Unveiling a Listeria monocytogenes Outbreak in a Rabbit Farm: Clinical Manifestation, Antimicrobial Resistance, Genomic Insights and Environmental Investigation

Listeria monocytogenes poses a threat to both human and animal health. This work describes an L. monocytogenes outbreak in a Portuguese rabbit farm, detailing the isolates' clinical manifestations, necropsy findings, and phenotypic and genomic profiles. Clinical signs, exclusively observed in does, included lethargy and reproductive signs. Post-mortem examination of does revealed splenomegaly, hepatomegaly with a reticular pattern, pulmonary congestion, and haemorrhagic lesions in the uterus, with thickening of the uterine wall and purulent greyish exudates. Positive L. monocytogenes samples were identified in fattening and maternity units across different samples, encompassing does and environmental samples. Core-genome Multi Locus Sequence Typing (cgMLST) analysis confirmed the outbreak, with the 16 sequenced isolates (lineage II, CC31, and ST325) clustering within a ≤2 allelic difference (AD) threshold. Antimicrobial susceptibility testing for five antibiotics revealed that 15 out of 19 outbreak isolates were resistant to sulfamethoxazole-trimethoprim (SXT). Concordantly, all SXT-resistant sequenced isolates were found to exclusively harbour a plasmid containing a trimethoprim-resistance gene (dfrD), along with loci linked to resistance to lincosamides (lnuG), macrolides (mphB), and polyether ionophores (NarAB operon). All sequenced outbreak isolates carried the antibiotic resistance-related genes tetM, fosX, lin, norB, lmrB, sul, and mprF. The outbreak cluster comprises isolates from does and the environment, which underscores the ubiquitous presence of L. monocytogenes and emphasizes the importance of biosecurity measures. Despite limited data on listeriosis in rabbit farming, this outbreak reveals its significant impact on animal welfare and production.

Gulls in Porto Coastline as Reservoirs for Salmonella spp.: Findings from 2008 and 2023

Gulls act as intermediaries in the exchange of microorganisms between the environment and human settlements, including Salmonella spp. This study assessed the antimicrobial resistance and molecular profiles of Salmonella spp. isolates obtained from fecal samples of gulls in the city of Porto, Portugal, in 2008 and 2023 and from water samples in 2023. Antimicrobial susceptibility profiling revealed an improvement in the prevalence (71% to 17%) and antimicrobial resistance between the two collection dates. Two isolate collections from both 2008 and 2023 underwent serotyping and whole-genome sequencing, revealing genotypic changes, including an increased frequency in the monophasic variant of S. Typhimurium. qacE was identified in 2008 and 2023 in both water and fecal samples, with most isolates exhibiting an MDR profile. The most frequently observed plasmid types were IncF in 2008 (23%), while IncQ1 predominated in 2023 (43%). Findings suggest that Salmonella spp. circulate between humans, animals, and the environment. However, the genetic heterogeneity among the isolates from the gulls' feces and the surface water may indicate a complex ecological and evolutionary dynamic shaped by changing conditions. The observed improvements are likely due to measures to reduce biological contamination and antimicrobial resistance. Nevertheless, additional strategies must be implemented to reduce the public health risk modeled by the dissemination of pathogens by gulls.

An Exploratory Study on Spoilage Bacteria and Listeria monocytogenes in Fresh Salmon: Extending Shelf-Life Using Vacuum and Seasonings as Natural Preservatives

A growing population increases the demand for food, but short shelf-lives and microbial hazards reduce supply and increase food waste. Fresh fish is highly perishable and may be consumed raw, such as salmon in sushi. This work aims to identify strategies to improve the shelf-life and safety of fresh salmon, using available methods (i.e., vacuum) and exploring the use of natural preservatives (i.e., seasonings). Vacuum packaging and good hygiene practices (which reduce initial flora) extended shelf-life up to 20 days. Carnobacterium maltaromaticum was dominant in vacuum packaging conditions and showed potential for inhibiting Listeria monocytogenes. For natural preservatives, L. monocytogenes required higher inhibitory concentrations in vitro when compared to the 10 spoilage bacteria isolated from fresh salmon fillets, presenting a minimum inhibitory concentration (MIC) of 0.13% for oregano essential oil (OEO), 10% for lemon juice, 50 mg mL^-1 for garlic powder, and >10% for NaCl. A good bacteriostatic and bactericidal effect was observed for a mixture containing 5% NaCl, 0.002% OEO, 2.5% lemon juice, and 0.08 mg mL^-1 garlic powder. Finally, using the salmon medium showed an adequate correlation with the commercial culture medium.

Microplastics altered cellular responses, physiology, behaviour, and regeneration of planarians feeding on contaminated prey

Freshwater benthic environments are among the major sinks of microplastics (MPs, < 5 mm) sourced on inland anthropogenic activities. The ecotoxicological effects of MPs on benthic macroinvertebrates have been assessed preferably in collectors, shredders, and filter-feeders, but resulting in insufficient knowledge on the potential trophic transfer and its effects on macroinvertebrates with predator behaviour such as planarians. This work evaluated the behavioural (feeding, locomotion), physiological (regeneration) and biochemical responses (aerobic metabolism, energy reserves, oxidative damage) of the planarian Girardia tigrina after consuming contaminated live prey Chironomus riparius larvae previously exposed to microplastics of polyurethane (PU-MPs; 7-9 μm in size; 375 mg PU-MPs/kg). After the feeding period (3 h), planarians consumed 20 % more contaminated prey than uncontaminated prey, probably related to increased curling/uncurling movements of larvae (that might be more appellative to planarians). Histological analysis revealed planarians' limited intake of PU-MPs, mainly detected near the pharynx. The consumption of contaminated prey (and intake of PU-MPs) did not result in oxidative damage but slightly increased the aerobic metabolism and energy reserves which show that the consumption of more prey was sufficient to cope with the potential adverse effects of internalized MPs. Moreover, no effects were observed in the locomotion of planarians in good agreement with the hypothesis of sufficient energy acquired by the exposed planarians. Despite the previous, it seems that the energy acquired was not allocated for planarians' regeneration since a significant delay in the regeneration of the auricles was observed for planarians feeding on contaminated prey. Therefore, further studies should be performed considering the potential long-term effects (i.e., reproduction/fitness) and the effects of MPs that might result from continuous feeding on contaminated prey, representing a more realistic exposure scenario.

Occurrence of Multidrug-Resistant Bacteria Resulting from the Selective Pressure of Antibiotics: A Comprehensive Analysis of ESBL K. pneumoniae and MRSP Isolated in a Dog with Rhinorrhea

Because of public health concerns, much greater scrutiny is now placed on antibiotic use in pets, especially for antimicrobial agents that have human analogs. Therefore, this study aimed to characterize the phenotypic and genotypic profiles of multidrug-resistant bacteria isolated from nasal swabs samples taken from a one-year-old male Serra da Estrela dog with rhinorrhea that was treated with amikacin. An extended-spectrum β-lactamases (ESBL) Klebsiella pneumoniae was isolated in the first sample taken from the left nasal cavity of the dog. Seven days later, methicillin-resistant (MRSP) Staphylococcus pseudintermedius was also isolated. Nevertheless, no alterations to the therapeutic protocol were performed. Once the inhibitory action of the antibiotic disappeared, the competitive advantage of the amikacin-resistant MRSP was lost, and only commensal flora was observed on both nasal cavities. The genotypic profile of extended-spectrum β-lactamase (ESBL)-producing Klebsiella pneumoniae revealed the same characteristics and close relation to other strains, mainly from Estonia, Slovakia and Romania. Regarding MRSP isolates, although resistance to aminoglycosides was present in the first MRSP, the second isolate carried aac(6')-aph(2″), which enhanced its resistance to amikacin. However, the veterinary action was focused on the treatment of the primary agent (ESBL K. pneumoniae), and the antibiotic applied was according to its phenotypic profile, which may have led to the resolution of the infectious process. Therefore, this study highlights the importance of targeted therapy, proper clinical practice and laboratory-hospital communication to safeguard animal, human and environmental health.

Mechanisms influencing the impact of microplastics on freshwater benthic invertebrates: Uptake dynamics and adverse effects on Chironomus riparius

Chironomids inhabit freshwater benthic ecosystems which are prone to microplastic contamination. This work aimed at understanding the factors and mechanisms influencing microplastic uptake and related adverse effects on Chironomus riparius, by exploring an extensive project database, conducting a literature review, and performing an agent-based model to explore trends in data. Results reveal that high concentrations of small microplastics fill the gut of fourth instar C. riparius (99.7 %). Ingested microplastics had an average size of 38-61 μm, presenting slower elimination rates than undigested organic or mineral particles. Ingestion rates of microplastics depend mainly on encounter rates, and therefore on available concentrations, until reaching a plateau corresponding to the maximum gut volume. Short-term toxicity of microplastics seems to result from damage to gut epithelium, with inflammatory reactions, production of reactive oxygen species, and a negative energy balance exacerbated by the lack of food (organic matter). Long-term toxicity is characterized by a reduction in larval body length and increase in mean time to emergence, seemly from increased energy costs rather than a decrease in nutrient absorption. Wild chironomids already present microplastics in their guts and environmental concentrations in hotspots may already exceed no effect concentrations. Therefore, environmental exposure to microplastics may induce adverse effects to wild C. riparius in freshwater benthic ecosystems, which could compromise their ecologic role as deposit-feeders (e.g., reducing their nutrient cycling ability) and key-stone species in aquatic food webs.

Effects of virgin and weathered polystyrene and polypropylene microplastics on Raphidocelis subcapitata and embryos of Danio rerio under environmental concentrations

Microplastics are ubiquitous contaminants of freshwater ecosystems. However, few ecotoxicity assays have been conducted on freshwater organisms using environmentally relevant concentrations of virgin and weathered microplastics. This work assessed the adverse effects of virgin and artificially weathered fragments of polystyrene and polypropylene on the microalga Raphidocelis subcapitata (72 h growth inhibition assay) and on embryos of the fish Danio rerio (96 h fish embryo assay) under environmentally relevant concentrations (2000-200,000 MP L^-1) and high concentrations (12.5-100 mg L^-1). Sizes of microplastics were measured as tens (polystyrene) to hundreds (polypropylene) of micrometers, while aging was assessed by measuring the carbonyl index. In the microalga, the tested high concentrations promoted growth, while environmentally relevant concentration induced either growth inhibition or promotion. In zebrafish embryos, environmentally relevant concentrations decreased body length and heart rates. No relevant effects were observed in organisms exposed to high concentrations for mortality, malformations, hatching rates, and swimming bladder inflation. Virgin microplastics presented slightly higher toxicity but direct comparison was hindered by the lack of a linear dose-response curve. Despite the lack of a clear pattern, adverse effects were often observed in the lowest environmentally relevant concentrations, raising concerns over the impacts of microplastics on freshwater ecosystems.

A straightforward method for microplastic extraction from organic-rich freshwater samples

The extraction of microplastics from organic-rich freshwater samples is challenging and limited information is available in the literature. This study aims at developing efficient methods for water volume reduction and organic matter removal in freshwater samples, while focusing on the reduction of the economic and environmental costs, maintaining microplastics integrity and avoiding contamination. For the water volume reduction approach, centrifuging freshwater samples (water, sediment, algae, leaves, driftwood, fish tissue) at different speeds (3500, 6000 rpm) and times (5, 10 min) showed that 3500 rpm for 5 min was efficient to settle the mineral and organic material, while preserving the polymers and showing high microplastic recovering rates (93 ± 6%). These recovery rates were significantly higher than the traditional sieving approach (77 ± 22%). The posterior minimal consumption of reagents resulting from the reduction of water volume helped to reduce the economic and environmental costs of the devised methodology, becoming more aligned with green chemistry principles. For biogenic organic matter removal, four digestion solutions were tested on freshwater samples, namely 10% potassium hydroxide, Fenton reagent (30% H₂O₂ + Fe(II)), 7% and 10% sodium hypochlorite (NaClO), under 3 periods of time (1, 6 and 15 h), at 50 °C. Both 7% and 10% NaClO showed the highest rates of organic matter removal (86 ± 1% and 90 ± 1%, respectively), after 6 h at 50 °C. Exposure of virgin and aged polymers (polyethylene, polypropylene, polystyrene, polyvinyl chloride, nylon, polyethylene terephthalate) to NaClO showed no weight, visual, surface structure, Fourier transform infrared spectra and carbonyl index changes, except for nylon, although not to an extent that affected its identification. This method resulted in high recovery rates of polymers (92 ± 6%). Thus, 7% NaClO at 50 °C for 6 h (or overnight) may be efficiently used for microplastic analysis in organic-rich freshwater samples.

Suspected microplastics in Atlantic horse mackerel fish (Trachurus trachurus) captured in Portugal

Microplastics have been found in fish, but most studies have focused on the digestive system without considering additional organs. Herein, the objective was to assess the presence of microplastics in internal organs (gills, guts, kidney, heart) of the Atlantic horse mackerel (Trachurus trachurus) captured of the coast of Portugal (Northeast Atlantic Ocean). Suspected microplastics were present in all organs, with particles of larger size (i.e., equivalent diameter) found in the gut and those of lower size in the heart and its luminal blood. Suspected microplastics of 1-10 μm were the most abundant (65.4%), more likely to translocate, owing to their minute size, but more difficult to properly characterize. These results highlight the need to expand the analytical work on organs and tissues for assessing microplastics in organisms, but also emphasize the actual need for developing analytical methods that allow for an accurate isolation, identification, and characterization of microplastics in biota.

The road to sustainable use and waste management of plastics in Portugal

As a European Union (EU) member, Portugal must comply with reductions in plastic waste. In Portugal, the 330 items/100 m of beach litter, comprising up to 3.9 million pieces and of which 88% is plastic, is higher than the EU median (149 items/100 m) and must be reduced to 20 items/100 m (94%). Integrative measures are needed to reduce littering and improve plastics' use and disposal under the circular economy. Of this 414 kt of plastic packaging waste, 163 kt were declared plastic packaging, 140 kt subjected to recycling, and 94 kt to energy recovery. The current recycling rate of plastic packaging (34%) should be improved to reach EU recycling averages (42%) and goals and to provide widespread benefits, considering revenues of 167 €/t. As a net importer of waste, Portugal could benefit from the valorization of imported waste. Besides increased recycling, pyrolysis and gasification could provide short-term alternatives for producing value-added substances from plastic waste, such as hydrogen, consistent with the National Plan of Hydrogen and improving ongoing regulations on single-use plastics. This manuscript provides an integrative view of plastics in Portugal, from use to disposal, providing specific recommendations under the circular economy.

ELECTRONIC SUPPLEMENTARY MATERIAL

Supplementary material is available in the online version of this article at 10.1007/s11783-021-1439-x and is accessible for authorized users.

An urgent call to think globally and act locally on landfill disposable plastics under and after covid-19 pandemic: Pollution prevention and technological (Bio) remediation solutions

Landfilling and illegal waste disposal have risen to deal with the COVID-19 potentially infectious waste, particularly in developing countries, which aggravates plastic pollution and inherent environmental threats to human and animal health. It is estimated that 3.5 million metric tonnes of masks (equivalent to 601 TIR containers) have been landfilled worldwide in the first year, with the potential to increase global plastic municipal solid waste by 3.5%, alter biogas composition, and release 2.3 × 10²¹ microplastics to leachates or adjacent environments, in the coming years. This paper reviews the challenges raised in the pandemic scenario on landfills and discusses the potential environmental and health implications that might drive us apart from the 2030 U.N. sustainable goals. Also, it highlights some innovative technologies to improve waste management (from collection to disposal, waste reduction, sterilization) and mitigates plastic leakage (emission control approaches, application of biotechnological and monitoring/computational tools) that can pave the way to environmental recovery. COVID-19 will eventually subside, but if no action is taken in the short-term towards effective plastic policies, replacement of plastics for sustainable alternatives (e.g., biobased plastics), improvement of waste management streams (prioritising flexible and decentralized approaches), and a greater awareness and responsibility of the general public, stakeholders, industries; we will soon reach a tipping-point in natural environments worldwide.

Risks of Covid-19 face masks to wildlife: Present and future research needs

The use of disposable face masks became essential to fight against the COVID-19 pandemic, resulting in an unprecedented rise in their production and, unfortunately, to a new form of environmental contamination due to improper disposal. Recent publications reported the abundance of COVID-19-related litter in several environments, wildlife interaction with such items, and the contaminants that can be released from such protective equipment that has the potential to induce ecotoxicological effects. This paper provides a critical review of COVID-19 face mask occurrence in diverse environments and their adverse physiological and ecotoxicological effects on wildlife. It also outlines potential remediation strategies to mitigate the environmental challenge impose by COVID-19-related litter.

Considerations when using microplates and Neubauer counting chamber in ecotoxicity tests on microplastics

The ubiquity of microplastics raises issues regarding contamination control measures and laboratory practices. The objective was to adapt the use of counting chambers and plastic microplates on the ecotoxicity evaluation of microplastics. Counting chambers, originally used to quantify cells, can also be used to count high concentrations of microplastics (<100 μm) used in laboratory assays. By decontaminating the chamber and mixing the test solution with Nile Red (1:1), fluorescent particles can be easily counted under optical microscopy. Microplate wells, due to their composition, can be contaminated or release microplastics to the test medium, which can interfere with the results of ecotoxicity assays or spectroscopy readings. A cleaning method based on ethanol was developed, which effectively removed particles by 91% without interfering with microalgae yield. Besides providing practical applications that can improve ecotoxicity assays, this work intends to raise awareness on the need to adapt laboratory practices when working with microplastics.

Preparation of biological samples for microplastic identification by Nile Red

Many methods have been used to isolate and identify microplastics from biological matrices. In biological samples, Nile Red can stain undigested residues, such as fats, soaps, and gels formed during organic matter removal, hindering the identification of fluorescent microplastics (≥2 μm). Thus, adjustments on sample preparation (e.g., fat removal) are required for the accurate identification of Nile Red stained microplastics. Multiples tests allowed to identify that digestion with 10% KOH at 60 °C for 24 h, followed by treatments with boiling water, acetone, and staining, produced good results in fourteen biological samples, including vertebrates and invertebrates. Digestion efficiencies were 94-100%, except for feces, which were 87%. Recovery rates of spiked microplastics were 97-100%, and few effects were observed in the infrared spectra and carbonyl index of seven polymers, with only the occasional yellowing suggesting surface changes. Filtration rates were improved by reducing the amount of sample. Small fluorescent microplastics could be identified in all samples under the microscope. Overall, the proposed method was efficient in removing natural organic matter from biological samples for Nile Red staining, requiring minimal sample handling, improving sample throughput, and allowing quantification of fluorescent microplastics in biological samples.

Selection of microplastics by Nile Red staining increases environmental sample throughput by micro-Raman spectroscopy

Nile Red staining enables visual identification and quantification of fluorescent particles as a proxy to microplastics at low cost and high throughput, including those of small sizes (≥2 μm), when preceded by proper natural organic matter removal, but providing no chemical characterization. On the other hand, micro-spectroscopy methods allow chemical characterization of particles based on their spectra, essential for polymer identification, but are costly and time-consuming. This work addresses the combination of both Nile Red staining with micro-Raman spectroscopy for the identification of microplastics. Besides being useful for quantification, Nile Red staining can be advantageously used as an objective criterion for pre-selection of particles for micro-Raman spectroscopy, producing little interference. The use of the 442 nm laser in micro-Raman spectroscopy induces Nile Red luminescence thus allowing to target the specific suspected microplastics when using an orange filter, reducing the number of particles subjected to identification and improving sample throughput. Staining dyes could also be used for mapping suspected microplastics before targeted analysis by micro-Raman spectroscopy. Thus, coupling Nile Red with micro-Raman spectroscopy can be useful to improve time efficiency while using this equipment.

A One Health perspective of the impacts of microplastics on animal, human and environmental health

Microplastics contamination is widespread in the environment leading to the exposure of both humans and other biota. While most studies overemphasize direct toxicity of microplastics, particle concentrations, characteristics and exposure conditions being used in these assays needs to be taken into consideration. For instance, toxicity assays that use concentrations over 100,000 times higher than those expected in the environment have limited practical relevance. Thus, adverse effects on animal and human health of current environmental concentrations are identified as a knowledge gap. Conversely, this does not suggest the lack of any significant effects of microplastics on a global scale. The One Health approach provides a novel perspective focused on the intersection of different areas, namely animal, human, and environmental health. This review provides a One Health transdisciplinary approach to microplastics, addressing indirect effects beyond simple toxicological effects. Microplastics can, theoretically, change the abiotic properties of matrices (e.g., soil permeability) and interfere with essential ecosystem functions affecting ecosystem services (e.g., biogeochemical processes) that can in turn impact human health. The gathered information suggests that more research is needed to clarify direct and indirect effects of microplastics on One Health under environmentally relevant conditions, presenting detailed knowledge gaps.

Microplastics and fibers from three areas under different anthropogenic pressures in Douro river

Sources contributing to specific concentration of microplastics and fibers are still not completely understood. This study aimed at assessing the concentrations of microplastics (2-5000 μm) and fibers (18-5667 μm) in three areas of distinct influences in the Douro river, Porto, Portugal: (i) a countryside area; (ii) a wastewater treatment effluent release zone; and (iii) an area in proximity to a boat dock and maintenance station. Nile Red staining coupled with microscopy allowed the identification of small microplastics (≥2 μm) with a median concentration of the three areas of 231 MP L^-1. Most were fragments (69%). Sizes <40 μm were the most abundant (84%). Highest concentrations of microplastics were found near the boat dock/maintenance and lowest in the countryside area. Fibers were mostly natural (non-synthetic, 63%). Highest concentrations of fibers were found in the area influenced by the wastewater effluent, especially of synthetic fibers, and lowest in the countryside area. Concentration of all fibers and synthetic fibers was 46 F L^-1 and 6 F L^-1, respectively. High concentrations of microplastics and fiber contamination suggest that the wastewater treatment plant effluent and boat dock/maintenance are the likely sources originating hotspot areas.

Microplastics on Barra beach sediments in Aveiro, Portugal

Microplastic (MPs) pollution has been recognized as a serious threat to marine environment with the growing use of plastics. There is no sufficient data on the extent and characteristics of MPs pollution in the beach sediments and sand in the Atlantic Ocean. The coastal area is one of the main tourist zones in Aveiro in Portugal, thus, impacted by both tourism and maritime traffic, which are major sources of MPs. Considering this issue, 33 sediment samples were collected from the Praia da Barra beach in Aveiro. This pilot study showed that large quantities of MPs are accumulated on this beach with a median concentration of 100 MP kg-1 (15-320 MP kg-1), that is dominated by polyethylene (30%), polypropylene (27%), polystyrene (18%), nylon (12%), and polyester (6%). Size <1 mm constituted 99.5% of particles, mostly of transparent or black colors, with highest concentrations closest to the water line.

Contamination issues as a challenge in quality control and quality assurance in microplastics analytics

Microplastics are widely distributed environmental contaminants. To understand their impacts on the environment and health, more high-quality results are needed. Since microplastics are present in every environment, including indoor air, proper precautions must be adopted in order to prevent contamination of samples and overestimation of environmental concentrations. Thus, to guarantee a proper quality of results, researchers must adopt strict contamination control measures. This review was conducted to understand current contamination control practices. A total of 50 studies published in 2019 were reviewed, including sampling of biota, air, soil, sediment, freshwater and saltwater, regarding 10 contamination control parameters. Overall, studies usually only comply with 4 out of 10 of these measures, which include avoiding the use of plastic materials, covering samples with glass lids or aluminum foil, filtering solutions, or running procedural blanks. The importance of these measures is also exemplified with real observation of contamination. Finally, seven measures to control for contamination are suggested in order to improve the quality of results in microplastic sampling in future assessments.

Increased plastic pollution due to COVID-19 pandemic: Challenges and recommendations

Plastics have become a severe transboundary threat to natural ecosystems and human health, with studies predicting a twofold increase in the number of plastic debris (including micro and nano-sized plastics) by 2030. However, such predictions will likely be aggravated by the excessive use and consumption of single-use plastics (including personal protective equipment such as masks and gloves) due to COVID-19 pandemic. This review aimed to provide a comprehensive overview on the effects of COVID-19 on macroplastic pollution and its potential implications on the environment and human health considering short- and long-term scenarios; addressing the main challenges and discussing potential strategies to overcome them. It emphasises that future measures, involved in an emergent health crisis or not, should reflect a balance between public health and environmental safety as they are both undoubtedly connected. Although the use and consumption of plastics significantly improved our quality of life, it is crucial to shift towards sustainable alternatives, such as bio-based plastics. Plastics should remain in the top of the political agenda in Europe and across the world, not only to minimise plastic leakage and pollution, but to promote sustainable growth and to stimulate both green and blue- economies. Discussions on this topic, particularly considering the excessive use of plastic, should start soon with the involvement of the scientific community, plastic producers and politicians in order to be prepared for the near future.

Effects of distance to the sea and geomorphological characteristics on the quantity and distribution of microplastics in beach sediments of Granada (Spain)

Microplastics became an unprecedented challenge and mapping their contamination all over the world is needed in order to establish baseline levels and identify the polymers in order to enhance adequate legislation and policy. The main objective of this study is to demonstrate the existence of microplastic pollution on three beaches on the coast of Granada (Spain), namely La Herradura, Motril Beach and La Rábita, characterizing the particles and the relationships in their distribution. This may contribute supporting the studies carried out at a national level in accordance with the Directive on Marine Strategy (2008/56/EC). The results showed a greater median concentration of particles/kg of dry sediment in La Herradura (45.0 ± 24.7) than in Motril (31.5 ± 21.5) and La Rábita (22.0 ± 23.2). These data revealed a higher contamination by microplastics in an enclosed bay-type beach (La Herradura) in comparison with open delta-type beaches. The predominant morphologies were microspheres and fragments, with maximum median concentrations of 38.0 ± 23.7 and 6.0 ± 0.7 particles/kg, respectively. The distribution and size of the particles is affected by the geomorphological and sedimentary characteristics of these beaches, which are different from any other in Spain and in the Mediterranean in general. The beaches of Granada showed more microplastic contamination than Greek or Slovenian beaches, but less than other Spanish beaches. In this area of the Mediterranean, the presence of microplastics can be affected by the wind, sea currents or methodological aspects such as the pore size of the filters used. All of these factors were analysed when comparing the beaches of Granada with other Mediterranean beaches. This study shows that there is contamination by microplastics on the beaches of Granada, which have been little explored until now due to the difficult geological and granulometric characteristics, and gives support to other national studies.

Rethinking and optimising plastic waste management under COVID-19 pandemic: Policy solutions based on redesign and reduction of single-use plastics and personal protective equipment

Plastics have been on top of the political agenda in Europe and across the world to reduce plastic leakage and pollution. However, the COVID-19 pandemic has severely disrupted plastic reduction policies at the regional and national levels and induced significant changes in plastic waste management with potential for negative impacts in the environment and human health. This paper provides an overview of plastic policies and discusses the readjustments of these policies during the COVID-19 pandemic along with their potential environmental implications. The sudden increase in plastic waste and composition due to the COVID-19 pandemic underlines the crucial need to reinforce plastic reduction policies (and to implement them into action without delays), to scale up in innovation for sustainable and green plastics solutions, and to develop dynamic and responsive waste management systems immediately. Policy recommendations and future research directions are discussed.

Worldwide contamination of fish with microplastics: A brief global overview

Widespread contamination of microplastics may lead to internalization in fish. This literature review from March 2019 to March 2020 details that a median of 60% of fish, belonging to 198 species captured in 24 countries, contain microplastics in their organs. Carnivores species ingested more microplastics than omnivores. Only 14% of fish were from aquaculture. Most studies focused on digestive systems, with presence in other organs currently being insufficiently assessed. Based on this assessment, knowledge gaps that should be addressed in future studies were identified.

The importance of contamination control in airborne fibers and microplastic sampling: Experiences from indoor and outdoor air sampling in Aveiro, Portugal

Airborne microplastics and microfibers are released from daily materials, contaminating both indoor and outdoor air. Sampling in Aveiro, Portugal, revealed concentrations of 6 fibers m^-3, with more synthetic fibers found in outdoor than indoor (8.5% vs. 4.1%, n = 6), with variations in fiber characteristics between sampling periods. Suspected microplastics (<10 μm) also followed this trend (12 vs. 5 particles m^-3). Synthetic fibers presented peculiar characteristics, with larger median sizes of 513 μm and 90% of lighter colors. Nonetheless, numerous fibers and suspected microplastics were found in field blanks, possibly from sampling contamination, reducing the reliability of results. Few previous works have reported field blanks so far, raising concerns about the quality of their results as well. Thus, quality assurance measures should be more strictly applied when working with airborne fibers and microplastics, while more research should focus on the factors involved in the variation of concentrations and characteristics of airborne fibers.

Environmental status of (micro)plastics contamination in Portugal

Plastics and microplastics are ubiquitous contaminants in aquatic ecosystems. This critical review is the first attempt at analyzing sources, concentration, impacts and solutions of (micro)plastic litter in Portugal based on all currently available literature. We found that, besides sea-based sources (e.g. shipping, fishing), 5717 t of mismanaged waste and 4.1 trillion microplastics from wastewater, mostly from untreated wastewater, are released to the environment every year. The highest concentrations are found in the North, Center and Lisbon regions, mostly comprised of consumer products, fishing gear and microplastics (<5 mm), especially fragments and pellets. This contamination has resulted in ingestion of plastics by organisms, including mussels, fishes, birds and turtles. Thus, every Portuguese citizen may consume 1440 microplastics a year based on the consumption of mollusks. Awareness campaigns, improvements in waste management and reductions in the release of untreated wastewater are recommended measures to reduce plastic pollution in Portugal.

COVID-19 Pandemic Repercussions on the Use and Management of Plastics

Plastics are essential in society as a widely available and inexpensive material. Mismanagement of personal protective equipment (PPE) during the COVID-19 pandemic, with a monthly estimated use of 129 billion face masks and 65 billion gloves globally, is resulting in widespread environmental contamination. This poses a risk to public health as waste is a vector for SARS-CoV-2 virus, which survives up to 3 days on plastics, and there are also broad impacts to ecosystems and organisms. Concerns over the role of reusable plastics as vectors for SARS-CoV-2 virus contributed to the reversal of bans on single-use plastics, highly supported by the plastic industry. While not underestimating the importance of plastics in the prevention of COVID-19 transmission, it is imperative not to undermine recent progress made in the sustainable use of plastics. There is a need to assess alternatives that allow reductions of PPE and reinforce awareness on the proper public use and disposal. Finally, assessment of contamination and impacts of plastics driven by the pandemic will be required once the outbreak ends.

COVID-19 Pandemic Repercussions on the Use and Management of Plastics

Plastics are essential in society as a widely available and inexpensive material. Mismanagement of personal protective equipment (PPE) during the COVID-19 pandemic, with a monthly estimated use of 129 billion face masks and 65 billion gloves globally, is resulting in widespread environmental contamination. This poses a risk to public health as waste is a vector for SARS-CoV-2 virus, which survives up to 3 days on plastics, and there are also broad impacts to ecosystems and organisms. Concerns over the role of reusable plastics as vectors for SARS-CoV-2 virus contributed to the reversal of bans on single-use plastics, highly supported by the plastic industry. While not underestimating the importance of plastics in the prevention of COVID-19 transmission, it is imperative not to undermine recent progress made in the sustainable use of plastics. There is a need to assess alternatives that allow reductions of PPE and reinforce awareness on the proper public use and disposal. Finally, assessment of contamination and impacts of plastics driven by the pandemic will be required once the outbreak ends.

Major factors influencing the quantification of Nile Red stained microplastics and improved automatic quantification (MP-VAT 2.0)

Automated count of Nile Red fluorescent microplastics allows fast and reliable quantification. However, factors involving staining, digital camera conditions and settings introduce variability to the results. The objective of this paper is to identify and propose solutions to these factors and improve on the previous MP-VAT script. While removal of digital sensor defects had little influence on results and staining can be reduced to 5 min, Nile Red concentrations cannot be reduced <0.01 mg mL^-1, the 470 nm LED lantern emission must be >1600 lx, and photographic conditions should be maintained as stable as possible ideally improving the filter membrane area and using the recommended settings of 2 s, ISO100, F5.6. It was also found that Nile Red can be removed from microplastics using acetone or hydrogen peroxide with iron. More importantly, both particles and fluorescent are lost with time and thus quantification should be conducted within a week. Finally, MP-VAT 2.0 was developed to remove unselected areas and to identify only red particles, excluding white reflections from quantification. This updated version of MP-VAT produced improved recovery rates of 98.2 ± 6.9 for spiked samples and 95.9 ± 10.3 on actual environmental samples, presenting a cheap and reliable complementary method for microplastic identification.

Effects of spatial and seasonal factors on the characteristics and carbonyl index of (micro)plastics in a sandy beach in Aveiro, Portugal

Coastal environments are highly contaminated with plastics of various sizes. In order to understand the distribution and factors influencing (micro)plastics contamination in the environment, sampling of a sandy beach in Costa Nova, Aveiro, Portugal, was conducted by collecting plastic particles and sediments for density separation in transects from the mean low tide line to the dunes, during wet and dry seasons. For surface collection, microplastics comprised 69.4% of plastics, presenting concentrations of 3-6 items m^-2 in the wet season, mostly polyethylene pellets carried ashore by storms, and <1 item m^-2 for dry season, lower due to less backwashing, were found. Collection of infrared spectra of these particles allowed characterization by polymer type and carbonyl index of all particles. Variations in carbonyl index were found to be related to season, site and particle color. Density separated microplastics, mostly fibers, presented 23 times higher concentrations than surface collection (22 microplastics kg^-1, 280 microplastics m^-2), due to the identification of smaller sizes, and with higher concentrations in dry seasons, likely from accumulation in sediment and bathing season. Overall, different sampling methods allowed identification of different particle types and sizes, which may vary according to seasonal and spatial factors.

An easy method for processing and identification of natural and synthetic microfibers and microplastics in indoor and outdoor air

Microplastics and microfibers can contaminate every matrix, including in the atmosphere, thus leading to incidental inhalation. However, concentrations of airborne synthetic particle in indoor and outdoor environments are not well understood due to the complexities of sampling, sample processing and identification. This work aims at producing a simple protocol to determine the concentrations of airborne microplastics and fibers. This is accomplished by removing organic matter using hydrogen peroxide (H₂O₂), followed by removal of mineral matter by density separation with sodium iodide (NaI). Finally, identification of fibers into synthetic or natural under the stereomicroscope can be achieved following a diagram produced by systematically observing the most common textile fibers. This method produces a recovery rate of 94.4 % for spiked samples and has been proven suitable for environmental samples.

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Fibers and microplastics in air are easier to identify after carbonaceous matter removal;

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No loss of microfiber is expected from the solutions used;

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Recovery rates of spiked samples is 94.4 %.

Exposure to BTEX in buses: The influence of vehicle fuel type

Diesel-fueled buses have been replaced by Compressed Natural Gas (CNG) to minimize the high level of emissions in urban areas. However, differences in indoor exposure levels to Benzene, Toluene, Ethylbenzene and Xylene (BTEX) in those vehicles have not been investigated so far. The primary aim of this study was to determine if passengers are exposed to different BTEX levels when using buses powered by CNG or by diesel, and further explore if indoor levels are influenced by external air quality. For this purpose, BTEX air concentrations were measured in bus cabins (CNG and diesel), parking stations and in a background urban area using passive air samplers. Results showed that BTEX concentrations inside vehicles were higher than outside, but no significant differences were found between buses powered by CNG or by diesel. In CNG vehicles, high and significant positive correlation was found between benzene and the number of journeys in the same route (r_s = 0.786, p < 0.05), vehicle operating time (r_s = 0.738, p < 0.05), exposure time (r_s = 0.714, p < 0.05) and exposure index (r_s = 0.738, p < 0.05), but this was not observed for diesel vehicles. Benzene in bus cabins was found to be significantly below reference value for human health protection. However, excepting p-xylene, all other aromatic pollutants have a mean concentration significantly above the lowest effect level (p ≤ 0.002 for all comparisons). Additionally, higher BTEX levels in cabin buses than in outdoor air suggest the presence of other emission sources in indoor cabins. These findings emphasize the need for further studies to fully characterize indoor emission sources in order to minimize the negative impact of BTEX exposure to human health.

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.

Identifying a quick and efficient method of removing organic matter without damaging microplastic samples

Natural organic matter may confound the detection of microplastics, requiring a removal step. However, most available protocols are long and lack information on removal efficiency and polymer degradation. Thus, we have determined the digestion efficiency (%) for a pool of organic matter (algae, driftwood, feathers, fish muscle, paraffin, palm oil) for five digestion solutions, hydrogen peroxide (H₂O₂), hydrogen peroxide with iron catalyst (H₂O₂ + Fe), potassium hydroxide (KOH), nitric acid (HNO₃), and sodium dodecyl sulphate (SDS), under two temperatures (room temperature at 25 °C, 50 °C) and two periods (1, 6 h). H₂O₂ + Fe and KOH at 50 °C for 1 h had the highest digestion efficiencies, of 65.9% and 58.3% respectively (mostly limited by driftwood and paraffin). Further testing revealed that H₂O₂ + Fe is more appropriate for plant material and KOH for animal tissue. Weight loss (%), Fourier transform infrared spectrometry and carbonyl index of 9 virgin and 6 weathered polymers (polyethylene, polypropylene, polystyrene, polyethylene terephthalate, polyvinyl chloride, cellulose acetate, nylon) revealed that only identification of cellulose acetate was hindered. Filters were also tested revealing that quartz and glass fibre filters are resistant to these protocols. Thus, a digestion protocol based on H₂O₂ + Fe or KOH at 50 °C for 1 h may be used on microplastic samples.

Solutions and Integrated Strategies for the Control and Mitigation of Plastic and Microplastic Pollution

Plastic pollution is generated by the unsustainable use and disposal of plastic products in modern society, threatening economies, ecosystems, and human health. Current clean-up strategies have attempted to mitigate the negative effects of plastic pollution but are unable to compete with increasing quantities of plastic entering the environment. Thus, reducing inputs of plastic to the environment must be prioritized through a global multidisciplinary approach. Mismanaged waste is a major land-based source of plastic pollution that can be reduced through improvements in the life-cycle of plastics, especially in production, consumption, and disposal, through an Integrated Waste Management System. In this review paper, we discuss current practices to improve life cycle and waste management of plastics that can be implemented to reduce health and environmental impacts of plastics and reduce plastics pollution. Ten recommendations for stakeholders to reduce plastic pollution include (1) regulation of production and consumption; (2) eco-design; (3) increasing the demand for recycled plastics; (4) reducing the use of plastics; (5) use of renewable energy for recycling; (6) extended producer responsibility over waste; (7) improvements in waste collection systems; (8) prioritization of recycling; (9) use of bio-based and biodegradable plastics; and (10) improvement in recyclability of e-waste.

Environmental and biological monitoring of benzene, toluene, ethylbenzene and xylene (BTEX) exposure in residents living near gas stations

The volatile organic compounds benzene, toluene, ethylbenzene, and xylene (BTEX) are emitted into the atmosphere at gas stations (GS) leading to chronic exposure of nearby residents, which raises public health concerns. This study aimes at determining the contribution of GS emissions to BTEX exposure in nearby residents. Three Control and Exposed areas to BTEX emissions from GS were defined in a medium-sized European city (Porto, Portugal). BTEX atmospheric levels were determined in Control and Exposed areas using passive samplers deployed outdoors (n = 48) and indoors (n = 36), and human exposure was estimated for 119 non-smoking residents using the first urine of the day. Results showed that median BTEX outdoor and indoor concentrations were significantly higher for Exposed than Control areas, with exception of ethylbenzene and xylene indoor concentrations, where no marked differences were found. Comparison of urinary concentrations between Exposed and Control residents demonstrated no significant differences for benzene and ethylbenzene, whereas levels of toluene and xylene were significantly higher in Exposed residents. No marked correlation was obtained between atmospheric BTEX concentrations and urinary concentrations. Data indicate the potential impact on air quality of BTEX emissions from GS, which confirms the importance of these findings in urban planning in order to minimize the impact on health and well-being of surrounding populations.

Influence of microplastics on the toxicity of the pharmaceuticals procainamide and doxycycline on the marine microalgae Tetraselmis chuii

Microplastics and pharmaceuticals are considered ubiquitous and emergent pollutants of high concern but the knowledge on their effects on primary producers is still limited, especially those caused by mixtures. Thus, the goal of the present study was to investigate if the presence of microplastics (1-5 μm diameter) influences the toxicity of the pharmaceuticals procainamide and doxycycline to the marine microalga Tetraselmis chuii. Bioassays (96 h) to investigate the toxicity of those substances individually and in mixtures (i.e. microplastics-procainamide mixtures and microplastics-doxycycline mixtures) were carried out. Effect criteria were the average specific growth rate (growth rate) and chlorophyll a concentration (chlorophyll). EC₁₀, EC₂₀ and EC₅₀ were determined. Microplastics alone had no significant effects on growth rate up to 41.5 mg/l, whereas chlorophyll was significantly reduced at 0.9 and 2.1 mg/l of microplastics, but not at higher concentrations. The 96 h EC₅₀ (growth rate and chlorophyll, respectively) determined for the other bioassays were: 104 and 143 mg/l for procainamide alone; 125 and 31 mg/l for procainamide in the presence of microplastics; 22 and 14 mg/l for doxycycline alone; 11 and 7 mg/l for doxycycline in the presence of microplastics. Significant differences (p < 0.001) between the toxicity curves of each pharmaceutical alone and in mixture with microplastics were found for procainamide (chlorophyll), and doxycycline (both parameters). Thus, both pharmaceuticals were toxic to T. chuii in the low ppm range, and microplastics-pharmaceutical mixtures were more toxic than the pharmaceuticals alone. Very high decreases of doxycycline concentrations in test media were found, indicating degradation of the antibiotic. Thus, although the biological results are expressed in relation to doxycycline concentration, the effects were likely caused by a mixture of the parental compound and its degradation products. The concentrations of microplastics and pharmaceuticals tested (low ppm range) are higher than those expected to be found in waters of the most part of marine ecosystems (ppt or ppb ranges). However, considering the widespread contamination by microplastics and pharmaceuticals, the concentrations already found in waters, sediments and/or organism of heavily polluted areas, the long-term exposure (over generations) of wild populations to such substances in polluted ecosystems and the possibilities of bioaccumulation and toxicological interactions, these findings are of concern and further research on microplastics-pharmaceuticals toxicological interactions is needed.