ISO Tar Yield Research Articles

Investigation of exposure biomarkers in human plasma following differing levels of tobacco-specific N-nitrosamines and nicotine in cigarette smoke

Tobacco-specific N-nitrosamines (TSNAs) are strong carcinogens widely found in tobacco products, environmental tobacco smoke, lake, and wastewater. The main objective of this study was to investigate the effects of cigarette smoke with different yields of TSNAs (NNK, NNN, NAT, NAB) and nicotine on the levels of biomarkers of exposure in smokers’ plasma. Three hundred healthy volunteers were recruited comprising 60 smokers of each of 3 mg, 8 mg and 10 mg ISO tar yield cigarettes and 60 smokers who smoked 10 mg, 8 mg, and 3 mg for 14 days sequentially and 60 non-smokers. All study participants were male, aged from 21 to 45 years old, and were recruited from a same unit in Hebei, China. We measured the levels of NNAL, NAT, NNN, NAB and cotinine in plasma from 240 smokers and 60 non-smokers using a novel method established by online two-dimensional solid phase extraction-liquid chromatography-tandem mass spectrometry. The results showed that NNAL, NAT, NNN, NAB and cotinine in the plasma of smokers smoking cigarette with low TSNAs and nicotine were lower than that with high TSNAs and nicotine. When smokers switched from higher to lower TSNA yields of cigarettes, their plasma NNAL, NAT, NNN, NAB levels significantly decreased. The plasma concentrations of NNAL were significantly correlated with those of cotinine, NNN, NAT and NAB for smokers (p < 0.001). Similarly, the plasma concentrations of cotinine were significantly correlated with those of NNN, NAT and NAB for smokers (p < 0.001). The plasma NNAL, NAT, NNN, NAB and cotinine levels for smokers were significantly higher than those for non-smokers. These findings suggested that the total NNAL, NNN, NAT, NAB and cotinine in plasma were valid and reliable biomarkers for human exposure to TSNAs and nicotine.

Validation of Part-Filter Analysis to Estimate Smokers' Mouth Level Exposure to ‘Tar’ and Nicotine

SUMMARY Part-filter analysis is a method used to assess mouth level exposure (MLE) of cigarette smokers to mainstream smoke constituents. We assessed the robustness of part-filter analysis to compare MLE to nicotine and ‘tar’ between smoker populations and during calibration. Three groups of subjects smoked two batches of the same brand of 1-mg ISO tar yield Hungarian cigarettes three times each. Eighteen calibration curves were produced with three operators using three smoking machines. Within each batch of cigarettes, MLE did not differ significantly between the three smoker groups or after repeated smoking within groups. MLE was marginally higher for cigarettes from Batch 1 than Batch 2. No significant differences were found between the slopes and intercepts of the calibration curves produced using different smoking machines and operators. Part-filter analysis offers a repeatable means of estimating smokers' ‘tar’ and nicotine MLE in large-scale studies in their everyday smoking environments.

Changes in levels of biomarkers of exposure and biological effect in a controlled study of smokers switched from conventional cigarettes to reduced-toxicant-prototype cigarettes

BackgroundDevelopment of cigarettes that reduce exposure to harmful smoke constituents is a suggested tobacco harm reduction strategy, but robust methods for measurement of change are required. We investigated whether changes in biomarkers of exposure (BoE), effective dose (BoED) and biological effect (BoBE) could be detected after switching from conventional cigarettes to a reduced-toxicant-prototype cigarette (RTP). MethodsRegular smokers of 6–8mg ISO tar yield cigarettes were recruited in Hamburg, Germany, and supplied with a conventional 7mg ISO tar yield cigarette for 2weeks then switched to the same cigarette with a different tipping paper (control) or the RTP for 6months. Subjects smoked mostly at home and attended five residential clinic visits where urine and blood samples were collected for analysis. Primary endpoints were changes in specific biomarker levels compared with non-smoker background levels. Changes in daily cigarette consumption were also investigated. ResultsBoE levels in controls generally increased over the study period, whereas most BoE and all BoED significantly declined in RTP smokers. Most BoBE data were similar across groups and/or too variable within individuals to detect changes. Increased daily cigarette consumption was affected by supply of free cigarettes, perceived shorter smoking time per cigarette than usual brands, and perceived reduced harm. ConclusionsDespite increased cigarette consumption, reductions in BoE and BoED were detectable.

Relationship between cigarette format and mouth-level exposure to tar and nicotine in smokers of Russian king-size cigarettes

Differences in length and circumference of cigarettes may influence smoker behaviour and exposure to smoke constituents. Superslim king-size (KSSS) cigarettes (17mm circumference versus 25mm circumference of conventional king-size [KS] cigarettes), have gained popularity in several countries, including Russia. Some smoke constituents are lower in machine-smoked KSSS versus KS cigarettes, but few data exist on actual exposure in smokers. We investigated mouth-level exposure (MLE) to tar and nicotine in Russian smokers of KSSS versus KS cigarettes and measured smoke constituents under machine-smoking conditions. MLE to tar was similar for smokers of 1mg ISO tar yield products, but lower for smokers of 4mg and 7mg KSSS versus KS cigarettes. MLE to nicotine was lower in smokers of 4mg KSSS versus KS cigarettes, but not for other tar bands. No gender differences were observed for nicotine or tar MLE. Under International Organization for Standardization, Health Canada Intense and Massachusetts regimes, KSSS cigarettes tended to yield less carbon monoxide, acetaldehyde, nitric oxide, acrylonitrile, benzene, 1,3-butadiene and tobacco-specific nitrosamines, but more formaldehyde, than KS cigarettes. In summary, differences in MLE were observed between cigarette formats, but not systematically across pack tar bands.

Approaches for the design of reduced toxicant emission cigarettes.

Cigarette smoking causes serious diseases through frequent and prolonged exposure to toxicants. Technologies are being developed to reduce smokers’ toxicant exposure, including filter adsorbents, tobacco treatments and substitutes. This study examined the effect of modifications to filter ventilation, variations in cigarette circumference and active charcoal filter length and loading, as well as combinations of these features in a reduced-toxicant prototype (RTP) cigarette, on the yields of toxicants in cigarette smoke. An air-dilution mechanism, called split-tipping, was developed in which a band of porous paper in the centre of the filter tipping functions to minimise the loss of effective filter ventilation that occurs at the high flow rates encountered during human-smoking, and to facilitate the diffusional loss of volatile toxicants. As compared with conventional filter ventilation cigarettes, split-tipping reduced tar and volatile smoke constituent emissions under high flow rate machine-smoking conditions, most notably for products with a 1-mg ISO tar yield. Furthermore, mouth level exposure (MLE) to tar and nicotine was reduced among smokers of 1-mg ISO tar cigarettes in comparison to smokers of cigarettes with traditional filter ventilation. For higher ISO tar level cigarettes, however, there were no significant reductions in MLE. Smaller cigarette circumferences reduced sidestream toxicant yields and modified the balance of mainstream smoke chemistry with reduced levels of aromatic amines and benzo[a]pyrene but increased yields of formaldehyde. Smaller circumference cigarettes also had lower mainstream yields of volatile toxicants. Longer cigarette filters containing increased levels of high-activity carbon (HAC) showed reduced machine-smoking yields of volatile toxicants: with up to 97% removal for some volatile toxicants at higher HAC loadings. Split-tipping was combined with optimal filter length and cigarette circumference in an RTP cigarette that gave significantly lower mainstream (up to ~90%) and sidestream (predominately 20%–60%) smoke yields of numerous toxicants as compared with a commercial comparator cigarette under machine-smoking conditions. Significantly lower mainstream and sidestream smoke toxicant yields were observed for an RTP cigarette comprising several toxicant reducing technologies; these observations warrant further evaluation in clinical studies where real-world relevance can be tested using biomarkers of exposure and physiological effect.Electronic supplementary materialThe online version of this article (doi:10.1186/2193-1801-3-374) contains supplementary material, which is available to authorized users.

Lack of effect of menthol level and type on smokers’ estimated mouth level exposures to tar and nicotine and perceived sensory characteristics of cigarette smoke

Menthol can reduce sensory irritation and it has been hypothesised that this could result in smokers of mentholated cigarettes taking larger puffs and deeper post-puff inhalations thereby obtaining higher exposures to smoke constituents than smokers of non-mentholated cigarettes. The aim of our study was to use part-filter analysis methodology to assess the effects of cigarette menthol loading on regular and occasional smokers of mentholated cigarettes. We measured mouth level exposure to tar and nicotine and investigated the effects of mentholation on smokers’ sensory perceptions such as cooling and irritation. Test cigarettes were produced containing no menthol and different loadings of synthetic and natural l-menthol at 1 and 4mg ISO tar yields. A target of 100 smokers of menthol cigarettes and 100 smokers who predominantly smoked non-menthol cigarettes from both 1 and 4mg ISO tar yield categories were recruited in Poland and Japan. Each subject was required to smoke the test cigarette types of their usual ISO tar yield. There were positive relationships between menthol loading and the perceived ‘strength of menthol taste’ and ‘cooling’ effect. However, we did not see marked menthol-induced reductions in perceived irritation or menthol-induced increases in mouth level exposure to tar and nicotine.

A study to evaluate the effect on Mouth Level Exposure and biomarkers of exposure estimates of cigarette smoke exposure following a forced switch to a lower ISO tar yield cigarette

A forced switch to a lower ISO tar yield cigarette was used in a clinical study, conducted in Germany, that compared two methods of estimating exposure to cigarette smoke. Pre- and post-switch estimates of Mouth Level Exposure (MLE) to nicotine, 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanone (NNK), pyrene and acrolein were obtained by chemical analysis of spent cigarette filters for nicotine content. Similarly, pre- and post-switch estimates of uptake of these smoke constituents were achieved by analysis of corresponding urinary biomarkers of exposure (BoE): total nicotine equivalents; total 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanol (NNAL); total 1-hydroxypyrene (1-OHP), and 3-hydroxypropyl-mercapturic acid (3-HPMA), plus the nicotine metabolite cotinine, in plasma and saliva. Three hundred healthy volunteers were recruited comprising 100 smokers of each of 9–10 and 4–6mg ISO tar yield cigarettes and 50 smokers of 1–2mg ISO tar yield cigarettes and 50 non-smokers. Fifty smokers of each of the 9–10 and 4–6mg ISO tar yield cigarettes took part in the switching aspects of this study whilst the remaining smokers formed non-switching control groups who smoked their usual ISO tar yield cigarette throughout the study. After 5days, all subjects were admitted into a clinic where baseline measures of MLE and BoE were obtained. The 10mg switching group was then switched to the 4mg ISO tar yield cigarette and the 4mg ISO tar yield switching group switched to the 1mg cigarette. Subjects returned home for 12days, continuing to smoke the supplied cigarettes before being readmitted into the clinic where samples were collected for MLE and BoE analysis. Changes in daily exposure estimates were determined on a group and individual basis for both methods. The pre- to post-switch directional changes in MLEs and their corresponding BoEs were generally consistent and the MLE/BoE relationship maintained. Switching to a lower yield cigarette generally resulted in reductions in exposure with the resultant exposure level being similar to that seen in regular smokers of the lower yield cigarette.

Urinary excretion of the acrylonitrile metabolite 2-cyanoethylmercapturic acid is correlated with a variety of biomarkers of tobacco smoke exposure and consumption

Acrylonitrile is an IARC class 2B carcinogen present in cigarette smoke. Urinary 2-cyanoethylmercapturic acid (CEMA) is an acrylonitrile metabolite and a potential biomarker for acrylonitrile exposure. The objective of this work was to study the dose response of CEMA in urine of non-smokers and smokers of different ISO tar yield cigarettes. We observed that smokers excreted >100-fold higher amounts of urinary CEMA than non-smokers. The CEMA levels in smokers were significantly correlated with ISO tar yield, daily cigarette consumption, and urinary biomarkers of smoke exposure. In conclusion, urinary CEMA is a suitable biomarker for assessing smoking-related exposure to acrylonitrile.

Estimation and correlation of cigarette smoke exposure in Canadian smokers as determined by filter analysis and biomarkers of exposure

A clinical study conducted in Canada compared two methods of estimating exposure to cigarette smoke in 192 volunteer subjects: 43 smokers of 4–6mg, 49 of 8–12mg and 50 of 14–15mg ISO tar yield cigarettes and 50 non-smokers. Estimates of mouth level exposure (MLE) to nicotine, 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanone (NNK), pyrene and acrolein were obtained by chemical analysis of spent cigarette filters. Estimates of smoke constituent uptake were achieved by analysis of urinary biomarkers for total nicotine equivalents (nicotine, cotinine, trans–3′-hydroxycotinine plus their glucuronide conjugates), NNK (total 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanol (NNAL) plus glucuronide), pyrene (1-hydroxy pyrene plus glucuronide) and acrolein (3-hydroxylpropyl-mercapturic acid) plus the nicotine metabolite cotinine in plasma and saliva. The objective of our study was to confirm the correlations between measures of human exposure obtained by filter analysis and biomarkers. Significant correlations (p<0.001) were found between MLE and the relevant biomarker for each smoke constituent. The adjusted values of the Pearson correlation coefficients (r) were 0.80 (nicotine), 0.77 (acrolein) and 0.44 (pyrene). NNK correlations could not be obtained because of the low NNK yield of Canadian cigarettes. Unexpectedly high levels of acrolein biomarker found in non-smokers urine on one of the two days sampled emphasised the need for more than one sampling occasion per period and an awareness of non-tobacco sources of smoke constituents under investigation. No consistent dose response, in line with ISO tar yield smoked, of MLE estimates was found for nicotine, pyrene and acrolein and respective biomarkers. The influence of demographics on our results has also been examined.

Mouth level smoke exposure using analysis of filters from smoked cigarettes: A study of eight countries

The analysis of spent cigarette filters enables the estimation of the nicotine and tar (nicotine-free dry particulate matter) yields obtained by smokers in their everyday environment and has been shown to correlate well with biomarkers of exposure.Leading products across the range of ISO tar yields were selected from Australia, Brazil, Canada, Germany, Japan, New Zealand, South Africa and Switzerland. At least fifty demographically representative smokers were recruited per product. Subjects, ⩾21years of age and smoking ⩾5 cigarettes per day, were asked to collect ⩾15 filters from cigarettes they had smoked. The collected filters were analysed for nicotine and UV absorbance to enable the smokers’ mouth level exposure to nicotine and tar to be estimated and a comparison of countries and tobacco blend styles to be made. Smoking history data were also collected.More than 80,000 filters were collected from 5703 smokers of 106 products from eight countries. Mean±SD estimated nicotine exposures per cigarette and per day ranged from 0.93±0.34mg/cigarette (Brazil) to 1.77±0.69mg/cigarette (South Africa) and from 16.4±11.1mg/day (Germany) to 31.5±14.8mg/day (South Africa), respectively. Male smokers obtained higher mean estimated tar and nicotine exposures than female smokers. These gender differences were statistically significant for six countries. Significant correlations were found between estimated nicotine exposure and ISO nicotine yield, and between estimated tar exposure and ISO tar yield (p<0.001).

Determination of tobacco-specific N-nitrosamines in urine of smokers and non-smokers

Tobacco-specific N-nitrosamines (TSNA) include 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanone (NNK), N′-nitrosonornicotine (NNN), N′-nitrosoanabasine (NAB) and N′-nitrosoanatabine (NAT) and are found in tobacco and tobacco smoke. TSNA are of interest for biomonitoring of tobacco-smoke exposure as they are associated with carcinogenesis. Both NNK and NNN are classified by IARC as Group 1 carcinogens. Samples of 24 h urine collections (n = 108) were analysed from smokers and non-smokers, using a newly developed and validated LC-MS/MS method for determining total 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanol (NNAL, the major metabolite of NNK), and total NNN, NAB and NAT. TSNA levels in smokers’ urine were significantly higher than in non-smokers. In smokers, urinary excretion of total TSNA correlated significantly (r > 0.5) with markers of smoking dose, such as daily cigarette consumption, salivary cotinine and urinary nicotine equivalents and increased with the ISO tar yield of cigarettes smoked. The correlation between urinary total NNN and the smoking dose was weaker (r = 0.4–0.5). In conclusion, this new method is suitable for assessing tobacco use-related exposure to NNK, NNN, NAB and NAT.

Urinary Excretion of Phenolic Polycyclic Aromatic Hydrocarbons (OH-PAH) in Nonsmokers and in Smokers of Cigarettes with Different ISO Tar Yields

Polycyclic aromatic hydrocarbons (PAH) are products of the incomplete combustion of organic materials, and they occur ubiquitously in the environment. They are also present in tobacco smoke. Some PAH have been classified as carcinogens; therefore, it is important to develop and assess suitable biomarkers for PAH exposure. A high-performance liquid chromatographic method with fluorescence detection was developed to determine 1- and 2-hydroxynaphthalene (1- and 2-OH-Nap), 2-hydroxyfluorene (2-OH-Flu), 2-/3-hydroxyphenanthrene (2-/3-OH-Phe), 1-/9-hydroxyphenanthrene (1-/9-OH-Phe), and 1-hydroxypyrene (1-OH-Pyr) in human urine. The method is sensitive (LOQ ranging from 0.01 ng/mL for 1-OH-Pyr to 1 ng/mL for the naphthols), precise (interday precision ranging from 1.4 to 6.9%), and accurate (97-106%). The method was applied to 108 urine samples from 25 nonsmokers and 83 smokers. Smokers excreted significantly higher amounts of 1-OH-Nap (16.1 vs. 2.9 microg/24 h), 2-OH-Nap (20.9 vs. 9.7 microg/24 h), 2-OH-Flu (1.87 vs. 0.75 microg/24 h), 2-/3-OH-Phe (0.73 vs. 0.50 microg/24 h), 1-/9-OH-Phe (0.66 vs. 0.35 microg/24 h), and 1-OH-Pyr (0.36 vs. 0.20 microg/24 h) compared to nonsmokers. In conclusion, the method is suitable for discriminating PAH exposure between different ISO tar yield cigarette smokers, and it may be applicable in evaluating future potential reduced exposure tobacco products.

A study to estimate and correlate cigarette smoke exposure in smokers in Germany as determined by filter analysis and biomarkers of exposure

A clinical study, conducted in Germany, compared two methods of estimating exposure to cigarette smoke. Estimates of mouth level exposure (MLE) to nicotine, 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanone (NNK), pyrene and acrolein were obtained by chemical analysis of spent cigarette filters for nicotine content. Estimates of smoke constituent uptake were achieved by analysis of corresponding urinary biomarkers: for nicotine; total nicotine equivalents (nicotine, cotinine, trans-3′-hydroxycotinine plus their glucuronide conjugates), for NNK; (4-(methylnitrosamino)-1-(3-pyridyl)-1-butanol (NNAL) plus glucuronide, for pyrene; 1-hydroxy pyrene (1-OHP) plus glucuronide and for acrolein; 3-hydroxylpropyl-mercapturic acid (3-HPMA) plus the nicotine metabolite cotinine in plasma and saliva. Two hundred healthy volunteer subjects were recruited; 50 smokers of each of 1–2 mg, 4–6 mg and 9–10 mg ISO tar yield cigarettes and 50 non-smokers (NS). Smokers underwent two periods of home smoking, each followed by residence in a clinic. Smoking was permitted ad libitum, and spent cigarette filters, cigarette consumption data, 24 h urine, as well as plasma and saliva samples were collected. Significant correlations ( p < 0.001) were found between MLE and the relevant biomarker for each smoke constituent. The Pearson correlation coefficients ( r) were 0.83 (nicotine), 0.76 (NNK), 0.82 (acrolein) and 0.63 (pyrene). Mean MLE estimates for nicotine, NNK and pyrene showed a dose response in line with ISO tar yield smoked, with 10 mg > 4 mg > 1 mg, and for acrolein 10 mg > 4 mg > *1 mg (where * indicates not significant at 95% confidence level). The mean exposure estimates from biomarkers for nicotine, NNK and acrolein also showed a dose response in line with ISO tar yield with 10 mg > 4 mg > 1 mg > NS, and for pyrene 10 mg > *4 mg > 1 mg > NS. This study shows that estimates of exposure obtained by filter analysis and biomarkers of exposure correlate significantly over a wide range of smoke exposures and that filter analysis may provide a simple and effective alternative to biomarkers for estimating smokers’ exposure.