Search

Organophosphate esters (OPEs) widely exist in the environment, raising increasing concerns about their potential health risks. This comprehensive review surveyed the occurrence of OPEs over the last decade in indoor microenvironments (i.e. residence, in-vehicle, office, and school/daycare center), outdoors, foodstuffs, drinking water, and human-related specimen (i.e. breast milk and urine) with a view to unraveling age-specific exposure to OPEs. Multiple exposure pathways including inhalation, dermal absorption, dust ingestion, and dietary ingestion were considered to prioritize their relative importance. The results showed that dietary ingestion was the main contributor, followed by dust ingestion, regardless of age. A healthy diet with less contaminated food can effectively reduce OPE intake. OPE concentrations in air and dust followed the sequence of in-vehicle and office > school/daycare center > residence > outdoors. Compared to other indoor settings, exposure in schools/daycare centers and offices contributed to a greater OPE intake in non-adults and adults, respectively. The estimated daily intake of OPEs followed the sequence of infants > toddlers > children > teenagers > adults > elderlies. Overall, OPEs posed low health risks to all age cohorts, but infants were vulnerable and subject to the highest risk, largely attributed to breast milk ingestion. This review highlights the need for more toxicity and bioaccessibility studies on OPE mixtures and metabolites to further refine the health risk assessment of OPEs. [ABSTRACT FROM AUTHOR]

Abstract Bioaccessibility of particle-bound hydrophobic organic contaminants and related particle size effects are significant for assessing the potential human health risk via inhalation exposure, but have not been clearly evaluated. To fill this knowledge gap, the present study developed an in vitro method to estimate the inhalation bioaccessibility of particulate polycyclic aromatic hydrocarbons (PAHs) using simulated human lung fluids, i.e. , a modified Gamble's solution (MGS) and artificial lysosomal fluid (ALF) with Tenax as the absorption media. Assay parameters, namely incubation time (10 d) and influence of filter use, were optimized for establishing the in vitro method. The results showed that the bioaccessibility of PAHs increased with increasing particle size, but other factors, such as total organic carbon and chemical hydrophobicity, also played a large role in the fate of these compounds. The results from this portion of the present study were then used to evaluate human health risk, which showed that the risk of these particle-bound PAHs by incorporating size-dependent PAHs bioaccessibility and deposition efficiency in the human respiratory tract into inhalation exposure risk calculations was reduced by >90% when compared to using total concentration. This suggested that the inhalation bioaccessibility and deposition efficiency of hydrophobic organic chemicals should be included in human health risk assessment. Graphical abstract Unlabelled Image Highlights • An in vitro method was developed for evaluating the IBAF of particle-bound HOCs. • The inhalation bioaccessibility of PAHs decreased with increasing hydrophobicity. • The IBAF of particle-bound HOCs is significant to human health risk assessment. [ABSTRACT FROM AUTHOR]

Barbecue (BBQ) is one of the most popular cooking activities with charcoal worldwide and produces abundant polycyclic aromatic hydrocarbons (PAHs) and particulate matter. Size distribution and clothing-air partitioning of particle-bound PAHs are significant for assessing potential health hazards to humans due to exposure to BBQ fumes, but have not been examined adequately. To address this issue, particle and gaseous samples were collected at 2-m and 10-m distances from a cluster of four BBQ stoves. Personal samplers and cotton clothes were carried by volunteers sitting near the BBQ stoves. Particle-bound PAHs (especially 4–6 rings) derived from BBQ fumes were mostly affiliated with fine particles in the size range of 0.18–1.8 μm. High molecular-weight PAHs were mostly unimodal peaking in fine particles and consequently had small geometric mean diameters and standard deviations. Source diagnostics indicated that particle-bound PAHs in BBQ fumes were generated primarily by combustion of charcoal, fat content in food, and oil. The influences of BBQ fumes on the occurrence of particle-bound PAHs decreased with increasing distance from BBQ stoves, due to increased impacts of ambient sources, especially by petrogenic sources and to a lesser extent by wind speed and direction. Octanol-air and clothing-air partition coefficients of PAHs obtained from personal air samples were significantly correlated to each other. High molecular-weight PAHs had higher area-normalized clothing-air partition coefficients in cotton clothes, i.e., cotton fabrics may be a significant reservoir of higher molecular-weight PAHs. Capsule Particle-bound PAHs from barbecue fumes are generated largely from charcoal combustion and food-charred emissions and mainly affiliated with fine particles. [ABSTRACT FROM AUTHOR]

Most organophosphate esters (OPEs) enter the marine environment through atmospheric deposition and surface runoff, yet the role of particle-mediated transport in their inputs and loss processes remains poorly understood. To fill this knowledge gap, samples of size-segregated atmospheric particles, suspended particulate matter (SPM) in seawater, and sediments in the Pearl River Estuary (PRE) were collected and analyzed for OPEs. Total concentrations of atmospheric particulate OPEs showed a decreasing trend with increasing offshore distance in the PRE. The spatial and vertical distribution patterns of OPEs in SPM were diverse, which could be largely affected by physicochemical properties of SPM, marine microbial activities, hydrodynamic conditions, and environmental factors. Sediment in the region close to Modaomen outlet was subject to relatively high OPE concentrations. Approximately 24,100 and 65,100 g d−1 of particulate OPEs were imported into the PRE through atmospheric deposition and surface runoff, respectively; 83,200 g d−1 of which were exported to the open sea. The input and environmental fate of particulate OPEs were found to be dependent on sources, particulate media, and chemical species. The present study provides insights into the influence of OPEs in the PRE through particle-mediated transport and calls for more concern on anthropogenic impact on the estuary. [Display omitted] • Atmospheric particulate OPEs in the PRE were dominated by TCEP and TCIPP. • Atmospheric deposition fluxes of particulate OPEs were size-dependent in the PRE. • Positive correlation existed between levels of SPM OPE and phytoplankton abundance. • Atmospheric deposition and surface SPM OPE levels showed consistent patterns. [ABSTRACT FROM AUTHOR]

[Display omitted] • Atmospheric release of PFAS intermediates was evidenced during waste treatment. • Landfills could be a point source of airborne PFAS into the atmosphere. • PFOS exhibited a consistent and distinct peak in the coarse particulate fraction. • Deposition of particulate PFAS in human lung was predicted to be size-dependent. Per- and polyfluoroalkyl substances (PFAS) have been applied in numerous industrial and consumer products, the majority of which flow into waste management infrastructures (WMIs) at the end of their life cycles, but little is known about atmospheric releases of PFAS from these facilities. In this study, we addressed this key issue by investigating 49 PFAS, including 23 ionic and 26 neutral and precursor PFAS, in the potential sources (n = 4; within or adjacent to WMIs) and reference sites (n = 2; coastal and natural reserve sites) in urban and rural areas of Hong Kong, China. Duplicate samples of air and size-segregated particulate matter were collected for 48 h continuously using a 11-stage Micro-Orifice Uniform Deposit Impactor (MOUDI). In general, fluorotelomer alcohols (FTOHs) and perfluoroalkane sulfonamides were the predominant PFAS classes found across sampling sites. We also demonstrated the release of several less frequently observed semivolatile intermediate products (e.g., secondary FTOHs) during waste treatment. Except for perfluorooctane sulfonate, the size-segregated distributions of particulate PFAS exhibited heterogeneity across sampling sites, particularly in the WMIs, implying combined effects of sorption affinity and emission sources. A preliminary daily air emission estimation revealed that landfill was a relatively important source of PFAS relative to the wastewater treatment plant. A simplified International Commission on Radiological Protection model was used to estimate lung depositional fluxes, and the results showed that inhaled particulate PFAS were mainly deposited in the head airway while fine and ultrafine particles carried PFAS deeper into the lung alveoli. The cumulative daily inhalation dose of gaseous and particulate PFAS ranged from 81.9 to 265 pg/kg/d. In-depth research is required to understand the health effect of airborne PFAS on workers at WMIs. [ABSTRACT FROM AUTHOR]

Few studies have focus on size-segregated particulate polycyclic aromatic hydrocarbons (PAHs) in the oceanic atmosphere. To better understand the impacts of anthropogenic activities on atmospheric PAHs, a heavily human-impacted estuary, the Pearl River Estuary (PRE), was chosen as a case study. We collected gaseous and size-segregated particulate samples of ambient air at two sites in the PRE, as well as from the exhaust emissions of the cruise ship used in the sampling campaign. In addition, surface seawater samples were collected. Size distribution patterns of high molecular-weight (HMW) particulate PAHs were bimodal at one site and unimodal at the other, suggesting PAHs at the former site were derived not only from long-range atmospheric transport but also from local sources. Gas–particle partition coefficients of HMW PAHs in size-segregated particles varied with particle sizes, mostly higher in fine particles (<1.8 μm). Dry deposition flux of Σ 23 PAHs (defined as the sum of 23 PAHs) was contributed mainly from coarse particles (>1.8 μm), and HMW PAHs with lower dry deposition velocities could be transported farther away. With respect to air–water exchange, lower MW PAHs tended to have net volatilization, whereas higher MW PAHs were likely to have net deposition. This study sheds new lights on the origins and fate of atmospheric PAHs over the PRE, and suggests the emissions of maritime traffics should be regulated. Collected near the metropolitan regions, atmospheric PAHs over the PRE were highly affected by anthropogenic activities, especially for HMW PAHs, which could pose a long-lasting impact to the oceanic atmosphere and marine organisms. Unlabelled Image • Airborne PAHs were mostly derived from vehicle emission and combustion sources. • Gas−particle partitioning of size-segregated PAHs varied with particle diameters. • Dry deposition flux of ∑ 23 PAHs was dominated by those in coarse particles. • Seawater of the PRE was likely to contribute lower MW PAHs to the atmosphere. [ABSTRACT FROM AUTHOR]

• Single FO and UF experiments using PSS as the DS and FS, respectively. • Designing PA-VRO cell using the results from single FO and UF experiments. • Application of inlet pressure matching the pressure generated inside the VRO cell. • Change in rejection of PSS in PA-VRO over 6 days. • Rejection of PFOA and PFOS within wastewater in PA-VRO process. Forward osmosis is an energy efficient process that is capable of recovering high-quality water from secondary wastewater treatment. However, regeneration of the draw solution (DS) is a problem that needs to be addressed. Herein, we developed and optimized a one-step process that does not require additional treatment for the DS. This process, called pressure assisted-volume retarded osmosis (PA-VRO), utilizes naturally occurring pressure with the aid of a small inlet pressure (< 1 bar). Poly(styrenesulfonate) was employed as the DS, for its high solubility in water and large molecular size (∼70,000 Da). Accordingly, real wastewater was employed as the feed solution for 48 h to remove perfluorooctanoate (PFOA) and perfluorooctane sulfonate (PFOS) through PA-VRO. The rejection rates for PFOA/PFOS and poly(sodium-4-styrenesulfonate) (PSS) were observed to exceed 98%, after 24 h and 99%, after 48 h. Moreover, there were no traceable amounts of PFOA/PFOS in the DS, and hence the detected concentrations of PFOA and PFOS can be attributed to the residuals from the equipment. Therefore, this well-optimized PA-VRO process can be utilized for potable water production from treated wastewater. [Display omitted] [ABSTRACT FROM AUTHOR]

Widespread application of the nanofiltration (NF) technique in wastewater reuse is still hindered by the NF membrane's fouling propensity and rejection efficiency. This study presents the fabrication of a micro-patterned NF (M-NF) membrane structured with micro-eggette morphology for simultaneously enhancing anti-fouling and rejection performance. The M-NF membrane was synthesized by combining optimized micro-molding phase inversion and classic interfacial polymerization reaction. Microscopic characterization and chemical analysis confirmed the formation of uniform 4 μm height patterns and the crosslinked polyamide layer. Separation and fouling tests demonstrated that the M-NF membrane possesses better anti-fouling and rejection performance. Ex-situ and in-situ fouling tests illustrated that, compared to the control membrane, the M-NF membrane could maintain high water permeation during fouling filtration while showing reduced flux decline, greater fouling resistance, and less fouling deposition owing to its enhanced trough and crest by micro-eggette morphology. The M-NF membrane also achieved 5–38 % higher mono/di-valent salts rejection and 6–8 % higher PFOS rejection than that of the NF270 membrane. Further computational fluid dynamics simulations showed that the surface pattern-disturbed hydrodynamic flow promoted the hydrodynamic forces exerted on the pollutant molecules. This work demonstrates the strong potential of membrane surface patterning for improving novel NF membranes' antifouling and rejection abilities. [Display omitted] • A novel micro-patterned nanofiltration (M-NF) membrane was facilely fabricated. • The M-NF membrane displayed a simultaneous improvement in anti-fouling and rejection. • Role of the micro-pattern in pollutant removal was quantitatively analyzed. • The pattern-distributed hydraulic field and hydrodynamic interactions were simulated. [ABSTRACT FROM AUTHOR]

[Display omitted] • Characterized changes in nanobubble size and concentration over 14 days. • Demonstrated the removal of antibiotics with both ozone and air nanobubbles. • Oxytetracycline was chosen as the target pollutant to be removed. • Artificial aquaculture wastewater was used as a complex feed solution. • Nanobubbles enhanced system performance and minimized adsorption of foulants. The discharge of untreated effluent containing excessive pharmaceutical chemicals (PCs) from aquaculture farms has caused several negative effects on the aquatic ecosystems. Herein, we used a hybrid system based on two emerging technologies, namely forward osmosis (FO) and nanobubbles (NBs), as an energy-efficient, sustainable, and effective alternative to conventional processes for the treatment and reuse of aquaculture wastewater. The combination of NB technology with FO served as a single-step treatment process for the removal of aquaculture pharmaceutical contaminants. In the hybrid system, the FO membrane removed organic matter, dissolved solids, and pharmaceutical chemical residues from aquaculture effluents with a high efficiency (∼98%), whereas NBs functioned as a physical membrane-cleaning agent that enhanced the performance and longevity of the FO membrane. Notably, the results revealed minimal contribution of NBs for the direct degradation of the tested PC i.e. oxytetracycline (OTC), where air and ozone NBs could only oxidize nearly 11% and 30% of the OTC in the water respectively. The relatively higher OTC degradation by ozone NBs was attributed to the ozone NBs-induced reactive hydroxyl radicals (HO•) that react with OTC for its oxidative decomposition. We believe that the tested hybrid system offers a sustainable solution for aquaculture wastewater treatment as well as the recovery of antibiotics from the wastewater and will play a vital role in the sustainable development of the fisheries industry. [ABSTRACT FROM AUTHOR]