Residential indoor airborne microplastics profiles: Levels, characterization, composition, and inhalation exposure assessment

In the days following the collapse of the World Trade Center (WTC) towers on September 11, 2001 (9/11), the U.S. Environmental Protection Agency (EPA) initiated numerous air monitoring activities to better understand the ongoing impact of emissions from that disaster. Using these data, EPA conducted an inhalation exposure and human health risk assessment to the general population. This assessment does not address exposures and potential impacts that could have occurred to rescue workers, firefighters, and other site workers, nor does it address exposures that could have occurred in the indoor environment. Contaminants evaluated include particulate matter (PM), metals, polychlorinated biphenyls, dioxins, asbestos, volatile organic compounds, particle-bound polycyclic aromatic hydrocarbons, silica, and synthetic vitreous fibers (SVFs). This evaluation yielded three principal findings. (1) Persons exposed to extremely high levels of ambient PM and its components, SVFs, and other contaminants during the collapse of the WTC towers, and for several hours afterward, were likely to be at risk for acute and potentially chronic respiratory effects. (2) Available data suggest that contaminant concentrations within and near ground zero (GZ) remained significantly elevated above background levels for a few days after 9/11. Because only limited data on these critical few days were available, exposures and potential health impacts could not be evaluated with certainty for this time period. (3) Except for inhalation exposures that may have occurred on 9/11 and a few days afterward, the ambient air concentration data suggest that persons in the general population were unlikely to suffer short-term or long-term adverse health effects caused by inhalation exposures. While this analysis by EPA evaluated the potential for health impacts based on measured air concentrations, epidemiological studies conducted by organizations other than EPA have attempted to identify actual impacts. Such studies have identified respiratory effects in worker and general populations, and developmental effects in newborns whose mothers were near GZ on 9/11 or shortly thereafter. While researchers are not able to identify specific times and even exactly which contaminants are the cause of these effects, they have nonetheless concluded that exposure to WTC contaminants (and/or maternal stress, in the case of developmental effects) resulted in these effects, and have identified the time period including 9/11 itself and the days and few weeks afterward as a period of most concern based on high concentrations of key pollutants in the air and dust.

Fingerprint detection is an essential component of any crime detection agency. Little information is available regarding the elemental constituents of powders that are available currently. One recent case of lead poisoning coupled with many complaints from the Vancouver identification Squad members initiated a study regarding the elemental composition of, and the occupational exposure to, these powders. Multi-elemental analysis of the powders investigated showed that all contained varying amounts of aluminum, calcium, zinc, iron, magnesium, manganese, and nickel. One powder, however, contained 41% lead. The time spent at the scene of crime during a normal working shift averaged 95.5 min. Assessment of inhalation exposure during this period by personal air sampling pumps never exceeded the occupational exposure standards for these elements. Secondary exposure from dust-contaminated police vehicles and clothing can be an important contributor to overall exposure.

Wearable passive samplers are inexpensive tools for assessing personal exposure to diverse contaminants through a combination of exposure pathways. This versatility, however, can be a disadvantage when it is critical to assess a specific pathway. Here, we aim to develop eyewear lenses as passive samplers that can capture inhalation exposure as a primary pathway for airborne contaminants. We designed polycarbonate lens samplers with and without a polydimethylsiloxane (PDMS) coating and compared their surface properties and chemical uptake. We compared the chemical profiles they sampled from indoor lab and office environments using solvent-soaked wipes to extract the chemicals by wiping the lens surfaces and analyzing the wipe extracts using non-targeted screening on LC-QTOF-MS. Compared to the comparably transparent uncoated lenses, the PDMS-coated lenses were up to six times rougher in morphology. This difference, unexpectedly, did not yield significant differences in the chemical profiles measured between the PDMS-coated and uncoated polycarbonate lenses. Combined, both lens types sampled over 900 features, with diverse physico-chemical properties, annotated at varying levels of confidence. Level 2 features include phthalates and organophosphate esters commonly used as plasticizers. These promising results form the foundation for further developing the lenses as passive sampling eyewear for easily assessing inhalation exposure at the population level.

A method of estimation of inhalation exposure to airborne soil contaminants is presented. this method is derived from studies of airborne soil particles with radioactive tags. The concentration of contaminants in air (g/m{sup 3}) can be derived from the product of M, the suspended respirable dust mass concentration (g/m{sup 3}), S, the concentration of contaminant in the soil (g/g), and E{sub f}, an enhancement factor. Typical measurement methods and values of M, and E{sub f} are given along with highlights of experiences with this method.

Size-distribution-based assessment of human inhalation and dermal exposure to airborne parent, oxygenated and chlorinated PAHs during a regional heavy haze episode

Permethrin is a common pesticide spray-applied to civilian clothing and military uniforms for protection against biting arthropods in an effort to reduce risks to arthropod-borne diseases. During mass clothing spray events, exposure is possible through the dermal, inhalation, and ingestion routes. The potentially exposed population during a spray event includes the pesticide applicator(s) and working party (personnel who handle clothing/uniforms by positioning on the ground, flipping, and removing after spraying is complete). Previous investigation is limited regarding permethrin exposure via multiple routes of entry. Additionally, most exposure assessments are limited to pesticide applicators rather than working party that support applicator personnel. The purpose of this investigation was to conduct a multi-route exposure assessment for all personnel normally participating in mass permethrin military uniform treatments. The protocol and Informed Consent Document were approved by the Uniformed Services University of the Health Sciences (USUHS) Institutional Review Board (IRB) before fieldwork initiation (IRB number: USUHS.2019-032). Sampling occurred during routine spray events performed by 14 U.S. Navy personnel (3 applicators and 11 working party) over 2 days. Personal exposures were measured with dermal sampling, and airborne concentrations were measured with area air sampling. Permethrin area air sampling and analysis were conducted using OSHA Versatile Sampler-2 sampling media (n = 36). Dermal exposure was measured using dosimeter gloves (n = 26) and a dermal patch (n = 26) worn by study participants. All air samples were reported below the 0.4 µg limit of quantification. Glove sample results ranged from 45 to 120,000 µg and patch results ranged from 0.57 to 45 µg. A repeated-measures ANOVA showed non-statistically significant differences in dermal concentrations (P-value = .8340) between the applicators and working party in patches and gloves. Results suggest dermal contact is the primary route of exposure compared to inhalation when mass spraying clothing with permethrin. Similar dermal exposures between these two occupations may necessitate reconsidering risk assessment procedures, training and personal protective equipment (PPE) requirements for mass spray uniform treatments. Specifically, while PPE requirements for applicators are highly regulated by the Armed Forces Pest Management Board and include items such as Tyvek suits, chemical protective gloves, and air-purifying respirators, PPE was not regulated for working party personnel before this investigation.

Recent advances in field-portable X-ray fluorescence (FP XRF) spectrometer technology have made it a potentially valuable screening tool for the industrial hygienist to estimate worker exposures to airborne metals. Although recent studies have shown that FP XRF technology may be better suited for qualitative or semiquantitative analysis of airborne lead in the workplace, these studies have not extensively addressed its ability to measure other elements. This study involved a laboratory-based evaluation of a representative model FP XRF spectrometer to measure elements commonly encountered in workplace settings that may be collected on air sample filter media, including chromium, copper, iron, manganese, nickel, lead, and zinc. The evaluation included assessments of (1) response intensity with respect to location on the probe window, (2) limits of detection for five different filter media, (3) limits of detection as a function of analysis time, and (4) bias, precision, and accuracy estimates. Teflon, polyvinyl chloride, polypropylene, and mixed cellulose ester filter media all had similarly low limits of detection for the set of elements examined. Limits of detection, bias, and precision generally improved with increasing analysis time. Bias, precision, and accuracy estimates generally improved with increasing element concentration. Accuracy estimates met the National Institute for Occupational Safety and Health criterion for nearly all the element and concentration combinations. Based on these results, FP XRF spectrometry shows potential to be useful in the assessment of worker inhalation exposures to other metals in addition to lead.

A model useful for predicting lung retention and tissue distribution following human inhalation exposure to 241AmO2 has been formulated. The model is based on inhalation studies in beagles exposed to either monodisperse or polydisperse aerosols of 241AmO2. It also describes lung retention for several cases of accidental human inhalation exposure to 241Am adequately. The model incorporates an expression for solubilization of 241AmO2 deposited in lung which is based on physicochemical characteristics of the inhaled particles. Comparison of predictions from this model and those of the International Commission of Radiological Protection in lCRP Publication 30 shows some important differences. Lung retention patterns of inhaled 241Am in dogs and humans after inhalation of 241AmO2 are very similar and do not conform with predictions of the ICRP 30 model. Although use of the ICRP 30 model for calculation of annual limits of intake produces similar values to predictions made from our model, a more complete assessment of accidental human exposures to 241AmO2 and the risk to individual organs can be made using the retention and dosimetry model formulated from these studies in dogs.

This study provides a quantitative assessment of inhalation exposure and deposited aerosol dose in the 14 nm to 20 μm particle size range based on the aerosol measurements conducted during realistic usage simulation of five nanotechnology-based and five regular spray products matching the nano-products by purpose of application. The products were also examined using transmission electron microscopy. In seven out of ten sprays, the highest inhalation exposure was observed for the coarse (2.5-10 μm) particles while being minimal or below the detection limit for the remaining three sprays. Nanosized aerosol particles (14-100 nm) were released, which resulted in low but measurable inhalation exposures from all of the investigated consumer sprays. Eight out of ten products produced high total deposited aerosol doses on the order of 101-103 ng kg-1 bw per application, ~85-88% of which were in the head airways, only <10% in the alveolar region and <8% in the tracheobronchial region. One nano and one regular spray produced substantially lower total deposited doses (by 2-4 orders of magnitude less), only ~52-64% of which were in the head while ~29-40% in the alveolar region. The electron microscopy data showed nanosized objects in some products not labeled as nanotechnology-based and conversely did not find nano-objects in some nano-sprays. We found no correlation between nano-object presence and abundance as per the electron microscopy data and the determined inhalation exposures and deposited doses. The findings of this study and the reported quantitative exposure data will be valuable for the manufacturers of nanotechnology-based consumer sprays to minimize inhalation exposure from their products, as well as for the regulators focusing on protecting the public health.

This paper investigated the concentrations of eight types of indoor VOCs - benzene, toluene, xylenes, butyl acetate, styrene, isopropylbenzene, undecane and formaldehyde. The tests were carried out in 50 dwellings in the main urban areas of Chongqing, China. According to the detected concentration, toluene was the most predominant among all the targeted compounds. Benzene and formaldehyde concentrations were lower than the reference levels regulated by the Chinese National Standard (GB/T 50325). Based on the activity patterns and exposure factors of adults in urban Chongqing, we used concentration data to estimate adults' inhalation exposures as well as health risks using Monte-Carlo simulations. The results indicated that the exposure doses of benzene and formaldehyde exceeded the benchmark. The highest hazard quotient (HQ) values were found in the case of formaldehyde (median = 0.293 for females and 0.292 for males) and the hazard index (HI) values were 0.326 and 0.325 for females and males, respectively. The highest lifetime cancer risk (LCR) values were found in formaldehyde (median = 7.16 × 10-5 for females; 6.56 × 10-5 for males). Formaldehyde was found to be the most important pollutant with relatively high toxic and carcinogenic risk levels, based on the exposure and health assessment. This was followed by benzene, toluene, xylenes and butyl acetate. This study can help us better understand the concentration levels of VOC contaminants in residential buildings, and help select appropriate decoration materials for buildings.

Inhalative exposure can occur accidentally when using cosmetic spray products. Usually, a tiered approach is applied for exposure assessment, starting with rather conservative, simplistic calculation models that may be improved with measured data and more refined modelling. Here we report on an advanced methodology to mimic in-use conditions for antiperspirant spray products to provide a more accurate estimate of the amount of aluminium possibly inhaled and taken up systemically, thus contributing to the overall body burden. Four typical products were sprayed onto a skin surrogate in defined rooms. For aluminium, size-related aerosol release fractions, i.e. inhalable, thoracic and respirable, were determined by a mass balance method taking droplet maturation into account. These data were included into a simple two-box exposure model, allowing calculation of the inhaled aluminium dose over 12min. Systemic exposure doses were calculated for exposure of the deep lung and the upper respiratory tract using the Multiple Path Particle Deposition Model (MPPD) model. The total systemically available dose of aluminium was in all cases found to be less than 0.5µg per application. With this study it could be demonstrated that refinement of the input data of the two-box exposure model with measured data of released airborne aluminium is a valuable approach to analyse the contribution of antiperspirant spray inhalation to total aluminium exposure as part of the overall risk assessment. We suggest the methodology which can also be applied to other exposure modelling approaches for spray products, and further is adapted to other similar use scenarios.

The present paper proposes a source-receptor model to schematically describe inhalation exposure to help understand the complex processes leading to inhalation of hazardous substances. The model considers a stepwise transfer of a contaminant from the source to the receptor. The conceptual model is constructed using three components, i.e. (i) the source, (ii) various transmission compartments and (iii) the receptor, and describes the contaminant's emission and its pattern of transport. Based on this conceptual model, a list of nine mutually independent principal modifying factors (MFs) is proposed: activity emission potential, substance emission potential, localized control, separation, segregation, dilution, worker behavior, surface contamination and respiratory protection. These MFs describe the exposure process at a high level of abstraction so that the model can be generically applicable. A list of exposure determinants underlying each of these principal MFs is proposed to describe the exposure process at a more detailed level. The presented conceptual model is developed in conjunction with an activity taxonomy as described in a separate paper. The proposed conceptual model and MFs should be seen as 'building blocks' for development of higher tier exposure models.

The primary beryllium industry has generated a large amount of data on airborne beryllium concentrations that has been used to characterize exposure by task-specific activities, job category, individual worker, and processing area using a variety of methods. These methods have included high-volume breathing zone sampling, high-volume process sampling, high- and low-volume respirable and area sampling, real-time monitoring, and personal sampling. Many of the beryllium studies have used these air sampling methods to assess inhalation exposure and chronic beryllium disease (CBD) risk to beryllium; however, available data do not show a consistent dose-response relationship between airborne concentrations of beryllium and the incidence of CBD. In this article, we describe the air sampling and exposure assessment methods that have been used, review the studies that have estimated worker exposures, discuss the uncertainties associated with the level of beryllium for which these studies have reported an increased risk of CBD, and identify future investigative exposure assessment strategies. Our evaluation indicated that studies of beryllium workers are often not directly comparable because they (1) used a variety of exposure assessment methods that are not necessarily representative of individual worker exposures, (2) rarely considered respirator use, and (3) have not evaluated changes in work practices. It appears that the current exposure metric for beryllium, total beryllium mass, may not be an appropriate measurement to predict the risk of CBD. Other exposure metrics such as mass of respirable particles, chemical form, and particle surface chemistry may be more related to the prevalence of CBD than total mass of airborne beryllium mass. In addition, assessing beryllium exposure by all routes of exposure (e.g., inhalation, dermal uptake, and ingestion) rather than only inhalation exposure in future studies may prove useful.

Introduction: Metals estimation assessment of substance exposure (MEASE) is tier1 tool to estimation exposures. The aim of present study was estimation of exposure to welding fumes using MEASE model and comparison of the results with NIOSH7300. Materials and methods: The metals including Cu, Fe, Ca, Al, Mg, Mn, K and Na in the MIG, MAG and SMAW welding were measured by NIOSH7300. Estimation of the metals' values was performed by MEASE (version1.02.01). Data analysis were done by SPSS21 using Student's t-test, One-WayANOVA and Spearman's correlation. Results and discussion: There was agreement between measured and estimated values in different metal fumes and welding processes (r = 0.131 to 0.933). A significant strong correlation was found between measured and estimated levels for Mg(r = 0.933; P = 0.001), Ca(r = 0.896; P = 0.001), K(r = 0.805; P = 0.001), Na(r = 0.716; P = 0.001), and Al(r = 0.756; P = 0.032). There was a significant strong correlation between measured and estimated values for SMAW(r = 0.708; P = 0.003) and MIG(r = 0.635; P = 0.036). The results showed that most of the estimated values were below the measured values (P < 0.05), except for Ca in MIG welding. The authors observed that the MEASE model cannot be wholly successfully applied for inhalation exposure assessment in occupational surveys.

Introduction: Airborne microplastics (AMPs), due to their small size and widespread dispersal, pose increasing risks to human respiratory health. Detected in both indoor and outdoor environments, AMPs raise concerns over chronic inhalation exposure. Their accumulation in lung tissue may lead to oxidative stress, inflammation, and epithelial barrier dysfunction. This systematic review evaluates the respiratory health effects of AMPs exposure. Materials and Methods: Following PRISMA guidelines, relevant articles were identified through systematic searches in Google Scholar, PubMed, Science Direct, and Springer Link. A total of 20 studies published between 2019 and 2024 were synthesized. Results: AMPs originate from degraded plastics and industrial emissions and can reach alveoli when inhaled. They induce inflammatory responses via oxidative stress and activation of pathways such as NF-κB. Chronic exposure is associated with elevated reactive oxygen species (ROS), mitochondrial dysfunction, and tissue damage, contributing to conditions like pulmonary fibrosis and COPD. AMPs also impair epithelial barriers by disrupting tight junctions and increasing tissue permeability. In vitro and in vivo studies confirm their cytotoxic and inflammatory effects. However, knowledge gaps remain, particularly regarding chronic low-dose exposure and interactions with other pollutants. Conclusion: This review highlights the health risks of AMPs and the need for stricter environmental policies and public education. Findings inform future research and support interventions to mitigate AMPs exposure and protect respiratory health.