Acute toxic effects of polyethylene microplastic on adult zebrafish

The plastic brain: neurotoxicity of micro- and nanoplastics

Given the global abundance and environmental persistence, exposure of humans and (aquatic) animals to micro- and nanoplastics is unavoidable. Current evidence indicates that micro- and nanoplastics can be taken up by aquatic organism as well as by mammals. Upon uptake, micro- and nanoplastics can reach the brain, although there is limited information regarding the number of particles that reaches the brain and the potential neurotoxicity of these small plastic particles.

Earlier studies indicated that metal and metal-oxide nanoparticles, such as gold (Au) and titanium dioxide (TiO₂) nanoparticles, can also reach the brain to exert a range of neurotoxic effects. Given the similarities between these chemically inert metal(oxide) nanoparticles and plastic particles, this review aims to provide an overview of the reported neurotoxic effects of micro- and nanoplastics in different species and in vitro. The combined data, although fragmentary, indicate that exposure to micro- and nanoplastics can induce oxidative stress, potentially resulting in cellular damage and an increased vulnerability to develop neuronal disorders. Additionally, exposure to micro- and nanoplastics can result in inhibition of acetylcholinesterase activity and altered neurotransmitter levels, which both may contribute to the reported behavioral changes.

Currently, a systematic comparison of the neurotoxic effects of different particle types, shapes, sizes at different exposure concentrations and durations is lacking, but urgently needed to further elucidate the neurotoxic hazard and risk of exposure to micro- and nanoplastics.

A sustainable solution to plastics pollution: An eco-friendly bioplastic film production from high-salt contained Spirulina sp. residues

Plastic products have become a major contaminant in environmental ecology due to their recalcitrant biodegradation, poor management and risky disposal. Therefore, much research attention has been paid to developing the biodegradable bio-based plastics. However, many of the substitute bioplastics derived from agricultural materials may present a potential threat to food security and eco-systems. Herein, we propose a sustainable, eco-friendly and simple procedure to convert the hazardous high-salt contained microalgal residues into bioplastic film. With 35 % poly (vinyl alcohol) (PVA) assistance, the composite bioplastic films achieved 22 MPa tensile strength under alkali condition and 77 % elongation at break under acidic condition. The average maximum contact angle of 94.4° confirmed a desirable water resistance potential. The synthesis mechanism demonstrated that the inorganic salts existed in microalgal residues could act as the filler in shape of sheets under alkali condition or as the cross linker under acidic condition, significantly enhancing the practical feasibility. This work demonstrates a promising biodegradable bioplastics formed from sustainable eco-friendly waste reutilization process, providing a new insight for fundamentally reducing the plastics pollution.

Toxicity of Microplastics and Nanoplastics in Mammalian Systems

Fragmented or otherwise miniaturized plastic materials in the form of micro- or nanoplastics have been of nagging environmental concern. Perturbation of organismal physiology and behavior by micro- and nanoplastics have been widely documented for marine invertebrates. Some of these effects are also manifested by larger marine vertebrates such as fishes. More recently, possible effects of micro- and nanoplastics on mammalian gut microbiota as well as host cellular and metabolic toxicity have been reported in mouse models. Human exposure to micro- and nanoplastics occurs largely through ingestion, as these are found in food or derived from food packaging, but also in a less well-defined manner though inhalation. The pathophysiological consequences of acute and chronic micro- and nanoplastics exposure in the mammalian system, particularly humans, are yet unclear. In this review, we focus on the recent findings related to the potential toxicity and detrimental effects of micro- and nanoplastics as demonstrated in mouse models as well as human cell lines. The prevailing data suggest that micro- and nanoplastics accumulation in mammalian and human tissues would likely have negative, yet unclear long-term consequences. There is a need for cellular and systemic toxicity due to micro- and nanoplastics to be better illuminated, and the underlying mechanisms defined by further work.

Molecular characterisation of cytochrome P450 enzymes in waterflea (Daphnia pulex) and their expression regulation by polystyrene nanoplastics

Cytochrome P450 (CYP) enzymes are one of the largest protein families, and they metabolise a wide range of lipophilic organic endogenous and exogenous compounds. Many cytochrome P450 genes have been cloned and characterised, and they are frequently used as biomarkers in environmental toxicology studies because of their sensitivity and inducibility. In the present study, the full-length cDNAs of DpCYP370B and DpCYP4 were cloned from Daphnia pulex for the first time. The sequence of DpCYP370B consisted of an ORF of 1515 bp that encoded a 504 amino acid polypeptide, while the sequence of DpCYP4 comprised an ORF of 1527 bp that encoded a 508 amino acid polypeptide. Homologous alignments revealed the presence of a conserved cysteine haeme-iron ligand signature, FxxGxxxCxG, located in the C-terminal portion. Both the proteins contained a sequence for a transmembrane region that was deduced to be located in the endoplasmic reticulum. Subsequently, the expression levels of DpCYP370B and DpCYP4, as well as those of CYP4AN1, CYP4C33, and CYP4C34, were investigated using quantitative real-time PCR after exposure to five polystyrene nanoplastic concentrations: 0 (control), 0.1, 0.5, 1, and 2 mg/L for 21 days. Except for DpCYP4, the highest mRNA expression was observed at 0.5 mg/L nanoplastics; next, the expression of three of the enzymes (DpCYP370B, CYP4AN1, CYP4C34,) decreased to that of the control level at 1 and 2 mg/L doses of nanoplastics. The expression of DpCYP4 did not significantly change compared with that of the control group. These results indicated that CYP genes might play an important role in protecting D. pulex against nanoplastic pollutants.