The 6:2 chlorinated polyfluoroalkyl ether sulfonic acids (6:2 Cl-PFAES), 2,3,3,3-tetrafluoro-2-(1,1,2,2,3,3,3-heptafluoropropoxy)-propanoic acid (HFPO-DA) and perfluoroethylcyclohexane sulfonate (PFECHS) are emerging per- and polyfluoroalkyl substances (PFASs) that are being applied to replace phased-out PFASs, which have high persistency, high bioaccumulation potential and high toxicity. Recently, these emerging PFASs were observed in estuary and marine areas with a pollution level of ng/L. In this study, three levels (10 ng L⁻¹, 100 ng L⁻¹ and 1000 ng L⁻¹) for these PFASs were selected to investigate the response of marine Chlorella sp. to 14 days of exposure. The growth of Chlorella sp. was significantly inhibited by each PFAS over time. Treatments with 1000 ng/L exposure caused the most severe reduction in growth for each PFAS treatment. For the first half of the experimental period (from Day 0 to Day 6), the influence of each PFAS was not significant (p > 0.05). However, treatments with all concentrations of 6:2 Cl-PFAES, HFPO-DA and 1000 ng L⁻¹ PFECHS significantly reduced the growth of Chlorella sp. from Day 8. The superoxide dismutase (SOD) activities in Chlorella sp. were significantly increased (p < 0.05) when exposed to 6:2 Cl-PFAES, HFPO-DA and PFECHS. The catalase (CAT) and peroxidase (POD) activities in Chlorella sp. were significantly inhibited (p < 0.05) by each PFAS. The glutathione (GSH) contents in Chlorella sp. were significantly increased by each PFAS. However, the increases in GSH concentration in Chlorella sp. were low. The inhibition of algal growth was primarily due to the reduction of the activities of CAT and POD. PFECHS had the lowest toxicity among the three PFASs, and it induced less oxidized damage to Chlorella sp. In conclusion, as alternatives to phased-out PFASs, the emerging PFASs are not safe in aquatic environment, and attention should be paid to the management and restriction of these emerging PFASs.

The presence of marine litter is a complex, yet persistent, threat to the health and biodiversity of the marine environment, and plastic is the most abundant, and ubiquitous type of marine litter. To monitor the level of plastic waste in an area, and the prospect of it entering the food chain, bioindicator species are used extensively throughout Northern European Seas, however due to their distribution ranges many are not applicable to the Mediterranean Sea. Guidance published for the Marine Strategy Framework Directive suggests that the contents of fish stomachs may be analyzed to determine trends of marine plastic ingestion. In order to equate transnational trends in marine plastic ingestion, the use of standardized fish species that widely occur throughout the basin is favoured, however for the Mediterranean Sea, specific species are not listed. Here we propose a methodology to assess how effective Mediterranean fish species, that are known to have ingested marine plastic, are as bioindicators. A new Bioindicator Index (BI) was established by incorporating several parameters considered important for bioindicators. These parameters included species distribution throughout the Mediterranean basin, several life history traits, the commercial value of each species, and the occurrence of marine litter in their gut contents. By collecting existing data for Mediterranean fish, ranked scores were assigned to each trait and an average value (BI value) was calculated for each species. Based on their habitat preferences, Engraulis encrasicolus (pelagic), Boops boops (benthopelagic), three species of Myctophidae (Hygophum benoiti, Myctophum punctatum and Electrona risso) (mesopelagic), Mullus barbatus barbartus (demersal) and Chelidonichthys lucerna (benthic), were identified as currently, the most suitable fish for monitoring the ingestion of marine plastics throughout the Mediterranean basin. The use of standardized indicator species will ensure coherence in the reporting of marine litter ingestion trends throughout the Mediterranean Sea.

Two hundred sixty-three fine particulate matter (PM₂.₅) samples were collected over fourteen months in Fresno and Bakersfield, California. Samples were analyzed for organic carbon (OC), elemental carbon (EC), water soluble organic carbon (WSOC), and 160 organic molecular markers. Chemical Mass Balance (CMB) and Positive Matrix Factorization (PMF) source apportionment models were applied to the results in order to understand monthly and seasonal source contributions to PM₂.₅ OC. Similar source categories were found from the results of the CMB and PMF models to PM₂.₅ OC across the sites. Six source categories with reasonably stable profiles, including biomass burning, mobile, food cooking, two different secondary organic aerosols (SOAs) (i.e., winter and summer), and forest fires were investigated. Both the CMB and the PMF models showed a strong seasonality in contributions of some sources, as well as dependence on wind transport for both sites. The overall relative source contributions to OC were 24% CMB wood smoke, 19% CMB mobile sources, 5% PMF food cooking, 2% CMB vegetative detritus, 17% PMF SOA summer, 22% PMF SOA winter, and 12% PMF forest fire. Back-trajectories using the Weather Research and Forecasting model combined with the FLEXible PARTicle dispersion model (WRF-FLEXPART) were used to further characterize wind transport. Clustering of the trajectories revealed dominant wind patterns associated with varying concentrations of the different source categories. The Comprehensive Air Quality Model with eXtensions (CAMx) was used to simulate aerosol transport from forest fires and thus confirm the impacts of individual fires, such as the Rough Fire, at the measurement sites.

Copper oxide nanoparticles (CuO NPs) is one of the most commonly used metal oxide nanoparticles for commercial and industrial products. An increase in the manufacturing and use of the CuO NPs based products has increased the likelihood of their release into the aquatic environment. This has attracted major attention among researchers to explore their impact in human as well as environmental systems. CuO NPs, once released into the environment interact with the biotic and abiotic constituents of the ecosystem. Hence the objective of the study was to provide a holistic understanding of the effect of abiotic factors on the stability and aggregation of CuO NPs and its correlation with their effect on the development of zebrafish embryo. It has been observed that the bioavailability of CuO NPs decrease in presence of humic acid (HA) and heteroagglomeration of CuO NPs occurs with clay minerals. CuO NPs, CuO NPs + HA and CuO NPs + Clay significantly altered the expression of genes involved in development of dorsoventral axis and neural network of zebrafish embryos. However, the presence of HA with clay showed protective effect on zebrafish embryo development. These findings provide new insights into the interaction of NPs with abiotic factors and combined effects of such complexes on developing zebrafish embryos genetic markers.

During the last 70 years 1, 2, 3, 4, 5, 6-Hexachlorocyclohexane (HCH) has been one of the most extensively used pesticides. Only the gamma-isomer has insecticidal properties. For the marketing of gamma-HCH (lindane) the other 85% HCH isomers which are formed as by-products during HCH production had to be separated and became finally hazardous waste. For each tonne of lindane 8–12 tonnes of waste HCH isomers were produced and production of the approximately 600,000 t of lindane has therefore generated 4.8 to 7.2 million tonnes of HCH/POPs waste. These waste isomers were mostly buried in uncontrolled dumps at many sites around the world. The stockpiles and the large contaminated sites can be categorized as “mega-sites”. Countries with HCH legacy problems include Albania, Argentina, Austria, Azerbaijan, Brazil, China, Croatia, Czech Republic, France, Germany, Hungary, India, Italy, Japan, Macedonia, Nigeria, Poland, Romania, Russia, Slovakia, South Africa, Spain, Switzerland, Turkey, The Netherlands, UK, Ukraine and the USA.As lindane and alpha- and beta-HCH have been listed as POPs in the Stockholm Convention since August 2010, the problem of stockpiles of HCH waste is now documented and globally acknowledged.This article describes briefly the legacy of HCH and lindane that has been created. Three of the mega-sites are being discussed and demonstrate the increase in pollution footprint over time. Recent developments in the EU (including the Sabinanigo project in Aragon/Spain) and on a global level are presented. A short overview is given on lack of activities and on actions of countries within their obligations as Parties of the Stockholm Convention. Furthermore, current country activities supported by the Global Environment Facility (GEF), the “financing mechanism” of the convention, are listed. Finally, conclusions and recommendations are formulated that will contribute to the solution of this problem over the next 25 years.

Total and organic mercury concentrations were determined for males, females and juveniles of Euphausia superba collected at three discrete locations in the Scotia Sea (South Orkney Islands, South Georgia and Antarctic Polar Front) to assess spatial mercury variability in Antarctic krill. There was clear geographic differentiation in mercury concentrations, with specimens from the South Orkney Islands having total mercury concentrations 5 to 7 times higher than Antarctic krill from South Georgia and the Antarctic Polar Front. Mercury did not appear to accumulate with life-stage since juveniles had higher concentrations of total mercury (0.071 μg g⁻¹ from South Orkney Islands; 0.014 μg g⁻¹ from South Georgia) than adults (0.054 μg g⁻¹ in females and 0.048 μg g⁻¹ in males from South Orkney Islands; 0.006 μg g⁻¹ in females and 0.007 μg g⁻¹ in males from South Georgia). Results suggest that females may use egg laying as a mechanism to excrete mercury, with eggs having higher concentrations than the corresponding somatic tissue. Organic mercury makes up a minor percentage of total mercury (15–37%) with the percentage being greater in adults than in juveniles. When compared to euphausiids from other parts of the world, the concentration of mercury in Antarctic krill is within the same range, or higher, highlighting the global distribution of this contaminant. Given the high potential for biomagnification of mercury through food webs, concentrations in Antarctic krill may have deleterious effects on long-lived Antarctic krill predators.

Various parameters can influence the toxic response to silver nanoparticles (Ag NPs), including the size and surface properties, as well as the exposure environment and the biological site of action. Herein, we assess the intestinal toxicity of three different sizes (10, 40, and 100 nm) of Ag NPs in embryonic zebrafish, and describe the relationship between the properties and behavior of Ag NPs in the exposure medium, and induction of lethal and sublethal effects. We find that the composition of the medium and the size contribute to differential NPs agglomeration, release of Ag ions, and subsequent effects during exposure. The exposure medium causes dramatic reduction in silver dissolution due to the presence of salts and divalent cations, which limits the lethal potential of silver ions. Lethality is observed primarily for embryos exposed to medium sized Ag NPs (40 nm), but not to the supernatant originated from particles, which suggests that the exposure to particulate silver is the main cause of mortality. On the other hand, the exposure to 10 nm and 100 nm NPs, as well as Ag ions, only causes sublethal developmental defects in skeletal muscles and intestine, and induces a nitric oxide imbalance.

There is limited evidence for short-term association between mortality and ambient air pollution in the Middle East and no study has evaluated exposure windows of about a month prior to death. We investigated all-cause non-accidental daily mortality and its association with fine particulate matter (PM₂.₅), nitrogen dioxide (NO₂), and the Air Quality Index (AQI) from March 2011 through March 2014 in the megacity of Tehran, Iran. Generalized additive quasi-Poisson models were used within a distributed lag linear modeling framework to estimate the cumulative effects of PM₂.₅, NO₂, and the AQI up to a lag of 45 days. We further conducted multi-pollutant models and also stratified the analyses by sex, age group, and season. The relative risk (95% confidence interval (CI)) for all seasons, both sexes and all ages at lag 0 for PM₂.₅, NO₂, and AQI were 1.004 (1.001, 1.007), 1.003 (0.999, 1.007), and 1.004 (1.001, 1.007), respectively, per inter-quartile range (IQR) increment (18.8 μg/m³ for PM₂.₅, 12.6 ppb for NO₂, and 31.5 for AQI). In multi-pollutant models, the PM₂.₅ associations were almost independent from NO₂. However, the RRs for NO₂ were slightly attenuated after adjustment for PM₂.₅ but they were still largely independent from PM₂.₅. The cumulative relative risks (95% CI) per IQR increment reached maximum during the cooler months, including: 1.13 (1.06, 1.20) for PM₂.₅ at lag 0–31 (for females, all ages); 1.17 (1.10, 1.25) for NO₂ at lag 0–45 (for males, all ages); and 1.13 (1.07, 1.20) for the AQI at lag 0–30 (for females, all ages). Generally, the RRs were slightly larger for NO₂ than PM₂.₅ and AQI. We found somewhat larger RRs in females, age group >65 years of age, and in cooler months. In summary, positive associations were found in most models. This is the first study to report short-term associations between all-cause non-accidental mortality and ambient PM₂.₅ and NO₂ in Iran.

Lead (Pb) contaminated soil is of particular concern for infants and children due to their susceptibility to exposure, fast metabolic rates and rapidly developing neuronal systems. Determining the bioaccessibility of Pb in soils is critical in human health risk assessments, which can vary due to different soil properties and sources of Pb contamination. In this study, the potential relationships between soil properties and Pb bioaccessibility from various Pb sources including Pb contamination from mining (specifically, Broken Hill), three shooting ranges, a smelter and two industry sites (pottery and battery), were investigated using the Relative Bioavailability Leaching Procedure (RBALP). We found the following: (1) CEC, TOC, sand and silt content, and total Pb were significantly different (p < 0.05) between the two particle size fractions of < 2 mm and < 250 μm; (2) EC, CEC and total Pb were significantly correlated to Pb bioaccessibility (p < 0.05); and (3) soil analyses based on source of Pb demonstrated a strongly significant relationship between Pb bioaccessibility and soil properties (CEC, EC, clay content and total Pb) for mining soils from Broken Hill (r² = 0.86, p < 0.05, n = 18). These results demonstrated the influences of Pb contamination sources, soil properties and particle size fractions on Pb bioaccessibility as well as the prediction of Pb bioaccessibility using soil properties. The findings documented here will help in developing a predictive tool for human health risk assessment and the remediation of Pb contaminated soils.

We previously found that folic acid (FA) attenuated cardiac defects in zebrafish embryos exposed to extractable organic matter (EOM) from PM2.5, but the underlining mechanisms remain to be elucidated. Since DNA methylation is crucial to cardiac development, we hypothesized that EOM-induced aberrant DNA methylation changes could be diminished by FA supplementation. In this study, zebrafish embryos were exposed to EOM in the absence or presence of FA. Genomic-wide DNA methylation analysis identified both DNA hypo- and hyper-methylation changes in CCGG sites in zebrafish embryos exposed to EOM, which were attenuated by FA supplementation. We identified a total of 316 genes with extensive DNA methylation changes in EOM samples but little or no DNA methylation changes in EOM plus FA samples. The genes were involved in critical cellular processes and signaling pathways important for embryo development. In addition, the EOM-decreased SAM/SAH ratio was counteracted by FA supplementation. Furthermore, FA attenuated the EOM-induced changes in the expression of genes involved in the regulation of DNA methylation and in folate biosynthesis. In conclusion, our data suggest that FA supplementation protected zebrafish embryos from the cardiac developmental toxicity of PM2.5 by alleviating EOM-induced DNA methylation changes.