Although humans have been exposed to airborne nanosized particles (NSPs; < 100 nm) throughout their evolutionary stages, such exposure has increased dramatically over the last century due to anthropogenic sources. The rapidly developing field of nanotechnology is likely to become yet another source through inhalation, ingestion, skin uptake, and injection of engineered nanomaterials. Information about safety and potential hazards is urgently needed. Results of older bio-kinetic studies with NSPs and newer epidemiologic and toxicologic studies with airborne ultrafine particles can be viewed as the basis for the expanding field of nanotoxicology, which can be defined as safety evaluation of engineered nanostructures and nanodevices. Collectively, some emerging concepts of nanotoxicology can be identified from the results of these studies. When inhaled, specific sizes of NSPs are efficiently deposited by diffusional mechanisms in all regions of the respiratory tract. The small size facilitates uptake into cells and transcytosis across epithelial and endothelial cells into the blood and lymph circulation to reach potentially sensitive target sites such as bone marrow, lymph nodes, spleen, and heart. Access to the central nervous system and ganglia via translocation along axons and dendrites of neurons has also been observed. NSPs penetrating the skin distribute via uptake into lymphatic channels. Endocytosis and biokinetics are largely dependent on NSP surface chemistry (coating) and in vivo surface modifications. The greater surface area per mass compared with larger-sized particles of the same chemistry renders NSPs more active biologically. This activity includes a potential for inflammatory and pro-oxidant, but also antioxidant, activity, which can explain early findings showing mixed results in terms of toxicity of NSPs to environmentally relevant species. Evidence of mitochondrial distribution and oxidative stress response after NSP endocytosis points to a need for basic research on their interactions with subcellular structures. Additional considerations for assessing safety of engineered NSPs include careful selections of appropriate and relevant doses/concentrations, the likelihood of increased effects in a compromised organism, and also the benefits of possible desirable effects. An interdisciplinary team approach (e.g., toxicology, materials science, medicine, molecular biology, and bioinformatics, to name a few) is mandatory for nanotoxicology research to arrive at an appropriate risk assessment.

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Nanotoxicology: An Emerging Discipline Evolving from Studies of Ultrafine Particles

Efforts to understand and mitigate the health effects of particulate matter (PM) air pollution have a rich and interesting history. This review focuses on six substantial lines of research that have been pursued since 1997 that have helped elucidate our understanding about the effects of PM on human health. There has been substantial progress in the evaluation of PM health effects at different time-scales of exposure and in the exploration of the shape of the concentration-response function. There has also been emerging evidence of PM-related cardiovascular health effects and growing knowledge regarding interconnected general pathophysiological pathways that link PM exposure with cardiopulmonary morbidity and mortality. Despite important gaps in scientific knowledge and continued reasons for some skepticism, a comprehensive evaluation of the research findings provides persuasive evidence that exposure to fine particulate air pollution has adverse effects on cardiopulmonary health. Although much of this research has been motivated by environmental public health policy, these results have important scientific, medical, and public health implications that are broader than debates over legally mandated air quality standards.

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Health effects of fine particulate air pollution: lines that connect

Polycyclic aromatic compounds (PACs) are known due to their mutagenic activity. Among them, 2-nitrobenzanthrone (2-NBA) and 3-nitrobenzanthrone (3-NBA) are considered as two of the most potent mutagens found in atmospheric particles. In the present study 2-NBA, 3-NBA and selected PAHs and Nitro-PAHs were determined in fine particle samples (PM 2.5) collected in a bus station and an outdoor site. The fuel used by buses was a diesel-biodiesel (96:4) blend and light-duty vehicles run with any ethanol-to-gasoline proportion. The concentrations of 2-NBA and 3-NBA were, on average, under 14.8 µg g−1 and 4.39 µg g−1, respectively. In order to access the main sources and formation routes of these compounds, we performed ternary correlations and multivariate statistical analyses. The main sources for the studied compounds in the bus station were diesel/biodiesel exhaust followed by floor resuspension. In the coastal site, vehicular emission, photochemical formation and wood combustion were the main sources for 2-NBA and 3-NBA as well as the other PACs. Incremental lifetime cancer risk (ILCR) were calculated for both places, which presented low values, showing low cancer risk incidence although the ILCR values for the bus station were around 2.5 times higher than the ILCR from the coastal site.

Occurrence of the potent mutagens 2- nitrobenzanthrone and 3-nitrobenzanthrone in fine airborne particles

In 2004, the first American Heart Association scientific statement on “Air Pollution and Cardiovascular Disease” concluded that exposure to particulate matter (PM) air pollution contributes to card...

https://cdr.lib.unc.edu/downloads/p2676x621

Particulate Matter Air Pollution and Cardiovascular Disease An Update to the Scientific Statement From the American Heart Association

Changes in Atmospheric Constituents and in Radiative Forcing

Daily measurements of sulfate, nitrate and chloride in PM10 have been made at three geographically separated UK sites over a three year period. Chloride shows a clear seasonal pattern with highest concentrations in winter, whilst sulfate and nitrate both show highest concentrations in the spring, apparently related to weather patterns. Spatial variability of both sulfate and nitrate is low in comparison to temporal variations, with high correlations of both species between all three sites, London (North Kensington), Harwell and Belfast, despite a geographic separation of 510 km. Both SO2−4/SO2 and NO−3/NOx ratios are considerably higher in summer than winter, reflecting a greater oxidising capacity of the atmosphere. SO42−/NO3− ratios are higher in summer than winter, suggesting that aqueous phase oxidation of SO2, expected to be most important in the winter months is not appreciably influencing production of sulfate aerosol, although greater dissociation of ammonium nitrate in summer may also play a role. Regression of concentrations at London, North Kensington with those from the proximate rural site of Harwell is interpreted as showing a similar effect of regional transport at the two sites and a small influence of local formation in the urban atmosphere or primary emissions, averaging 0.46 μg m−3 of nitrate and 0.22 μg m−3 of sulfate.

An analysis of spatial and temporal properties of daily sulfate, nitrate and chloride concentrations at UK urban and rural sites

Exposure to volatile organic compounds (VOCs) is ubiquitous and can result in a wide range of acute and chronic health effects, such as sensory irritation, nervous system impairment, asthma, and cancer (Caprino and Tonga 1998) Epidemiologic studies play an important role in investigating the health effects of air pollution and are one of the principal bases for setting regulations to protect the public against adverse health effects In epidemiologic studies, personal exposures (PEs) are estimated from a) centrally located monitors, b) from the combination of fixed-point monitors in individual microenvironments and activity data defining the times spent in each of the microenvironments, or c) from PE monitoring (Leung and Harrison 1998; Payne-Sturges et al 2004)

Direct measurement of human exposure to VOCs via personal monitoring is the most accurate exposure assessment method currently available However, its wide-scale application to evaluating exposures at the population level is prohibitive both in terms of cost and time, and sometimes even impractical for certain subpopulations (Liu et al 2007) Using centrally located monitors has a tendency to underestimate exposures (Serrano-Trespalacios et al 2004) Consequently, indirect measurements via a combination of microenvironment concentrations and personal activity diaries represent a potentially useful alternative

Earlier studies showed that modeled PEs can provide a good prediction of overall measured PE (Dodson et al 2007) Therefore, microenvironment modeling offers an effective mean of estimating population exposures to these pollutants without the considerable logistical difficulties of personal sampling

None of the previous proposed time-weighted models required PE measures, that is, subjects carrying personal samplers; however, all these models still required measuring concentrations in subject-related environments Therefore, collecting microenvironment samples was still required to inform these models A model that does not require direct PE or microenvironment sampling, which uses only lifestyle information collected in questionnaires and a proposed range of microenvironment concentrations structured in different strata such as traffic burden, environmental tobacco smoke (ETS) exposure, and season, has not yet been proposed in the literature Moreover, increasing the understanding of the variety of factors that influence microenvironment concentrations and hence PEs to air pollutants may lead to improved exposure assessment for use in large-scale epidemiologic studies in which individual measurements are not feasible (Nethery et al 2008) Consequently, a model that uses large numbers of individual and microenvironment samples under different conditions is able to extrapolate exposures to the general population and hence propose microenvironment concentrations that reflect the range of variability in pollutant concentrations over space and time for key microenvironments would be useful to allow a probabilistic approach in the use of exposure models (Harrison et al 2002) that does not require subjects’ personal or micro-environment measurements

So far, it is known that the determination of an individual’s exposure to air pollution depends on the locations where individuals spend time; the individual activity patterns, which are reflected in the time spent in different microenvironments; the type of activities in which individuals are involved (Dodson et al 2007; Harrison et al 2002); sociodemographics that define time/activity patterns (Edwards et al 2006) and environmental factors such as seasonality and community/area effect (Sexton et al 2004) Some studies have quantified the level of contribution of each microenvironment or activity to the total PE in the general non-occupationally exposed population and have identified sources affecting PEs (Edwards et al 2001; Kim et al 2002; Loh et al 2006)

Although previous studies have shed light upon the distribution of concentrations for PE and much work has been conducted toward modeling population exposures to air pollutants using information collected in time/ activity diaries and microenvironment concentrations, very little has been done toward validating such models at the level of the individual Because PE models can be useful to assess potential public health impacts from VOCs and to assist in the development of environmental policies to reduce human exposures to and risks from VOCs, it is important to know how well exposure models estimate PE Therefore, the validation of models with independent data sets is useful to check whether the proposed models serve as surrogates for PE concentrations and to know the extent of the exposure estimation error, which should be accounted for in epidemiologic studies and risk assessments (Liu et al 2007)

The MATCH project sought to help advance our understanding of the causes and magnitude of exposures to VOC and to establish whether collecting lifestyle information is sufficient to model PEs reliably compared with exposures evaluated independently by personal samplers In this article, we present the results of model development and validation for 15 VOCs We propose several models and estimate the confidence with which PEs can be reconstructed using measured microenvironment concentrations A range of activities affecting VOC concentrations and PEs are identified from information contained on the models and the effect of these activities on PEs is quantified for a UK-based nonsmoking non-occupationally exposed population

Model development and validation of personal exposure to volatile organic compound concentrations.

Risk Assessment of Metals in the Environment

Differential health effects of short-term exposure to source-specific particles in London, U.K.

Recent studies have highlighted the importance of drinking water as a route of human exposure to lead. Whilst there are ample data on lead concentrations in drinking water, little is known of its physical and chemical forms (physicochemical speciation). Such information is important as the speciation of ingested lead influences the efficiency of absorption from the gastrointestinal tract. Knowledge of speciation should also provide a fuller understanding of the factors controlling the solubility of lead in potable waters and hence assist in devising the most cost-effective means of plumbosolvency control. We have determined experimentally the speciation of lead in three different tapwaters and report here diverse forms of dissolved and particle-associated lead, dependent primarily on the chemical matrix of the raw water.

Roy M. Harrison

Papers

An analysis of spatial and temporal properties of daily sulfate, nitrate and chloride concentrations at UK urban and rural sites

Model development and validation of personal exposure to volatile organic compound concentrations.

Risk Assessment of Metals in the Environment

Differential health effects of short-term exposure to source-specific particles in London, U.K.

Physicochemical speciation of lead in drinking water