horn was recorded on the cut side after ovariectomy. The concept of a local control mechanism in the region of the uterotubal junction with a positive control of the uterus by the oviduct is suggested. (+info)