Estimating the yield to smokers of tar, nicotine, and carbon monoxide from the 'lowest yield' ventilated filter-cigarettes

Cigarette filter ventilation, product appeal and regulatory options: a review of the influence of ventilation on consumers' sensory and risk perceptions

OBJECTIVE

Cigarette filter ventilation may enhance product appeal, support initiation and sustained smoking, and increase smoking prevalence. We reviewed recent evidence on how filter ventilation affects consumers' perceptions of product appeal and considered product use preferences to inform regulatory options.

DATA SOURCES

PubMed, Embase and PsycINFO databases were searched up to December 2023. Systematic search strategies used terms based on cigarette filter ventilation, and multiple constructs comprising product appeal and user perceptions.

STUDY SELECTION

Two reviewers screened all 917 retrieved titles and abstracts independently and applied a consensus strategy to identify 16 articles that met eligibility criteria.

DATA EXTRACTION

Extracted data focused on study design, dependent variables or outcomes, and major conclusions.

DATA SYNTHESIS

While remaining popular, awareness and risk perception of ventilated cigarettes is generally low. Cigarettes with filter ventilation are perceived as smoother and less irritating than non-ventilated cigarettes. These modified sensory experiences shape perceptions of reduced health risks. Pack text descriptors and colours convey further information to consumers about smoothness, supporting lowered risk perceptions.

CONCLUSIONS

Filter ventilation and its associated marketing continue to influence consumers' perceptions of smoothness creating misperceptions about health risks. Standardised ('plain') packaging regulations are recommended to restrict communication of ventilation themes as well as evidence-based health communications to correct consumer misperceptions about smoothness and health risks. Since filter ventilation has no benefits for public health, policy makers could consider banning filter ventilation or even disallowing filters.

The influencing factors of health hazards of benzo[a]pyrene in cigarette mainstream smoke: The example of one brand in Beijing

INTRODUCTION

METHODS

RESULTS

CONCLUSIONS

Health without filters: the health and environmental impacts of cigarette filters

Tobacco-related diseases kill eight million people worldwide ever year and are responsible for thousands of cases of cancer, cardiovascular disease and other illnesses in Brazil. Cigarette filters are believed by many to reduce the health risks of smoking. This article outlines the history of the technology of filters and discusses the impacts of these cigarette design features and their regulation. We conducted a literature review to assess the impacts of this technology. The results show that filters were initially developed for aesthetic purposes and later improved and marketed as a harm reduction technology. The most widely-used filters are those made of cellulose acetate with or without activated carbon. Despite smokers' beliefs and advertising claims, filters have no health benefits and filter tip ventilation can increase the health risks of smoking. Filters can also make cigarettes more appealing and cause significant environmental impacts. Cigarette filters have no health benefits and lull smokers into a false sense of security and should therefore be banned.

Impact of Filter on the Estimation of Quantitative Mixture Risk Caused by Some Chemical Constituents Generated from Popular Cigarette Brands in Iran

Background

This study was conducted to evaluate the impact of filter on the eventual carcinogenic and non-carcinogenic risks caused by the main toxic constituents of popular cigarette brands in Iran.

Methods

At this laboratory study, the concentration of benzene, formaldehyde, arsenic, and cadmium in the mainstream smoke of 11 popular cigarette brands in Iran, on the without and with-filter modes was determined based on an established method. The hazard quotient (HQ), incremental lifetime cancer risk (ILCR), and mixture quantitative risk assessments (QRAs) were performed based on the QRA method recommended by United States Environmental Protection Agency (USEPA).

Findings

The mean of HQ due to benzene, formaldehyde, arsenic, and cadmium in without-filter cigarette smoke was from 3.96 to 3505. The findings indicated that the HQs related to benzene, formaldehyde, arsenic, and cadmium in cigarette smoke were decreased with filter by 48.3%, 25.3%, 37.6%, and 49.1%, respectively. The filter of cigarette decreased ILCR of benzene, formaldehyde, arsenic, and cadmium in cigarette smoke by 53.02%, 25.31%, 37.70%, and 61.01%, respectively. The mixture of non-carcinogenic and carcinogenic estimated risks due to inhalation of studied cigarettes smoke was very high and unacceptable.

Conclusion

The cigarette filter plays an essential role in reducing inhalation exposure to hazardous compounds in mainstream cigarette smoke; nevertheless, the average of overall mixture HQs and ILCRs estimated caused by studied compounds was higher than the acceptable value. It is recommended that future empirical studies investigate the impact of the type of fiber used in cigarette filter on reducing carcinogenic and non-carcinogenic risks caused by cigarette smoke.

Mixture risk assessment of selected mainstream cigarette smoke constituents generated from low-yield cigarettes in South Korean smokers

A total of 38 hazardous constituents in mainstream cigarette smoke of low-yield cigarettes sold in Korea were selected and analyzed using established methods. Risk calculations were performed using risk algorithms employed in previous studies and Korean population-based exposure parameters. The median cumulative incremental lifetime cancer risk of male smokers could vary from 828 × 10-6 to 2510 × 10-6, and that of female smokers could range from 440 × 10-6 to 1300 × 10-6, depending on the smoking regimens. The median hazard index as the sum of hazard quotients of male smokers varied from 367 to 1,225, and that of female smokers varied from 289 to 970, depending on the smoking regimens. The sensitivity analysis for this risk assessment indicated that the constituent yields in mainstream cigarette smoke, average number of cigarettes smoked per day or year, and mouth-spill rate are the main risk factors. Statistical positive correlations between the average daily dose calculated by the exposure algorithm used in this study for individual smokers and biomarkers verified the reliability of this assessment. It could be concluded that inhalation of the constituents present in the mainstream of low-yield cigarettes has significant cancer and non-cancer health risks, although its effect on risk reduction is still unknown under the fixed machine-smoking conditions.

Assessment of tobacco heating product THP1.0. Part 8: Study to determine puffing topography, mouth level exposure and consumption among Japanese users

A four-arm study was undertaken in Japan to determine the puffing topography, mouth level exposure and average daily consumption by consumers of the tobacco heating products (THPs): the non-mentholated THP1.0(T), the mentholated THP1.0(M) and a tobacco heating system (THS). The extent of lip blocking of air inlet holes while using THP1.0(T) was also assessed. Groups 1, 2, and 4 included smokers, and group 3 included regular THP users. Smokers of 7-8 mg ISO nicotine free dry particulate matter (NFDPM) non-mentholated cigarettes took on average larger mean puff volumes from THPs than from conventional cigarettes, but puff numbers and durations were similar. Mouth level exposure to NFDPM and nicotine levels were significantly lower when using THPs than conventional cigarettes. Similar trends were observed among smokers of 7-8 mg ISO NFDPM mentholated cigarettes who used mentholated cigarettes and THP1.0(M). Regular users of commercial THS had similar puffing behaviours irrespective of whether they were using THS or THP1.0(T), except for mean puff volume which was lower with THP1.0(T). No smokers blocked the air inlet holes when using THP1.0(T). The puffing topography results support the machine puffing regime used to generate toxicant emissions data and in vitro toxicology testing.

Reduced nicotine content cigarettes in smokers of low socioeconomic status: study protocol for a randomized control trial

BACKGROUND

The Family Smoking Prevention and Tobacco Control Act gave the Food and Drug Administration jurisdiction over the regulation of all tobacco products, including their nicotine content. Under this act, a major strategy to reduce harm from cigarette tobacco is lowering the nicotine content without causing unintended adverse consequences. Initial research on reduced nicotine content (RNC) cigarettes has shown that smokers of these cigarettes gradually decrease their smoking frequency and biomarkers of exposure. The effectiveness of this strategy needs to be demonstrated in different populations whose response to RNC cigarettes might be substantially mediated by personal or environmental factors, such as low socioeconomic status (SES) populations. This study aims to evaluate the response to a reduced nicotine intervention in low SES smokers, as defined here as those with less than 16 years of education, by switching smokers from high nicotine commercial cigarettes to RNC cigarettes.

METHODS/DESIGN

Adults (N = 280) who have smoked five cigarettes or more per day for the past year, have not made a quit attempt in the prior month, are not planning to quit, and have less than 16 years of education are recruited into a two-arm, double-blinded randomized controlled trial. First, participants smoke their usual brand of cigarettes for 1 week and SPECTRUM research cigarettes containing a usual amount of nicotine for 2 weeks. During the experimental phase, participants are randomized to continue smoking SPECTRUM research cigarettes that contain either (1) usual nicotine content (UNC) (11.6 mg/cigarette) or (2) RNC (11.6 to 0.2 mg/cigarette) over 18 weeks. During the final phase of the study, all participants are offered the choice to quit smoking with nicotine replacement therapy, continue smoking the research cigarettes, or return to their usual brand of cigarettes. The primary outcomes of the study include retention rates and compliance with using only research cigarettes and no use of other nicotine-containing products. Secondary outcomes are tobacco smoke biomarkers, nicotine dependence measures, smoking topography, stress levels, and adverse health consequences.

DISCUSSION

Results from this study will provide information on whether low SES smokers can maintain a course of progressive nicotine reduction without increases in incidence of adverse effects.

TRIAL REGISTRATION

ClinicalTrials.gov, NCT01928719 . Registered on 21 August 2013.

Direct measurement of toxicants inhaled by water pipe users in the natural environment using a real-time in situ sampling technique

While narghile water pipe smoking has become a global phenomenon, knowledge regarding its toxicant content and delivery, addictive properties, and health consequences is sorely lagging. One challenge in measuring toxicant content of the smoke in the laboratory is the large number of simplifying assumptions that must be made to model a "typical" smoking session using a smoking machine, resulting in uncertainty over the obtained toxicant yields. In this study, we develop an alternative approach in which smoke generated by a human water pipe user is sampled directly during the smoking session. The method, dubbed real-time in situ sampling (RINS), required developing a self-powered portable instrument capable of automatically sampling a fixed fraction of the smoke generated by the user. Instrument performance was validated in the laboratory, and the instrument was deployed in a field study involving 43 ad libitum water pipe use sessions in Beirut area cafés in which we measured inhaled nicotine, carbon monoxide (CO), and water pipe ma'ssel-derived "tar." We found that users drew a mean of 119 L of smoke containing 150 mg of CO, 4 mg of nicotine, and 602 mg of ma'ssel-derived "tar" during a single use session (mean duration = 61 min). These first direct measurements of toxicant delivery demonstrate that ordinary water pipe use involves inhaling large quantities of CO, nicotine, and dry particulate matter. Results are compared with those obtained using the Beirut method smoking machine protocol.

Acute effects of smoking light cigarettes on coronary microvascular functions

BACKGROUND

To date, there has been no study comparing the possible acute effects on coronary microvascular functions of smoking light cigarettes (those with low tar and nicotine yield) and regular cigarettes.

METHODS

Twenty healthy volunteers (8 women and 12 men; mean age, 25.8 +/- 5.8 years) were included in a single-blind, open-label, cross-over study to compare the effects of smoking light cigarettes (containing 0.6 mg nicotine, 8 mg tar, 9 mg carbon monoxide) and smoking regular cigarettes (containing 0.9 mg nicotine, 12 mg tar, 12 mg carbon monoxide) on coronary flow reserve (CFR). For each participant, CFR values were measured at baseline, after smoking 2 regular or light cigarettes, and 15 days later after smoking 2 cigarettes of the other kind.

RESULTS

After smoking 2 cigarettes, CFR values declined from 2.8 +/- 0.56 (baseline) to 2.31 +/- 0.51 after smoking light cigarettes (P = .003), and from 2.8 +/- 0.56 (baseline) to 2.21 +/- 0.45 after smoking regular cigarettes (P < .001). After smoking light and regular cigarettes, CFR values were similar (P = .678).

CONCLUSIONS

Light cigarette smoking has similar acute detrimental effects on coronary microvascular function and CFR as does regular cigarette smoking.

DNA solution(R) in cigarette filters reduces polycyclic aromatic hydrocarbon (PAH) levels in mainstream tobacco smoke

Tobacco consumption represents a major health hazard to humans and, despite anti-smoking campaigns, the number of smokers remains high; thus the reduction of toxic compounds from tobacco smoke may reduce the health hazards of smoking. In the last 25 years cigarette manufacturers have introduced a variety of filter designs to reduce toxic and carcinogenic substances in tobacco smoke (normal filters, NF). However, large quantities of harmful constituents are inefficiently retained by commonly used cigarette filters. Following a patented method we modified commercial cigarette filters (modified filter, MF) by injecting a DNA solution into the filter tips; we then evaluated the reduced polycyclic aromatic hydrocarbon (PAH) levels in mainstream tobacco smoke of MF relative to NF. The PAH measured were: fluoranthene (FLUO), pyrene (PY), benzo(a)anthracene (B(a)A), chrysene (CRY), benzo(a)pyrene (B(a)P), benzo(b)fluoranthene (B(b)F), benzo(k)fluoranthene (B(k)F), benzo(g,h,i)perylene (BGP), dibenzo(a,h)anthracene (DBA). The levels of PAH in cigarette smoke after MF were significantly reduced (P<0.001) compared to NF, using a variety of cigarette brands in a smoking machine (44.5%+/-8.4 % and 41.8%+/-5% for total and carcinogenic PAH, respectively, means+/-SE). Using B(a)P(TEF) values the reduction in PAH concentrations were similar for all cigarette brands with the exception of Camel, where the reduction was lower considering B(a)P(TEF) values. Amongst carcinogenic PAH, B(a)A, B(b)F and B(k)F) were reduced by 50-58%, CRY, B(a)P and DBA by about 40%. In conclusion MF filters treated with DNA have the potential of decreasing the exposure to PAH in cigarette smoke. Since, unlike some previously proposed biological filters MF do not retain additional nicotine, the main addictive compound of tobacco smoke, these filters may not induce increased smoking to compensate for the reduction in the nicotine delivery to smokers.

Analysis of volatile organic compounds in mainstream cigarette smoke

Mainstream cigarette smoke is a complex aerosol containing more than 4400 chemicals. The proliferation of new brands has necessitated development of faster and more reliable methods capable of analyzing a wide range of compounds in cigarette smoke. Although the International Agency for Research on Cancer has classified whole cigarette smoke as a human carcinogen, many of the individual chemicals are themselves highly biologically active as carcinogens, teratogens, or have implications for cardiovascular disease. Among these chemicals are many volatile organic compounds (VOCs), e.g., benzene, ethylbenzene, and styrene. To analyze VOCs in mainstream cigarette smoke, we developed a novel headspace collection technique using polyvinylfluoride bags for sample collection followed by cannula transfer to evacuated standard 20-mL auto sampler vials. Coupling collection of the vapor-phase cigarette smoke with automated analysis by solid-phase microextraction and gas chromatography/mass spectrometry enabled us to routinely quantify selected VOCs in mainstream cigarette smoke. This technique has similar reproducibility to previous cold trap and impinger collection methods with significantly higher sample throughput and virtually no solvent waste. In this report we demonstrate the method's analytical capabilities by quantitatively analyzing 13 selected VOCs in mainstream cigarette smoke from top-selling domestic brands.

The effect of filter vent blocking and smoking topography on carbon monoxide levels in smokers

Two studies were conducted to examine the effect of filter vent blocking and smoking topography on carbon monoxide (CO) levels in smokers. In Study 1, 12 participants smoked two types of cigarettes (Marlboro Light and Carlton 100) under two types of blocking conditions (unblocked and half-blocked) while using a smoking topography device. Participants were restricted to 8 puffs, separated by 45 s. Significant main effects of CO boost for cigarette type and blocking condition replicated previous findings. A significant increase in CO boost for the Marlboro Light blocked condition is a novel finding for this best-selling brand. That result and the finding that topography measures did not predict CO boost made us question the reliability of CO boost. In Study 2, we examined the reliability of CO boost by recruiting 12 participants to smoke three unblocked Carlton 100 cigarettes in one session and three half-blocked in another. CO boost was significantly greater for the blocked sessions compared to the unblocked and CO boost did not differ within session, thus supporting the reliability of the measure. When participants do not switch brands within a session, smoking topography measures are predictive of CO boost.

Analysis of complex mixtures--cigarette smoke

Mainstream cigarette smoke is a complex mixture that is inhaled into the respiratory system. The physical characteristics and chemical composition of mainstream smoke are reviewed and briefly compared with that of sidestream smoke. Special attention is paid to ageing effects and artifact formation during the sampling and testing of cigarette smoke, with specific examples of artifact formation during sampling discussed (nitrogen dioxide, methyl nitrite, etc.). Historically, the generation of cigarette smoke for chemical and biological testing has been based on standard smoke generation procedures that are intended for product comparisons. More recently, emerging global regulations have called for alternative smoke generation methods, with emphasis on results relevant to conditions of product use, e.g., estimates of maximum smoke emissions. Strategies for establishing such alternative smoke generation methods are discussed and the potential effects of alternative smoking conditions on analytical accuracy and precision are addressed. Current regulatory requirements that include Hoffmann analyte analysis (i.e., constituents reported to be associated with the risks of cigarette smoking) are also summarized and the potential effect of alternative smoke generation methods on individual constituent yields considered. Finally, a limited critique of emerging regulation that relates to mainstream cigarette smoke measurements, including a discussion of recent WHO recommendations, is offered.

Determination of 14 polycyclic aromatic hydrocarbons in mainstream smoke from domestic cigarettes

Polycyclic aromatic hydrocarbons (PAHs) are a class of environmental pollutants created primarily from incomplete combustion of various organic materials including tobacco. Cigarette smoke is a complex mixture of various classes of compounds, including numerous PAHs, in both the mainstream and the sidestream smoke fractions. We measured the levels of 14 PAHs in mainstream smoke from unfiltered custom cigarettes made from individual tobacco types and 30 brands of domestic blended cigarettes using standardized smoking conditions, extraction from the Cambridge filter pads, and gas chromatography/mass spectrometry. Differences in smoke PAHs from cigarettes with selected tobacco blends were identified and illustrate how blend composition contributes to the overall mainstream smoke PAH profile. The PAH levels varied among the different commercial cigarette brands, with the amount of total mainstream smoke PAHs ranging from 1 to 1.6 microg per cigarette. Under machine smoking conditions, the mainstream smoke from domestic cigarettes had individual PAHs ranging from benzo[k]fluoranthene at levels below 10 ng/cigarette to naphthalene at levels of around 500 ng/cigarette. Low delivery cigarettes smoked with blocked filter vent holes dramatically increased the mainstream smoke PAH deliveries with respect to their unblocked counterparts. Inhalation of PAHs and other harmful chemicals from cigarette smoke are unique as they represent a routine voluntary exposure to common environmental pollutants.

The case of the disappearing nitrosamines: a potentially global phenomenon

The cigarette usually carries in its smoke significant doses of carcinogenic tobacco specific nitrosamines (TSNAs), which have been implicated as causes of oral, lung, oesophageal, and pancreatic cancer. However, there is substantial variation in nitrosamine content of the smoke of modern cigarettes. This variation is both unacceptable and unnecessary, as TSNAs can be readily removed during the manufacturing process. Removing a known carcinogen needs no justification, even though proof of benefit may not be forthcoming for decades.

Solid-phase microextraction-based approach to determine free-base nicotine in trapped mainstream cigarette smoke total particulate matter

Characterizing nicotine delivery from tobacco products is important in the understanding of their addictive potential. Most previous studies report total nicotine and have not differentiated between nicotine in its protonated or free-base form. Rather than simply determining total nicotine, the method described in this paper determines the amount of free-base nicotine associated with trapped mainstream smoke particulate matter generated using a standardized smoking machine protocol. This method quantitatively determines volatile free-base nicotine associated with the particulate phase portion of mainstream cigarette smoke using solid-phase microextraction combined with gas chromatography-mass spectrometry. The headspace above total particulate matter from mainstream cigarette smoke trapped on a Cambridge filter pad (CFP) was analyzed for free-base nicotine in 26 cigarette brands. The selected cigarette brands were chosen to cover a wide range of tar and nicotine deliveries as measured under Federal Trade Commission machine smoking conditions. In the CFP's headspace the free-base nicotine levels ranged from 0.01 to 0.08 mg/cigarette. The measured ranges of free-base nicotine were remarkably similar over the different tar and nicotine delivery categories of full-flavored, light, and ultralight cigarette brands.

Cigarette filter ventilation is a defective design because of misleading taste, bigger puffs, and blocked vents

OBJECTIVE

To review tobacco industry documents on filter ventilation in light of published studies and to explore the role of filter ventilation in the design of cigarettes that deliver higher smoke yields to smokers than would be expected from standard machine smoked tests (Federal Trade Commission (FTC), International Organization for Standardization (ISO)).

DATA SOURCES

Searched from November 1999 to November 2000 internet databases of industry documents (www.pmdocs.com, www.rjrtdocs.com, www.lorillarddocs.com, www.bw.aalatg.com, www.cdc.gov/tobacco/industrydocs, www.tobaccodocuments.org, www.tobaccopapers.org, www.hlth.gov.bc.ca/Guildford, www.cctc.ca/ncth/Guildford, www.cctc.ca/ncth/Guildford2) for documents related to filter ventilation. Documents found dated from 1955 through 1994.

STUDY SELECTION

Those documents judged to contain the most relevant information or data on filter ventilation related to cigarette taste and compensatory smoking, while also trying to avoid redundancy from various documents deriving from the same underlying data.

DATA SYNTHESIS

Filter ventilation is a crucial design feature creating three main problems for lower tar cigarettes as measured by official smoking machine testing. Firstly, it misleadingly makes cigarettes taste lighter and milder, and, therefore, they appear less dangerous to smokers. Secondly, it promotes compensation mainly by facilitating the taking of larger puffs. Thirdly, for very heavily ventilated cigarettes (that is, > 65% filter air dilution), behavioural blocking of vents with lips or fingers is an additional contributor to compensatory smoking. These three effects are found in industry research as well as published research.

CONCLUSIONS

Filter ventilation is a dangerous, defective technology that should be abandoned in less hazardous nicotine delivery systems. Health interested groups should test cigarettes in a way that reflects compensatory smoking. Lower tar (vented filter) cigarettes should be actively countermarketed.

The less harmful cigarette: a controversial issue. a tribute to Ernst L. Wynder

The dose-response relationship between number of cigarettes smoked and risk for lung cancer was established in 1950 by epidemiological studies. Laboratory assays with tobacco tar on mouse skin and smoke inhalation experiments with hamsters provided further evidence for this relationship. In cigarette smoke, among 4800 identified compounds, 69 are carcinogens, and several are tumor promoters or cocarcinogens. The major toxic agents are nicotine, carbon monoxide, hydrogen cyanide, nitrogen oxides, some volatile aldehydes, some alkenes, and some aromatic hydrocarbons. Public health information and education have led to a reduction of cigarette smokers among U.S. adults from 40 to 25%. However, in high school students, smoking increased to 35% and in adults with less than a high school education it remains high at 33.3%. Intervention studies were augmented with attempts of risk reduction by changing the tobacco composition and makeup of cigarettes. This led to cigarettes that, according to the FTC, reduced the tar and nicotine yields from an average of 37 and 2.7 mg to 12 and 0.85 mg. The anticipated reduction of mortality rates from chronic diseases among cigarette smokers did not occur, primarily, because of a major adjustment in smoking intensity and depth of inhalation by the habitual smokers. It is, therefore, imperative that smoking control efforts are intensified and that, short of banning cigarette sales, cigarettes delivering smoke with the lowest potential for toxicity, addiction, and carcinogenicity are declared a matter of public health policy.

Declining lung cancer mortality of young Australian women despite increased smoking is linked to reduced cigarette 'tar' yields

Lung cancer data were examined to determine whether the mortality rates of young Australian women have continued to increase in line with the proportions of them who have smoked tobacco. Trends in annual age-specific lung cancer mortality were estimated for 1965-1998. Age-specific mortality rates and age-adjusted ratios of mortality rates were calculated for birth cohorts. Proportions of smokers in those cohorts were estimated from results of eight national surveys of smoking, and their mean ages of commencement and years of smoking were assessed from surveys of smokers in two states. Lung cancer mortality rates of 20-44-year-old Australian women peaked in 1986. Age-adjusted mortality rates are lower for women born in the 1950s and 1960s than for women born in the 1940s, despite higher proportions of smokers, younger age of commencement and longer duration of smoking by age 30 years in the more recent cohorts. Increased smoking has not resulted in higher lung cancer mortality for Australian women born in the 1950s and 1960s. Reductions in tar yields of Australian-made cigarettes, which would have affected primarily those born after the 1940s, may be responsible.

Quantitation of flavor-related alkenylbenzenes in tobacco smoke particulate by selected ion monitoring gas chromatography-mass spectrometry

Little is known about the possible health effects associated with inhaling alkenylbenzenes through cigarette smoking, even though these flavor-related compounds have known toxic effects in animals. We developed a rapid and sensitive solid-phase extraction (SPE) method to quantify seven alkenylbenzenes and piperonal in mainstream cigarette smoke particulate. The smoke particulate fraction of a single cigarette was collected on Cambridge filter pads, solvent extracted, concentrated, purified with SPE, and analyzed by selected ion monitoring gas chromatography-mass spectrometry. We positively identified and quantified five alkenylbenzenes compounds (eugenol, isoeugenol, methyleugenol myristicin, and elemicin) and piperonal in the smoke particulate from eight U.S. brands with mean levels (measured in triplicate) ranging from 6.6 to 4210 ng per cigarette. Additionally, complete blocking of nearly invisible ventilation holes in the cigarette filter increased 2- to 7-fold the percent transfer of alkenylbenzenes from tobacco to the particulate fraction of mainstream smoke.

Doses of nicotine and lung carcinogens delivered to cigarette smokers

BACKGROUND

Cigarette smoke yields of tar and nicotine obtained under the Federal Trade Commission (FTC)-specified machine-smoking protocol (35-mL puff volume drawn for 2 seconds once per minute) may not accurately reflect the delivery of toxins and carcinogens to the smoker. We conducted this study to obtain more realistic estimates of exposure to components of cigarette smoke that affect lung cancer risk.

METHODS

We used a pressure transducer system to evaluate puffing characteristics for 133 smokers of cigarettes rated by the FTC at 1.2 mg of nicotine or less (56 smokers of low-yield cigarettes [</=0.8 mg of nicotine per cigarette] and 77 smokers of medium-yield cigarettes [0.9-1.2 mg of nicotine per cigarette]). We programmed measurements from a randomly chosen subset of 72 of these smokers into a piston-type machine to generate smoke from each smoker's usual brand of cigarettes for assays of nicotine, carbon monoxide, tar, and the lung cancer-causing agents 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanone and benzo[a]pyrene. The FTC protocol was also used to assess levels of targeted components in the 11 brands most frequently smoked by study subjects.

RESULTS

Compared with the FTC protocol values, smokers of low- and medium-yield brands took in statistically significantly larger puffs (48.6 and 44.1 mL, respectively) at statistically significantly shorter intervals (21.3 and 18.5 seconds, respectively), and they drew larger total smoke volumes than specified in the FTC parameters. They received, respectively, 2.5 and 2.2 times more nicotine and 2.6 and 1.9 times more tar than FTC-derived amounts, as well as about twofold higher levels of benzo[a]pyrene and 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanone. Smokers of medium-yield cigarettes compared with smokers of low-yield cigarettes received higher doses of all components.

CONCLUSIONS

The FTC protocol underestimates nicotine and carcinogen doses to smokers and overestimates the proportional benefit of low-yield cigarettes. Thus, FTC-based nicotine medication doses prescribed/recommended for smoking cessation may need to be reassessed.

The adverse health effects of tobacco and tobacco-related products

Tobacco use continues to occur in epidemic proportions and with it, significant morbidity and mortality. One third of smokers will die prematurely of a smoking-related disease. This article reviews the adverse health effects of tobacco use so that clinicians can be aware of the benefits patients will reap when they stop using this lethal substance.

Smokers' misperceptions of light and ultra-light cigarettes may keep them smoking

INTRODUCTION

This study examined smokers' understanding of the relative tar deliveries of Ultra-light, Light, and Regular cigarettes, reasons for smoking Ultra-light/Light cigarettes, and the likelihood of both quitting smoking and switching to Regular cigarettes if they came to learn that one Ultra-light/Light cigarette gave the same amount of tar as one Regular cigarette.

DESIGN

Ten- to fifteen-minute random-digit-dialed, computer-assisted telephone interviews (CATI) were conducted with both a national probability sample (n = 788) and a state random sample (n = 266) of daily smokers over the age of 18.

RESULTS

Less than 10% of smokers in the national sample and only 14% of smokers in the state sample knew that one Light cigarette could give the same amount of tar as one Regular cigarette. Less than 10% of smokers in the state sample knew that one Ultra-light cigarette could give the same amount of tar as one Regular cigarette. Thirty-two percent of the Light and 26% of the Ultra-light smokers in the national sample, and 27% of Light and 25% of Ultra-light smokers in the state sample, said they would be likely to quit smoking if they learned one Light/Ultra-light equaled one Regular.

CONCLUSION

Many Light and Ultra-light smokers are smoking these cigarettes to reduce the risks of smoking and/or as a step toward quitting. However, these smokers are unaware that one Ultra-light/Light cigarette can give them the same amount of tar and nicotine as one Regular cigarette. Many of the Ultra-light/Light smokers sampled in this study stated that they would be likely to quit if they knew this information. Mistaken beliefs about low-yield brands are reducing intentions to quit smoking.

Blocking filter vents increases carbon monoxide levels from ultralight, but not light cigarettes

Effect of vent blocking on carbon monoxide (CO) exposure from a best-selling light cigarette was examined in 12 daily cigarette smokers. Mean CO boosts were not different from each other with (a) 0% filter vents blocked (5.0 ppm), (b) vents covered with lips (4.9 ppm), (c) 50% of vents covered with tape (4.8 ppm), and (d) vents covered with a pinch of the fingertips (4.9 ppm). A second study in another 12 smokers was conducted to replicate these findings as well as earlier findings that blocking vents doubles CO intake from 1-mg tar cigarettes. While blocking half the vents with fingers significantly increased CO boost from ultralight cigarettes (2.8 vs. 5.4 ppm, p < 0.001), it did not influence boosts from light cigarettes (6.3 vs. 6.5 ppm, p = 0.8). The lowest yield cigarettes (1 mg tar) may be special. Smoking machine simulations provide poor models of human smoke intake. It is unclear whether tar and nicotine intake from light cigarettes was influenced by vent blocking.

Nicotine regulates smoking patterns

BACKGROUND

Since 1953, the sales-weighted average "tar" and nicotine yields of commercial cigarettes in developed countries have significantly declined. However, the risk for chronic obstructive pulmonary disease (COPD) and for cancer of the lung has not decreased; adenocarcinoma incidence even continues to rise faster than the rate of squamous cell carcinoma of the lung. Undiminished risk of cigarette smokers for COPD and lung cancer is largely due to more intense smoking and deeper inhalation of the smoke of "low-yield" cigarettes and to significant changes in the smoke yields of certain lung carcinogens.

METHODS

Puff frequency, puff duration, and puff volume of cigarette smokers were determined by a microcomputer-assisted flow transducer. These parameters were then programmed into a smoking machine to generate mainstream smoke for quantifying nicotine and lung carcinogens.

RESULTS

Simulating the human smoking characteristics increases the yields of "tar" and nicotine per cigarette two- to threefold above Federal Trade Commission-reported levels. Smoke yields of lung carcinogens like benzo[alpha]pyrene and 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanone parallel those of nicotine and "tar."

CONCLUSIONS

The way people smoke and the total number of cigarettes consumed daily determine the uptake, i.e., the administered dose of nicotine, other toxic, and genotoxic smoke constituents. It is important to communicate this to consumers rather than letting the smokers believe that they are truly smoking a cigarette of lower smoke yields when they choose "light" or "ultralight" products.

The biological significance of tobacco-specific N-nitrosamines: smoking and adenocarcinoma of the lung

In the U.S., there has been a steeper rise of the incidence of lung adenocarcinoma than of squamous cell carcinoma of the lung among cigarette smokers. Since 1950, the percentage of all cigarettes sold that had filter tips increased from 0.56 to 92% in 1980 and to 97% in 1990. The tobacco of the filter cigarettes is richer in nitrate than that of the nonfilter cigarettes manufactured in past decades. Because the smoker of cigarettes with lower nicotine yield tends to smoke more intensely and to inhale the smoke more deeply than the smoker of plain cigarettes, the peripheral lung is exposed to higher amounts of nitrogen oxides, nitrosated compounds, and lung-specific smoke carcinogens. It is our working hypothesis that more intense smoking, deeper inhalation of the smoke, and higher smoke delivery of the organ-specific lung carcinogen NNK to the peripheral lung are major contributors to the increased risk of cigarette smokers for lung adenocarcinoma. Bioassay data and biochemical studies in support of this concept are discussed.

Comparison of measured and FTC-predicted nicotine uptake in smokers

Cigarette smokers have a wide variety of "tar" and nicotine yields to choose from in the current market, ranging from 0.5 mg "tar" and less than 0.05 mg nicotine to 27 mg "tar" and 1.8 mg nicotine by the Federal Trade Commission (FTC) method. To understand better the relationship between FTC nicotine yields and actual nicotine uptake in smokers, we have studied nicotine uptake in 33 smokers of self-selected products representing four "tar" groupings: 1 mg "tar" (1MG), ultra-low "tar" (ULT), full-flavor low "tar" (FFLT), and full flavor (FF) cigarettes. These cigarette categories had mean FTC nicotine yields of 0.14, 0.49, 0.67, and 1.13 mg/cigarette, respectively. The subjects smoked their usual brand of cigarette ad libitum and provided a 24-h urine sample for total nicotine uptake analysis over a period during which the number of cigarettes smoked was recorded. Nicotine uptake was determined by monitoring urinary nicotine and its metabolites, including the glucuronide conjugates. Daily nicotine uptake was 9.1 +/- 7.3 mg (range 1-21 mg) for 1MG, 19.2 +/- 10.0 mg (range 4-42 mg) for ULT, 21.8 +/- 9.4 mg (range 13-38 mg) for FFLT, and 37.1 +/- 14.4 mg (range 21-60 mg) for FF smokers. On a per cigarette basis, yields were 0.23 +/- 0.11, 0.56 +/- 0.23, 0.60 +/- 0.18, and 1.19 +/- 0.43 mg nicotine, respectively. Although individual variability was fairly large (CVs of 0.39-0.80), means for the different groups showed that lower FTC yield smokers not only absorb less nicotine per 24-h period, but also per cigarette smoked. These data suggest that nicotine uptake is a function of individual smoking behavior within product design limits. We conclude from these data that, while FTC yield cannot precisely predict nicotine uptake for an individual smoker, it is useful in predicting and comparing actual nicotine uptake by smokers who select cigarettes with a particular FTC yield.

Misuse of "light" cigarettes by means of vent blocking

Best-selling "light" cigarettes (9-12 mg tar, by FTC method; Federal Trade Commission, 1990) generally employ filter vents to reduce standard tar and nicotine yields. Earlier research on "ultra light" cigarettes (1-4 mg tar) showed that filter vents were blocked by human smokers leading to dramatic increases in tar and nicotine yields. An objective indicator of vent blocking was applied to a sample of 158 discarded light cigarette butts, and results indicated extreme vent blocking in 47% 27% ( +/- 8, 95% CI), some vent blocking in 26% ( +/- 8), and no vent blocking in 47% ( +/- 8). Cigarette consumers need to be informed of the risks of vent blocking as a countermeasure to the marketing of light cigarettes to health-conscious smokers.

Tobacco-specific N-nitrosamines and Areca-derived N-nitrosamines: chemistry, biochemistry, carcinogenicity, and relevance to humans

Nicotine and the minor tobacco alkaloids give rise to tobacco-specific N-nitrosamines (TSNA) during tobacco processing and during smoking. Chemical-analytical studies led to the identification of seven TSNA in smokeless tobacco (< or = 25 micrograms/g) and in mainstream smoke of cigarettes (1.3 micrograms TSNA/cigarette). Indoor air polluted by tobacco smoke may contain up to 24 pg/L of TSNA. In mice, rats, and hamsters, three TSNA, N'-nitrosonornicotine (NNN), 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanone (NNK), and 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanol (NNAL), are powerful carcinogens; two TSNA are moderately active as carcinogens; and two TSNA appear not to be carcinogenic. The TSNA are procarcinogens, agents that require metabolic activation. The active forms of the carcinogenic TSNA react with cellular components, including DNA, and with hemoglobin (Hb). The Hb adducts in chewers and smokers serve as biomarkers for the uptake and metabolic activation of carcinogenic TSNA and the urinary excretion of NNAL as free alcohol and as glucuronide for the uptake of TSNA. The review presents evidence that strongly supports the concept that TSNA contribute to the increased risk for cancer of the upper digestive tract in tobacco chewers and for the increased risk of lung cancer, especially pulmonary adenocarcinoma, in smokers. The high incidence of cancer of the upper digestive tract especially among men on the Indian subcontinent has been causally associated with chewing of betel quid mixed with tobacco. In addition to the TSNA, the betel quid chewers are exposed to four N-nitrosamines that are formed during chewing from the Areca alkaloids, two of these N-nitrosamines are carcinogens. The article also reviews approaches toward the reduction of the carcinogenic potency of smokeless tobacco, betel quid-tobacco mixtures, and cigarette smoke. Although the safest way to reduce the risk for tobacco-related cancers is to refrain from chewing and smoking, modifications of smokeless tobacco and of cigarettes are indicated to lead to less toxic products. Another more recent approach for reducing the carcinogenic effect of tobacco products is the application of chemopreventive agents, primarily of micronutrients. Future aspects in tobacco carcinogenesis, especially as it relates to TSNA, are expected in the field of molecular biochemistry and in biomarker studies, with the goal of identifying those tobacco and betel quid chewers and tobacco smokers who are at especially high risk for cancer.

Arterial blood nicotine concentration and coronary vasoconstrictive effect of low-nicotine cigarette smoking

Low-nicotine cigarettes have been advertised to the public as less harmful to the cardiovascular system. We studied the effects of smoking two low-nicotine cigarettes on arterial and venous blood nicotine levels, hemodynamics, and coronary vascular tone in 12 patients referred for diagnostic coronary arteriography. All were chronic smokers as evidenced by their elevated baseline arterial and venous cotinine blood levels (139 +/- 30 ng/ml and 155 +/- 34 ng/ml, respectively). High-resolution coronary angiograms were evaluated "blindly" before and after smoking. An electronic caliper was used to measure the diameter of disease-free coronary segments of the left anterior descending and circumflex arteries. Arterial nicotine levels rose from 5 +/- 1 ng/ml at baseline to 37 +/- 7 ng/ml (p less than 0.01) after the first cigarette was smoked and to 45 +/- 8 ng/ml (p less than 0.01) after the second cigarette. Venous nicotine levels rose from 8 +/- 2 ng at baseline to 15 +/- 3 ng/ml (p less than 0.05) after the first cigarette and to 20 +/- 3 ng/ml (p less than 0.01) after the second cigarette. After the first cigarette heart rate increased 8 +/- 2 beats/min (p less than 0.003) and double product 1229 +/- 400 beats/min x mm Hg (p less than 0.02). Compared to baseline values, after the second cigarette heart rate increased 9 +/- 1 beats/min (p less than 0.001) and double product 1767 +/- 486 beats/min x mm Hg (p less than 0.01). Systolic, diastolic, and mean blood pressure did not change significantly after either the first or second cigarette.(ABSTRACT TRUNCATED AT 250 WORDS)

Ultralow-yield cigarettes and type of ventilation: the role of ventilation blocking

Habitual smokers of perforation-ventilated cigarettes and of channel-ventilated cigarettes (18 male and 18 female subjects each; nicotine yield 0.1-0.3 mg, 0.2 mg, respectively) were compared with respect to different smoke exposure indicators and puffing behavior. The role of ventilation blocking was assessed by comparing normal lip contact with smoking through a cigarette holder. The presmoking concentrations (plasma nicotine, cotinine, respiratory CO) were higher for channel-filter than for perforation-ventilated cigarettes, as were the pre- to postsmoking boosts (nicotine, CO) with normal lip smoking. Holder smoking resulted in lower boosts than lip smoking for the channel filter cigarettes, although the puffing behavior was considerably intensified. The boosts for perforation-ventilated cigarettes remained unchanged and were reached with only moderately intensified puffing behavior. The results indicate the importance of ventilation blocking in everyday lip smoking for channel-filter cigarettes, but not for conventional, perforated cigarettes.

Self-selected blocking of vents on low-yield cigarettes

Blockers of vents in ultra-low-yield cigarettes had higher levels of carbon monoxide (CO) and salivary cotinine than did nonblockers. None of the blockers reported that they blocked vents. Exposure differences seemed not to be due simply to vent blocking, but also to be the result of syndromes of heavier (blocking, more cigarettes per day, and starting earlier in the morning) or lighter smoking (not blocking, fewer cigarettes per day, and starting later in the morning). The results are interpreted in light of the boundary model. Cigarette smoking and brand selection should be studied as they occur naturally, as well as in experimentally contrived studies.

Prevalence of the misuse of ultra-low-tar cigarettes by blocking filter vents

Evidence from tar-stain patterns in 135 cigarette filters discarded in ashtrays in public areas of shopping malls was used to estimate the prevalence of behaviorally blocked air dilution vents in ultra-low-yield cigarettes. Nineteen per cent (+/- 4, standard errors of the mean) of the filters had been blocked extremely, 39 per cent (+/- 5 SEM) had been blocked to some degree, and 42 per cent (+/- 5 SEM) had not been blocked at all. Smokers, health practitioners, and researchers need to be warned of the risks of vent blocking.

Pharmacologic determinants of tobacco self-administration by humans

Tobacco is a naturally occurring source of nicotine, which is a chemical of demonstrable abuse liability and dependence potential. All commonly used forms of tobacco result in the delivery of nicotine to the central nervous system (CNS), where its actions affect the probability of subsequent use. The role of nicotine as a determinant of patterns of tobacco self-administration and other tobacco-associated responses has frequently been confounded by the complexity of this form of drug self-administration, since the amount of nicotine delivered to the CNS is not a simple function of the amount of tobacco consumed. The present paper is a summary of data which indicate that nicotine administration and withdrawal are determinants of tobacco ingestion. Recent data that are reviewed include those which indicate that the following effects of nicotine bear an orderly relation to the dose administered: (1) reduction of cigarette smoking, (2) production of discriminative effects, and (3) blockade of tobacco withdrawal symptoms. A secondary intent of the present paper is to describe aspects of tobacco dependence which are relevant to the appreciation of the subsequent papers appearing in this series of eight.

Nicotine yield and measures of cigarette smoke exposure in a large population: are lower-yield cigarettes safer?

We examined the relationship of machine-estimated nicotine yield by cigarette brand with the level of cigarette consumption and two biochemical measures of smoke exposure (expired-air carbon monoxide and plasma thiocyanate) in a large, population-based sample of smokers (N = 713). The lower the nicotine yield of the cigarette, the greater the number of cigarettes smoked per day. Prior to adjusting for number of cigarettes smoked per day, nicotine yield was not related to the actual measures of smoke exposure. Smokers of ultralow-yield cigarettes had laboratory tests of smoke exposure which were not significantly different from those of smokers of higher-yield brands. Only after adjustment for number of cigarettes smoked per day did nicotine yield become significantly related to expired-air carbon monoxide and to plasma thiocyanate. In multivariate analysis, the number of cigarettes smoked per day accounted for 28 per cent and 22 per cent of the variance in observed expired-air carbon monoxide and plasma thiocyanate levels, respectively, whereas nicotine yield accounted for only 1 per cent and 2 per cent of the variance, respectively. The relative lack of an effect of nicotine yield on the biochemical measure appears to be due to the fact that smokers of lower nicotine brands smoked more cigarettes per day, thereby compensating for reduced delivery of smoke products. Our data do not support the concept that ultralow-yield cigarettes are less hazardous than others. Machine estimates suggesting low nicotine yield underrepresent actual human consumption of harmful cigarette constituents.

Cigarette filter vent blocking: effects on smoking topography and carbon monoxide exposure

Two studies were conducted using smokers of unventilated cigarettes to determine the effects of filter vent blocking on smoke exposure (Experiment 1) and smoking topography (Experiment 2). In both studies, subjects were exposed to ultra low yield cigarettes that had 0%, 50%, and 100% of their filter vents blocked with tape. In Experiment 1, carbon monoxide (CO) exposure from eight 60 ml puffs increased in an orderly fashion as a function of filter vent blocking. By blocking filter vents, smoke was no longer diluted with air as it passed through the filter, and hence, exposure to smoke constituents was increased. In Experiment 2, when puff and inhalation parameters were allowed to vary, subjects took significantly more puffs, and larger puffs from unblocked cigarettes than from completely blocked cigarettes, but CO exposure from the completely blocked cigarette was double that from the unblocked cigarette (8.96 ppm vs. 4.32 ppm). The increased number and volume of puffs taken from ultra low yield cigarettes with unblocked filter vents may be due to changes in physical characteristics of the cigarette, and not to smokers actively compensating for reduced smoke constituent yields.

Reduction of tar, nicotine and carbon monoxide intake in low tar smokers

Blood nicotine, cotinine, and carboxyhaemoglobin (COHb) concentrations were measured in 392 smokers (255 women and 137 men) of "middle tar" (17-22 mg), "low to middle" (11-16 mg), and "low tar" (less than 11 mg) cigarettes. Since tar intake cannot yet be measured directly, we devised an index to estimate it based on the use of measured levels of an intake marker (eg, blood nicotine) and the ratio of the tar to marker yields of the cigarettes. This approach was validated by its ability to enhance the prediction of levels of one marker by use of another. In a practical test, using COHb and the CO/nicotine yield ratio of the cigarettes, the mean blood nicotine concentration of the low tar smokers was predicted to be 31.9 ng/ml compared with the measured mean of 31.8 ng/ml. Our main findings were that despite substantial compensatory increases in inhalation, the low tar smokers took in about 25% less tar, about 15% less nicotine, and about 10% less carbon monoxide than smokers of middle and low to middle tar cigarettes. These results indicate that low tar cigarettes of the type available in Britain since the late 1970s are likely to prove less harmful than other brands. Monitoring of smoke intakes could supplement epidemiological approaches and provide earlier evidence of whether changing cigarette designs lead to any significant dosage reduction that could affect the risk of disease.

Estimates of maximum or average cigarette tar, nicotine, and carbon monoxide yields can be obtained from yields under standard conditions

Average yields of tar, nicotine, and carbon monoxide per liter of smoke and per cigarette were determined for 10 brands of cigarettes smoked under 27 different conditions (one standard and 26 nonstandard). Per cigarette yields were highly variable across smoking conditions due to differences in the total volume of smoke taken for analysis. The results of a simple linear regression analysis indicated that up to 95% of the variation in tar yield per cigarette could be explained by variations in the total volume of smoke produced per cigarette. Per liter yields for tar, nicotine, and carbon monoxide were almost constant over the conditions investigated. Since most smokers inhale less than this amount, yields per liter provide a rough estimate of the maximum amount to which a smoker might be exposed. Yields per liter, taken over all 26 conditions, are highly correlated with per cigarette yields under standard conditions. Consequently, values on one scale can be converted to the other, at least for the 10 brands investigated. The average conversion factor for tar, nicotine, and carbon monoxide is 2.5 when proceeding from milligrams per king-size cigarette under standard conditions to milligrams per liter. This relationship is true for both vented and nonvented cigarettes when ventilation holes are not blocked.

Analytical cigarette yields as predictors of smoke bioavailability

The smoke intake of 865 undisturbed smokers of over 10 cigarettes per day was measured using plasma nicotine and cotinine, and expired carbon monoxide (CO) as markers. While nicotine yields, according to Federal Trade Commission (FTC) analytical standards, varied 16-fold from 0.1 to 1.6 mg/cigarette, the corresponding plasma nicotine values varied from around 25 to 45 ng/ml, and estimated mean nicotine intake of smokers varied from around 0.75 to 1.25 mg/cigarette. Expired CO and plasma cotinine values also varied in similar proportion, but mean daily cigarette consumption was independent of the FTC nicotine yield of the cigarettes smoked. The results indicate that pharmacodynamic satiation causes behavioral regulation, and that smokers of very high yield brands compensate downward, and vice versa. The ratio of tar yield to nicotine yield usually increases with increasing tar yield; therefore tar intake is likely to increase at higher tar yields, even though the increment of nicotine intake is small. It follows that FTC analytical determinations are poor predictors of relative intake of nicotine, CO, or tar, while rankings based on mean tar-to-nicotine ratio of a brand's smoke could be more meaningful. Moreover, the considerable variation of individual smoking behavior suggests that precise numerical rankings of cigarettes are not justified. An analogic ranking of cigarettes into a few broad classes would better reflect the realities and expectations of average consumers.

Switching to low tar cigarettes: are the tar league tables relevant?

Background

Chronic hepatitis B (CHB) is a dynamic disease that may be affected by immune changes in pregnancy. Guidelines suggest consideration of nucleos/tide analogs (NA), i.e., tenofovir, (TDF) in highly viremic mothers to reduce vertical transmission risk. HBV variability affects CHB outcome, but little is known about HBV genetic changes in pregnancy due to immune or NA selection.

Objectives

To evaluate HBV diversity in NA treated or untreated pregnant vs. post-partum CHB carriers.

Study Design

In plasma collected from 21 mothers (7 matching pre/post-partum), HBV serological tests, genotype and viral load were assayed. The HBV pre-surface (S) /S overlapping polymerase (P) (N = 20), pre-core (C) /C (N = 11) and/or full genome PCR amplicons (N = 3) underwent clonal sequence analysis.

Results

The median age was 31 y, 71% Asian, 68% genotype B or C, 33% HBV eAg+, 5 received TDF (median HBV DNA 8.5 log IU/ml). In untreated mothers, median antepartum vs. post-partum ALT was 21 vs. 24 U/L and HBV DNA was 2.7 vs. 2.4 log(10) IU/ml. ALT and/or HBV DNA flares occurred during pregnant and/or post-partum period in 47% (10/21). Clonal sequencing antepartum showed the presence of minor “a determinant” and/or vaccine escape mutants (VEM) but drug resistant variants were infrequent. Analysis of pregnant vs. post-partum samples showed different HBV variants and viral diversity.

Conclusions

Differences in immune and/or by NA selective pressures during pregnancy may affect HBV evolution during pregnancy. The presence of minor VEM warrant infant follow-up.

Switching to low tar cigarettes: are the tar league tables relevant?

Representative samples of smokers of regular middle tar and regular low tar cigarettes responded to a questionnaire concerning their smoking habits and participated in a blind product test, returning 24 hour butt collections from the smoking of both middle tar and low tar cigarettes. An estimate of the mouth intake of tar derived from a measurement of filter nicotine confirmed partial compensation by the low tar smokers relative to the middle tar smokers, resulting in 32% lower tar delivery rather than the 46% expected from the standard machine values. Most middle tar smokers (98%) achieved an estimated tar delivery within or below that of the league table middle tar band when smoking middle tar cigarettes, while 70% of low tar smokers had a mouth intake of 10 X 49 mg or below within the low tar band when smoking low tar cigarettes. These results support the current tar league tables as a guide to the smoker in selecting a lower delivery cigarette.

Maintain levels of nicotine but reduce other smoke constituents: a formula for "less-hazardous" cigarettes?

Twenty-two volunteers who smoked more than 20 cigarettes with "high" nicotine yields (0.8 to 1.2 mg) per day participated in an 8-week study designed to test the hypothesis that smoking cigarettes with a constant level of nicotine but reduced deliveries of tar, carbon monoxide, and hydrogen cyanide leads to a decrease in smoke absorption. All subjects smoked their usual high-nicotine brand for the first 3 weeks (P1), and the absorption of smoke constituents was determined from levels of thiocyanate and cotinine in saliva and serum, levels of carbon monoxide in expired air, and levels of carboxyhemoglobin in the blood. During the final 5 weeks (P2), the treatment group (16 subjects) switched to the "light" version of their usual brands (similar yields of nicotine but with reduced yields of tar, carbon monoxide, and hydrogen cyanide); the control group (6 subjects) smoked their usual brands for the duration of the study. Average levels of cotinine for the subjects who switched during P2 were not significantly different from those of the control group as was expected. Slight reductions were noted in average expired-air carbon monoxide levels, blood carboxyhemoglobin, and saliva thiocyanate, but these reductions were smaller than anticipated based on brand characteristics. The results suggest that the ratio of smoke constituents is different when individuals, rather than machines, smoke cigarettes. Yields determined under subject-defined conditions are necessary in order to properly evaluate the role of nicotine in the design of "less-hazardous" cigarettes.