Evaluating differences between measured personal exposures to volatile organic compounds and concentrations in outdoor and indoor air

Environmental pollutants exposure-derived extracellular vesicles: crucial players in respiratory disorders

BACKGROUND

Individual exposure to environmental pollutants, as one of the most influential drivers of respiratory disorders, has received considerable attention due to its preventability and controllability. Considering that the extracellular vesicle (EV) was an emerging intercellular communication medium, recent studies have highlighted the crucial role of environmental pollutants derived EVs (EPE-EVs) in respiratory disorders.

METHODS

PubMed and Web of Science were searched from January 2018 to December 2023 for publications with key words of environmental pollutants, respiratory disorders and EVs.

RESULTS

Environmental pollutants could disrupt airway intercellular communication by indirectly stimulating airway barrier cells to secrete endogenous EVs, or directly transmitting exogenous EVs, mainly by biological pollutants. Mechanistically, EPE-EVs transferred specific contents to modulate biological functions of recipient cells, to induce respiratory inflammation and impair tissue and immune function, which consequently contributed to the development of respiratory diseases, such as asthma, chronic obstructive pulmonary disease, pulmonary fibrosis, pulmonary hypertension, lung cancer and infectious lung diseases. Clinically, EVs could emerged as promising biomarkers and biological agents for respiratory diseases attributed by their specificity, convenience, sensibility and stability.

CONCLUSIONS

Further studies of EPE-EVs are helpful to understand the aetiology and pathology of respiratory diseases, and facilitate the precision respiratory medicine in risk screening, early diagnosis, clinical management and biotherapy.

Health Risk Assessment Based on Exposure to Chemicals in Air

Few studies have investigated personal exposure concentrations of not only some volatile organic compounds but also more types of chemicals including acidic gases and acrolein. We measured the personal exposure concentrations of 35 chemicals including these chemicals in indoor and outdoor air in Chiba-shi, Japan, for 7 days in summer and winter to assess the associated health risks in 22 people. The personal exposure concentrations of nitrogen dioxide were higher in winter than in summer, and those of formaldehyde, p-dichlorobenzene, and tetradecane were higher in summer than in winter. The personal exposure concentrations were mostly equal to or lower than the concentrations in indoor air, contrary to the results of a lot of previous studies. The high-risk chemicals based on personal exposure concentrations were identified as acrolein (max. 0.43 μg/m³), benzene (max. 3.1 μg/m³), and hexane (max. 220 μg/m³) in summer, and acrolein (max. 0.31 μg/m³), nitrogen dioxide (max. 320 μg/m³), benzene (max. 5.2 μg/m³), formic acid (max. 70 μg/m³), and hexane (max. 290 μg/m³) in winter. In addition, we estimated personal exposure concentrations according to the time spent at home and the chemical concentrations in indoor and outdoor air. We found that the estimated concentrations of some participants largely differed from the measured ones indicating that it is difficult to estimate personal exposure concentrations based on only these data.

Spatial Variations of Indoor Air Chemicals in an Apartment Unit and Personal Exposure of Residents

Indoor air quality (IAQ) can greatly affect health in people spending much time indoors. However, the influence of IAQ on personal exposure to chemical compounds in Japan remains poorly investigated. Hence, this study aimed to clarify this influence thoroughly within one apartment. We surveyed the concentrations of 61 chemical compounds in the air in nine different spaces within an apartment unit, as well as the personal exposure of two residents in Japan. Using three kinds of diffusive samplers, this study was conducted continuously for 7 days in summer and winter. Health risks were evaluated by calculating the margin of exposure (MOE) using the measured concentrations. Some chemical concentrations showed large spatial variations and the personal exposure concentrations of these compounds also differed among residents. According to the calculated MOE, the chemicals with the highest health risk were acrolein, p-dichlorobenzene, and acetaldehyde in summer and acrolein, nitrogen dioxide, formic acid, p-dichlorobenzene, and benzene in winter. The IAQ of the house could be divided in two, and the IAQ in the space where residents spent much time (i.e., bedroom) highly affected each of the residents' exposure. Investigating chemical concentrations in multiple spaces (including bedroom and living room) is necessary to understand the effect of IAQ on personal exposure.

Evaluation of potential health effects associated with occupational and environmental exposure to styrene - an update

The potential chronic health risks of occupational and environmental exposure to styrene were evaluated to update health hazard and exposure information developed since the Harvard Center for Risk Analysis risk assessment for styrene was performed in 2002. The updated hazard assessment of styrene's health effects indicates human cancers and ototoxicity remain potential concerns. However, mechanistic research on mouse lung tumors demonstrates these tumors are mouse-specific and of low relevance to human cancer risk. The updated toxicity database supports toxicity reference levels of 20 ppm (equates to 400 mg urinary metabolites mandelic acid + phenylglyoxylic acid/g creatinine) for worker inhalation exposure and 3.7 ppm and 2.5 mg/kg bw/day, respectively, for general population inhalation and oral exposure. No cancer risk value estimates are proposed given the established lack of relevance of mouse lung tumors and inconsistent epidemiology evidence. The updated exposure assessment supports inhalation and ingestion routes as important. The updated risk assessment found estimated risks within acceptable ranges for all age groups of the general population and workers with occupational exposures in non-fiber-reinforced polymer composites industries and fiber-reinforced polymer composites (FRP) workers using closed-mold operations or open-mold operations with respiratory protection. Only FRP workers using open-mold operations not using respiratory protection have risk exceedances for styrene and should be considered for risk management measures. In addition, given the reported interaction of styrene exposure with noise, noise reduction to sustain levels below 85 dB(A) needs be in place.

Environmental Factors Impacting Bone-Relevant Chemokines

Chemokines play an important role in normal bone physiology and the pathophysiology of many bone diseases. The recent increased focus on the individual roles of this class of proteins in the context of bone has shown that members of the two major chemokine subfamilies-CC and CXC-support or promote the formation of new bone and the remodeling of existing bone in response to a myriad of stimuli. These chemotactic molecules are crucial in orchestrating appropriate cellular homing, osteoblastogenesis, and osteoclastogenesis during normal bone repair. Bone healing is a complex cascade of carefully regulated processes, including inflammation, progenitor cell recruitment, differentiation, and remodeling. The extensive role of chemokines in these processes and the known links between environmental contaminants and chemokine expression/activity leaves ample opportunity for disruption of bone healing by environmental factors. However, despite increased clinical awareness, the potential impact of many of these environmental factors on bone-related chemokines is still ill defined. A great deal of focus has been placed on environmental exposure to various endocrine disruptors (bisphenol A, phthalate esters, etc.), volatile organic compounds, dioxins, and heavy metals, though mainly in other tissues. Awareness of the impact of other less well-studied bone toxicants, such as fluoride, mold and fungal toxins, asbestos, and chlorine, is also reviewed. In many cases, the literature on these toxins in osteogenic models is lacking. However, research focused on their effects in other tissues and cell lines provides clues for where future resources could be best utilized. This review aims to serve as a current and exhaustive resource detailing the known links between several classes of high-interest environmental pollutants and their interaction with the chemokines relevant to bone healing.

Quantification and human health risk assessment of by-products of photo catalytic oxidation of ethylbenzene, xylene and toluene in indoor air of analytical laboratories

The by-products of TiO2-based photocatalytic oxidation (PCO) of ethylbenze, p,m-xylene, o-xylene and toluene (EXT) in vapour phase and those adsorbed on the catalyst surface (solid phase) were identified and quantified on GC/GC-MS. A factor was developed in terms of μg of by-product produced per mg of EXT removed per sq-meter surface area of catalyst for estimating the mass of by-products produced. The by-products quantified were: acetone, hexane, cyclohexane, benzene, crotonaldehyde, toulene, 1,4-benzoquinone, benzaldehyde, phenol, benzylalcohol, cresol, hydroquinone and benzoic acid. The by-products accounted for 2.3-4.2% of the total mass of EXT treated. For treating concentrations of 220μg/m(3) (ethylbenzene), 260μg/m(3) (p,m-xylene), 260μg/m(3) (o-xylene) and 320μg/m(3) (toluene), at a flow rate of 7L/min for 12h in a laboratory of volume 195m(3), the estimated cancer risks of by-products to the occupants were 1.51×10(-6), 1.06×10(-6), 4.69×10(-7), and 1.58×10(-9) respectively. The overall hazard index (HI) of the by-products for EXT was of the order 10(-4); which is much less than desired level of 1.0. The estimated risks were within the acceptable level. This study has also suggested the photocatalytic degradation pathways for EX which are through formation of toluene.

Do time-averaged, whole-building, effective volatile organic compound (VOC) emissions depend on the air exchange rate? A statistical analysis of trends for 46 VOCs in U.S. offices

We used existing data to develop distributions of time-averaged air exchange rates (AER), whole-building 'effective' emission rates of volatile organic compounds (VOC), and other variables for use in Monte Carlo analyses of U.S. offices. With these, we explored whether long-term VOC emission rates were related to the AER over the sector, as has been observed in the short term for some VOCs in single buildings. We fit and compared two statistical models to the data. In the independent emissions model (IEM), emissions were unaffected by other variables, while in the dependent emissions model (DEM), emissions responded to the AER via coupling through a conceptual boundary layer between the air and a lumped emission source. For 20 of 46 VOCs, the DEM was preferable to the IEM and emission rates, though variable, were higher in buildings with higher AERs. Most oxygenated VOCs and some alkanes were well fit by the DEM, while nearly all aromatics and halocarbons were independent. Trends by vapor pressure suggested multiple mechanisms could be involved. The factors of temperature, relative humidity, and building age were almost never associated with effective emission rates. Our findings suggest that effective emissions in real commercial buildings will be difficult to predict from deterministic experiments or models.

Improvement in 8h-sampling rate assessment considering meteorological parameters variability for biogas VOC passive measurements in the surroundings of a French landfill

Passive sampling technology has been extensively used for long-term VOC atmospheric concentrations' monitoring. Its performances regarding the short-term measurements and related to VOC from biogas were evaluated in this work: laboratory scale experiments have been conducted in order to check the suitability of Radiello® diffusive samplers for the assessment of 8 h-VOC levels in highly changeable meteorological conditions; in a second step a short pilot field campaign was implemented in the vicinity of a West-French landfill. First of all, it was assessed that amongst a diversified list of 16 characteristic compounds from biogas, mercaptans, some halogenated, oxygenated compounds and terpenes could not be measured accurately by this passive technique either because they are not captured by the sorbent or they are not quantitatively desorbed in the chosen mediated analytical conditions. Moreover, it has been confirmed that sampling rates (SR) related to isopentane, THF, cyclohexane, toluene, p-xylene and n-decane are influenced by environmental factors: the main influence concerns the wind speed. From 2 m s(-1), when the velocity increases by 1 m s(-1), the SR increases from 12 to 32% depending on the COV (considering a linear dependence between 2 and 7 m s(-1)). Humidity has no effect on SR, and temperature influence is rather limited to less than 3% per degree. A comprehensive uncertainty estimation, including uncertainties linked to meteorological changes, has led to global relative uncertainties comprising between 18% and 54% from one VOC to another: a quite high value comparatively to those obtained without considering meteorological condition influences. To illustrate our results, targeted VOC were quantified in the field, on a single day: concentrations range between LD to 3 µg m(-3): relatively very low concentrations compared to those usually reported by literature.

Domestic exposure to volatile organic compounds in relation to asthma and allergy in children and adults

Over the past decades, the prevalence of asthma, allergic disease and atopy has increased significantly and in parallel with the increased use of products and materials emitting volatile organic compounds (VOCs) in the indoor environment. The purpose of this review is to examine the evidence of the relationship between quantitatively measured domestic exposure to VOCs and allergic diseases and allergy in children and adults. Sources, potential immune-inflammatory mechanisms and risks for development and severity of asthma and allergy have been addressed. Available evidence is based on studies that have mainly used observational designs of variable quality. Total, aromatic, aliphatic, microbial VOCs and aldehydes have been the most widely investigated VOC classes, with formaldehyde being the most commonly examined single compound. Overall, the evidence is inadequate to draw any firm conclusions. However, given indicative evidence from a few high-quality studies and significant potential for improvements in asthma outcomes in those with established disease, there is a need to consider undertaking further investigation of the relationship between domestic VOC exposure and asthma/allergy outcomes that should encompass both high-quality, robust observational studies and ultimately clinical trials assessing the impact of interventions that aim to reduce VOC exposure in children and adults with asthma.

Personal exposure of primary school children to BTEX, NO₂ and ozone in Eskişehir, Turkey: relationship with indoor/outdoor concentrations and risk assessment

Personal exposures of 65 primary school children to benzene, toluene, ethyl benzene, xylenes (BTEX), nitrogen dioxide (NO2) and ozone (O3) were measured during 24h by using organic vapor monitors and tailor-made passive samplers. Two schools were selected to represent students living in more polluted (urban) and less polluted (sub-urban) areas in the city of Eskişehir, Turkey. The pollutant concentrations were also measured in indoor and outdoor environments during the personal sampling to investigate the contribution of each micro-environment on measured personal concentrations. Socio-demographic and personal time-activity data were collected by means of questionnaires and half-hour-time resolution activity diaries. Personal exposure concentrations were found to be correlated with indoor home concentrations. Personal, indoor and outdoor concentrations of all studied pollutants except for ozone were found to be higher for the students living at the urban traffic site. Ozone, on the other hand, had higher concentrations at the sub-urban site for all three types of measurements (personal, indoor and outdoor). Analysis of the questionnaire data pointed out to environmental tobacco smoke, use of solvent based products, and petrol station nearby as factors that affect personal exposure concentrations. Cancer and non-cancer risks were estimated using the personal exposure concentrations. The mean cancer risk for the urban school children (1.7×10(-5)) was found to be higher than the sub-urban school children (0.88×10(-5)). Children living with smoking parents had higher risk levels (1.7×10(-5)) than children living with non-smoking parents (1.08×10(-5)). Overall, the risk levels were <1×10(-4). All hazard quotient values for BTEX for the non-cancer health effects were <1 based on the calculations EPA's Risk Assessment Guidance for Superfund (RAGS) part F.

Formaldehyde personal exposure measurements and time weighted exposure estimates in children

Residential concentrations of formaldehyde have been associated with poor respiratory health in children, where formaldehyde has been measured using stationary monitors inside homes. Although children spend most of their time indoors at home, there are few studies of children's personal exposure to formaldehyde. The aim of this study was to investigate the relationship between personal exposure formaldehyde concentrations, microenvironmental concentrations and time weighted exposure estimates in children. Forty-one primary school children (aged between 9 and 12 years) wore a personal passive sampler over two 24h periods in two seasons and completed 24h daily activity diaries and a questionnaire about lifestyle and behaviour. Samplers were co located indoors at home, outdoors at centralised locations and indoors at school for the corresponding period. Personal exposure formaldehyde concentrations in this group of children were generally low with a geometric mean concentration of 9.1 ppb (range <detection limit to 27.3 ppb). There were strong correlations between personal exposure concentrations and both domestic indoor (r(s)=.779, p<0.001) and time weighted estimated (r(s)=.802, p<0.001) concentrations. The time weighted model did not improve the estimate of personal exposure compared with stationary indoor concentrations. Indoor air concentration measured with a single stationary monitor was a suitable surrogate for personal exposure.

Measured and modeled personal and environmental NO2 exposure

Background

Measured or modeled levels of outdoor air pollution are being used as proxies for individual exposure in a growing number of epidemiological studies. We studied the accuracy of such approaches, in comparison with measured individual levels, and also combined modeled levels for each subject’s workplace with the levels at their residence to investigate the influence of living and working in different places on individual exposure levels.

Methods

A GIS-based dispersion model and an emissions database were used to model concentrations of NO₂ at the subject’s residence. Modeled levels were then compared with measured levels of NO₂. Personal exposure was also modeled based on levels of NO₂ at the subject’s residence in combination with levels of NO₂ at their workplace during working hours.

Results

There was a good agreement between measured façade levels and modeled residential NO₂ levels (r_s = 0.8, p > 0.001); however, the agreement between measured and modeled outdoor levels and measured personal exposure was poor with overestimations at low levels and underestimation at high levels (r_s = 0.5, p > 0.001 and r_s = 0.4, p > 0.001) even when compensating for workplace location (r_s = 0.4, p > 0.001).

Conclusion

Modeling residential levels of NO₂ proved to be a useful method of estimating façade concentrations. However, the agreement between outdoor levels (both modeled and measured) and personal exposure was, although significant, rather poor even when compensating for workplace location. These results indicate that personal exposure cannot be fully approximated by outdoor levels and that differences in personal activity patterns or household characteristics should be carefully considered when conducting exposure studies. This is an important finding that may help to correct substantial bias in epidemiological studies.

Relationship of personal exposure to volatile organic compounds to home, work and fixed site outdoor concentrations

Personal exposures of 100 adult non-smokers living in the UK, as well as home and workplace microenvironment concentrations of 15 volatile organic compounds were investigated. The strength of the association between personal exposure and indoor home and workplace concentrations as well as with central site ambient air concentrations in medium to low pollution areas was assessed. Home microenvironment concentrations were strongly associated with personal exposures indicating that the home is the driving factor determining personal exposures to VOCs, explaining between 11 and 75% of the total variability. Workplace and central site ambient concentrations were less correlated with the corresponding personal concentrations, explaining up to 11-22% of the variability only at the low exposure end of the concentration range (e.g. benzene concentrations <2.5 μg m(-3)). One of the reasons for the discrepancies between personal exposures and central site data was that the latter does not account for exposure due to personal activities (e.g. commuting, painting). A moderate effect of season on the strength of the association between personal exposure and ambient concentrations was found. This needs to be taken into account when using fixed site measurements to infer exposures.

A three year study on 14 VOCs at one site in Rome: levels, seasonal variations, indoor/outdoor ratio and temporal trends

Fourteen volatile organic compounds (VOCs)—twelve hydrocarbons and two organochlorine compounds—were monitored both outdoors and indoors for three years at one site in Rome. Results showed that 118 out of 168 indoor seasonal mean values were higher than the corresponding outdoor concentrations. The most relevant source of outdoor hydrocarbons was automotive exhaust emissions. Due to the enforcement of various measures to protect health and the environment, outdoor levels of monoaromatic hydrocarbons decreased about ten fold over 15 years, and aliphatic hydrocarbons also decreased. With the decrease in these outdoor concentrations, indoor air sources are likely to be more relevant for indoor air exposures. Winter outdoor values for monoaromatic hydrocarbons were generally markedly higher than the summer ones. The gradual replacement of the current fleet of circulating cars with new cars complying with EURO 5 standards, further reducing hydrocarbon emissions, may possibly lead to an increase in the observed indoor/outdoor ratios. It is indeed more difficult to remove indoor sources, some of which are still unknown.

Evaluating methods for predicting indoor residential volatile organic compound concentration distributions

Accurate modeling of exposure to volatile organic compounds (VOCs) over a large study population depends on proper characterization of concentrations in the indoor residential environment. However, owing to the high expense of field sampling campaigns for determining indoor air concentrations, such studies have only been conducted for limited populations. Therefore, there is a need to determine the degree to which results can be extrapolated to unstudied settings through the use of models, the most appropriate information required to do so and the potential errors associated with the use of sub-optimal information. The goal of this analysis is to evaluate three different source indicators used to predict indoor VOC concentration distributions for a new study population. Data from two field studies are used. For each data set, source strength, indoor-outdoor (I-O) difference and indoor/outdoor (I/O) ratio, collectively referred to as source indicators, are calculated and fit with distributions. These distributions, as well as distributions for air exchange, volume and outdoor concentrations for the new study population, are used for predicting indoor concentrations using Monte Carlo simulations, which are then compared with actual distributions. As expected, the source strength often provides the most effective predictions (11 out of 20 instances), but is slightly outperformed by, although is still comparable with, the I-O difference on some occasions (4 out of 20). The I/O ratio generally has the greatest prediction errors, given its dependence on outdoor concentrations, but performs optimally in a limited number of cases (5 out of 20). When deciding between the source strength and I-O difference, one must consider the availability and fidelity of both current and future data. On the basis of our findings, exposure-monitoring studies should report the distribution statistics for I-O differences and, if the data are available, for source strengths.

Socioeconomic and personal behavioral factors affecting children's exposure to VOCs in urban areas in Korea

Volatile organic compounds (VOCs) are known to cause adverse health effects. We investigated the relationships between children's VOC exposure and socioeconomic and human activity factors with passive personal samplers, questionnaires, and time-activity diaries (TAD). Statistical analyses were conducted using SAS 9.1, and the results were organized using SigmaPlot 8.0 software. Chemicals such as benzene, toluene, 2-butanone, ethylbenzene, xylene, chloroform, n-hexane, heptane, and some kinds of decanes, which are known to adversely affect public health, were identified in measured samples. These were mainly emitted from outdoor sources (e.g., vehicular traffic) or indoor sources (e.g., household activities such as cooking and cleaning) or both. We concluded that region was the most important socioeconomic factor affecting children's VOC exposure, and the significant compounds were n-hexane (p = 0.006), 1,1,1-trichloroethane (p = 0.001), benzene (p = 0.003), toluene (p = 0.002), ethylbenzene (p = 0.020), m-, p-xylene (p = 0.014), dodecane (p = 0.003), and hexadecane (p = 0.001). Parental education, year of home construction and type of housing were also slightly correlated with personal VOC exposure. Only the concentration of o-xylene (p = 0.027) was significantly affected by the parental education, and the concentrations of benzene (p = 0.030) and 2-butanone (p = 0.049) by the type of housing. Also, tridecane (p = 0.049) and n-hexane (p = 0.033) were significantly associated with the year of home construction. When household activities such as cooking were performed indoors, children's VOC concentrations tended to be higher, especially for n-hexane, chloroform, heptane, toluene (p < 0.05), 1,1,1-trichloroethane, benzene, dodecane, and hexadecane (p < 0.01). However, smoking had a significant effect for only dodecane, and cleaning had no impact on any VOC concentrations. Considering both socioeconomic and personal behavioral factors simultaneously, socioeconomic factors such as region had a greater effect on children's VOC exposures than indoor activities. From this study, we can suggest that socioeconomic factors as well as environmental factors should be considered when formulating environmental policy to protect children's health.

Indoor/ambient residential air toxics results in rural western Montana

Indoor and ambient concentrations of 21 volatile organic compounds (including 14 hazardous air pollutants) were measured in the homes of nearly 80 western Montana (Missoula) high school students as part of the 'Air Toxics Under the Big Sky' program during the 2004/2005 and 2005/2006 school years. Target analytes were measured using low flow air sampling pumps and sorbent tubes, with analysis of the exposed samples by thermal desorption/gas chromatography/mass spectrometry (TD/GC/MS). The results reported here present the findings of the first indoor/ambient air toxics monitoring program conducted in a semi-rural valley location located in the Northern Rocky Mountain/Western Montana region. Of all of the air toxics quantified in this study, toluene was found to be the most abundant compound in both the indoor and ambient environments during each of the two school years. Indoor log-transformed mean concentrations were found to be higher when compared with ambient log-transformed mean concentrations at P < 0.001 for the majority of the compounds, supporting the results of previous studies conducted in urban areas. For the air toxics consistently measured throughout this program, concentrations were approximately six times higher inside the student's homes compared to those simultaneously measured directly outside their homes. For the majority of the compounds, there were no significant correlations between indoor and ambient concentrations.

[Indoor air pollution of volatile organic compounds: indoor/outdoor concentrations, sources and exposures]

In this review, we discussed about volatile organic compounds (VOC) concentrations, sources of VOC, exposures, and effects of VOC in indoor air on health in Japan. Because the ratios of indoor concentration (I) to outdoor concentration (O) (I/O ratios) were larger than 1 for nearly all compounds, it is clear that indoor contaminations occur in Japan. However, the concentrations of basic compounds such as formaldehyde and toluene were decreased by regulation of guideline indoor values. Moreover, when the sources of indoor contaminations were investigated, we found that the sources were strongly affected by to outdoor air pollutions such as automobile exhaust gas. Since people live different lifestyles, individual exposures have been investigated in several studies. Individual exposures strongly depended on indoor concentrations in houses. However, outdoor air pollution cannot be disregarded as the sources of VOC. As an example of the effect of VOC on health, it has been indicated that there is a possibility of exceeding a permissible cancer risk level owing to exposure to VOC over a lifetime.

Novel porous single-crystalline ZnO nanosheets fabricated by annealing ZnS(en)0.5 (en = ethylenediamine) precursor. Application in a gas sensor for indoor air contaminant detection

Novel single-crystalline ZnO nanosheets with porous structure have been fabricated by annealing ZnS(en)(0.5) (en = ethylenediamine) complex precursor. The morphology and structure observations performed by field emission scanning electronic microscopy (FESEM) and high-resolution transmission electron microscopy (HRTEM) indicate that numerous mesopores with a diameter of about 26.1 nm distribute all through each nanosheet with a high density. The transformation of structure and composition of samples obtained during thermal treatment processes were investigated by x-ray diffraction (XRD), x-ray photoelectron spectrometry (XPS), thermogravimetric analysis (TGA), and Fourier transform infrared (FTIR) absorption spectroscopy. The formation mechanism of the porous structure is proposed. For indoor air contaminant detection in which formaldehyde and ammonia are employed as target gases, the as-prepared ZnO nanosheets were applied for the fabrication of gas sensors. It was found that the as-fabricated sensors not only exhibit highly sensitive performance, e.g., high gas-sensing responses, short response and recovery time, but also possess significant long-term stability. It is indicated that these ZnO nanostructures could promisingly be applied in electronic devices for environmental evaluation.

Predictors of personal air concentrations of chloroform among US adults in NHANES 1999-2000

Volunteer studies suggest that showering/bathing with chlorinated tap water contributes to daily chloroform inhalation exposure for the majority of US adults. We used data from the 1999-2000 US National Health and Nutrition Examination Survey (NHANES) and weighted multiple linear regression to test the hypothesis that personal exposure microevents such as showering or spending time at a swimming pool would be significantly associated with chloroform levels in 2-3 day personal air samples. The NHANES data show that eight of 10 US adults are exposed to detectable levels of chloroform. Median (1.13 microg/m(3)), upper percentile (95th, 12.05 microg/m(3)), and cancer risk estimates were similar to those from recent US regional studies. Significant predictors of log personal air chloroform in our model (R(2)=0.34) included age, chloroform concentrations in home tap water, having no windows open at home during the sampling period, visiting a swimming pool during the sampling period, living in a mobile home/trailer or apartment versus living in a single family (detached) home, and being Non-Hispanic Black versus Non-Hispanic White, although the race/ethnicity estimates appear influenced by several outlying observations. Reported showering activity was not a significant predictor of personal air chloroform, possibly due to the wording of the NHANES shower question. The NHANES measurements likely underestimate true inhalation exposures since subjects did not wear sampling badges while showering or swimming, and because of potential undersampling by the passive monitors. Research is needed to quantify the potential difference.

Indoor air VOC concentrations in suburban and rural New Jersey

Indoor VOC air concentrations of many compounds are higher than outdoor concentrations due to indoor sources. However, most studies have measured residential indoor air in urban centers so the typical indoor air levels in suburban and rural regions have not been well characterized. Indoor VOC air concentrations were measured in 100 homes in suburban and rural areas in NJ to provide background levels for investigations of the impact from subsurface contamination sources. Of the 57 target compounds, 23 were not detected in any of the homes, and 14 compounds were detected in at least 50% of the homes with detection limits of approximately 1 microg/m3. The common compounds identified included aromatic and aliphatic hydrocarbons from mobile sources, halogenated hydrocarbons commonly used in consumer products or from chlorinated drinking water, acetone and 2-butanone emitted from cosmetic products, and Freons. Typical concentrations were in the low microg/m3 range, though values of tens, hundreds or even thousands of microg/m3 were measured in individual homes in which activities related to specific sources of VOCs were reported. Compounds with known similar sources were highly correlated. The levels observed are consistent with concentrations found in the air of urban homes.

Panel classification of self-reported exposure histories: a useful exposure index after a mass-casualty event

OBJECTIVE

Although rapid epidemiologic investigations of toxic exposures require estimates of individual exposure levels, objective measures of exposure are often unavailable. We investigated whether self-reported exposure histories, when reviewed and classified by a panel of raters, provided a useful exposure metric.

METHODS

A panel reviewed exposure histories as reported by people who experienced a chlorine release. The panelists received no information about health-care requirements or specific health effects. To each exposure case, each panelist assigned one of five possible exposure severity ratings. When assigned ratings were not in initial agreement, the panelists discussed the case and assigned a consensus rating. Percent agreement and kappa statistics assessed agreement among panelists, Kendall's W measured agreement among panelists in their overall ordering of the exposure histories, and Spearman's rho compared the resultant rankings with individual health outcome.

RESULTS

In 48% of the cases, the panelists' initial ratings agreed completely. Overall, initial ratings for a given case matched the consensus rating 69% to 89% of the time. Pair-wise comparisons revealed 85% to 95% agreement among panelists, with weighted kappa statistics between 0.69 and 0.83. In their overall ranking of the exposure histories, the panelists reached significant agreement (W = 0.90, p < 0.0001). Disagreement arose most frequently regarding probable chlorine concentration and duration of exposure. This disagreement was most common when panelists differentiated between adjacent categories of intermediate exposure. Panel-assigned exposure ratings significantly correlated with health outcome (Spearman's rho = 0.56; p < 0.0001).

CONCLUSION

Epidemiologists and public health practitioners can elicit and review self-reported exposure histories and assign exposure severity ratings that predict medical outcome. When objective markers of exposure are unavailable, panel-assigned exposure ratings may be useful for rapid epidemiologic investigations.

Zeolite-based cataluminescence sensor for the selective detection of acetaldehyde

The reactions of acetaldehyde with O atoms in the cages of large-pore zeolites have been discovered to result in light emission. The luminescence characteristics of acetaldehyde vapours passing through the surface of chosen zeolites were studied using a cataluminescence-based detection system. To demonstrate the feasibility of the method, the detection of acetaldehyde using catalysts was studied systematically and a linear response of 0.06-31.2 microg/mL acetaldehyde vapour was obtained. Methanol, ethanol, isopropanol, methylbenzene, chloroform, dichlormethane and acetonitrile did not interfere with the determination of acetaldehyde. Acetaldehyde vapour could also be distinguished from some homologous series such as formaldehyde, cinnamaldehyde, glutaraldehyde and benzaldehyde on this catalyst, possibly due to the stereoselectivity of the zeolite and its specific reaction mechanism. Moreover, acetaldehyde was quantified without detectable interference from formaldehyde in four artificial samples. Thus, this kind of cataluminescence-based sensor could be potentially extended to the analysis of volatile organic compounds in air, and the simple and portable properties of cataluminescence-based sensors could also make them beneficial in many areas of analytical science.

Measured and modeled personal exposures to and risks from volatile organic compounds

We developed a personal exposure model using volatile organic compound data collected for teachers and office workers as part of the Boston Exposure Assessment in Microenvironments (BEAM) study. We included participant-specific time-activity and concentration measurements of residential outdoor, residential indoor, and workplace microenvironments, along with average concentrations in various dining, retail, and transportation microenvironments. We used a series of time-weighted personal exposure models to compare measured personal concentrations using median regression models, with bias estimates representing the difference between measured and modeled personal exposures. Incorporating only the outdoor microenvironment results in an unbiased estimate of personal exposure only for carbon tetrachloride. Adding the residential indoor microenvironment provides an unbiased estimate for trichloroethene as well. A model incorporating residential outdoor, indoor, and workplace microenvironments provides an unbiased estimate for the above compounds and chloroform, 1,4-dichlorobenzene, benzene, and alpha-pinene, and adding the transportation microenvironment adds ethylbenzene. A fully saturated model, including outdoor, indoor, workplace, transportation, and all other microenvironments, provides an unbiased estimate for the previously listed compounds along with tetrachloroethene and styrene. MTBE, toluene, o-xylene, d-limonene, formaldehyde, and acetaldehyde were not fully characterized even in the saturated model, emphasizing that additional time-activity and concentration information would more fully characterize personal exposure.

Sample preparation for the analysis of volatile organic compounds in air and water matrices

This review summarizes literature data from the past 5 years on new developments and/or applications of sample preparation methods for analysis of volatile organic compounds (VOC), mainly in air and water matrices. Novel trends in the optimization and application of well-established airborne VOC enrichment techniques are discussed, like the implementation of advanced cooling systems in cryogenic trapping and miniaturization in adsorptive enrichment techniques. Next, focus is put on current tendencies in integrated sampling-extraction-sample introduction methods such as solid phase microextraction (SPME) and novel in-needle trapping devices. Particular attention is paid to emerging membrane extraction techniques such as membrane inlet mass spectrometry (MIMS) and membrane extraction with a sorbent interface (MESI). For VOC enrichment out of water, recent evolutions in direct aqueous injection (DAI) and liquid-liquid extraction (LLE) are highlighted, with main focus on miniaturized solvent extraction methods such as single drop microextraction (SDME) and liquid phase microextraction (LPME). Next, solvent-free sorptive enrichment receives major attention, with particular interest for innovative techniques such as stir bar sorptive extraction (SBSE) and solid phase dynamic extraction (SPDE). Finally, recent trends in membrane extraction are reviewed. Applications in both immersion and headspace mode are discussed.

Estimating volatile organic compound concentrations in selected microenvironments using time-activity and personal exposure data

Repeated measures of personal exposure to 14 volatile organic compounds (VOC) were obtained over 3 seasons for 70 healthy, nonsmoking adults living in Minneapolis-St. Paul. Matched data were also available for participants' time-activity patterns, and measured VOC concentrations outdoors in the community and indoors in residences. A novel modeling approach employing hierarchical Bayesian techniques was used to estimate VOC concentrations (posterior mode) and variability (credible intervals) in five microenvironments: (1) indoors at home; (2) indoors at work/school; (3) indoors in other locations; (4) outdoors in any location; and (5) in transit. Estimated concentrations tended to be highest in "other" indoor microenvironments (e.g., grocery stores, restaurants, shopping malls), intermediate in the indoor work/school and residential microenvironments, and lowest in the outside and in-transit microenvironments. Model estimates for all 14 VOC were reasonable approximations of measured median concentrations in the indoor residential microenvironment. The largest predicted contributor to cumulative (2-day) personal exposure for all 14 VOC was the indoor residential environment. Model-based results suggest that indoors-at-work/school and indoors-at-other-location microenvironments were the second or third largest contributors for all VOC, while the outside-in-any-location and in-transit microenvironments appeared to contribute negligibly to cumulative personal exposure. Results from a mixed-effects model indicate that being in or near a garage increased personal exposure to o-xylene, m/p-xylene, benzene, ethylbenzene, and toluene, and leaving windows and doors at home open for 6 h or more decreased personal exposure to 13 of 14 VOC, all except trichloroethylene.

Spatial and temporal trend evaluation of ambient concentrations of 1,3-butadiene and chloroprene in Texas

This paper provides information on 1,3-butadiene (BD) and chloroprene as atmospheric pollutants in Texas and reviews available emission estimates and monitoring data. Ambient BD concentrations in most areas of Texas are predominantly influenced by on-road and off-road vehicular emissions or biomass burning, since BD is a product of combustion. However, large industrial point sources of BD emissions in Texas locally influence ambient concentrations. Total industrial BD emissions to the atmosphere in Texas for 2003 were estimated at 695 tonnes per year (TPY), approximately 70% of the total reported national industrial BD air emissions. Since 1998, there have not been any large industrial sources of chloroprene emissions in Texas, and total industrial chloroprene emissions for 2003 was estimated at only 0.09 TPY. Chloroprene was never detected at air monitoring sites. In 2003, the Texas Commission on Environmental Quality (TCEQ) monitored BD ambient air concentrations at 57 sites, some of which have been operational since 1992. These air monitors provide information on ambient BD concentrations in Texas and allow spatial and temporal trend evaluation. In 2003, annual average concentrations at monitoring sites in Texas ranged from less than the reporting limit of 0.01 to 3.2 parts per billion by volume (ppbv) with an overall average of 0.2 ppbv. This overall average is reduced to 0.1 ppbv if BD data from monitoring sites in Port Neches and Milby Park in Houston, which are located downwind of significant point sources of BD, are excluded. Ambient air monitoring has been conducted in Port Neches and in Milby Park in Houston since 1996 and 1999, respectively. At the Port Neches monitor, trend evaluation indicates that ambient concentrations of BD have declined since 1996 due to cooperative agreements with industries emitting BD. Annual average BD concentrations at the Port Neches monitor decreased from 8.3ppbv in 1996 to 1.3 ppbv in 2003, giving an 8-year average of 3.8 ppbv. Annual average BD concentrations at the Milby Park monitor varied between 2.1 and 4.4 ppbv from 1999 through 2003, giving a 5-year average of 3.1 ppbv. The results of cancer cluster studies based on Cancer Registry 1995-2001 incidence data and 1993-2002 mortality data conducted by the Texas Department of State Health Services for zip codes 77017/77012 (Houston) and 77651 (Port Neches) will be presented.

Children's exposure to volatile organic compounds as determined by longitudinal measurements in blood

Blood concentrations of 11 volatile organic compounds (VOCs) were measured up to four times over 2 years in a probability sample of more than 150 children from two poor, minority neighborhoods in Minneapolis, Minnesota. Blood levels of benzene, carbon tetrachloride, trichloroethene, and m-/p-xylene were comparable with those measured in selected adults from the Third National Health and Nutrition Examination Survey (NHANES III), whereas concentrations of ethylbenzene, tetrachloroethylene, toluene, 1,1,1-trichloroethane, and o-xylene were two or more times lower in the children. Blood levels of styrene were more than twice as high, and for about 10% of the children 1,4-dichlorobenzene levels were greater than or equal to 10 times higher compared with NHANES III subjects. We observed strong statistical associations between numerous pairwise combinations of individual VOCs in blood (e.g., benzene and m-/p-xylene, m-/p-xylene and o-xylene, 1,1,1-trichloroethane and m-/p-xylene, and 1,1,1-trichloroethane and trichloroethene). Between-child variability was higher than within-child variability for 1,4-dichlorobenzene and tetrachloroethylene. Between- and within-child variability were approximately the same for ethylbenzene and 1,1,1-trichloroethane, and between-child was lower than within-child variability for the other seven compounds. Two-day, integrated personal air measurements explained almost 79% of the variance in blood levels for 1,4-dichlorobenzene and approximately 20% for tetrachloroethylene, toluene, m-/p-xylene, and o-xylene. Personal air measurements explained much less of the variance (between 0.5 and 8%) for trichloroethene, styrene, benzene, and ethylbenzene. We observed no significant statistical associations between total urinary cotinine (a biomarker for exposure to environmental tobacco smoke) and blood VOC concentrations. For siblings living in the same household, we found strong statistical associations between measured blood VOC concentrations.

Outdoor, indoor, and personal exposure to VOCs in children

We measured volatile organic compound (VOC) exposures in multiple locations for a diverse population of children who attended two inner-city schools in Minneapolis, Minnesota. Fifteen common VOCs were measured at four locations: outdoors (O), indoors at school (S), indoors at home (H), and in personal samples (P). Concentrations of most VOCs followed the general pattern O approximately equal to S < P less than or equal to H across the measured microenvironments. The S and O environments had the smallest and H the largest influence on personal exposure to most compounds. A time-weighted model of P exposure using all measured microenvironments and time-activity data provided little additional explanatory power beyond that provided by using the H measurement alone. Although H and P concentrations of most VOCs measured in this study were similar to or lower than levels measured in recent personal monitoring studies of adults and children in the United States, p-dichlorobenzene was the notable exception to this pattern, with upper-bound exposures more than 100 times greater than those found in other studies of children. Median and upper-bound H and P exposures were well above health benchmarks for several compounds, so outdoor measurements likely underestimate long-term health risks from children's exposure to these compounds.