Given the ubiquitous presence of microplastics in aquatic environments, an evaluation of their toxicity is essential. Microplastics are a heterogeneous set of materials that differ not only in particle properties, like size and shape, but also in chemical composition, including polymers, additives and side products. Thus far, it remains unknown whether the plastic chemicals or the particle itself are the driving factor for microplastic toxicity. To address this question, we exposed Daphnia magna for 21 days to irregular polyvinyl chloride (PVC), polyurethane (PUR) and polylactic acid (PLA) microplastics as well as to natural kaolin particles in high concentrations (10, 50, 100, 500 mg/L, ≤ 59 μm) and different exposure scenarios, including microplastics and microplastics without extractable chemicals as well as the extracted and migrating chemicals alone. All three microplastic types negatively affected the life-history of D. magna. However, this toxicity depended on the endpoint and the material. While PVC had the largest effect on reproduction, PLA reduced survival most effectively. The latter indicates that bio-based and biodegradable plastics can be as toxic as their conventional counterparts. The natural particle kaolin was less toxic than microplastics when comparing numerical concentrations. Importantly, the contribution of plastic chemicals to the toxicity was also plastic type-specific. While we can attribute effects of PVC to the chemicals used in the material, effects of PUR and PLA plastics were induced by the mere particle. Our study demonstrates that plastic chemicals can drive microplastic toxicity. This highlights the importance of considering the individual chemical composition of plastics when assessing their environmental risks. Our results suggest that less studied polymer types, like PVC and PUR, as well as bioplastics are of particular toxicological relevance and should get a higher priority in ecotoxicological studies.

The influence of palm oil biodiesel content on the cytotoxicity, mutagenicity and genotoxicity of particle- and gas-phase diesel vehicle emissions was investigated. The emissions were collected on-board of a EURO IV diesel truck, fuelled with mixtures of 10% (B10), 20% (B20) and 100% (B100) of palm oil biodiesel, under real driving conditions. Organic extracts of the particulate matter (PM) and gases were characterised for 17 PAH (including EPA priority) and used for the biological assay. Increasing biodiesel content in the fuel mixture results in a decrease in the PM and PAH emission factors, both in the particulate and gas-phase. The majority of the PAH are present in the gas-phase. The mutagenic potencies, in TA98 bacteria, are higher for B20 in both phases, whereas the mutagenicity emission factor, that takes into account the lower emission of PM and PAH, is not significantly different between the fuels. Higher direct mutagenicity (TA98 + S9) is observed in all the tested fuels, indicating the action of carcinogenic compounds other than non-substituted PAH. The gas-phase extracts present higher cytotoxicity and genotoxicity in lung epithelial cell A549, which may be related to the higher PAH content in the gas-phase. The increase in biodiesel content have a different impact on cytotoxicity, being larger in the gas-phase and lower in the particle-phase. This indicates that pulmonary toxicity may be higher for the gaseous emissions, due to the role of different toxic compounds compared to the PM. The adverse biological effects when biodiesel content increases are not consequent with the reduction of the PAH characterised, indicating that other toxic compounds are more relevant. Further investigations to identify these compounds are required in order to update and focus the efforts regarding emission targets and controls.

Although anthropogenic emissions decreased, polluted days still occurred in the Beijing–Tianjin–Hebei (BTH) region during the initial outbreak of the coronavirus disease (COVID-19). Analysis of the characteristics and source distribution of large-scale air pollution episodes during the COVID-19 outbreak (from 23 January to April 8, 2020) in the BTH region is helpful for exploring the efficacy of control measures and policy making. The results indicated that the BTH region suffered two large-scale air pollution episodes (23–28 January and 8–13 February), which were characterized by elevated PM₂.₅, SO₂, NO₂, and CO concentrations, while the O₃ concentration decreased by 1.5%–33.9% (except in Shijiazhuang, where it increased by 16.6% during the second episode). These large-scale air pollution episodes were dominated by unfavorable meteorological conditions comprising a low wind speed and increased relative humidity. The transport pathways and source distribution were explored using the Hybrid Single Particle Lagrangian Integrated Trajectory (HYSPLIT), potential source contribution function (PSCF), and concentration weighted trajectory (CWT) models. The air pollution in the BTH region was mainly affected by local emission sources during the first episode, which contributed 51.6%–60.6% of the total trajectories in the BTH region with a PM₂.₅ concentration ranging from 146.2 μg/m³ to 196.7 μg/m³. The short-distance air masses from the southern and southwestern areas of the BTH region were the main transport pathways of airflow arriving in the BTH region during the second episode. These contributed 51.9%–57.9% of the total trajectories and originated in Hebei, Henan, central Shanxi, and Shaanxi provinces, which were the areas contributing the most to the PM₂.₅ level and exhibited the highest PSCF and CWT values. Therefore, on the basis of local emission reduction, enhancing regional environmental cooperation and implementing a united prevention and control of air pollution are effective mitigation measures for the BTH region.

Cardiovascular diseases (CVD) are leading global health issue. More studies have linked indoor air pollution from solid fuel usage to hypertension risk, a leading risk factor for CVD. We conducted a systematic review and meta-analysis of observational studies assessing the relationship of indoor air pollution from solid fuel with hypertension risk. Using a protocol standardized a priori, two independent reviewers searched PubMed, the Cochrane Library, Ovid MEDLINE, Web of Science and EMBASE for available studies published before Dec.1, 2019. A random effects model was used to analyse the pooled results. Out of 3740 articles, 47 were reviewed in depth and 11 contributing to this meta-analysis. The use of household solid fuel was significantly associated with an increased risk of hypertension (OR = 1.52, 95% CI = 1.26 to 1.85). The smoking-controlled group (OR = 2.38, 95% CI = 1.58 to 3.60) had greater effect size of hypertension than the uncontrolled group (OR = 1.11, 95% CI = 1.10 to 1.11). These findings implicate that indoor air pollution from solid fuel may be an important risk factor for hypertension.

Tasmanian recreational fishers have reported the presence of dark pigmentations in the usually white fillets of southern sand flathead (Platycephalus bassensis), a phenomenon known as muscle melanisation. Based on histology, it is suggested that eumelanin and pheomelanin are involved in the occurrence of the phenomenon. A gross melanisation scoring system was validated through a comparison with an image analysis technique, that quantified the percentage surface area of the fillets affected by muscle melanisation. The occurrence of muscle melanisation was most severe in fish inhabiting Deceitful Cove, Tamar Estuary. This indicated that muscle melanisation in P. bassensis may be caused by yet to be identified site specific factors. No significant relationships were evident between the percentage surface area of melanised muscle with condition index, age, sex, maturation stage, fish weight, fish length and size of melano-macrophage centres in the liver or spleen. Overall, this study has provided critical information that will frame the direction and focus of future P. bassensis muscle melanisation research.

DNA-based analyses of bacterial communities were performed to identify the bacteria co-occurring with cyanobacterial blooms in samples collected at a single site over 2 years. Microcystis aeruginosa was the most predominant species (81% in 2018, and 94% in 2019) within the phylum Cyanobacteria, and microcystins were detected during all cyanobacterial blooms. The stereo microscope and scanning electron microscope observations showed bacterial associations on and around the aggregated M. aeruginosa cells. Culture-independent analyses of filtered bacterial communities showed that the Flavobacterium species in phylum Bacteroidetes (19%) was dominant in the cyanobacterial phycosphere, followed by the Limnohabitans species in Betaproteobacteria (11%). Using principal component analysis, major bacterial genus, including Microcystis and Flavobacterium species, were clustered during cyanobacterial blooms in both years. To identify key bacterial species that develop long-term symbiosis with M. aeruginosa, another culture-independent analysis was performed after the environmental sample had been serially subcultured for 1 year. Interestingly, Brevundimonas (14%) was the most dominant species, followed by Porphyrobacter (7%) and Rhodobacter (3.5%) within the Alphaproteobacteria. Screening of 100 colonies from cyanobacterial bloom samples revealed that the majority of culturable bacteria belonged to Gammaproteobacteria (28%) and Betaproteobacteria (57%), including Pseudomonas, Curvibacter, and Paucibacter species. Several isolates of Brevundimonas, Curvibacter, and Pseudomonas species could promote the growth of axenic M. aeruginosa PCC7806. The sensitivity of M. aeruginosa PCC7806 cells to different environmental conditions was monitored in bacteria-free pristine freshwater, indicating that nitrogen addition promotes the growth of M. aeruginosa.

Endocrine-disrupting chemicals (EDCs) are compounds that interfere with the expression, synthesis, and activity of hormones in organisms. They are released into the environment from flame retardants and products containing plasticizers. Persistent pesticides, such as dichlorodiphenyltrichloroethane (DDT) and hexachlorobenzene, also disrupt the endocrine system through interaction with hormone receptors. Endogenous hormones, such as 17β-estradiol (E2), are released in the urine and feces of farm animals and seep into terrestrial and aquatic ecosystems through sewage. Pigs are widely used as animal models to determine the effects of EDCs because they are physiologically, biochemically, and histologically similar to humans. EDCs primarily disrupt the reproductive and nervous systems of pigs. Moreover, embryonic development during the prenatal and early postnatal periods is particularly sensitive to EDCs. Mycotoxins, such as zearalenone, are food contaminants that alter hormonal activities in pigs. Mycotoxins also alter the innate immune system in pigs, making them vulnerable to diseases. It has been reported that farm animals are exposed to various types of EDCs, which accumulate in tissues, such as those of gonads, livers, and intestines. There is a lack of an integrated understanding of the impact of EDCs on porcine reproduction and development. Thus, this article aims to provide a comprehensive review of literature regarding the effects of EDCs in pigs.

The wide ecological relevance of lipid homeostasis modulators in the environment has been increasingly acknowledged. Tributyltin (TBT), for instance, was shown to cause lipid modulation, not only in mammals, but also in fish, molluscs, arthropods and rotifers. In vertebrates, TBT is known to interact with a nuclear receptor heterodimer module, formed by the retinoid X receptor (RXR) and the peroxisome proliferator-activated receptor (PPAR). These modulate the expression of genes involved in lipid homeostasis. In the present work, we isolated for the first time the complete coding region of the Echinodermata (Paracentrotus lividus) gene orthologues of PPAR and RXR and evaluated the ability of a model lipid homeostasis modulator, TBT, to interfere with the lipid metabolism in this species. Our results demonstrate that TBT alters the gonadal fatty acid composition and gene expression patterns: yielding sex-specific responses in fatty acid levels, including the decrease of eicosapentaenoic acid (C20:5 n-3, EPA) in males, and increase of arachidonic acid (20:4n-6, ARA) in females, and upregulation of long-chain acyl-CoA synthetase (acsl), ppar and rxr. Furthermore, an in vitro test using COS-1 cells as host and chimeric receptors with the ligand binding domain (LBD) of P. lividus PPAR and RXR shows that organotins (TBT and TPT (Triphenyltin)) suppressed activity of the heterodimer PPAR/RXR in a concentration-dependent manner. Together, these results suggest that TBT acts as a lipid homeostasis modulator at environmentally relevant concentrations in Echinodermata and highlight a possible conserved mode of action via the PPAR/RXR heterodimer.

The growing use of graphene-based nanomaterials (GBNs) for various applications increases the probability of their environmental releases and calls for a systematic assessment of their potential impacts on soil invertebrates that serve as an important link along terrestrial food chains. Here, we investigated the response of earthworms (Eisenia fetida) to three types of multi-layer graphenes (MLGs) (G1, G2 and G3 with 12–15 layers) with variable morphology (lateral sizes: 7.4 ± 0.3, 6.4 ± 0.1 and 2.8 ± 0.1 μm; thicknesses: 5.0 ± 0.1, 4.2 ± 0.1 and 4.0 ± 0.2 nm, respectively) and hydrophobicity ((O + N)/C ratios: 0.029, 0.044 and 0.075; contact angles: 122.8, 118.8 and 115.1°, respectively). Exposure to these materials was conducted for 28 days (except for 48-h avoidance test) separately in potting or farm soil at 0.2% and 1% by weight. Earthworms avoided both soils when amended with 1% of the smaller and more hydrophilic MLGs (G2 and G3), leading to a decreased trend in worm cocoon formation. The smallest and most hydrophilic MLG (G3), which was easier to assimilate, also significantly inhibited the viability (20.2–56.0%) and mitochondrial membrane potential (32.0–48.5%) of worm coelomocytes in both soils. In contrast, oxidative damage (indicated by lipid peroxides) was more pronounced upon exposure to more hydrophobic and larger graphenic materials (G1 and G2), which were attributed to facilitated adhesion to and disruption of worm membranes. These findings highlight the importance of MLG morphology and hydrophobicity in their potential toxicity and mode of action, as well as ecological risks associated with incidental and accidental releases.

The microparticle content of 37 common facial and body scrubs commercially available in the United Arab Emirates was analyzed. The chemical composition, ash content, physical characteristics, loading, particle size and shape of the microparticles were determined. Only 11 out of 37 products were found to have microplastic content. Many of the remaining products exhibited microparticles composed of microcrystalline cellulose and crushed walnut shells. Differential scanning calorimetry showed that microplastic products had softening points as low as 84 °C. Plastic microbeads of 2 products were found to fuse at 100 °C. The fusion altered the flotation characteristics of the microbeads of one product. Heat treatment of the product at 100 °C in the presence of silica gel led to entrainment of the silica and partial fragmentation of the beads upon cooling. This may be understood as one mechanism of fragmentation of a microplastic with a low softening point in the presence of hard soil particles under temperature cycling.