The bioaccessibility of organic pollutants is a key factor in human health risk assessments. We developed a novel in vitro method for determining the mass fraction of bioaccessible atmospheric polycyclic aromatic hydrocarbons (PAHs) using an air-washing device containing simulated human lung fluid. The experimental parameters were optimized based on the deposition fractions (DFs) of PAHs in human lung fluids. The DFs were measured for PAHs based on the mass of compounds in the mainstream and exhaled cigarette smoke. The mass fractions of bioaccessible PAHs were measured by passing the mainstream cigarette smoke through the air-washing device, and they were calculated via a simple mass balance equation based on the PAHs in the fluid and mainstream cigarette smoke. The DFs of individual PAHs ranged from 20.5% to 78.1%, and the bioaccessible mass fractions varied between 45.5% and 99.8%. The octanol-water partition coefficients (KOW) significantly influenced both the DFs and bioaccessible mass fractions of PAHs, and the optimized in vitro method could be used to estimate the bioavailable atmospheric PAHs. This in vitro method can potentially be used to measure the mass fraction of bioaccessible atmospheric PAHs and to assess the health risk related to human exposure to airborne PAHs.

Samples of plastic collected from two beaches in southwest England (n = 185) have been analysed by XRF spectrometry for elements that are hazardous or restricted in synthetic polymers (namely, As, Ba, Br, Cd, Cr, Hg, Pb, Sb and Se). Overall, one or more restricted element was detected in 151 samples, with 15 cases exhibiting non-compliance with respect to the Restriction of Hazardous Substances (RoHS) Directive. Twelve plastics that were RoHS-non-compliant were subsequently processed into microplastic-sized fragments and subjected to an avian physiologically-based extraction test (PBET) that simulates the chemical conditions in the gizzard-proventriculus of the northern fulmar. Kinetic profiles of metal and metalloid mobilisation in the PBET were fitted using a pseudo-first-order diffusion model with rate constants ranging from ∼0.02 to 0.5 h−1, while profiles for Br were better fitted with a parabolic diffusion model and rate constants of 7.4–9.5 (μg L−1)−1h−1/2. Bioaccessibilities, based on maximum or equilibrium concentrations mobilised relative to total (XRF) concentrations, ranged from <1% for Cd and Se in polyethylene and polypropylene to over 10% for Br in a sample of expanded polystyrene and Pb in a sample of PVC. Calculations suggest that ingested plastic could contribute about 6% and 30% of a seabird's exposure to and accumulation of Pb and brominated compounds, respectively.

This study investigates the occurrence of six phthalates and distribution of the three most-detected phthalates in the karst region of northern Puerto Rico (KRNPR) using data from historical records and current field measurements. Statistical data analyses, including ANOVA, Chi-Square, and logistic regression models are used to examine the major factors affecting the presence and concentrations of phthalates in the KRNPR. The most detected phthalates include DEHP, DBP, and DEP. At least one phthalate specie is detected above DL in 7% of the samples and 24% of the sampling sites. Concentrations of total phthalates average 5.08 ± 1.37 μg L−1, and range from 0.093 to 58.4 μg L−1. The analysis shows extensive spatial and temporal presence of phthalates resulting from dispersed phthalate sources throughout the karst aquifers. Hydrogeological factors are significantly more important in predicting the presence and concentrations of phthalates in eogenetic karst aquifers than anthropogenic factors. Among the hydrogeological factors, time of detection and hydraulic conductivities larger than 300 m d−1 are the most influential factors. Persistent presence through time reflects continuous sources of phthalates entering the aquifers and a high capacity of the karst aquifers to store and slowly release contaminants for long periods of time. The influence of hydraulic conductivity reveals the importance of contaminant fate and transport mechanisms from contamination sources. This study improves the understanding of factors affecting the spatial variability and fate of phthalates in karst aquifers, and allows us to better predict their occurrence based on these factors.

This paper evaluates the UV photodegradation of 17β-estradiol (E2) on silica gel and in natural soil with different soil components. Silica gel was chosen as a stable and pure support to simulate the photochemical behavior of E2 on the surface of natural soil. Ultraviolet light, rather than visible light, was confirmed to play a decisive role in the photodegradation of E2 on silica gel. The effect of three soil components, including humic acid (HA), inorganic salts, and relative humidity (RH), on the photochemical behavior of E2 on silica gel or soil under UV irradiation was then evaluated. Two HA concentrations (10 and 20 mg g⁻¹) and three salts (ferric sulfate, copper sulfate and sodium carbonate) were observed to obviously inhibit the degradation of E2 on silica gel. Interestingly, nitrate was found to obviously improve the removal efficiency of E2. Both too-dry and too-wet conditions obviously reduced the removal rate of E2, and the optimum relative humidity (RH) value was found to be approximately about 35% (30 °C). Furthermore, twenty intermediate products and two major pathways were proposed to describe the transformation processes of E2 treated by UV irradiation, among which oligomers were found to be the major intermediate products before complete mineralization. The efficient UV removal of E2 on silica gel and natural soil suggested a feasible strategy to remediate E2 contaminated soil.

The emission factors (EFs) of polycyclic aromatic hydrocarbons (PAHs) in PM2.5 were measured from commonly used stoves and fuels in the rural Guanzhong Plain, China. The toxicity of the PM2.5 also was measured using in vitro cellular tests. EFs of PAHs varied from 0.18 mg kg−1 (maize straw charcoal burning in a clean stove) to 83.3 mg kg−1 (maize straw burning in Heated Kang). The two largest influencing factors on PAH EFs were air supply and volatile matter proportion in fuel. Improvements in these two factors could decrease not only EFs of PAHs but also the proportion of 3-ring to 5-ring PAHs. Exposure to PM2.5 extracts caused a concentration-dependent decline in cell viability but an increase in reactive oxygen species (ROS), tumor necrosis factor a (TNF-α) and interleukin 6 (IL-6). PM2.5 emitted from maize burning in Heated Kang showed the highest cytotoxicity, and EFs of ROS and inflammatory factors were the highest as well. In comparison, maize straw charcoal burning in a clean stove showed the lowest cytotoxicity, which indicated a clean stove and fuel treatment were both efficient methods for reducing cytotoxicity of primary PM2.5. The production of these bioreactive factors were highly correlated with 3-ring and 4-ring PAHs. Specifically, pyrene, anthracene and benzo(a)anthracene had the highest correlations with ROS production (R = 0.85, 0.81 and 0.80, respectively). This study shows that all tested stoves emitted PM2.5 that was cytotoxic to human cells; thus, there may be no safe levels of exposure to PM2.5 emissions from cooking and heating stoves using solid fuels. The study may also provide a new approach for evaluating the cytotoxicity of primary emitted PM2.5 from solid fuel burning as well as other PM2.5 sources.

Ultrafine (<100 nm) particles related to traffic are of high environmental and human health concern, as they are supposed to be more toxic than larger particles. In the present study transmission electron microscopy (TEM) is applied to obtain a concrete picture on the nature, morphology and chemical composition of non-volatile ultrafine particles in the exhaust of state-of-the-art, Euro 6b, Gasoline and Diesel vehicles. The particles were collected directly on TEM grids, at the tailpipe, downstream of the after-treatment system, during the entire duration of typical driving cycles on the chassis dynamometer. Based on TEM imaging coupled with Energy Dispersive X-ray (EDX) analysis, numerous ultrafine particles could be identified, imaged and analyzed chemically. Particles <10 nm were rarely detected. The ultrafine particles can be distinguished into the following types: soot, ash-bearing soot and ash. Ash consists of Ca, P, Mg, Zn, Fe, S, and minor Sn compounds. Most elements originate from lubricating oil additives; Sn and at least part of Fe are products of engine wear; minor W ± Si-bearing nearly spherical particles in Diesel exhaust derive from catalytic coating material. Ultrafine ash particles predominate over ultrafine soot or are nearly equal in amount, in contrast to emissions of larger sizes where soot is by far the prevalent particle type. This is probably due to the low ash amount per volume fraction in the total emissions, which does not favor formation of large ash agglomerates, opposite to soot, which is abundant and thus easily forms agglomerates of sizes larger than those of the ultrafine range. No significant differences of ultrafine particle characteristics were identified among the tested Gasoline and Diesel vehicles and driving cycles. The present TEM study gives information also on the imaging and chemical composition of the solid fraction of the unregulated sub-23 nm size category particles.

Illicit drugs have been identified as emerging aquatic pollutants because of their widespread presence in freshwaters and potential toxicity towards aquatic organisms. Among illicit drug residues, cocaine (COC) and its main metabolites, namely benzoylecgonine (BE) and ecgonine methyl ester (EME), are commonly detected in freshwaters worldwide at concentration that can induce diverse adverse effects to non-target organisms. However, the information of toxicity and mechanisms of action (MoA) of these drugs, mainly of COC metabolites, to aquatic species is still fragmentary and inadequate. Thus, this study was aimed at investigating the toxicity of two concentrations (0.3 and 1.0 μg/L) of COC, BE and EME similar to those found in aquatic ecosystems on zebrafish (Danio rerio) embryos at 96 h post fertilization through a functional proteomics approach. Exposure to COC and both its metabolites significantly altered the protein profile of zebrafish embryos, modulating the expression of diverse proteins belonging to different functional classes, including cytoskeleton, eye constituents, lipid transport, lipid and energy metabolism, and stress response. Expression of vitellogenins and crystallins was modulated by COC and both its main metabolites, while only BE and EME altered proteins related to lipid and energy metabolism, as well as to oxidative stress response. Our data confirmed the potential toxicity of low concentrations of COC, BE and EME, and helped to shed light on their MoA on an aquatic vertebrate during early developmental period.

Inflammation may play an important role in the association between exposure to polycyclic aromatic hydrocarbons (PAHs) and atherosclerotic cardiovascular disease (ASCVD) risk. However, the underlying mechanisms remain unclear.To investigate the association of PAHs exposure with ASCVD risk and effects of mean platelet volume (MPV) or Club cell secretory protein (CC16) on the association.A total of 2022 subjects (689 men and 1333 women) were drawn from the baseline Wuhan residents of the Wuhan-Zhuhai Cohort study. Data on demography and the physical examination were obtained from each participant. Urinary monohydroxy PAH metabolites (OH-PAHs) levels were measured by a gas chromatography-mass spectrometry. We estimated the association between each OH-PAHs and the 10-year ASCVD risk or coronary heart disease (CHD) risk using logistic regression models, and further analyze the mediating effect of MPV or plasma CC16 on the association by using structural equation modeling.The results of multiple logistic regression models showed that some OH-PAHs were positively associated with ASCVD risk but not CHD risk, including 2-hydroxyfluoren (β = 1.761; 95% CI: 1.194–2.597), 9-hydroxyfluoren (β = 1.470; 95% CI: 1.139–1.898), 1-hydroxyphenanthrene (β = 1.480; 95% CI: 1.008–2.175) and ΣOH-PAHs levels (β = 1.699; 95% CI: 1.151–2.507). The analysis of structural equation modeling shows that increased MPV and increased plasma CC16 levels contributed 13.6% and 15.1%, respectively, to the association between PAHs exposure and the 10-year ASCVD risk (p < 0.05).Exposure to PAHs may increase the risk of atherosclerosis, which was partially mediated by MPV or CC16.

Environment pollution often occurs as an obvious combined effect involving two (or more) elements, and this effect changes with the concentrations of the different elements. The effects on barley root elongation were studied in hydroponic systems to investigate the toxicity of Cu–Ni combined at low doses and at a fixed concentration ratio. For low doses of Cu–Ni, the addition of Ni (<0.5 μM) to Cu significantly decreased Cu toxicity for barley, but the addition of Cu (<0.25 μM) had no significant effect on Ni toxicity. At a fixed concentration ratio, according to the single effective concentration (EC) (barley root elongation inhibitory concentration) values of Cu and Ni, five sets of Cu–Ni fixed ratios were used: ECn(Cu)+ECm(Ni) (n + m = 100) (ECn and ECₘ indicate toxicity unit value for n% and m% inhibition of barley root length, respectively). The calculated toxicity unit value for 50% inhibition of root length ranged from 0.44 to 0.98 (i.e., <1), indicating a synergistic effect. To consider the interactions between the metal ions, the extended concentration addition model (e-CA) was established by integrating the Cu–Ni interaction into the concentration addition model (CA), and the data of two groups (the low doses of Cu–Ni and at a fixed concentration ratio) were respectively fitted. The e-CA accurately predicted the root length of barley under the Cu–Ni combined action. The correlation coefficient (r) and the root-mean-square error (RMSE) between predicted and observed values were 0.97 and 6.6 (low-dose group) and 0.96 and 8.12 (fixed-ratio group), respectively, and e-CA significantly improved the prediction accuracy compared to the traditional CA model without consideration of the Cu–Ni competition (r = 0.89, RMSE = 14.16). The results provided a theoretical basis for evaluation and remediation of soil contaminated with heavy metal composites.

Surfactants are high production volume chemicals used in numerous domestic and industrial applications and, after use, the most abundant organic contaminants in wastewater. Their discharge might jeopardize the receiving aquatic ecosystems, including sediments, where they tend to accumulate. This is the first comprehensive study on their distribution and fate in this environmental compartment as we performed simultaneous analysis of the three main classes of surfactants (anionic: LAS; nonionic: NPEO and AEO; cationic: DTDMAC, DADMAC, BAC, and ATMAC) and some of their transformation products (SPC, NP, NPEC, and PEG). To account for spatial and time trends, surface sediments and dated cores were collected from Jamaica Bay, a heavily sewage-impacted estuary in New York City. The concentrations of surfactants in surface sediments were between 18 and > 200 μg g⁻¹ and showed slight variation (<10%) over different sampling years (1998, 2003 and 2008). Cationic surfactants were found at the highest concentrations, with DTDMAC accounting for between 52 and 90% of the total sum of target compounds. Vertical concentration profiles in dated cores from the most contaminated station, in the vicinity of the biggest local sewage treatment plant (STP), indicated two sub-surface surfactant peaks in the mid-1960s (469 μg g⁻¹) and late 1980s (572 μg g⁻¹) coinciding with known STP upgrades. This trend was observed for most target compounds, except for DADMAC, C22ATMAC, and PEG, which showed a continuous increase towards the top of the cores. In-situ degradation was studied by comparing sediment core samples taken 12 years apart (1996 and 2008) and revealed a net decrease in PEG and specific surfactants (BAC, ATMAC, NPEO, and AEO) accompanied by growing concentrations of metabolites (SPC, NP, and NPEC). DTDMAC, DADMAC, and LAS, however, remained stable over this period, suggesting recalcitrant behavior under the anaerobic conditions in Jamaica Bay sediments.Chronology of major synthetic surfactants are illustrated in the dated sediment cores, as well as their different diagenetic fates.