Exposure Assessment for Air-to-skin Uptake of Semi-volatile Organic Compounds (SVOCs) Indoors PDF Download
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Author: Javier Alfonso Garrido
Publisher:
ISBN: 9780438290259
Category :
Languages : en
Pages :
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Book Description
Semi-volatile organic compounds (SVOCs) are ubiquitous in the indoor environment and a priority for exposure assessment because of the environmental health concerns that they pose. Direct air-to-skin dermal uptake has been shown to be relevant and comparable to the inhalation fraction for compounds with certain chemical properties. In this study, we aim to further understand the transport of these type of chemicals through the skin, specifically through the stratum corneum (SC), and we do so by collecting three subsequent forehead skin wipes, each removing pollutants deeper from the skin layers, and using this wipe analysis to determine the skin concentration profiles. The removal of SVOCs with repeated wipes reveals the concentration profiles with depth and provides a way to characterize penetration efficiency and potential to be absorbed into the bloodstream. Concentration profiles of SVOCs were simulated using a diffusive model in the skin and compared with the measured values. We found that two phthalates, dimethyl and diethyl phthalates, penetrate deeper in the skin with similar times of exposure, as compared to other phthalates and targeted SVOCs, an observation supported by the model results as well. We also report the presence of statistically significant declining patterns with skin depth for most SVOCs, indicating that their diffusion through the SC is relevant and eventually can reach the blood vessels in the vascularized dermis. Finally, different oxidationproducts, linked to respiratory irritation symptoms, formed from the reaction between ozone and squalene, were identified in the skin by a non-target approach.
Author: Javier Alfonso Garrido
Publisher:
ISBN: 9780438290259
Category :
Languages : en
Pages :
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Book Description
Semi-volatile organic compounds (SVOCs) are ubiquitous in the indoor environment and a priority for exposure assessment because of the environmental health concerns that they pose. Direct air-to-skin dermal uptake has been shown to be relevant and comparable to the inhalation fraction for compounds with certain chemical properties. In this study, we aim to further understand the transport of these type of chemicals through the skin, specifically through the stratum corneum (SC), and we do so by collecting three subsequent forehead skin wipes, each removing pollutants deeper from the skin layers, and using this wipe analysis to determine the skin concentration profiles. The removal of SVOCs with repeated wipes reveals the concentration profiles with depth and provides a way to characterize penetration efficiency and potential to be absorbed into the bloodstream. Concentration profiles of SVOCs were simulated using a diffusive model in the skin and compared with the measured values. We found that two phthalates, dimethyl and diethyl phthalates, penetrate deeper in the skin with similar times of exposure, as compared to other phthalates and targeted SVOCs, an observation supported by the model results as well. We also report the presence of statistically significant declining patterns with skin depth for most SVOCs, indicating that their diffusion through the SC is relevant and eventually can reach the blood vessels in the vascularized dermis. Finally, different oxidationproducts, linked to respiratory irritation symptoms, formed from the reaction between ozone and squalene, were identified in the skin by a non-target approach.
Author: Srinandini Parthasarathy
Publisher:
ISBN:
Category :
Languages : en
Pages : 121
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Book Description
Humans spend most of their time indoors, in residences and commercial buildings. In this thesis, I evaluate exposures to volatile (VOCs) and semivolatile organic compounds (SVOCs) in indoor environments. I use a combination of literature review and evaluation, mechanistic modeling, and skin-wipe collection and analysis to develop an understanding of the role of indoor air as an exposure medium for inhalation and passive dermal uptake of pollutants. This dissertation explores three related research topics on indoor environments and human exposures. In Chapter 2, I conduct a comprehensive review of reported measurements of pollutants found in commercial buildings. I used the literature review to estimate concentration ranges that can be compared to health-based exposure limits as basis for hazard assessment. I use the regulatory exposure limits set by government agencies to calculate hazard indices as the ratio of observed concentrations to regulatory standards. I also compare the odor and pungency thresholds of individual pollutants to observed concentrations to evaluate their potential to exceed odor thresholds. The hazard evaluation identifies the potential for health impacts at concentrations commonly found in commercial buildings. This analysis focuses exclusively on VOCs and SVOCs in commercial buildings and identified a limited set of pollutants that pose health concerns. I also characterize the selected pollutants in terms of the chemical properties that,affect partitioning to various indoor surfaces, and subsequently their fate and transport in indoor environments. Based on chemical properties and indoor fate, I grouped the pollutants into five groups. I use an hierarchical k-means analysis based on octanol-air partitioning coefficient, octanol-water partitioning coefficient, air-water partitioning coefficient, and molecular weight. The pollutants in each group are expected to behave similarly in indoor environments. In Chapter 3, I evaluate the role of buildings operation parameters such as ventilation and filtration in limiting exposures to pollutants originating from indoor and outdoor sources. I use a simple well-mixed-air model of an indoor space to study the impact of ventilation on concentrations of ozone, nitrogen dioxide, carbon monoxide, and radon. I employ a chemical-thermodynamics-(fugacity)-based mass balance model in conjunction with a particle mass balance to study the fate and transport of particulate matter, VOCs, and SVOCs. The fugacity mass balance model accounts for chemical partitioning among air, air-borne particles, and indoor surfaces. I ran the fugacity model with indoor and outdoor source of VOCs and SVOCs and indoor and outdoor sources of particulate matter. I evaluate the consequent inhalation exposures these sources with two outcome metrics, intake fraction (iF) for indoor sources and indoor/outdoor concentration ratio for outdoor sources. The exposure to particulate matter of indoor and outdoor origin was evaluated using the outcome metrics iF and the indoor proportion of outdoor particles (iPOP). The model evaluation shows that ventilation is most effective at controlling exposures to VOCs that have an indoor source. Filtration is seen to be effective at controlling exposures to particulate matter and SVOCs that partition preferentially onto particulate matter. In Chapter 4, I explore the role of indoor air in delivering SVOCs to human occupants through passive dermal uptake. I collected wipe samples from thirteen subjects who were randomly chosen. For each subject, I collected three sequential wipe samples from the forehead and one sample from the palm. I analyzed the samples for a suite of SVOCs and skin lipids (squalene and sapienic acid) in an analytical laboratory using gas chromatography and liquid chromatography. All forehead wipe samples contained SVOCs indicating that air to skin transfer of pollutants for passive dermal uptake could be a significant exposure pathway for SVOCs. Because skin lipid concentrations decrease with depth the quantitation of skin lipid concentrations from each wipe allowed me to estimate the depth of sampling by each skin wipe. This is the first study to quantitatively evaluate the depth of sampling by skin wipes. I use the experimental results together with a theoretical model to explore the potential role of skin as a passive sampler for short-term personal exposures, indoors. For this I develop a metric called the equivalent time of exposure (ETE) to study the usefulness of sequential skin wipe samples as a passive sampler. I used partitioning coefficients from air to skin surface, combined with a dynamic skin mass transport model, to study the theoretical transport of pollutant through the stratum corneum. I compare the modeled concentrations to measured concentrations, at comparable depths. The ETE is the amount of time to which the subject would have to be exposed to a constant air concentration to attain the observed skin-wipe concentration depth profile in the stratum corneum. Based on the ETE, I find that skin wipe samples could be indicative of exposures up to 6 hours prior to wipe sampling, depending on the diffusion coefficient of the pollutant. The overarching goal of this research is to evaluate the role of indoor air in mediating the transfer to human receptors of pollutants released indoors or brought indoors from outdoor sources. The indoor air mass controls the fate and transport of pollutants in indoor spaces, and the rate of delivery of pollutants for inhalation and dermal uptake. The research highlights the important role of air-to-surface and air-to-particle partitioning in facilitating or mitigating source-receptor relationships. The work illustrates future research opportunities for tracking the complex web of indoor/outdoor pathways that bring pollutants into the human environment and into the blood and other viable tissues of the human population.
Author: Matti Jantunen
Publisher: WHO Regional Office Europe
ISBN: 9789289013420
Category : Air
Languages : en
Pages : 168
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Book Description
Most people spend most of their time indoors, and the poor quality of the indoor environment is a strong determinant of a variety of health problems. The principal way of preventing adverse health effects is to eliminate exposure to hazardous factors. But first, standardized methods of assessing exposure are necessary to assess the risk to health and to select optimal risk management actions. This book aims to facilitate the implementation of exposure assessment methods in public health practice.
Author: Jeong-Eun Oh
Publisher:
ISBN: 0444643397
Category :
Languages : en
Pages : 388
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Book Description
Analysis and Fate of Emerging Brominated and Fluorinated Organic Pollutants, Volume 87 in the Comprehensive Analytical Chemistry series, contains a wide range of topics on flame retardants in the environment, specifically focusing on halogenated flame retardants. New chapters in this release include an Introduction of emerging halogenated flame retardants in the environment, Analysis of emerging halogenated flame Retardants in environment, Toxicity of emerging halogenated organic chemicals, Occurrence and fate of emerging halogenated flame retardants in environment, Emerging halogenated flame retardants in indoor environment, Food contamination on emerging halogenated flame retardants, Human exposure to emerging halogenated flame retardants, and much more. Provides the current research results on emerging halogenated flame retardants Contains all research subjects about emerging halogenated flame retardants, from analysis to human exposure Presents critical information on halogenated flame retardants
Author: Joseph Ocheje Okeme
Publisher:
ISBN:
Category :
Languages : en
Pages :
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Book Description
Human exposure to semi-volatile organic compounds (SVOCs) including flame retardants (FRs) and plasticizers used in consumer products from indoor sources is a serious concern. These compounds are then advected to the outdoor environment which leads to regional and long-range transport and exposure to the ecosystem. This thesis aims to improve our understanding of exposure to selected SVOCs by developing tools, methods and providing data to facilitate exposure assessment particularly regarding indoor air. Three new passive air samplers (PAS), namely silicone rubber (polydimethylsiloxane, PDMS), styrene-divinylbenzene copolymer (XAD)-Pocket and XAD-PDMS were calibrated against an active air sampler and compared to the more popular polyurethane foam (PUF) PAS. Although the indoor sampling rates vary, we recommend from these studies a generic sampling rate of 1.7 m3 day-1dm-2 and 0.94 m3 day-1dm-2 for PDMS and PUF, respectively. The active air sampler was also used to assess the gas-particle distribution of the target compounds. The particle-phase partitioning fractions of SVOCs is a key determinant of their environmental behaviour and potential for exposure thus toxicity. A key finding here, is that some relatively volatile organophosphate ester FRs are present in the gas-phase where most published studies of active air sampling report them largely in the particle phase, indicating a sampling artifact. To improve chemical screening and modelling of the transport and fate, this thesis provides experimentally determined values of vapour pressures and octanol-air partition coefficients for over 50 SVOCs measured here using the well-established gas chromatography retention time method. Deployment of PDMS and PUF in residential homes gave comparable estimates of air concentrations for SVOCs in the gas-phase, although PUF was more able to capture compounds with higher fractions in the particulate phase. PDMS shows promise as a tool for estimating exposure to a wide range of SVOCs indoors, although its particle sampling efficiency warrants further work.
Author: National Research Council
Publisher: National Academies Press
ISBN: 0309042844
Category : Science
Languages : en
Pages : 338
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Book Description
Most people in the United States spend far more time indoors than outdoors. Yet, many air pollution regulations and risk assessments focus on outdoor air. These often overlook contact with harmful contaminants that may be at their most dangerous concentrations indoors. A new book from the National Research Council explores the need for strategies to address indoor and outdoor exposures and examines the methods and tools available for finding out where and when significant exposures occur. The volume includes: A conceptual framework and common terminology that investigators from different disciplines can use to make more accurate assessments of human exposure to airborne contaminants. An update of important developments in assessing exposure to airborne contaminants: ambient air sampling and physical chemical measurements, biological markers, questionnaires, time-activity diaries, and modeling. A series of examples of how exposure assessments have been applied-properly and improperly-to public health issues and how the committee's suggested framework can be brought into practice. This volume will provide important insights to improve risk assessment, risk management, pollution control, and regulatory programs.
Author: Samreen Siddiqui
Publisher: Springer Nature
ISBN: 3031531302
Category :
Languages : en
Pages : 174
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Book Description
Author: Kyunghoon Kim
Publisher:
ISBN:
Category : Environmental toxicology
Languages : en
Pages : 126
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Book Description
Exposure to semivolatile organic compounds (SVOCs) in indoor environments and its potential impact on human health have been receiving increased public attention, because people in developed countries spend over 80% of their time indoors, SVOC levels are several orders of magnitude higher indoors than outdoors, and many SVOCs have various toxicities and endocrine disrupting potential. Concentrations of SVOCs in biological (e.g., human serum) and environmental (e.g., household dust, indoor air) media can help us better understand human exposure to SVOCs. For example, SVOC concentrations in biological media collected over several years may shed light on temporal trends of exposure due to the changes in consumer use or regulations. In addition, SVOC concentrations in indoor dust repeatedly collected in the same home may allow us to examine temporal variability of exposure via non-dietary dust ingestion. Lastly, SVOC concentrations in upholstered home furniture with frequent skin contact may improve our understanding of exposure via direct skin contact with furniture surfaces, particularly for infants and young children. My dissertation studies include three sub-studies: (1) examining temporal trends and determinants of concentrations of SVOCs in blood serum samples, (2) examining temporal variability of dust concentrations and factors affecting dust concentrations for SVOCs, and (3)evaluating couch polyurethane foam (PUF) for a potential passive sampler of SVOCs. In the first study, I utilized measured concentrations of per- and polyfluoroalkyl substances (PFAS), one class of SVOCs, in serum collected from California mothers with a young child. Then, I used multiple regression to estimate geometric means of PFAS concentrations for each sampling year (2009-2016), with adjustment for sampling year and other population characteristics that may affect PFAS concentrations in maternal serum. I observed that perfluorooctanoate (PFOA), perfluorooctane sulfonate (PFOS), and perfluorohexane sulfonate (PFHxS) decreased over the study period, consistent with results of some studies reported for other U.S. populations and other studies outside the USA. My study showed that body burden of some common long-chain PFAS decreased over the study period among California mothers with a young child.In the second study, I utilized measured concentrations of a wide range of SVOCs in dust collected three times from the same home during a period of 22 months. To test for within-home temporal variability of SVOC concentrations in household dust, I computed intraclass correlation coefficients (ICCs), a ratio of between-home variance to total variance (within-home variance +between-home variance). Among 26 compounds that were detected in more than 50% of the samples at all three visits, 20 compounds had ICCs above 0.50 and 6 compounds had ICCs below 0.50. For 19 out of 26 compounds, correlation coefficients between spring and fall (r =0.48-0.98) were higher than those between summer and winter (r = 0.09-0.92), implying seasonal effects on dust concentrations. My study showed that within-home temporal variability of dust concentrations was small (ICC > 0.50) for most SVOCs, but dust concentrations may vary overtime for some SVOCs with seasonal variations in source rates, such as product use.In the third study, I utilized measured concentrations of non-flame retardant SVOCs in couch PUF at three different depths. Then, I examined concentration changes with depths and developed predictive equations for the PUF-air partition coefficient (KPUF-air). Among 29 detected compounds, 11 compounds were detected in more than 50% of the samples at all depths. Among the 11 compounds, concentrations of phenanthrene, 2-benzylideneoctanal, galaxolide, tonalide, and homosalate decreased with depth. Among the studied SVOCs, calculated log KPUF-air values varied from 2.46 (dimethyl phthalate) to 7.80 (homosalate), and Koa(r2 = 0.62) was a stronger predictor of KPUF-air than VP (r2 = 0.47). My study showed that couch PUF can absorb many SVOCs but may not be an effective passive sampling medium for those that were less frequently detected in couch PUF and had low correlation coefficients between concentrations in dust and PUF.
Author: Lidia Morawska
Publisher: John Wiley & Sons
ISBN: 3527609202
Category : Science
Languages : en
Pages : 467
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Book Description
Covering the fundamentals of air-borne particles and settled dust in the indoor environment, this handy reference investigates: * relevant definitions and terminology, * characteristics, * sources, * sampling techniques and instrumentation, * exposure assessment, * monitoring methods. The result is a useful and comprehensive overview for chemists, physicists and biologists, postgraduate students, medical practitioners, occupational health professionals, building owners and managers, building, construction and air-conditioning engineers, architects, environmental lawyers, government and regulatory professionals.
Author: Hongwan Li
Publisher:
ISBN:
Category :
Languages : en
Pages : 0
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Book Description
Semi-volatile organic compounds (SVOCs), such as phthalates, organophosphates, and polybrominated diphenyl ethers (PBDEs), are emerging pollutants associated with serious health concerns. SVOCs are extensively used as plasticizers and flame retardants in building materials and consumer products. Because SVOCs are not chemically bound to polymers, they are slowly emitted from source materials to indoor environments, where people spend most of their time. However, due to our poor understanding of their sources, fate, and transport in indoor environments, effective strategies to reduce exposures remain unclear. The goal of this dissertation is to characterize SVOC emissions rapidly and investigate their fate and transport in indoor environments. The specific objectives are to 1) develop a novel rapid micro-emission-cell method to characterize SVOC emissions from building materials and consumer products; 2) develop a sensitive and accurate needle-trap-device (NTD) method for sampling and analysis of SVOCs in air; 3) investigate SVOC levels in indoor air, settled dust, and heating, ventilation, and air conditioning (HVAC) filter dust in U.S. high schools. Emissions of phthalates, organophosphates, and PBDEs from a wide range of source materials (e.g., vinyl flooring, insulation boards, crib mattress covers, and changing pad foams) were characterized in the micro emission cell rapidly. The steady state SVOC concentrations were reached within minutes or hours, which were significantly reduced from the time of previous chamber studies (weeks or months). The developed NTD method was evaluated in both laboratory and field studies. The results were in good agreement with data obtained using conventional air sampling methods, but with significantly improvements on sensitivity, repeatability, reproducibility, and reliability. Sampling volume using the NTD method was reduced by a factor of four compared to conventional air sampling methods. A number of SVOCs were detected in U.S. high school indoor environments, including certain banned or severely restricted compounds. Significant impacts of seasonal variations and building characteristics were found for certain SVOC levels in different environmental media. This dissertation, which connects emission characterizations, measurement developments, and field studies in real indoor environments, will be valuable to identify major indoor SVOC sources, monitor indoor SVOC pollutions accurately, understand the fate and transport of SVOCs in indoor environments, and develop strategies to reduce SVOC exposures
