Studies on microplastics featured in Nature and Journal of Toxicological Studies highlight their adverse impacts on health

2024-10-14

Plastics have become ubiquitous in every facet of human daily life, and those with a particle size of less than 5mm are termed microplastics. These microplastics are readily ingested by living organisms and eventually make their way into the human body through the food chain. Not only are these minuscule plastic particles pervasive in soil, seas, and air, but they also represent an environmental issue that is increasingly demonstrating its severity. Moreover, they have infiltrated human bodies, posing a significant threat to human health.

A study by Max Kozlov, published in Nature, revealed that individuals with tiny plastic particles lodged in a key blood vessel were at a higher risk of experiencing heart attacks, strokes, or death [1]. Further research, such as that conducted by Mei Ha [2], has indicated that exposure to nano/microplastics triggers inflammatory responses and oxidative stress. This, in turn, compromises the integrity of the blood-testis barrier (BTB), a crucial component of the blood-testing process. The disruption of the BTB integrity stimulates spermatogenic cell apoptosis by activating the JNK and p38/MAPK-Nrf2/NF-κB pathways and induces ovarian granulosa cell pyroptosis, as well as apoptosis, leading to subsequent ovarian fibrosis via the Wnt/β-Catenin and NLRP3/Caspase-1 pathways.

Figure 1. The unfavorable influence of NPs/MPs on male reproductive health and underlying mechanisms.

Researches into microplastics are still in its early stages, and the extent of pollution and health hazards they pose is not yet fully comprehended. The ongoing exploration and disclosure of related studies are not only crucial for the development of environmental and health policies but also serve as a warning to the public to reduce plastic pollution and safeguard public health.

References:

1. Max Kozlov. Landmark study links microplastics to serious health problems. Nature. Mar 6, 2024. doi: https://doi.org/10.1038/d41586-024-00650-3

2. Mei Ha, Wanzhen Tang, Jichun Huang, et al. Threats of nano/microplastics to reproduction and offspring: Potential mechanisms and perspectives. Journal of Toxicological Studies, 2024; 2(1): 443. doi: https://doi.org/10.59400/jts.v2i1.443

Insecticides represent the most used control method against the insect pests of stored food products. But there are strains of insects which are resistant to these insecticides: it is the case of the beetle of the chickpea Callosobruchus maculatus . The present study has for objective the evaluation of the biological activity of chitinolytic enzymes extracted from the fish offals Scorpaena scrofa (scorpion fish) on this beetle at different doses (3%, 6%, 9%, 12%, 15% and 21%) prepared with the buffer solution. The results obtained from three treatments (T 1 , T 2 and T 3 ) realized according to the dose of the crude enzyme and the time of exposure were compared with those of the controls and have showed a very significant efficiency of our crude enzyme on the reduction of the fertility rate of 100% by treating the couple (T 1 ) at the same time as to treat the male (T 3 ) and the female (T 2 ) separately with the strongest dose (21%) for 48 h of exposure. It would be thus desirable to demonstrate the activity of these enzymes in the real conditions of storage.

Na + -K + -ATPase is a membrane bound enzyme responsible for the transport of ions through the membrane and immediate release of energy. This enzyme is known to be an early target for oxygen radical induced damage to intact cell. Exposure of C. punctatus to subacute concentrations of lindane for 96 h caused significant reduction in the activities of Na + -K + -ATPase in all the tissues of the fish tested; brain being maximally affected and the heart being least affected organ at the highest concentration of lindane (0.1 mg/L). The effect of pesticide was concentration dependent. The percent decrease in the activity of Na + -K + -ATPase in brain, gills, heart, kidney, liver and muscle was found to be 36.7, 23.4, 19.2, 29, 22.9 and 29.7, respectively. The order of level of enzyme activity recorded was as following: liver > gills > kidney > brain > muscle > heart in the control.

Due to the ubiquitous occurrence in the aquatic environment and terrestrial ecosystem and underlying eco-environmental risks, nano/microplastics (NPs/MPs) have sparked great public concerns. The purpose of this work is aimed to summarize the harmful influence of NPs/MPs on reproduction and offspring health and further explore the potential mechanisms of action, thereby facilitating the more comprehensive understanding of NPs/MPs features. Literature search databases included EMBASE, Web of Science, and PubMed. The study selection and data extraction were implemented according to the inclusion criteria. NPs/MPs could accumulate and trigger reproductive toxic responses and thereafter generate deleterious effects on the offspring health. Accordingly, the reproductive toxicity of NPs/MPs was characterized as the sperm deformity, decline in sperm count and motility, follicular growth tardiness, ovarian fibrosis, granulosa cell death, disorder of reproductive hormone secretion, as well as the fetal growth restriction, glycolipid metabolism disorder, and inflammatory responses of the next generation. Additionally, mechanism research revealed that NPs/MPs exposure brought about inflammatory responses and oxidative stress and thereafter, destroyed the blood-testis barrier (BTB) integrity, motivated spermatogenic cell apoptosis by activating the JNK and p38/MAPK-Nrf2/NF-κB pathways, and induced ovarian granulosa cell pyroptosis and apoptosis and subsequent ovarian fibrosis via the Wnt/β-Catenin and NLRP3/Caspase-1 pathways. Nevertheless, this work also highlighted the imperative requirements for scientific and systematic risk assessments of NPs/MPs, so as to identify the feasible risk mitigation strategies.