Dermal uptake of nicotine from air and clothing: Experimental verification.

This study aims to elucidate in greater detail the dermal uptake of nicotine from air or from nicotine-exposed clothes, which was demonstrated recently in a preliminary study. Six non-smoking participants were exposed to gaseous nicotine (between 236 and 304 µg/m3 ) over 5 hours while breathing clean air through a hood. Four of the participants wore only shorts and 2 wore a set of clean clothes. One week later, 2 of the bare-skinned participants were again exposed in the chamber, but they showered immediately after exposure instead of the following morning. The 2 participants who wore clean clothes on week 1 were now exposed wearing a set of clothes that had been exposed to nicotine. All urine was collected for 84 hours after exposure and analyzed for nicotine and its metabolites, cotinine and 3OH-cotinine. All participants except those wearing fresh clothes excreted substantial amounts of biomarkers, comparable to levels expected from inhalation intake. Uptake for 1 participant wearing exposed clothes exceeded estimated intake via inhalation by >50%. Biomarker excretion continued during the entire urine collection period, indicating that nicotine accumulates in the skin and is released over several days. Absorbed nicotine was significantly lower after showering in 1 subject but not the other. Differences in the normalized uptakes and in the excretion patterns were observed among the participants. The observed cotinine half-lives suggest that non-smokers exposed to airborne nicotine may receive a substantial fraction through the dermal pathway. Washing skin and clothes exposed to nicotine may meaningfully decrease exposure.

Measurements of dermal uptake of nicotine directly from air and clothing.

In this preliminary study, we have investigated whether dermal uptake of nicotine directly from air or indirectly from clothing can be a meaningful exposure pathway. Two participants wearing only shorts and a third participant wearing clean cotton clothes were exposed to environmental tobacco smoke (ETS), generated by mechanically "smoking" cigarettes, for three hours in a chamber while breathing clean air from head-enveloping hoods. The average nicotine concentration (420 µg/m3 ) was comparable to the highest levels reported for smoking sections of pubs. Urine samples were collected immediately before exposure and 60 hour post-exposure for bare-skinned participants. For the clothed participant, post-exposure urine samples were collected for 24 hour. This participant then entered the chamber for another three-hour exposure wearing a hood and clothes, including a shirt that had been exposed for five days to elevated nicotine levels. The urine samples were analyzed for nicotine and two metabolites-cotinine and 3OH-cotinine. Peak urinary cotinine and 3OH-cotinine concentrations for the bare-skinned participants were comparable to levels measured among non-smokers in hospitality environments before smoking bans. The amount of dermally absorbed nicotine for each bare-skinned participant was conservatively estimated at 570 µg, but may have been larger. For the participant wearing clean clothes, uptake was ~20 µg, and while wearing a shirt previously exposed to nicotine, uptake was ~80 µg. This study demonstrates meaningful dermal uptake of nicotine directly from air or from nicotine-exposed clothes. The findings are especially relevant for children in homes with smoking or vaping.

Very volatile organic compounds: an understudied class of indoor air pollutants.

Very volatile organic compounds (VVOCs), as categorized by the WHO, are an important subgroup of indoor pollutants and cover a wide spectrum of chemical substances. Some VVOCs are components of products commonly used indoors, some result from chemical reactions and some are reactive precursors of secondary products. Nevertheless, there is still no clear and internationally accepted definition of VVOCs. Current approaches are based on the boiling point, and the saturation vapor pressure or refer to analytical procedures. A significant problem is that many airborne VVOCs cannot be routinely analyzed by the usually applied technique of sampling on Tenax TA® followed by thermal desorption GC/MS or by DNPH-sampling/HPLC/UV. Some VVOCs are therefore often neglected in indoor-related studies. However, VVOCs are of high significance for indoor air quality assessment and there is need for their broader consideration in measurement campaigns and material emission testing.

Human sensory response to acetone/air mixtures.

The release of organic compounds from building products may influence the perceived air quality in the indoor environment. Consequently, building products are assessed for chemical emissions and for the acceptability of emitted odors. A procedure for odor evaluations in test chambers is described by the standard ISO 16000-28. A panel of eight or more trained subjects directly determines the perceived intensity Π (unit pi) of an air sample via diffusers. For the training of the panelists, a comparative Π-scale is applied. The panelists can use acetone/air mixtures in a concentration range between 20 mg/m(3) (0 pi) and 320 mg/m(3) (15 pi) as reference. However, the training and calibration procedure itself can substantially contribute to the method uncertainty. This concerns the assumed odor threshold of acetone, the variability of panelist responses, and the analytical determination of acetone concentrations in air with online methods as well as the influence of the diffuser geometry and the airflow profile.

Application of proton-transfer-reaction-mass-spectrometry for Indoor Air Quality research.

In the field of Indoor Air Quality research, the measurement of volatile organic compounds (VOCs) demands instruments that are rapid, mobile, robust, highly sensitive and allow for simultaneous monitoring of multiple compounds. These instruments should also compensate for possible interferences from permanent gases and air humidity. Proton-transfer-reaction-mass-spectrometry (PTR-MS) has proved to be a valuable and promising technique that fits the mentioned requirements for a suitable online measuring device. In this study, five exemplary applications of PTR-MS are described: (i) release of paint additives during drying process, (ii) emission of VOCs from active hardcopy devices, (iii) reference material evaluation, (iv) diffusion studies, and (v) emission testing of building products. The examples are selected to illustrate possibilities and limitations of the PTR technique in this field of research. The quadruple-based PTR-QMS was able to determine the emission characteristics during the experiments, especially in case of depleting emission sources (e.g., reference material). This allows for chemometrical analysis of the measured release patterns and detection of underlying processes. However, PTR-QMS reaches a functional limit in case of compound identification. If identification of VOCs is necessary, the measurements need to be accompanied by GC/MS analytics or a PTR instrument with higher mass-resolution (e.g., PTR-TOF-MS).

Does e-cigarette consumption cause passive vaping?

UNLABELLED: Electronic cigarette consumption ('vaping') is marketed as an alternative to conventional tobacco smoking. Technically, a mixture of chemicals containing carrier liquids, flavors, and optionally nicotine is vaporized and inhaled. The present study aims at the determination of the release of volatile organic compounds (VOC) and (ultra)fine particles (FP/UFP) from an e-cigarette under near-to-real-use conditions in an 8-m(3) emission test chamber. Furthermore, the inhaled mixture is analyzed in small chambers. An increase in FP/UFP and VOC could be determined after the use of the e-cigarette. Prominent components in the gas-phase are 1,2-propanediol, 1,2,3-propanetriol, diacetin, flavorings, and traces of nicotine. As a consequence, 'passive vaping' must be expected from the consumption of e-cigarettes. Furthermore, the inhaled aerosol undergoes changes in the human lung that is assumed to be attributed to deposition and evaporation. PRACTICAL IMPLICATIONS: The consumption of e-cigarettes marks a new source for chemical and aerosol exposure in the indoor environment. To evaluate the impact of e-cigarettes on indoor air quality and to estimate the possible effect of passive vaping, information about the chemical characteristics of the released vapor is needed.

Indoor aerosols: from personal exposure to risk assessment.

Motivated by growing considerations of the scale, severity, and risks associated with human exposure to indoor particulate matter, this work reviewed existing literature to: (i) identify state-of-the-art experimental techniques used for personal exposure assessment; (ii) compare exposure levels reported for domestic/school settings in different countries (excluding exposure to environmental tobacco smoke and particulate matter from biomass cooking in developing countries); (iii) assess the contribution of outdoor background vs indoor sources to personal exposure; and (iv) examine scientific understanding of the risks posed by personal exposure to indoor aerosols. Limited studies assessing integrated daily residential exposure to just one particle size fraction, ultrafine particles, show that the contribution of indoor sources ranged from 19% to 76%. This indicates a strong dependence on resident activities, source events and site specificity, and highlights the importance of indoor sources for total personal exposure. Further, it was assessed that 10-30% of the total burden of disease from particulate matter exposure was due to indoor-generated particles, signifying that indoor environments are likely to be a dominant environmental factor affecting human health. However, due to challenges associated with conducting epidemiological assessments, the role of indoor-generated particles has not been fully acknowledged, and improved exposure/risk assessment methods are still needed, together with a serious focus on exposure control.

Estimating human indoor exposure to elemental mercury from broken compact fluorescent lamps (CFLs).

UNLABELLED: The 2008 EU regulation, which prohibits conventional incandescent light bulbs, is to be implemented in phases, completing in 2012. One of the possible substitutes is the compact fluorescent lamp (CFL), which, however, does contain up to 5 mg of mercury in its elemental or amalgamated form. The question arises as to the possible exposure of individuals to mercury as a result of lamp breakage during operation or when disconnected from the power supply. Therefore, an apparatus was built to shatter CFLs and drop the shards onto glycol-modified polyethylene terephthalate, a carpeted floor, or laminate floor under defined climatic parameters and operating conditions. Six CFLs of different types and mercury content were studied. After the breakage of a common CFL containing liquid mercury, concentrations up to 8000 ng/m(3) were reached in the chamber. Much lower peak values were obtained with amalgam-type lamps (414 ng/m(3)) or with lamps with a shatter-proof coating (60 ng/m(3)). It was found that ventilation can considerably reduce the indoor air concentration within 20 min. Acute health effects would only be expected if the mercury is not removed immediately. Careful collection and disposal of the lamp fragments would also prevent dwellers from the risk of long-term exposure. PRACTICAL IMPLICATIONS: After accidental breakage of a compact fluorescent lamp (CFL) indoors, dwellers could be exposed to high mercury concentrations. From the results of our studies in test chambers and real rooms using different lamp types and scenarios, it was possible to estimate the possible human uptake of mercury by inhalation. Immediate action is important to reduce indoor mercury concentrations to a minimum level. The first step is to maximize ventilation followed by careful collection of spilled mercury.

Airborne particles in indoor environment of homes, schools, offices and aged care facilities: The main routes of exposure.

It has been shown that the exposure to airborne particulate matter is one of the most significant environmental risks people face. Since indoor environment is where people spend the majority of time, in order to protect against this risk, the origin of the particles needs to be understood: do they come from indoor, outdoor sources or both? Further, this question needs to be answered separately for each of the PM mass/number size fractions, as they originate from different sources. Numerous studies have been conducted for specific indoor environments or under specific setting. Here our aim was to go beyond the specifics of individual studies, and to explore, based on pooled data from the literature, whether there are generalizable trends in routes of exposure at homes, schools and day cares, offices and aged care facilities. To do this, we quantified the overall 24h and occupancy weighted means of PM10, PM2.5 and PN - particle number concentration. Based on this, we developed a summary of the indoor versus outdoor origin of indoor particles and compared the means to the WHO guidelines (for PM10 and PM2.5) and to the typical levels reported for urban environments (PN). We showed that the main origins of particle metrics differ from one type of indoor environment to another. For homes, outdoor air is the main origin of PM10 and PM2.5 but PN originate from indoor sources; for schools and day cares, outdoor air is the source of PN while PM10 and PM2.5 have indoor sources; and for offices, outdoor air is the source of all three particle size fractions. While each individual building is different, leading to differences in exposure and ideally necessitating its own assessment (which is very rarely done), our findings point to the existence of generalizable trends for the main types of indoor environments where people spend time, and therefore to the type of prevention measures which need to be considered in general for these environments.

Plastics additives in the indoor environment--flame retardants and plasticizers.

Phthalic acid esters and phosphororganic compounds (POC) are generally known as semivolatile organic compounds (SVOCs) and are frequently utilized as plasticizers and flame retardants in commercial products. In the indoor environment, both compound groups are released from a number of sources under normal living conditions and accumulate in air and dust. Therefore, inhalation of air and ingestion of house dust have to be considered as important pathways for the assessment of exposure in living habitats. Especially in the case of very young children, the oral and dermal uptake from house dust might be of relevance for risk assessment. A critical evaluation of indoor exposure to phthalates and POC requires the determination of the target compounds in indoor air and house dust as well as emission studies. The latter are usually carried out under controlled conditions in emission test chambers or cells. Furthermore, chamber testing enables the determination of condensable compounds by fogging sampling. In the case of automobiles, specific scenarios have been developed to study material emissions on a test stand or to evaluate the exposure of users while the vehicle is driving. In this review, results from several studies are summarized and compared for seven phthalic esters and eight POC. The available data for room air and dust differ widely depending on investigated compound and compartment. Room air studies mostly include only a limited number of measurements, which makes a statistical evaluation difficult. The situation is much better for house dust measurements. However, the composition of house dust is very inhomogeneous and the result is strongly dependent on the particle size distribution used for analysis. Results of emission studies are presented for building products, electronic equipment, and automobiles. Daily rates for inhalation and dust ingestion of phthalic esters and POC were calculated from 95-percentiles or maximum values. A comparison of the data with results from human biomonitoring studies reveals that only a small portion of intake takes place via the air and dust paths.

A routine method for the determination of the TVOC content in wallcoverings using headspace gas-chromatography.

A method for the fast routine analysis of the total content of volatile organic compounds in wallcoverings and paper products was developed, using headspace gas-chromatography for quantification. 57 wallcoverings of different types were investigated. Typical components were toluene, methyl-ethyl ketone, methyl-iso-butyl ketone, n-butyl acetate and iso-butyl acetate, all compounds being used as industrial solvents. The TVOC concentrations are calculated in toluene-carbon equivalents and ranged from 0.31 microg/g to 1789 microg/g with an average value of 123.22 microg/g and a median of 20.37 microg/g. To obtain an estimation of VOC-concentrations in indoor air, 10 selected wallcoverings were also analyzed in a 1 m(3) climate test chamber. A correlation between headspace data and chamber concentrations could not be observed, which might be a result of increased analytical uncertainties at low emission rates under chamber conditions.

Chemical composition of burnt smell caused by accidental fires: environmental contaminants.

The chemical composition of the odors typical of fires has recently been deciphered. Basically the constituents are mixtures of acetophenone, benzyl alcohol, hydroxylated derivatives of benzaldehyde, methoxylated and/or alkylated phenols and naphthalene. This finding makes it possible to develop objective, practical analytic measurement methods for the burnt smell as a contribution to improving fire damage assessment and remediation monitoring. With the aid of an artificially produced burnt smell and a panel of testers the odor detection threshold of a test mixture was determined olfactometrically to 2 µg m⁻³. Using a defined burnt-smell atmosphere in a test chamber, analytical methods with active sampling, the adsorbents XAD 7 and TENAX TA, and GC/MS measurement were then optimized and tested with a view to being able to carry out sensitive quantitative measurement of burnt smells. A further practical method with particular application to the qualitative characterization of this odor is based on the use of a new SPME (solid-phase microextraction) field sampler with DVB/CAR/PDMS (divinylbenzene/Carboxen™/polydimethylsiloxane) fibers.

Surface-catalysed reactions on pollutant-removing building products for indoor use.

In order to evaluate the potential for emission of secondary reaction products from building materials designed to remove pollutants from indoor air, four samples of ceiling tiles--three commercially available and one custom-made--were investigated in chamber experiments. The chambers were irradiated with artificial light simulating indoor conditions and formaldehyde as well as several VOCs (2-butanone, n-butanol, toluene, hexanal, n- butylacetate, 2-butoxyethanol, alpha-pinene, benzaldehyde, n-decane, limonene and 1,2-dichlorobenzene) were added. Depending on the individual substrate-substance combination, it was possible to identify secondary emissions, e.g. formaldehyde, furfural, acetophenone, n-butylbutyrate, n-butyl-i-butyrate, n-butylpropionate, 4-heptanone, acetic acid, i-butyraldehyde and crotonaldehyde. These were generated by cleavage, hydrolysis, rearrangement or radical reactions. Some of these reactions also occurred with samples not containing photocatalysts. All these secondary emissions have to be taken seriously into account when evaluating the performance of materials designed to remove pollutants from indoor air, as they can prove detrimental to human health.

Photocatalytic surface reactions on indoor wall paint.

The reduction of indoor air pollutants by air cleaning systems has received considerable interest, and a number of techniques are now available. So far, the method of photocatalysis was mainly applied by use of titanium dioxide (TiO2) in flow reactors under UV light of high intensity. Nowadays, indoor wall paints are equipped with modified TiO2 to work as a catalyst under indoor daylight or artificial light. In chamber experiments carried out under indoor related conditions itwas shown thatthe method works for nitrogen dioxide with air exchange and for formaldehyde without air exchange at high concentrations. In further experiments with volatile organic compounds (VOCs), a small effect was found for terpenoids with high kOH rate constants. For other VOCs and carbon monoxide there was no degradation at all or the surface acted as a reversible sink. Secondary emissions from the reaction of paint constituents were observed on exposure to light. From the results it is concluded that recipes of photocatalytic wall paints need to be optimized for better efficiency under indoor conditions.

A microscale device for measuring emissions from materials for indoor use.

Emission test chambers or cells are used to determine organic vapour emissions from construction products under controlled conditions. Polymeric car trim component emissions are typically evaluated using direct thermal desorption/extraction. The Microchamber/Thermal Extractor (mu-CTE, Markes International) was developed to provide both a complementary tool for rapid screening of volatile organic compound (VOC) emissions--suitable for industrial quality control--and a means for thermal extraction of larger, more representative samples of car trim components. To determine the degree of correlation between conventional emission test methods and the microchamber, experiments were carried out under different conditions of temperature, air change rate and sample conditioning time. Good quantitative and qualitative correlation was obtained for measurements at ambient temperature. Moreover, it was shown that ambient-temperature emissions data collected using the mu-CTE as rapidly as possible--i.e. with minimal or no sample conditioning time--nevertheless provided a reliable guide as to how well that material would perform in subsequent 3-day chamber tests of VOC emissions. The parameters found to have the greatest influence on data correlation for experiments carried out at elevated temperatures were the sample mass (for bulk emissions testing) and the conditioning time. The results also showed that, within the constraints of inherent sample homogeneity, the mu-CTE gave reproducible emissions data, despite its small sample size/capacity relative to that of conventional chambers. Preliminary results of modelling the air flow within a microchamber using computational fluid dynamics showed a high degree of turbulent flow and two potential areas of still air which could cause sink effects. However, the experimental data reported here and in previous studies showed enhanced recovery of semivolatile components from the mu-CTE relative to a recovery from a 1 m(3) conventional chamber. This indicates that if these areas of relatively still air are present within the microchamber, they do not appear to be significant in practice.

Influence of molecular parameters on the sink effect in test chambers.

UNLABELLED: The determination of the specific emission rates of individual products and materials under indoor-related conditions requires the use of climate-controlled emission test chambers. However, most chambers demonstrate an inherent sink effect, i.e. the released components undergo adsorption/desorption processes with construction materials. Furthermore, this sink effect is enhanced by introducing an adsorbing sample surface into the test chamber. The degree of adsorption, as well as the extent of the recovery, can vary significantly for different chambers and samples and also depends on the physical properties of the relevant substance. Whereas the sink effect caused by the chamber itself can be reduced by using appropriate construction materials, it is not possible to avoid the sink effect attributable to the actual sample. For this reason it is of importance to evaluate chambers and samples for possible sink effects, taking into consideration the physical properties of substances. This can be achieved by kinetic modeling of emission data and determination of rate constants. The kinetic parameters obtained from curve fitting were combined with molecular parameters and applied to multivariate statistics. The properties of three different chambers with and without sink could be compared by cluster analysis. Principal component analysis revealed that the sink effect essentially depends on the boiling point of the substances examined. PRACTICAL IMPLICATIONS: Emission test chambers are operated by research institutions and testing laboratories for different purposes. The determined emission rate value of a building product is a function of the chamber construction, the material to be tested and the molecular properties of the target compound. In this work it is demonstrated, which parameters have the main influence on the test result. Furthermore it is shown how multivariate statistical analysis can be applied to experimental data to characterize the sink effect under dynamic conditions. This new technique provides a suitable tool for the evaluation and comparison of test chambers.

Numerical simulation of pile-up distorted time-correlated single photon counting (TCSPC) data.

A model, which is based on the binominal distribution, is derived for understanding and investigating the effect of statistical pulse pile-up. The model is applied to constant and exponential decaying sources and is compared with some experimental results.

Release of acetic acid and furfural from cork products.

Cork samples were exposed to different temperatures and volatile ingredients were analyzed using gas chromatography/mass spectrometry (GC/MS). Thermal treatment at 180 degrees C yielded considerable amounts of furfural and acetic acid. In accordance with previous investigations it was concluded that both compounds are produced under thermal stress from degradation of polyoses.

Trace analysis of pentachlorophenol (PCP) in wood and wood-based products--comparison of sample preparation procedures.

The main problem with routine analyses of pentachlorophenol (PCP) and sodium pentachlorophenolate (Na-PCP) in wood and wood-based products is to determine critical PCP-contents. This task requires a reliable analytical method and statistical testing. An analytical procedure is described, which permits the determination of PCP and Na-PCP with sufficient sensitivity and accuracy. A medium size sieve (4 x 4 mm quadratic mesh) was found suitable for the grinding step. Different extraction techniques and solvents were tested systematically. Extraction by a combination of ultrasonication and shaking in the solvent mixture toluene/sulfuric acid showed best recoveries. The eluted PCP and Na-PCP were derivatized with acetic anhydride and determined by GC/ECD. The limits of detection and determination were 0.14 mg/kg and 0.40 mg/kg, respectively.