Anthropogenic contamination of tap water, beer, and sea salt

A method for the characterisation of microplastics in sludge

Microplastics (MP) have become a concern owing to their increasing detection in the environment and potential impact on ecosystems. One of the main MP reservoirs is sludge generated during wastewater treatment. Estimates suggest that, through sludge settling, treatment processes remove between 80 and 90 % of MP present in wastewater. Nevertheless, reliable measurements of actual plastics loads retained by sludge are still lacking for management purposes. Hence, our goal was to validate a quick method for MP quantitation in sludge. Recovery tests were conducted with red low-density polyethylene (LDPE) fragments whose sizes ranged between 5 to 1 mm, 1 to 0.5 mm and 500 to 150 μm. For each size fraction, either 10 or 100 LDPE fragments were spiked into wet sludge (50 mL). Subsequent LDPE analysis involved steps such as freeze-drying, sieving, Fenton purification, visual shorting and FTIR identification. When expressed as number of fragments, quantitative (i.e. percentage values between 80 and 100) were obtained regardless of size fraction or initial spiked number. In terms of total spiked LDPE weight, however, recoveries consistently exceeded 100 % because LDPE fragments retained other materials. Such residues contributed to an overestimation of MP by weight up to 33 % of the 500−150 μm fraction.

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Method was validated by spiking LDPE fragments.

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Recoveries based on MP number showed good precision and accuracy.

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Residues attached to MP resulted in overestimated recoveries by MP weight up to 33 %.

Plastic Particle Ingestion by Wild Freshwater Fish: A Critical Review

Plastic pollution, especially microplastics (MP) pollution, is a hot topic in both mainstream media and scientific literature. Although rivers are potentially the major transport pathway of this pollution to the sea, plastic contamination in freshwater bodies is comparatively understudied. Microplastic pollution in freshwater fish is of growing interest, and while few studies exist, discrepancies do occur in the sampling, extraction, and identification of MP and in the expression of the results. Even though those differences hamper comparisons between some studies, a comparative work has been performed to identify the factors influencing MP ingestion by fish and consequently to target potential ecological traits that can be used to monitor species. Monitoring plastic ingested by fish will give relevant ecological information on MP pollution. This review focuses on MP ingestion by wild freshwater and estuarine fish. In addition to providing an overview of the existing data concerning contamination levels in wild freshwater fish, we aimed to (1) propose several overall recommendations on the methodologies applicable to all biota, (2) compare MP contamination levels in fish and in their environment, and (3) determine which parameters could help to define fish species for monitoring.

A new approach for routine quantification of microplastics using Nile Red and automated software (MP-VAT)

Microplastics are widespread contaminants in the environment. However, most identification protocols rely on long and subjective visual counting, which could be improved using staining dyes. Thus, the objective of this work is to identify the best staining dye protocol and create an objective and quick automated counting software for microplastics. Tests were conducted to identify the most appropriate of eight staining dye solutions and of six wavelengths for virgin and weathered synthetic polymers, textile fibers, natural organic matter and filters. Nile Red produced the best results (without interfering in infrared spectra) rendering microplastics fluorescent at 254 nm, but with limited number of fluorescent polymers, and at 470 nm (with orange filter), with fluorescence of plastics as well as natural organic matter (requiring a digestion step). Next, a script was developed in ImageJ for the automatic quantification and characterization in shape (fiber, fragment, particle) and size of fluorescent microplastics, the Microplastics Visual Analysis Tool (MP-VAT). MP-VAT was evaluated, producing recovery rates in the range of 89.0-111.1% in spiked filters under 470 nm. Furthermore, this package is accompanied by a script that sets a scale from a known filter diameter, MP-SCALE, and a script that allows user threshold setting, MP-ACT.

Impacts of plastic products used in daily life on the environment and human health: What is known?

Plastics are indispensable and persistent materials used in daily life that can be fragmented into micro- or nanoplastics. They are long polymer chains mixed with additives that can be toxic when in contact with distinct species. The toxicity can result from polymer matrix, additives, degradation products and adsorbed contaminants. Notwithstanding, there is still an immense gap of information concerning the individual and mixed impacts of plastics. Hence, in this study, we characterize the most common plastic materials widely used in our daily life by its polymer type and compile the environmental and human health hazards of these polymers including the impacts of monomers, additives, degradation products and adsorbed contaminants based on literature review. In summary, polyvinyl chloride is the most toxic polymer type used daily (monomer and additives); additives are more toxic than monomers to wildlife and humans; and the most toxic additives are benzene, phthalates and lead stabilisers.

Microplastics: an emerging threat to food security and human health

Microplastic presence in seafood and foodstuff have been documented globally in recent studies. Consequently, human exposure to microplastics through the ingestion of contaminated food is inevitable and pose a risk to food security and human health. In this review, microplastics and related xenobiotics are defined, global evidence of microplastic pollution in seafood is reviewed, the impacts to commercial marine species and food security are discussed, and the current knowledge of its direct effects on human health is reviewed. In addition, limited information regarding food security and scientific gaps are identified. Although microplastics in the marine environment and its effects on marine organisms have been well documented, more research is needed to completely understand the implications of microplastics over food security and human health. Further research must focus on monitoring and eliminating microplastics along the food supply chain and determining the extent to which food security is affected by microplastic pollution.

Identification of Microfibers in the Environment Using Multiple Lines of Evidence

Microfibers, characterized as small fibers shed from textiles that are less than 5 mm in size, are a prominent contaminant in the environment. Thus, it is important that we have methods to accurately quantify and characterize them, including in water, sediment, wildlife, seafood, and drinking water samples. Unfortunately, their small size and the presence of different dyes on the microfibers themselves cause difficulties in identification via conventional spectroscopic methods of total attenuated resonance-Fourier transform infrared and Raman. To help solve some of these methodological challenges, we developed a new method employing polymer-dye binding chemistry, density tests, unique surface morphological traits, and fluorescent staining to identify microfibers in environmental samples. The identification method introduced here was tested in our laboratory via trials using microfibers shed from new textiles and environmental samples. We found that the method can be successfully applied to identify the different polymer types of microfibers, which can ultimately help source apportion microfiber contamination in the environment.

Long-term aquaria study suggests species-specific responses of two cold-water corals to macro-and microplastics exposure

Plastic pollution has been identified as a major threat for coastal marine life and ecosystems. Here, we test if the feeding behaviour and growth rate of the two most common cold-water coral species, Lophelia pertusa and Madrepora oculata, are affected by micro- or macroplastic exposures. Low-density polyethylene microplastics impair prey capture and growth rates of L. pertusa after five months of exposure. Macroplastic films, mimicking plastic bags trapped on deep-sea reefs, had however a limited impact on L. pertusa growth. This was due to an avoidance behaviour illustrated by the formation of skeletal 'caps' that changed the polyp orientation and allowed its access to food supply. On the contrary, M. oculata growth and feeding were not affected by plastic exposure. Such a species-specific response has the potential to induce a severe change in coral community composition and the associated biodiversity in deep-sea environments.

Detection of Various Microplastics in Human Stool: A Prospective Case Series

BACKGROUND

Microplastics are ubiquitous in natural environments. Ingestion of microplastics has been described in marine organisms, whereby particles may enter the food chain.

OBJECTIVE

To examine human feces for the presence of microplastics to determine whether humans involuntarily ingest them.

DESIGN

Prospective case series in which participants completed a food diary and sampled stool according to step-by-step instructions.

SETTING

Europe and Asia.

PARTICIPANTS

Eight healthy volunteers aged 33 to 65 years.

MEASUREMENTS

After chemical digestion, Fourier-transform infrared microspectroscopy was used to analyze the presence and shape of 10 common types of microplastic in stool samples.

RESULTS

All 8 stool samples tested positive for microplastics. A median of 20 microplastics (50 to 500 µm in size) per 10 g of human stool were identified. Overall, 9 plastic types were detected, with polypropylene and polyethylene terephthalate being the most abundant.

LIMITATIONS

There were few participants, and each provided only 1 sample. The origin and fate of microplastics in the gastrointestinal tract were not investigated.

CONCLUSION

Various microplastics were detected in human stool, suggesting inadvertent ingestion from different sources. Further research on the extent of microplastic intake and the potential effect on human health is needed.

PRIMARY FUNDING SOURCE

None.

Photoreforming of Nonrecyclable Plastic Waste over a Carbon Nitride/Nickel Phosphide Catalyst

With over 8 billion tons of plastic produced since 1950, polymers represent one of the most widely used—and most widely discarded—materials. Ambient-temperature photoreforming offers a simple and low-energy means for transforming plastic waste into fuel and bulk chemicals but has previously only been reported using precious-metal- or Cd-based photocatalysts. Here, an inexpensive and nontoxic carbon nitride/nickel phosphide (CN_x|Ni₂P) photocatalyst is utilized to successfully reform poly(ethylene terephthalate) (PET) and poly(lactic acid) (PLA) to clean H₂ fuel and a variety of organic chemicals under alkaline aqueous conditions. Ni₂P synthesized on cyanamide-functionalized carbon nitride is shown to promote efficient charge separation and catalysis, with a photostability of at least 5 days. The real-world applicability of photoreforming is further verified by generating H₂ and organics from a selection of nonrecyclable waste—including microplastics (polyester microfibers) and food-contaminated plastic—and upscaling the system from 2 to 120 mL while maintaining its efficiency for plastic conversion.

Microparticles in Table Salt: Levels and Chemical Composition of the Smallest Dimensional Fraction

This study evaluates the chemical composition of microplastic materials (MPs) and non-synthetic particles in different table salts of marine origin by the µFT-IR technique. This research focuses on the microparticles fraction within 10–150 µm of size. Eleven commercial trademarks coming from Italy (IT = 6) and Croatia (CRO = 5) were grouped in two different cost ranges, cheap (n = 5) and expensive (n = 6) and were analysed in replicates (n = 3). Levels and chemical composition of microparticles measured in commercial products were correlated on a statistical basis to some factors of variability of potential scientific interest (geographical origin of marine salt, cost of commercial products, etc.). Results of analyses performed on the tested size fraction of microparticles (10–150 µm) evidence that: (i) levels of MPs are within 0.17–0.32 items/g (IT) and 0.07–0.20 items/g (CRO); (ii) non-synthetic particles detected are mostly made by fibres made of cellulose acetate; (iii) Nations show a different chemical composition of MPs recovered in analysed trademarks (PET and PVC from Italy; PA, PP, and nylon from Croatia); (iv) the annual amount ingested by humans from marine salt consumption ranges between 131.4–372.3 items/y (CRO) and 306.6–580.35 items/y (IT) considering a dose of 5 g of salt per day; (v) statistics performed on factors of interest evidenced that the geographical origin of marine salt do not affect neither levels nor chemical composition of MPs in tested trademarks; while slight correlations are recorded with non-synthetic particles. Further studies are needed to better explore on statistical basis if both levels and chemical composition of MPs in table salts of marine origin can be used or not as good indicators of marine pollution.

A preliminary screening of HBCD enantiomers transported by microplastics in wastewater treatment plants

Hexabromocyclododecane (HBCD), a commonly used flame retardant, causes public concern due to its potential negative effects on organisms. Microplastics are suspected to contain certain amounts of HBCD. Wastewater treatment plants (WWTPs) are believed to be one of the largest sources of microplastics and a sink for micropollutants, providing opportunities for interactions between them, especially for hydrophobic micropollutants such as HBCD. There is a lack of studies focusing on the prevalence of microplastics and HBCD they carry. The present study investigated two typical WWTPs in Hong Kong, Stonecutters Island WWTP (SCI) and Shek Wu Hui WWTP (SWH), which employ different treatment technologies. The abundance of microplastics decreased with the treatment flow, and the microplastic concentrations in effluent were at intermediate levels (0.40 and 0.27particles/L) compared with the levels reported in previous studies. The concentrations of HBCD transported by microplastics reached 4184.4 ng/g in the effluent, whereas that in sewage water (dissolved phase) was 0.8 pg/L. For microplastics, 7.32 × 10⁷ and 2.24 × 10⁷ particles per day were estimated to be released from SCI and SWH, respectively into the environment; the release of HBCD carried by microplastics potentially reached 15.5 g per day, whereas the dissolved HBCD in the effluent may reach 0.067 g per day. A preliminary risk assessment of HBCD transported by microplastics showed that HBCD posed negligible risk; nevertheless, attention should be paid to the continual discharge of microplastics from WWTPs.

Microplastic contamination of table salts from Taiwan, including a global review

Plastic pollution is a rapidly worsening environmental problem, especially in oceanic habitats. Environmental pollution with microplastic particles is also causing food consumed by humans to be increasingly polluted, including table salts. Therefore, we present the first study which focuses only on table salt products purchased in Taiwan which we examined for the presence of microplastics. We used Fourier transform infrared spectroscopy to identify the polymer type of each particle. Within 4.4 kg of salt, we detected 43 microplastic particles which averages to 9.77 microplastic particles/kg. The identified polymer types were, in descending abundance, polypropylene, polyethylene, polystyrene, polyester, polyetherimide, polyethylene terephthalate, and polyoxymethylene. We combined our novel results with those of previous studies to provide the first global review of microplastic contamination of table salts. We found that 94% of salt products tested worldwide contained microplastics, with 3 out of 27 polymer types (polyethylene terephthalate, polypropylene, polyethylene) accounting for the majority of all particles. Averaging over seven separate studies, table salts contain a mean of 140.2 microplastic particles/kg. With a mean annual salt consumption of ~3.75 kg/year, humans therefore annually ingest several hundred microplastic particles from salt alone.

Human Consumption of Microplastics

Microplastics are ubiquitous across ecosystems, yet the exposure risk to humans is unresolved. Focusing on the American diet, we evaluated the number of microplastic particles in commonly consumed foods in relation to their recommended daily intake. The potential for microplastic inhalation and how the source of drinking water may affect microplastic consumption were also explored. Our analysis used 402 data points from 26 studies, which represents over 3600 processed samples. Evaluating approximately 15% of Americans' caloric intake, we estimate that annual microplastics consumption ranges from 39000 to 52000 particles depending on age and sex. These estimates increase to 74000 and 121000 when inhalation is considered. Additionally, individuals who meet their recommended water intake through only bottled sources may be ingesting an additional 90000 microplastics annually, compared to 4000 microplastics for those who consume only tap water. These estimates are subject to large amounts of variation; however, given methodological and data limitations, these values are likely underestimates.

Microplastics in freshwaters and drinking water: Critical review and assessment of data quality

Microplastics have recently been detected in drinking water as well as in drinking water sources. This presence has triggered discussions on possible implications for human health. However, there have been questions regarding the quality of these occurrence studies since there are no standard sampling, extraction and identification methods for microplastics. Accordingly, we assessed the quality of fifty studies researching microplastics in drinking water and in its major freshwater sources. This includes an assessment of microplastic occurrence data from river and lake water, groundwater, tap water and bottled drinking water. Studies of occurrence in wastewater were also reviewed. We review and propose best practices to sample, extract and detect microplastics and provide a quantitative quality assessment of studies reporting microplastic concentrations. Further, we summarize the findings related to microplastic concentrations, polymer types and particle shapes. Microplastics are frequently present in freshwaters and drinking water, and number concentrations spanned ten orders of magnitude (1 × 10-2 to 108 #/m3) across individual samples and water types. However, only four out of 50 studies received positive scores for all proposed quality criteria, implying there is a significant need to improve quality assurance of microplastic sampling and analysis in water samples. The order in globally detected polymers in these studies is PE ≈ PP > PS > PVC > PET, which probably reflects the global plastic demand and a higher tendency for PVC and PET to settle as a result of their higher densities. Fragments, fibres, film, foam and pellets were the most frequently reported shapes. We conclude that more high quality data is needed on the occurrence of microplastics in drinking water, to better understand potential exposure and to inform human health risk assessments.

Analysis and Prevention of Microplastics Pollution in Water: Current Perspectives and Future Directions

The analysis, prevention, and removal of microplastics (MPs) pollution in water is identified as one major problem the world is currently facing. MPs can be directly released to water or formed by the degradation of bigger plastics. Nowadays, it is estimated that annually between 4 and 12 million tonnes of plastic go into the seas and oceans-with a forecast for them to outweigh the amount of fish in 2050. Based on the existing studies, the characterization of MPs in waters is still one of the remaining challenges because they can be easily confused with organic or other types of matter. Consequently, there is an urgent necessity to establish pathways for the chemical identification of the MP nature. In this perspective, the recent techniques and instrumentation for MP characterization (Raman and Fourier-transform infrared spectroscopies and microscopies, pyrolysis and thermal desorption gas chromatography, imaging techniques, etc.) are discussed including considerations to the multidimensionality of the problem. This perspective also summarizes and provides updated data on the sources and occurrence, transport and fate of MPs in aquatic ecosystems, as well as influencing conditions and factors affecting dispersal. Additionally, how engineering and biotechnological tools, such as advanced water treatments, would help to control, reduce, or even eliminate MP pollution in the near future is outlined.

Microplastics Detection in Streaming Tap Water with Raman Spectroscopy

Microplastic particles have been found in drinking water sources worldwide and, thus, also in our food and beverages. Especially small microplastics, with sizes of 1 mm and less, cannot be identified reliably without spectroscopic means such as Fourier transform infrared spectroscopy (FTIR) or Raman spectroscopy, usually applied to the particles extracted from the samples. However, for drinking and tap water, with its comparatively low biological loads, direct observation may be possible and allows a point-of-entry monitoring for beverages and food to ensure uncontaminated drinking water is being used. In a proof of concept, we apply Raman spectroscopy to observe individual microplastic particles in tap water with added particulate and fluorescent contaminants streaming with 1 L/h through a custom-made flow cell. We evaluated several tubing materials for compatibility with microplastic suspensions containing three different polymers widely found in microplastic surveys worldwide. The experiment promises the monitoring of streaming tap water and even clear surface waters for microplastics smaller than 0.1 mm.

Review of micro- and nanoplastic contamination in the food chain

Whereas the dramatic environmental impact of plastic waste rightfully receives considerable attention by scientists, policy makers and public in general, the human health impact of micro- and nanoplastics contamination of our food and beverages remains largely unknown. Indeed, most studies aim at understanding the environmental impact rather than the human health impact of a possible exposure to micro- and nanoplastics. In addition, these papers generally lack a methodological, standardised approach. Furthermore, some studies focus on the damage to and contamination level of animal species collected from the wild environment, and others investigate the rate and biology of microplastic uptake of animals fed with microplastics in laboratory. This review aims at understanding human exposure. Since there is, with few exceptions, no evidence available on the presence of micro- and nanoplastics in a normal diet, this study takes an indirect approach and analyses peer-reviewed publications since 2010 that document the presence of micro- and nanoplastics in those animals (more than 200 species) and food products that are part of the human food chain and that may thus contribute directly or indirectly to the uptake of micro- and nanoplastics via the human diet. It also addresses the question of the definitions, the methodologies and the quality criteria applied to obtain the reported results. This review suggests that, beyond a few estimations and comparisons, precise data to assess the exact exposure of humans to micro- and nanoplastics through their diet cannot be produced until standardised methods and definitions are available.

The Anthropology of Plastics: An Agenda for Local Studies of a Global Matter of Concern

Anthropology has largely ignored plastics, even as they have emerged as the paradigmatic material-and problem-of our times. In this article, we make the case for an anthropology of plastics as a priority for environmental and medical anthropological research. Drawing from exploratory fieldwork in India, we briefly highlight the benefits and risks of different types of plastics, identify areas for anthropological investigations of human-plastic entanglements, and unpack major debates about plastic control. We recommend analyses that take into account the social life of plastics and the life cycle of plastic production, consumption, circulation, disposal, retrieval, and decomposition. We propose a facilitator role for anthropologists in bringing environmental NGOs and the plastic industry to the table to reduce the human and environmental health risks related to widespread reliance on plastics. Overall, we argue that anthropological analyses are urgently needed to address environmental and global health concerns related to plastics.

Microscopy and elemental analysis characterisation of microplastics in sediment of a freshwater urban river in Scotland, UK

Understanding of the sources, fate, and impact of microplastics (MPs, < 5 mm) remains limited, particularly in freshwater environments, while limited comparability across available surveys hinders adequate monitoring and risk assessment of these contaminants. Here, the distribution of microscopic debris in an urban river close to the marine environment in the West of Scotland was investigated to assess concentration and distribution of primary and secondary MPs. Also, the efficiency of light and scanning electron microscopy with energy-dispersive spectroscopy (SEM-EDS) was evaluated for characterisation and quantification of MPs sized 2.8 mm-11 μm. Bank sediment samples were collected twice from the River Kelvin in Glasgow and were size-fractionated and processed for extraction of MPs by density separation. Sample MPs spiking and use of procedural blanks allowed the influence of processing on field data quality to be considered. Total abundances were 161-432 MPs kg^-1 dry sediment, with fibres as the dominant type, comprising > 88% of total counts. Nevertheless, fibres in blanks suggest potential contributions from atmospheric contamination. Moreover, fibres concentrated mainly in fractions < 0.09 mm suggesting that their fate may be influenced by drivers of fine sediment dynamics in rivers. While no primary MPs were observed, metallic and glass pellets were present in high abundances in settled material and could be easily misidentified by visual inspection, demonstrating that compositional analysis is needed to avoid analytical errors from MP misidentification and overestimation. SEM-EDS allowed for a quick screening of plastic vs non-plastic pellets and improved identification of smaller fragments, whereas more advanced techniques are needed for proper identification of fibres. This study is the first to report on MPs in freshwater rivers in Scotland and suggests that diffuse sources of pollution may be delivering secondary MPs to the river. Their sources, fate, and risk in these systems will thus warrant further attention.

Nanoplastics formed during the mechanical breakdown of daily-use polystyrene products

Large amounts of plastics are released into the environment every day. These released plastics have a clearly documented negative effect on wildlife. Much research attention has been given to large plastic pieces and microplastics. However, if the breakdown of plastics is a continous process, eventually nanoplastics will be produced. Nanoplastics will affect wildlife differently from larger plastic pieces. We have studied the products formed by the mechanical breakdown of two commonly used polystyrene products, takeaway coffee cup lids and expanded polystyrene foam. After breakdown using a food processor, we characterized the breakdown products using seven different methods and found nanosized polystyrene particles with different shapes and negative or nearly neutral surface charges. These results clearly demonstrate that daily-use polystyrene products can break down into nanoparticles. Model polystyrene particles with different sizes and surface modifications have previously been shown to have different negative effects on wildlife. This indicates that breakdown nanoparticles might have the potential to cause cocktail effects in nature.

Emergence of Nanoplastic in the Environment and Possible Impact on Human Health

On account of environmental concerns, the fate and adverse effects of plastics have attracted considerable interest in the past few years. Recent studies have indicated the potential for fragmentation of plastic materials into nanoparticles, i.e., "nanoplastics," and their possible accumulation in the environment. Nanoparticles can show markedly different chemical and physical properties than their bulk material form. Therefore possible risks and hazards to the environment need to be considered and addressed. However, the fate and effect of nanoplastics in the (aquatic) environment has so far been little explored. In this review, we aim to provide an overview of the literature on this emerging topic, with an emphasis on the reported impacts of nanoplastics on human health, including the challenges involved in detecting plastics in a biological environment. We first discuss the possible sources of nanoplastics and their fates and effects in the environment and then describe the possible entry routes of these particles into the human body, as well as their uptake mechanisms at the cellular level. Since the potential risks of environmental nanoplastics to humans have not yet been extensively studied, we focus on studies demonstrating cell responses induced by polystyrene nanoparticles. In particular, the influence of particle size and surface chemistry are discussed, in order to understand the possible risks of nanoplastics for humans and provide recommendations for future studies.

Transfer of PCBs from Microplastics under Simulated Gut Fluid Conditions Is Biphasic and Reversible

The role of plastic as a vector for bioaccumulation of toxic chemicals is central to the risk assessment of microplastic for human health and the environment. However, transfer kinetics of sorbed contaminants from ingested microplastics are poorly understood. We develop and parametrize a chemical exchange model on microplastics in a gut fluid mimic of aquatic biota, and also included food to provide a better representation of contaminant dynamics when plastic and food are ingested, as would occur in nature. The transfer kinetics of 14 polychlorinated biphenyls (PCBs) were measured in gut fluid mimic systems under three environmentally relevant exposure scenarios of plastic ingestion by organisms, for low-density polyethylene (LDPE) and polyvinyl chloride (PVC), and were evaluated with the model. Chemical transfer was demonstrated to be biphasic and fully reversible, with fast exchange within hours followed by a slow transfer lasting for weeks to months. In clean gut systems, the bioavailability of plastic-associated PCBs for lugworms and cod ranged from 14 to 42% and 45-83% respectively. However, in contaminated gut systems, clean microplastic was capable of rapidly extracting ("cleaning") PCBs from food inside the gut, thus demonstrating that the effect of microplastic is context dependent. Therefore, chemical contamination and cleaning are likely to occur simultaneously due to the ingestion of microplastic.

Abundance and characteristics of microplastics in market bivalves from South Korea

Microplastic contamination in marine organisms is a growing environmental issue with implications for seafood safety. Among marine organisms, shellfish are considered to be an important route of human exposure to microplastics because they filter a large volume of seawater while feeding and, thus, accumulate microplastics from seawater; furthermore, they are consumed whole, without gut removal. In this study, a market survey was carried out to understand microplastic contamination in domestic bivalves sold in fishery markets in three major cities of South Korea. Four popular bivalve species, oyster (Crassostrea gigas), mussel (Mytilus edulis), Manila clam (Tapes philippinarum) and scallop (Patinopecten yessoensis), were selected as monitoring species, which together account for 79-84% of total shellfish consumption in Korea. The mean concentration of microplastics in these four species was 0.15 ± 0.20 n/g and 0.97 ± 0.74 n/individual. Fragments and particles smaller than 300 μm were dominant shape and size, accounting for 76% and 65% of total microplastics, respectively. Polyethylene (PE), polypropylene (PP), polystyrene (PS), and polyester were the major polymer types. Interestingly, differing polymer compositions were observed according to the culture methods and habitat characteristics of each species. PS was found in high proportions in oysters and mussels cultured in the upper layer of the water column, while the proportions decreased and those of polyester increased in Manila clams and scallops that were cultured in intertidal sediments or the middle and bottom layers of the water column. The annual dietary intake of microplastics by the Korean population via shellfish consumption was estimated as 212 n/person·year. Our results suggested that microplastic pollution is widespread in commercial bivalves and we recommend a systematic and integrative market-basket survey to clarify the current status of human exposure to microplastics.

Microplastic abundance, distribution and composition in the Pearl River along Guangzhou city and Pearl River estuary, China

Like many urban rivers, the Pearl River in China is contaminated with microplastics. Compared with marine environments, microplastic pollution in freshwater is less understood, especially in urban rivers. In the present study, the abundance and distribution of microplastics in water from the Pearl River was investigated, including the estuary and the urban section along Guangzhou. The average abundance of microplastics was 19,860 items/m³ and 8902 items/m³ in the urban section and estuary, respectively. Wastewater effluents from cities might be a main source of microplastics in the Pearl River, and the urban tributaries might act as retention systems for microplastics. Among these microplastics, over 80% of them were less than 0.5 mm. The main shapes of microplastics were film, fragment, and fiber, mostly blue or transparent. Moreover, the most common polymer types of these microplastics were polyamide (26.2%) and cellophane (23.1%). This study reveals the contamination and characteristics of microplastics in the Pearl River, and provides important data for further research on microplastics in freshwater ecosystems.

Biodegradation of Microplastic Derived from Poly(ethylene terephthalate) with Bacterial Whole-Cell Biocatalysts

At present, the pollution of microplastic directly threatens ecology, food safety and even human health. Polyethylene terephthalate (PET) is one of the most common of microplastics. In this study, the micro-size PET particles were employed as analog of microplastic. The engineered strain, which can growth with PET as sole carbon source, was used as biocatalyst for biodegradation of PET particles. A combinatorial processing based on whole-cell biocatalysts was constructed for biodegradation of PET. Compared with enzymes, the products can be used by strain growth and do not accumulated in culture solution. Thus, feedback inhibition of products can be avoided. When PET was treated with the alkaline strain under high pH conditions, the product concentration was higher and the size of PET particles decreased dramatically than that of the biocatalyst under neutral conditions. This shows that the method of combined processing of alkali and organisms is more efficient for biodegradation of PET. The novel approach of combinatorial processing of PET based on whole-cell biocatalysis provides an attractive avenue for the biodegradation of micplastics.

Global Pattern of Microplastics (MPs) in Commercial Food-Grade Salts: Sea Salt as an Indicator of Seawater MP Pollution

Previous studies have identified microplastics (MPs) in commercial table salts but could not exactly address the origin of the MPs because of several limitations. The present study is based on the hypothesis that commercial sea salts can act as an indicator of MP pollution in the surrounding environment unless the MPs are filtered out during the manufacturing process. A total of 39 different salt brands produced at geospatially different sites, including 28 sea salt brands from 16 countries/regions on six continents, were investigated. A wide range of MP content (in number of MPs per kg of salt; n/kg) was found: 0-1674 n/kg (excluding one outlier of 13 629 n/kg) in sea salts, 0-148 n/kg in rock salt, and 28-462 n/kg in lake salt. Relatively high MP content was identified in sea salts produced in Asian countries/regions. The abundance of MPs in unrefined sea salts ( n = 25) exhibited significant linear correlations with plastic emissions from worldwide rivers ( r²= 0.33; p = 0.003) and with the MP pollution levels in surrounding seawater ( r²= 0.46; p = 0.021) in the published literature. The results indicate that not only is Asia a hot spot of global plastic pollution, as previous studies have suggested, but also that sea salt can be a good indicator of the magnitude of MP pollution in the surrounding marine environment.

Contamination of Indian sea salts with microplastics and a potential prevention strategy

This study reports the contamination of Indian sea salts with different microplastic particles, as a consequence of using contaminated sea water. Samples from all eight brands of investigated sea salts were found contaminated, and concentrations of these particles ranged from 103 ± 39 to 56 ± 49 particles kg^-1 of salt. Both fibers and fragments were observed with large variation in size. Eighty percent of the extracted fibers and the fragments were smaller than 2000 μm and 500 μm respectively. Extracted particles were mostly polyesters, polyethylene terephthalate (PET), polyamide, polyethylene, and polystyrene. Their total mass concentration was also estimated as 63.76 μg kg^-1 of salt. These results are significant, since India is a leading producer and exporter of sea salts. A simple sand filtration of artificially contaminated sea water could effectively (> 85% removal by weight and > 90% removal by number) remove these microplastics and has the potential for preventing the transfer of microplastics into the salt from contaminated sea waters.

Synthetic Polymer Contamination in Bottled Water

Eleven globally sourced brands of bottled water, purchased in 19 locations in nine different countries, were tested for microplastic contamination using Nile Red tagging. Of the 259 total bottles processed, 93% showed some sign of microplastic contamination. After accounting for possible background (lab) contamination, an average of 10.4 microplastic particles >100 um in size per liter of bottled water processed were found. Fragments were the most common morphology (66%) followed by fibers. Half of these particles were confirmed to be polymeric in nature using FTIR spectroscopy with polypropylene being the most common polymer type (54%), which matches a common plastic used for the manufacture of bottle caps. A small fraction of particles (4%) showed the presence of industrial lubricants. While spectroscopic analysis of particles smaller than 100 um was not possible, the adsorption of the Nile Red dye indicates that these particles are most probably plastic. Including these smaller particles (6.5-100 um), an average of 325 microplastic particles per liter of bottled water was found. Microplastic contamination range of 0 to over 10,000 microplastic particles per liter with 95% of particles being between 6.5 and 100 um in size. Data suggests the contamination is at least partially coming from the packaging and/or the bottling process itself. Given the prevalence of the consumption of bottled water across the globe, the results of this study support the need for further studies on the impacts of micro- and nano- plastics on human health.

Marine microplastic debris: An emerging issue for food security, food safety and human health

Recent studies have demonstrated the negative impacts of microplastics on wildlife. Therefore, the presence of microplastics in marine species for human consumption and the high intake of seafood (fish and shellfish) in some countries cause concern about the potential effects of microplastics on human health. In this brief review, the evidence of seafood contamination by microplastics is reviewed, and the potential consequences of the presence of microplastics in the marine environment for human food security, food safety and health are discussed. Furthermore, challenges and gaps in knowledge are identified. The knowledge on the adverse effects on human health due to the consumption of marine organisms containing microplastics is very limited, difficult to assess and still controversial. Thus, assessment of the risk posed to humans is challenging. Research is urgently needed, especially regarding the potential exposure and associated health risk to micro- and nano-sized plastics.