The Microplastics and Human Health: Focus on the Reproductive System

The threat of plastic waste in the environment has evoked rising concern over the past decades. While these versatile and incredibly popular polymer materials undoubtedly fulfil unprecedented services, their extreme durability and alleged toxicity represent major downsides, once in the environment. As plastics break down into smaller microplastics (MP) they evidently pollute almost every thinkable habitat on the globe today. While an estimated 5–12 million tons of plastic end up in the oceans every year, rivers are important pathways, carrying an annual freight of 0.41–4 million tons downstream. The Rhine River, one of Europe’s main streams and one of the World’s busiest waterways, reportedly holds substantial amounts of MP in its near-surface waters and sediments. However, little is known about potential MP sources, seasonal dynamics and the MP pollution of benthic sediments of this major river. In my dissertation I address three pivotal knowledge gaps about MP in the Rhine River and investigate a new type of method to safely and efficiently separate MP from surrounding environmental sample matrices. The surface water MP pollution of the Rhine River was earlier characterised by the distinct appearance of vast amounts (~60%) of rigid polystyrene microbeads of unknown origin and former purpose. In a sustained investigation of a defined river stretch in the Lower Rhine downstream Cologne, we managed to narrow down the entry region of these pollutants and close-to-certainly unveil the particle’s former purpose as ion-exchange resin beads used in diverse fluid purification applications. As more data on MP in rivers emerges, an interesting gap opens: empirical field studies tend to generate temporally restricted snapshot data while modellers, laudably seeking the bigger picture, are confronted with enormous uncertainties in their results. In a bid to reduce this void we embarked on a quadruplicate surface water MP observation in the Rhine catchment during 2016–2017. The investigation included three nival discharge regime tributaries and the Rhine in Switzerland as well as a pluvial Rhine River section towards the German-Dutch border. It became evident that despite a coherent increasing MP concentration gradient downstream, reflecting average discharge and catchment size, overall variability in environmental MP data was large. This hampers clear-cut estimations about concentration fluctuations but at the same time reinforces the theory of high MP seasonal pollution fluxes in the European winter months, when Rhine discharge is highest. Seeking to contribute to the very scarce knowledge of MP and benthic sediment interaction in large dynamic rivers, we took a diving bell and a dredging vessel to the riverbed at two previously identified surface MP hotspots at the German Middle and Lower Rhine. Due to expected water turbulence and flow velocity, substantial settling of MP in such stretches is not necessarily anticipated. Interestingly, it showed that even the Rhine riverbed is not spared from vast MP pollution. The applied research technology allowed for reliable detection of MP down to particle sizes of 11 μm and yielded strongly varying concentrations of 260–11,000 MP kg^–1, with a strongly skewed size class distribution towards the smallest MP particles. Experience showed us that environmental sample preparation for MP research can be a tedious and resource-intensive enterprise – including health and environmental hazards. Instead of attacking the unwanted portions in a sample (e.g. biogenic residue to isolate MP), a more efficient approach is to select the MP specifically. We refined a proposed lipophilicity-based separation technique and broadened its scope by successfully testing it to four different types of environmental matrices. This one-for-all approach may present a promising means for quicker, cheap, safe and efficient MP data compilation. The method was successfully applied for the seasonal surface MP investigation presented in this dissertation.

Effects of polystyrene nanoplastics on the female reproductive system in mice: Implications for ovarian function and follicular development.

Microplastics (MPs) as pollutants in river ecosystems have received considerable research attention in recent years. However, in Africa, research on MPs is sparse, and more needs to be done. Empirical evidence suggests that MP can act as vectors of organic chemical pollutants due to their diverse functional groups and other physical-chemical properties, such as their small sizes, crystal structure and porosity. MPs acting as vectors of chemical pollutants, adds to the complexity of understanding the risk posed to both the ecosystem and human health. Regarding the so-called vector effect, the role of seasonality, land use type, adsorption kinetics, and MP properties has yet to receive the necessary research in the literature, especially concerning pharmaceutical active compounds and other organic pollutants in river systems. This is particularly true for Africa, including South Africa. This study, therefore, aimed to fill these existing research gaps. Overall, the study aimed to investigate the potential of selected microplastic polymers of a particular size range as vectors of organic pollutants in urban rivers within the Eastern Cape of South Africa. To achieve this aim, the study explored the influence of spatial-temporal variability, MPs particle sizes, and various physicochemical variables on the adsorption of antibiotics: Sulfamethoxazole, ciprofloxacin, and endocrine disruptors: 17β-Estradiol, 4-(2, 6-dimethyl-2-heptyl) phenol. The adsorption kinetics mechanism was also investigated and established. Polyethylene Terephthalate (PET) and polypropylene (PP) MPs were seasonally deployed once in the summer and autumn seasons, i.e. 20th January 2022 in Bloukrans River and 21st January 2022 in Swartkops River for the summer season and 7th April 2022 in Bloukrans River and 8th April 2022 in Swartkops River for the autumn season. Deployed MPs were of two size ranges, type 1 (2 mm<-≤5 mm) and type 2 (0.5mm<-≤2 mm). The sites where the MPs were deployed had different land use practices: informal settlements, discharge points of wastewater treatment works (WWTWs), agricultural farms, and control sites, considered as the least impacted sites. This was done to analyse land use types' role in the adsorption of chemical pollutants onto MPs. MPs were retrieved in periodic intervals of 7 days, 14 days and 35days calculated based on the day of deployment for both summer and autumn seasons and analysed for Sulfamethoxazole, Ciprofloxacin, 17β-Estradiol, 4-(2, 6-dimethyl-2-heptyl) phenol using high-resolution liquid chromatography–mass spectrometry LC-MS/MS equipped with a triple quadrupole (QqQ) analyser. Concurrent with MP retrieval water physicochemical variables: pH, dissolved oxygen (DO), temperature, turbidity, electrical conductivity (EC), total suspended solids (TSS), total dissolved solids, total alkalinity and total hardness. The adsorption kinetics mechanism was studied in the laboratory between PET and PP of two size ranges and Sulfamethoxazole, Ciprofloxacin, and 17β-Estradiol model chemical. The results indicate that land use practices significantly impacted the concentration of the adsorbed chemicals on MPs. Sites downstream of the WWTW had higher concentrations of Sulfamethoxazole: 11119.6001±12552.4120ngL-1 and ciprofloxacin: 30285.19± 28783.7821ngL-1 adsorbed onto MPs in the Bloukrans River compared to the concentration of same compounds from other land use types along the same River catchment. Agriculturally impacted sites had higher concentrations of 17β-Estradiol on MPs; 11624.5611 ± 15382.2923ngL-1 and 100.3635± 29.6321ngL-1 in Swartkops and Bloukrans Rivers respectively compared to other sites. These results suggest that land use is an essential factor influencing chemical inputs into rivers and their adsorption onto MPs. Adsorption was higher for the MP of smaller sizes compared to MPs with bigger sizes, indicating that size is an essential factor that influences the vector effects of MPs. Adsorption was significantly higher after 35 days than all other days during the two seasons (P< 0.05). The adoption kinetics data fitted well with the pseudo-second-order model (R2> 0.99), indicating that chemisorption mechanisms may be the rate-limiting step. Data did not fit the intraparticle diffusion model. Both film diffusion and intraparticle diffusion possibly influenced the rate-limiting adsorption step simultaneously. Regarding the relationship between adsorption and water physico-chemical variables, of special interest a positive correlation between total alkalinity, electrical conductivity, total hardness, and total suspended salts (TDS) and the concentration of the adsorbed chemicals was observed. While the relationship between adsorption and dissolved oxygen was negative. The physicochemical variables with a positive relationship with adsorption are indicative of pollution. Therefore, the result suggests that increasing pollution tends to favour higher adsorption. The results in this study highlight the insights on i) the influence of land use on adsorption, ii) the role of exposure duration on adsorption, iii) the influence of seasonality and MP sizes on adsorption iv) relationship between water physicochemical parameters and adsorption as well as v) establishing adsorption kinetic mechanism. These findings are critical to better understanding the so-called vector effects of MPs and the management associated with MPs in river systems and form essential data sets needed in developing effective pollution mitigation strategies that are region-specific.

Plastic pollution has become a global problem for marine ecosystems. Microplastics (MPs) are consumed by several marine organisms, including benthic and pelagic fish species that confuse them with food sources, thus contributing to bioaccumulation along the food chain. In addition to structural intestinal damage, ingestion of MPs represents a pathway for fish exposure to potentially hazardous chemicals, too. Most of them are endocrine disrupters, genotoxic or induce immune depression in fish.Accordingly, we assessed the combined toxicological effects of microplastics (MPs) and adsorbed pollutants by adding them to marine fish diet. European sea bass (Dicentrarchus labrax) juveniles were fed for 60 days with feeds containing polypropylene MPs, either virgin or contaminated with chemical pollutants (a blend of dichlorodiphenyldichloroethylene, chlorpyrifos, and benzophenone-3). The data demonstrated a synergic action of MPs and chemical pollutants to induce an inflammatory-like response in distal intestine of sea bass as shown by the up regulation of cytokine il-6 and tnf-α expression. Morphological analysis detected the presence of a focus of lymphocytes in anterior and posterior intestinal segments of fish fed with contaminants in the diet. With regard to microbiota, significant changes in bacterial species richness, beta diversity, and composition of gut microbiota were observed as a consequence of both pollutants and polluted MPs ingestion. These perturbations in gut microbial communities, including the reduction of beneficial lactic acid bacteria and the increase in potential pathogenic microorganism (Proteobacteria and Vibrionales), were undeniable signs of intestinal dysbiosis, which in turn confirmed the signs of inflammation caused by pollutants, especially when combined with MPs. The results obtained in this study provide, therefore, new insights into the potential risks of ingesting MPs as pollutant carriers in marine fish.

The evidence of in-vivo and in-vitro studies on microplastic and nano plastic toxicity in mammals: A possible threat for an upcoming generation?

• MPs detected in foods and water across 10 Arab countries, raising health concerns • Bottled water, salt, seafood, meat, and poultry found contaminated with MPs • Marine plastic pollution is a major source of MPs in fish, mollusks, and crustaceans • High plastic use and poor waste systems drive dietary MP exposure in the Arab region • Urgent need for monitoring and policy to reduce MP risks to food safety and health : The widespread presence of microplastics (MPs) and nanoplastics (NPs) emerged as a global health concern. These particles have been detected in different components of the food chain, raising increasing concern regarding their potential effects on human health. This narrative review examines the existing body of literature on dietary exposure to MPs and NPs within the Arab region. Despite the growing use of plastics and escalating environmental pollution, research on dietary exposure to MPs and NPs in this region remains limited. : This narrative review screened multiple databases and identified 30 published research articles related to the presence of MPs and NPs in food and drinking water across the Arab countries. These articles were analyzed to examine key parameters, including particle type, size, shape, color, and the specific food or water sources affected. : MPs are prevalent across the Arab region, including Lebanon, Kuwait, Oman, Egypt, Algeria, Sudan, UAE, Saudi Arabia, Morocco, and Tunisia. Numerous food products, including bottled water, salt, meat and poultry have been reported to be heavily contaminated. Marine ecosystems, particularly in the Mediterranean and Red Seas, have shown substantial plastic pollution, contributing to the presence of MPs in marine species such as fish, mollusks, and crustaceans. These contaminated products enter the human food chain, leading to adverse health effects. : The presence of MPs and potential NP infiltration is due to the region’s high rates of plastic waste mismanagement, limited wastewater treatment infrastructure, and increasing plastic consumption. The findings underscore the need for comprehensive monitoring efforts and policy interventions to mitigate plastic pollution and its impact on food safety and public health in the Arab world.

Microplastic concentrations and risk assessment in water, sediment and invertebrates from Simon's Town, South Africa

Plastic pollution and its degradation into microplastics (MPs) represent a critical environmental challenge. Initially studied in aquatic ecosystems, MPs are now recognized as ubiquitous emerging contaminants, detected in atmosphere, water, soils, compost and soft tissues of living organisms. This widespread occurrence raises increasing concern about their environmental fate and potential impacts on ecosystems and human health, particularly in terrestrial matrices such as compost and agricultural soils. Our goal was to develop and evaluate a method for extracting and determination MPs in these complex matrices, given their significance for agricultural sustainability. A methodology was developed based on reported techniques, adapted to overcome the inherent heterogeneity of the samples. The protocol included physical separation and analysis. Characterization involved Fourier-transform infrared spectroscopy (FTIR) for polymer identification, optical microscopy for morphometric analysis, and statistical methods to compare samples. Extraction was performed via sequential density fractionation (NaCl: 1.2 g·mL⁻¹; ZnCl₂: 1.6 g·mL⁻¹; NaI: 1.8 g·mL⁻¹) and oxidative digestion with H₂O₂, followed by filtration and stereomicroscope counting. We analysed three compost samples with different C/N ratios and one reference sample, four paddy soil samples from surface and subsurface horizons, flood sediment, soil amended with pelleted compost, and an undisturbed forest soil as a negative control. Process blanks and air controls (with/without air conditioning) were included to assess laboratory air quality. Results confirmed the presence of MPs in all samples, with maximum extraction in the intermediate-density solution (1.6 g·mL⁻¹). In compost, concentrations ranged from 1,793 to 8,736 microparticles per kilogram (MP kg⁻¹). In soils, surface horizons contained higher MP abundance (≥ 5 × 10³ MP kg⁻¹) than subsurface horizons (≤ 10³ MP kg⁻¹), with amended soils and sediment showing intermediate levels. Statistical analysis revealed significant differences between samples and a positive association between MP abundance and organic matter content. Air controls indicated airborne contamination, exacerbated by air conditioning use. Although FTIR could not conclusively identify polymers due to fouling, detailed analysis of particle shape, size, and colour was achieved via spectroscopic microscopy. MPs in the reference compost were attributed to cross-contamination, highlighting the challenge of avoiding it. In summary, the method successfully extracted MPs, showing a predominance of mid-density plastics isolated with ZnCl₂. Our findings also emphasize the need for strict anti-contamination measures, especially in non-specialized labs. This preliminary study underscores the urgency of developing efficient and reproducible protocols for accurate polymer identification and confirms MP pollution as a priority issue in compost and agricultural soil research.

Disrupted intestinal mucosal barrier mediated by alcohol consumption aggravates systemic microplastic accumulation

Due to the ecological risk posed by plastic pollution, biodegradable plastics (BDPs) usage in agriculture has gained attention as an alternative to conventional plastics. However, agricultural soil remains a major reservoir of microplastics (MPs) in today’s global environment. Given the persistence of MPs, few studies have focused on the fate and transport of conventional MPs from agricultural topsoil. However, understanding the transport of biodegradable MPs is largely unknown. The aim of this study is to analyze the erosion and transport behavior of biodegradable polylactic acid (PLA) MPs (size 250 – 300 μm) under simulated heavy rainfall events on fallow and crusted agricultural soils. The experiment used fluorescent PLA filament to obtain the MPs. Based on the fluorescent property of the PLA MPs, a simple, reliable, and cost-effective method using darkroom photography under a 365nm UV lamp, and an Image J script was developed for quantification. The study was conducted on three plots (1m × 1m) of loamy soil at an agricultural field in the Czech Republic. A concentration of 4 g m-2 of PLA MPs was incorporated into the top 5 cm of the soil in each plot. Rainfall simulations with an intensity of 60 mm h-1 were carried out twice within one week in April 2022. The results showed a general depletion of biodegradable PLA MPs in the delivered sediment. Eroded sediments showed mean enrichment ratios of 0.59 ± 0.05 in the fallow plot and 1.45 ± 0.37 in the crusted plot. Higher MP enrichment and sediment delivery were observed on crusted soil compared to fallow soil, suggesting a more conservative erosion and transport for the latter. Overall, our study highlights that a relatively high-density biodegradable MP, such as PLA, tends to remain within the topsoil and is negligibly affected by rainfall-induced surface runoff and very low infiltration capacity.

Plastic waste is a major source of microplastic (MP) pollution, posing adverse environmental and public health risks. This study assessed MP abundance in 24 urban ponds and lakes within the Kolkata Municipal Corporation, India, during the post- and pre-monsoon seasons of 2022-2023. Results showed that MP concentrations were significantly higher in the post-monsoon season (20 ± 3.46 items L⁻1; ANOVA, p < 0.05), with red, white, and black particles being the most prevalent. MPs prevalently ranged between 500 and 1000µm with fibers constituting 58-59% of the total MPs. Fourier-transform infrared (FTIR) analysis identified polyethylene (PE) as the dominant polymer. MP abundance showed negative correlations with dissolved oxygen and turbidity, and positive associations with pH, TDS, BOD₅, and total coliform counts. A Support Vector Machine (SVM) model was developed for morphology-based MP classification, achieving an accuracy of 89%. Additionally, remote sensing and GIS techniques were used to develop index-based models for water-body identification and MP quantification (items L⁻1) using spectral data from Sentinel-2 imagery. These models demonstrated high validation accuracy of 98.01% and 92.60%, respectively. Metal analysis of sediment and MPs of water detected chromium, suggesting possible MP-metal interactions within sediments. Although the Pollution Load Index (PLI) indicated relatively low contamination levels, the Polymer Hazard Index (PHI) exceeded 1000, indicating substantial ecological risk. Future studies should focus on long-term monitoring, socio-economic and health impact assessments and development of effective mitigation strategies particularly addressing plastic-waste derived-MPS.

Plastic pollution has become a problem for many marine organisms. The omnipresent microplastics (MPs) are of particular concern due to their effect on a variety of species, including reef-building corals. Corals have been found to interact with MPs, ingest, and even incorporate them into their skeletons. However, knowledge on what affects the responses of coral polyps to these indigestible particles is still constrained. Here, we aimed to unravel factors influencing the feeding responses of coral polyps to MPs. Particularly, we (I) assessed coral feeding responses (i.e., reaction, ingestion, and incorporation) to different MP polymers and shapes in the presence vs. absence of a biofilm and food during feeding trials. We (II) characterized polymer-biofilm-associated compounds to infer potential mechanistic processes underlying the observed differences. We (III) evaluated effects of food availability on polyp activity under continuous MPs exposure. We found that the polymer type most strongly influenced the feeding response, and that MP shape additionally affected ingestion and incorporation. While we detected species-specific differences in responses, the presence of a biofilm and food had only minor effects. We identified 11 polymer-biofilm-associated compounds with potential stimulating and toxic influence. Polyp activity was not altered by the prevalence of natural food. These findings suggest that the particle recognition mechanisms of corals are, although generally well suited to differentiate between MPs and natural particles, rely primarily on chemoreception of substances leaching from MP polymers, with mechanoreception contributing to shape-specific responses. We conclude that future assessments of coral-MPs interactions should consider polymer- and shape-specific effects, as these appear to be the key driver of the coral feeding response to MPs.

The review discusses the ways in which marine pollution proliferates due to plastics and microplastics and provides an overview of the possible influences of the plastics in water body along with its detrimental effects. Erosion and degradation of plastics on the beaches end up in their surface embrittlement in addition to microcracking, it yields micro-particles which are then carried by carriers into the water-body by the tidal waves or winds. Opposing the inorganic fine particles existing in ocean water-body, microplastics tend to accumulate into the persistent organic pollutants (POPs) by breakdown and detachment. The POPs are distributed amongst many types of plastics that pollute the environment. Most of the pollutants under POPs polluting water show it is consequent due to micro-plastics and other plastic mediums. Also, when these micro-particles containing a tremendous amount of POPs are ingested by marine biota and species, it poses a remarkable influence on them. However, Bioavailability and how much potential transfers of POPs can occur in distinct levels of trophic is still unknown while the harm caused by such POPs in species needs to be studied and quantified with help of proper scientific modelling techniques. As the plastic pollution in oceans is rising at an alarming rate it is necessary to understand probable impacts of plastics and microplastics in oceans and other water bodies.

Study questionIs there any indication for presence of viral RNA in FF, CC, immature oocytes or endometrial biopsy (EB) of SARS-CoV–2 patients undergoing ovarian stimulation?Summary answerViral RNA is undetectable in FF, CC and EB with RT-PCR. However, S-protein expression on corona radiata cells suggests susceptibility to SARS-CoV–2 infection.What is known alreadyThe effects of a SARS-CoV–2 infection on the female reproductive system are still poorly understood. Theoretically, co-localisation of the angiotensin converting enzyme (ACE2) and transmembrane serine protease 2 (TMPRSS2) on human blastocysts implies susceptibility to viral infection, mediated by the coronavirus spike (S) protein. To date, SARS-CoV–2 RNA was undetectable in mature oocytes from COVID–19 patients, despite the expression of ACE2 and TMPRSS2. The presence of viral RNA in endometrial tissue, immature oocytes, CC or FF has not yet been investigated in samples from patients with positive nasopharyngeal SARS-CoV–2 test.Study design, size, durationThis is a prospective, single-centre, observational study including ten patients with a positive nasopharyngeal swab for SARS-CoV–2, performed 48 hours before oocyte retrieval (OR), from September 2020 to January 2021. A patient was eligible if she preferred to continue treatment following adequate counselling of the unknown but presumably low risk for vertical transmission. Since a freeze-all strategy was applied, an EB was performed.Participants/materials, setting, methodsDuring OR, all protective measures were taken. Pooled FF, CC and EB from each patient were tested for viral RNA presence with RealStar® SARS-CoV–2 RT-PCR-Kit1.0 (Altona-Diagnostics). Ct values <40 were considered positive. EB was collected for pathological evaluation and cultured to obtain endometrial stromal cells (EnSC). Immature oocytes and EnSC were tested for S-protein expression by immunohistochemistry with anti-S antibody (MA5–35958, Thermo-Fisher Scientific) followed by Alexa Fluor™ 488-donkey-anti-mouse (Thermo-Fisher Scientific) and visualized with confocal microscopy.Main results and the role of chanceSARS-CoV–2 RNA was undetectable in the pooled FF, CC and EB from all patients included in the study. Histological analysis of the EB showed no pathological modifications, including inflammatory reaction, as compared to biopsies collected from swab negative patients. After staining with anti-S antibody, cultured EnSC and immature oocytes tested negative for the S-protein. However, the binding of anti-S antibody was demonstrated on the corona radiata cells remaining on the zona pellucida after oocyte denudation for intra-cytoplasmatic sperm injection, indicating presence of SARS-CoV–2. In that case, the explanation for the undetectable viral RNA in CC could be that the viral RNA concentration remained under the detection limit of the currently used RT-PCR test.Limitations, reasons for cautionThis study was conducted in a small population (ten patients included) with different viral load, with mild or without symptoms of COVID–19. Another important limitation is the absence of validation of the RT-PCR protocol for the investigation of other types of samples than nasopharyngeal swabs.Wider implications of the findings: The absence of SARS-CoV–2 RNA in all samples analysed represents a step further in reassuring a safe ART program for COVID–19 patients. However, the presence of S-protein on corona radiata cells warrants further investigation, since the theoretical possibility to infect human oocytes and/or embryos cannot be ruled out.Trial registration numberNCT04425317

The past several decades have seen alarming declines in the reproductive health of humans, animals and plants. While humans have introduced numerous pollutants that can impair reproductive systems (such as well-documented endocrine disruptors), the potential for microplastics (MPs) to be contributing to the widespread declines in fertility is particularly noteworthy. Over the same timespan that declines in fertility began to be documented, there has been a correlated shift towards a “throw-away society” that is characterised by the excessive consumption of single-use plastic products and a concomitant accumulation of MPs pollution. Studies are showing that MPs can impair fertility, but data have been limited to rodents that were force-fed hundreds of thousands of times more plastics than they would be exposed in the environment. As a first step to link in vitro health effects with in vivo environmental exposure, we quantified microplastics in the follicular fluid of women and domestic cows. We found that the concentrations of polystyrene microplastics that naturally occurred in follicular fluid were sufficient to compromise the maturation of bovine oocytes in vitro. Collectively, these findings demonstrate that microplastics may also be contributing to the widespread declines in fertility that have been occurring over recent Anthropocene decades.