Polycyclic aromatic hydrocarbons (PAHs) in human milk from Italian women: influence of cigarette smoking and residential area

The presence of PAH in breast milk collected from 32 smoking and non-smoking lactating women, residing in urban and rural areas of Tuscany (Italy) was investigated. The results indicated a significant contribution of tobacco smoke to the PAH contamination of milk: the condensate contained in the cigarettes smoked daily by each subject was strongly related with the polynuclear hydrocarbon content (R(2)=0.92, P<0.005). An experiment carried out under controlled exposure conditions to cigarette smoke allowed to demonstrate that individual metabolic activity and smoking habits affect the PAH concentration in milk samples. Mothers living in rural environments showed significantly lower PAH concentrations than those observed in urban subjects. The risk evaluation due to PAH ingestion via breast milk was assessed on the basis of the acceptable daily intake of Benzo(a)pyrene in drinking water, evidencing that a hazard cannot be excluded for heavy smokers residing in urban areas.     

Environmental and biological monitoring of occupational exposure to organic micropollutants in gasoline.

An exposure risk assessment of workers in a refinery production unit was undertaken. Gasoline and its main components were investigated through environmental and biological monitoring. Measured variables were environmental benzene, toluene, pentane and hexane; benzene and toluene in blood and urine; tt-MA (metabolite of benzene) in urine. Multivariate statistical analysis of the data showed that worker's exposure to the above substances fell within the limits specified by organisations such as ACGIH. Also, biological values complied with reference values (RV) for non-occupationally-exposed population. Different values of biological variables were determined by separating smokers from non-smokers: smokers had hematic and urinary benzene values significantly higher than non-smokers. During a 3-yr sampling, it was possible to identify a significant decrease of benzene in the workplace air and of hematic benzene for non-smokers. The most exposed department, one in which tank-lorries were loaded, needs further investigation and extended monitoring.     

Association of exposure to benzene and smoking with oxidative damage to nucleic acids by means of biological monitoring of general population volunteers

In this study, the validation of liquid chromatography-tandem mass spectrometry (HPLC-MS/MS) isotopic dilution method for the determination of benzene and nicotine metabolites in urine was carried out. Limit of detection are 0.026 μg/L for S-phenylmercapturic acid (SPMA), 0.55 μg/L for t,t-muconic acid (t,t-MA), and 12.41 μg/L for the cotinine, and the relative combined uncertainty was also calculated. The study involves 446 healthy volunteer residents since at least 10 years in an area of central Italy. SPMA resulted to be strongly correlated with cotinine (p?=?0.75), its concentration in smokers (93) being about ten times than in non/ex-smokers (197/156), while the t,t-MA of smokers is about twice the non/ex-smokers value. A cutoff value for the definition of smoker is set at 100 μg/g creat. Oxidative stress was studied in smokers and non- and ex-smokers by means of the determination of the biomarkers 8-Oxo-7,8-dihydro-2′-deoxyguanosine (8-oxodGuo), 8-Oxo-7,8-dihydroguanosine (8-oxoGuo), and 8-Oxo-7,8-dihydroguanine (8-oxoGua): no significant differences were found between smokers and non/ex-smokers, but when subjects are classified according to the cotinine cutoff value, a correlation in smokers’ urinary 8-oxodGuo is found with SPMA and cotinine (p?=?0.60 and p?=?0.57). Results were confirmed by chemometric analysis that also identified the experimental variables most contributing the discrimination as cotinine and t,t-MA.     

Evaluation of exposure level of N-methyl-beta-carboline-3-carboxamide (FG 7142), an anxiogenic agent in humans

beta-Carboline-3-carboxylic acid methylamide (FG 7142), an anxiogenic agent, has been detected in human urine. The urinary excretion level of FG 7142 in non-smokers was found to be 0.503 +/- 0.25 ng per day (mean +/- S.D., n=10), while that in smokers was found to be 2.418 +/- 0.384 ng per day (n=10). This suggests that humans are exposed to FG 7142 and that smokers are exposed to higher levels of FG 7142 than non-smokers. Considering the previous findings that FG 7142 is present in cigarette smoke, indoor and outdoor air and smoke condensate of tree leaves, humans may be exposed to FG 7142 via the airways and lungs, although we cannot exclude the possibility of exposure via foodstuffs. Results of animal experiments suggest that FG 7142 which enters the bloodstream is excreted into the urine via the kidneys within 24 h in an unchanged form. Therefore, monitoring the level of FG 7142 in urine may be useful for monitoring the exposure level of FG 7142.     

Dioxins in human milk and smoking of mothers

BACKGROUND: The relation between the levels of dioxins in human breast milk and the smoking habits of the mothers is controversial. To clarify this relationship, we analyzed data from the human milk survey in Japan. METHODS: The human milk survey has been conducted in Japan since 1997. Healthy pregnant women aged 20-39 years were recruited and 50 ml of breast milk was collected from them at 30 days after delivery. PCDDs, PCDFs, and dioxin-like PCBs were measured by using GC/MS. The smoking habits of the mothers were established by interviewing them soon after delivery and were classified into four categories: current smokers, ever smokers who quit smoking at the pregnancy, ever smokers who quit smoking before the pregnancy, and never smokers. The levels of dioxins in breast milk were compared in the four categories of smoking among 853 primiparas. In addition, we analyzed the association between dioxin levels and passive smoking among never smokers. The geometric means of the dioxin concentrations were calculated in order to compare the differences between dioxins. RESULTS: The geometric means of dioxin-like PCBs in milk of never smokers was the highest (9.2 pg TEQ/g fat); followed by ever smokers who quit smoking before the pregnancy, ever smokers who quit smoking at the pregnancy, and current smokers (7.5, 7.2, and 6.6 pg TEQ/g fat, respectively). The differences between these levels were statistically significant (ANOVA, p<0.001). No significant difference was observed between the level of dioxins in milk from never smokers subjected to passive smoking status and those who had not experienced passive smoking. CONCLUSION: The levels of dioxin-like PCBs in human milk were negatively related to the smoking habits of mothers.     

Benzene exposure in Helsinki,Finland

Personal exposures and microenvironmental concentrations of benzene were measured in the residential indoor, residential outdoor and workplace environments for 201 participants in Helsinki, Finland, as a component of the EXPOLIS-Helsinki study. Median benzene personal exposures were 2.47 (arithmetic standard deviation (ASD)=1.62) μg m⁻³ for non-smokers, 2.89 (ASD=3.26) μg m⁻³ for those exposed to environmental tobacco smoke in any microenvironment and 3.08 (ASD=10.04) μg m⁻³ for active smokers. Median residential indoor benzene concentrations were 3.14 (ASD=1.51) μg m⁻³ and 1.87 (ASD=1.93) μg m⁻³ for environments with and without tobacco smoke, respectively. Median residential outdoor benzene concentrations were 1.51 (ASD=1.11) μg m⁻³ and median workplace benzene concentrations were 3.58 (ASD=1.96) μg m⁻³ and 2.13 (ASD=1.49) μg m⁻³ for environments with and without tobacco smoke, respectively. Multiple step-wise regression identified indoor benzene concentrations as the strongest predictor for personal benzene exposures of those not exposed to tobacco smoke, followed sequentially by time spent in a car, time in the indoor environment, indoor workplace concentrations and time in the home workshop. Relationships between indoor and outdoor microenvironment concentrations and personal exposures showed considerable variation between seasons, due to differences in ventilation patterns of homes in these northern latitudes. Automobile use-related activities were significantly associated with elevated benzene levels in personal and indoor measurements when tobacco smoke was not present, which demonstrates the importance of personal measurements in the assessment of exposure to benzene.     

Reductions in human benzene exposure in the California South Coast Air Basin

Benzene typically contributes a significant fraction of the human cancer risk associated with exposure to urban air pollutants. In recent years, concentrations of benzene in ambient air have declined in many urban areas due to the use of reformulated gasolines, lower vehicle emissions, and other control measures. In the California South Coast Air Basin (SoCAB) ambient benzene concentrations have been reduced by more than 70% since 1989. To estimate the resulting effect on human exposures, the Regional Human Exposure (REHEX) model was used to calculate benzene exposures in the SoCAB for the years 1989 and 1997. Benzene concentration distributions in 14 microenvironments (e.g. outdoor, home, vehicle, work) were combined with California time-activity patterns and census data to calculate exposure distributions for 11 demographic groups in the SoCAB. For 1997, the calculated average benzene exposure for nonsmoking adults in the SoCAB was 2 ppb, compared to 6 ppb for 1989. For nonsmokers, about half of the 1997 exposure was due to ambient air concentrations (including their contributions to other microenvironments), but only 4% for smokers. Passive tobacco smoke contributed about one-fourth of all exposure for adult nonsmokers. In-transit microenvironments and attached garages contributed approximately 15 and 10%, respectively. From 1989 to 1997, decreases in passive smoke exposure accounted for about one-sixth of the decrease in exposure for nonsmoking adults, with the remainder due to decreases in ambient concentrations. The reductions in exposure during this time period indicate the effectiveness of reformulated fuels, more stringent emission standards, and smoking restrictions in significantly reducing exposure to benzene.     

Exposure to methyl tertiary butyl ether and benzene in close proximity to service stations

Exposure estimates based solely on proximity to air pollution sources are not sound and require confirmation. Accordingly, since a very limited amount of actual data for this type of exposure estimate is currently available, this study was conducted to provide actual data on residents' exposure to two important gasoline constituents [methyl tertiary butyl ether (MTBE) and benzene] relative to their proximity to roadside service stations. The results confirmed that residents in neighborhoods near service stations are exposed to elevated ambient MTBE and benzene levels compared with those living farther from such a source. However, it was also found that the presumed elevated outdoor benzene levels (a mean of 1.7 ppb) even in close proximity to service stations did not exceed the indoor levels (a mean of 2.2 ppb) of exposure for those living nearby. Regardless of residents' distance from service stations, an indoor source (cigarette smoking) appeared to be the major contributor to their benzene exposure. Conversely, for MTBE, roadside service stations were found to be the major contributor to residents' exposure. In addition, the residents close to the stations were exposed to elevated indoor and outdoor MTBE levels. The sampling period (daytime and nighttime) and season (winter and summer) were additional parameters for the outdoor MTBE and benzene levels and the indoor MTBE levels. Meanwhile, the breathing zone air concentrations of service station attendants for both MTBE and benzene were significantly higher than those of drivers (p < 0.05). In addition, the breathing zone concentrations were significantly higher during summer than during winter for both drivers and attendants (p < 0.05).     

Exposure to specific polychlorinated biphenyls and some chlorinated pesticides via breast milk in Poland

The aim of our study was to obtain the data on the exposure of breast-fed infants to polychlorinated biphenyls (PCBs) and selected organochlorine pesticides (OCPs) in the Wielkopolska province (Poland). The levels of indicator PCBs, and selected OCPs, including two DDT metabolites (HCB, p,p'-DDT, p,p'-DDD, p,p'-DDE and alpha,beta,gamma-HCH) were determined in 27 human milk samples, collected in 2000-2001, according to WHO protocol. Estimated daily intakes (EDIs) of all analytes were calculated. Our results were compared with those obtained by an analysis of human milk samples from other European and non-European countries, collected in the same period time. We have stated that median exposure of Wielkopolska first breast-fed infants to OCPs is comparable (EDI(HCB) = 0.086 microg/kgbw/day; EDI(beta-HCH)=0.063 microg/kgbw/day) or higher (EDI(p,p'-DDE) = 3.495 microg/kgbw/day) than in other European countries, while exposure to PCBs (EDI(Sigma7PCB) = 0.364 microg/kgbw/day) is situated at the low end of the intake of these xenobiotics by breast-fed infants from different regions of Europe.     

Outdoor tobacco smoke exposure at the perimeter of a tobacco-free university

There are few studies measuring exposure to outdoor tobacco smoke (OTS). Tobacco users often gather at the boundaries of tobacco-free campuses, resulting in unintended consequences. The objective of this study was to measure exposure levels from OTS on sidewalks bordering a tobacco-free university campus. Data were collected while walking along a sidewalk adjacent to a medium traffic road between May and August 2011. Monitoring occurred during “background,” “stop,” and “walk-through” conditions at and near hot spot area to measure fine particulate matter (<2.5 μm; PM_2.5) from OTS using a portable aerosol monitor. The average PM_2.5 levels during stop and walk-through conditions were significantly higher than during background conditions. PM_2.5 peak occurrence rate and magnitude of peak concentration were significantly different depending on smoking occurrence. The peak occurrence rate during the stop condition was 10.4 times higher than during the background condition, and 3.1 times higher than during the walk-through condition. Average peak PM_2.5 concentrations during the stop condition were 48.7% higher than during the background condition. In conclusion, individuals could be exposed to high levels of PM_2.5 when stopping or even passing by smokers outdoors at the perimeter of tobacco-free campuses. The design and implementation of tobacco-free campus policies need to take into account the unintended consequences of OTS exposure at the boundaries.

Implications:In this study, outdoor tobacco smoke (OTS) exposure was measured at the perimeter of tobacco-free campus. OTS exposure could be determined by peak analysis. Peak occurrence rate and peak concentration for OTS exposure were identified by using peak analysis. People could be exposed to high levels of PM_2.5 when standing or even passing by smokers at the perimeter of tobacco-free campus. OTS exposure measurement in other outdoor locations with smokers is needed to support outdoor smoking regulation.     

Determination of the levels of aromatic amines in indoor and outdoor air in Italy

We studied the concentration of 10 primary aromatic amines (AA), which are classified as suspected carcinogens, in indoor and outdoor air in Italy. The measured AA included: aniline, o-toluidine, m-toluidine, p-toluidine, 2,3-dimethylaniline, 2,4-dimethylaniline, 2,5-dimethylaniline, 2,6-dimethylaniline, 2-naphtylamine and 4-aminobiphenyl. In the indoor environment (homes, offices and public buildings) the level of contamination (expressed as sum of 9 AA, excluding aniline) varied from 3 ng/m3 (hospital ward) to 207 ng/m3 (discotheque). In most indoor environments with no contamination from cigarette smoke the AA levels were below 20 ng/m3, whereas in the presence of smokers higher values were observed. Aniline levels were more erratic (varying from 53 ng/m3 (office of non-smokers) to 1929 ng/m3 (discotheque) and were not related to cigarette smoke. The concentration range of AA (excluding aniline) in the outside air varied from 3 ng/m3 (Siena) to 104 ng/m3 (Brindisi); aniline concentration was extremely variable. Most samples of outdoor air had AA levels lower than 40 ng/m3. In conclusion, AA are widespread air contaminants and attain a high concentration in heavily contaminated indoor environments, due to smoking and poor ventilation. AA occasionally attain a high level in outdoor air as well. Therefore, a strategy of reduction of the exposure to AA should consider the abatement of multiple sources of contamination.     

Bioaccumulation and physiological effects of tetrabromobisphenol A in coontail Ceratophyllum demersum L

Tetrabromobisphenol A (TBBPA) is one of the most widely used brominated flame retardants. In the present study, the accumulation of TBBPA and its consequent biological responses were examined in coontail (Ceratophyllum demersum L.) over 14 days' exposure. Most of the TBBPA was accumulated after 4d exposure and TBBPA concentration in plant increased with increasing TBBPA concentration in growth solution (R(2)=0.99). By using electron paramagnetic resonance (EPR), we found that the TBBPA exposure significantly increased total free radicals generation in the plants. A good positive relationship (R(2)=0.99) was found between the free radicals formation and accumulation level of TBBPA in plant. Lipid peroxidation was enhanced and chlorophyll content showed declined after TBBPA exposure. The activities of superoxide dismutase (SOD), peroxidase (POD), and the contents of glutathione were also detected. The results suggest that TBBPA accumulation in C. demersum induces oxidative stress and the level of tolerance depends on the antioxidative capacity of the plants.     

Markers of oxidative stress and toxicant exposure among young waterpipe smokers in the USA

Waterpipe (aka hookah) tobacco smokers are exposed to toxicants that can lead to oxidative DNA and RNA damage, a precursor to chronic disease formation. This study assessed toxicant exposure and biomarkers of DNA [8-oxo-7, 8-dihydro-2′-deoxyguanosine (8-oxodG)] and RNA [8-oxo-7,8-dihydroguanosine (8-oxoGuo)] oxidative damage during smoking of flavored and non-flavored waterpipe tobacco. Thirty waterpipe smokers completed two counterbalanced 2-h lab waterpipe smoking sessions (flavored vs. non-flavored waterpipe tobacco). Urinary concentrations of 8-oxodG and 8-oxoGuo and expired carbon monoxide (eCO) were measured before and after the smoking sessions. A significant increase in the urinary concentrations of 8-oxodG (from 2.12 ± 0.83 to 2.35 ± 0.91 ng/mg creatinine, p = 0.024) and 8-oxoGuo (from 2.96 ± 0.84 to 3.45 ± 0.76 ng/mg creatinine, p = 0.003) were observed after smoking the non-flavored and flavored waterpipe tobacco, respectively. Our results also showed that the mean ± SD of eCO increased significantly after smoking the flavored (from 1.3 ± 1.1 to 20.3 ± 23.6 ppm, p < 0.001) and non-flavored waterpipe tobacco (from 1.8 ± 1.2 to 24.5 ± 26.1 ppm, p < 0.001). There were no significant differences in the means of 8-oxodG (p = 0.576), 8-oxoGuo (p = 0.108), and eCO (p = 0.170) between the flavored and non-flavored tobacco sessions. Smoking non-flavored and flavored waterpipe tobacco leads to oxidative stress and toxicant exposure. Our findings add to the existing evidence about the adverse effects of waterpipe tobacco smoking (WTS) and the need for strong policies to inform and protect young people from the risks of WTS.

     

Oxidative DNA damage estimated by urinary 8-hydroxydeoxyguanosine: influence of taxi driving,smoking and areca chewing

Nitrogen oxides (NOx) and polycyclic aromatic hydrocarbons are common air pollutants generated from automobile exhaust and cigarette smoke. This study was to investigate urinary 8-hydroxydeoxyguanosine (8-OHdG) as an effective biomarker on DNA damage from traffic exhaust and/or smoking in exposed and non-exposed individuals. With subject consents, the levels of plasma NOx, urinary 1-hydroxypyrene (1-OHP) and 8-OHdG were determined for 95 male taxi drivers and 75 male community residents as the reference group. After adjusting for associate variables, there was a significant correlation between the levels of urinary 8-OHdG and 1-OHP but not NOx. The average level of urinary 8-OHdG was significantly higher in drivers than in community men (13.4+/-4.7 vs. 11.5+/-4.7 microg/g creatinine in mean+/-standard deviation). Compared with non-smoking community men, the multivariate logistic regression showed that the odds ratios (OR) of having elevated levels of urinary 8-OHdG (greater than the overall median value, 12.1 microg/g creatinine) were 6.6 (95% confidence interval (CI)=2.1-20.8) for smoking community men, 5.0 (95% CI=1.7-14.7) for non-smoking taxi drivers and 4.6 (95% CI=1.4-15.0) for smoking taxi drivers. Higher risk was also observed for areca quid chewers compared with non-chewers (OR=1.6; 95% CI=1.1-3.6). In conclusion, taxi driving and smoking may contribute independently to elevated DNA damage using urinary 8-OHdG levels as a sensitive biomarker. This effect is most potent on heavy smokers.     

Determination of secondhand smoke leakage from the smoking room of an Internet café

Although Internet cafes have been designated as nonsmoking areas in Korea, smoke-free legislation has allowed the installation of indoor smoking rooms. The purposes of this study were to determine secondhand smoke (SHS) leakage from an Internet café smoking room and to identify factors associated with SHS leakage. PM_2.5 (particulate matter with an aerodynamic diameter ≤2.5 μm) mass concentrations were measured simultaneously both inside and outside the door to the smoking room. During each measurement, a field technician observed how long the smoking room door was opened and closed, the direction of door opening, and the number of smokers. A multivariate linear regression model was used to identify the causality of SHS leakage from the smoking room. A time series of PM_2.5 concentrations both inside and outside the door to the smoking room showed a similar trend. SHS leakage was significantly increased because of factors associated with the direction of the smoking room door being opened, the duration of how long the smoking room door was opened until it was closed, and the average PM_2.5 concentration inside the smoking room when the door was opened. SHS leakage from inside the smoking room to outside the smoking room was evident especially when the smoking room door was opened. Since the smoking room is not effective in preventing SHS exposure, the smoking room should be removed from the facilities to protect citizens from SHS exposure through revision of the current legislation, which permits installation of a smoking room.

Implications: This paper concerns secondhand smoke (SHS) leakage from indoor smoking room. Unlike previous studies, the authors statistically analyzed the causality of PM_2.5 concentration leakage from a smoking room using time-series analysis. Since the authors selected the most common smoking room, the outcomes could be generalized. The study demonstrated that SHS leakage from smoking room and SHS leakage were clearly associated with door opening. The finding demonstrated ineffectiveness of smoking room to protect citizens and supports removal of indoor smoking room.     

Cadmium in blood of Tunisian men and risk of bladder cancer: interactions with arsenic exposure and smoking

Prior investigations identified an association between low-level blood arsenic (As) and bladder cancer risk among Tunisian men but questions remain regarding confounding by cadmium (Cd), a well-established bladder carcinogen. A case–control study of Tunisian men was re-examined to assess the levels of cadmium in blood and reparse the association between the simultaneous exposure to these metals and bladder cancer risk. Levels of blood Cd were significantly twice higher among cases than in controls (P?<?0.05) and were positively correlated with smoking and age. Additionally, analysis of metal levels among non-smokers according to the region of residence showed very high blood Cd and As levels for the coastal regions of Sfax and central Tunisia. After controlling for potential confounders, for low blood As levels (<0.67 μg/L), the OR for blood Cd was 4.10 (95 % CI 1.64–10.81), while for higher levels (>0.67 μg/L), it was reduced to 2.10 (CI, 1.06–4.17). Adjustment for Cd exposure did not alter the risk associated to As exposure. This study is the first to report the relationship between Cd exposure and risk of bladder cancer occurrence in interaction with smoking and As exposure. Smoking is shown to be the main exposure source to Cd in the Tunisian population but also environmental pollution seems to be responsible of Cd exposure among non-smokers. Exposure assessment studies encompassing a wider population are needed.     

Urinary dialkyl phosphate levels before and after first season chlorpyrifos spraying amongst farm workers in the Western Cape, South Africa

The study investigated urinary levels of dialkyl phosphates resulting from pesticide exposure amongst 40 farm workers. Workers were tested (urinary dialkyl phosphate levels, anthropometry, short exposure questionnaire) before and after the first day of seasonal chlorpyrifos spraying. Median baseline urinary dialkyl phosphates was high amongst both non-applicators (1587.5 μg/g creatinine, n = 8) and applicators (365.6 μg/g creatinine, n = 9). There was not much evidence of an increase in post-spray dialkyl phosphates levels from pre-spray levels amongst both applicators and non-applicators. Hours mixing, spraying, driving a tractor and hours worked by non-applicators were not significantly associated with an increase in post-spray dialkyl phosphate levels, adjusting for age, height, weight, gender, use of empty pesticide containers and self-reported kidney problems. Past applicator status was weakly positively associated with pre-spray dialkyl phosphate levels adjusting for age, height, weight, and gender, self-reported kidney problems, smoking and alcohol (β= 1019.5, p = 0.307, R2 = 0.28). The high dialkyl phosphate levels call for an epidemiological investigation into the health effects of organophosphorous pesticides.     

Benzene exposure and the effect of traffic pollution in Copenhagen,Denmark

Benzene is a carcinogenic compound, which is emitted from petrol-fuelled cars and thus is found ubiquitous in all cities. As part of the project Monitoring of Atmospheric Concentrations of Benzene in European Towns and Homes (MACBETH) six campaigns were carried out in the Municipality of Copenhagen, Denmark. The campaigns were distributed over 1 year. In each campaign, the personal exposure to benzene of 50 volunteers (non-smokers living in non-smoking families) living and working in Copenhagen was measured. Simultaneously, benzene was measured in their homes and in an urban network distributed over the municipality. The Radiello diffusive sampler was applied to sample 5 days averages of benzene and other hydrocarbons. Comparison of the results with those from a BTX-monitor showed excellent agreement. The exposure and the concentrations in homes and in the urban area were found to be close to log-normal distribution. The annual averages of the geometrical mean values were 5.22, 4.30 and 2.90 μg m⁻³ for personal exposure, home concentrations and urban concentrations, respectively. Two main parameters are controlling the general level of benzene in Copenhagen: firstly, the emission from traffic and secondly, dispersion due to wind speed. The general level of exposure to benzene and home concentrations of benzene were strongly correlated with the outdoor level of benzene, which indicated that traffic is an important source for indoor concentrations of benzene and for the exposure to benzene.     

Real-time measurement of outdoor tobacco smoke particles

The current lack of empirical data on outdoor tobacco smoke (OTS) levels impedes OTS exposure and risk assessments. We sought to measure peak and time-averaged OTS concentrations in common outdoor settings near smokers and to explore the determinants of time-varying OTS levels, including the effects of source proximity and wind. Using five types of real-time airborne particle monitoring devices, we obtained more than 8000 min worth of continuous monitoring data, during which there were measurable OTS levels. Measurement intervals ranged from 2 sec to 1 min for the different instruments. We monitored OTS levels during 15 on-site visits to 10 outdoor public places where active cigar and cigarette smokers were present, including parks, sidewalk cafés, and restaurant and pub patios. For three of the visits and during 4 additional days of monitoring outdoors and indoors at a private residence, we controlled smoking activity at precise distances from monitored positions. The overall average OTS respirable particle concentration for the surveys of public places during smoking was approximately 30 microg m(-3). OTS exhibited sharp spikes in particle mass concentration during smoking that sometimes exceeded 1000 microg m(-3) at distances within 0.5 m of the source. Some average concentrations over the duration of a cigarette and within 0.5 m exceeded 200 microg m(-3), with some average downwind levels exceeding 500 microg m(-3). OTS levels in a constant upwind direction from an active cigarette source were nearly zero. OTS levels also approached zero at distances greater than approximately 2 m from a single cigarette. During periods of active smoking, peak and average OTS levels near smokers rivaled indoor tobacco smoke concentrations. However, OTS levels dropped almost instantly after smoking activity ceased. Based on our results, it is possible for OTS to present a nuisance or hazard under certain conditions of wind and smoker proximity.     

Determinants of indoor benzene in Europe

This study identified the key determinants associated with the indoor benzene concentrations that were measured between 1996 and 2000 using the EXPOLIS protocol in the residences of six European cities, including Athens (Greece), Basel (Switzerland), Helsinki (Finland), Milan (Italy), Oxford (United Kingdom), and Prague (Czech Republic). Two consecutive days of home indoor and home outdoor measurements of benzene were carried out at the homes of adult participants on different dates and seasons during the sampling period. Regression models, with interactions searched by all-possible subset method, were used to assess the city effects and the determinants of home indoor benzene (adjusted R²=0.57, n=412). Outdoor benzene concentrations, outdoor temperature, wind speed, the use of anti-moth products, and indoor smoking in terms of number of cigarettes consumed per day were shown to be the key determinants of indoor benzene concentrations. The model was further used to predict the indoor benzene levels in cities. Non-linear relationships were commonly found, indicating that a unit change in the indoor concentration cannot be simply estimated by a proportional change of the determinant, and the pattern of relationships could be differed in different places. This finding is important in formulating indoor air quality guidelines as well as calculating an accurate health risk estimate based on the estimates of population's lifetime exposure levels.