Microplastic sample purification methods - Assessing detrimental effects of purification procedures on specific plastic types.

In search of effective, fast, and cheap methods to purify environmental samples for microplastic analysis, scientific literature provides various purification protocols. However, while most of these protocols effectively purify the samples, some may also degrade the targeted polymers. This study was conducted to systematically compare the effects of purification protocols based on acidic, alkaline, oxidative, and enzymatic digestion and extraction via density separation on eight of the most relevant plastic types. It offers insights into how specific purification protocols may compromise microplastic detection by documenting visible and gravimetric effects, analyzing potential surface degradation using Fourier transform infrared spectroscopy (FTIR) and bulk erosion on a molecular level using gel permeation chromatography (GPC). For example, protocols using strong acids and high temperatures are likely to completely dissolve or cause strong degradation to a wide range of polymers (PA, PC, PET, PS, PUR & PVC), while strong alkaline solutions may damage PC and PET. Contrarily, Fenton's reagent, multiple enzymatic digestion steps, as well as treatment with a zinc chloride solution frequently used for density-separation, do not degrade the eight polymers tested here. Therefore, their implementation in microplastic sample processing may be considered an essential stepping-stone towards a standardized protocol for future microplastics analyses.

Moving Toward Standardized Toxicity Testing Procedures with Particulates by Dietary Exposure of Gammarids.

Ecotoxicological effect assessment of particulate materials and sparingly soluble substances is an emerging field. Current standard toxicity tests of aquatic organisms are based on soluble substances which are added to the aqueous phase. Although soluble substances distribute homogeneously, particles can form aggregates, resulting in inhomogeneous distribution and unpredictable exposure. Therefore, test scenarios need to be adapted to overcome these uncertainties. We present a dietary particle exposure tool for the toxicity testing of sparingly soluble substances or particles in combination with a standardizable food source for gammarids based on decomposition and consumption tablets (DECOTABs). Four food supplements in the DEOCOTAB formulation were compared to test their influence on the energy reserves of gammarids. Although feeding rate was constant for most supplements, mortality and energy reserves revealed clear differences. Tabs supplemented with algae-based phyll or animal protein-based trout food best met all of the requirements. Fluorescent plastic microparticles (10-65 µm) were homogenously distributed and stable in the DECOTABs. Constant feeding was observed, and the number of ingested microparticles by Gammarus roeseli was quantified in relation to the consumed food. The developed method provides a realistic and methodologically reliable uptake from the oral pathway and allows the quantification of inner exposition via feeding rate, providing a promising tool for standardized dietary exposure scenarios with particles. Environ Toxicol Chem 2021;40:1463-1476. © 2021 The Authors. Environmental Toxicology and Chemistry published by Wiley Periodicals LLC on behalf of SETAC.

Analysis of microplastics of a broad size range in commercially important mussels by combining FTIR and Raman spectroscopy approaches.

Microplastic (MP) contamination is present in the entire marine environment from the sediment to the water surface and down to the deep sea. This ubiquitous presence of MP particles opens the possibility for their ingestion by nearly all species in the marine ecosystem. Reports have shown that MP particles are present in local commercial seafood species leading to the possible human ingestion of these particles. However, due to a lack of harmonized methods to identify microplastics (MPs), results from different studies and locations can hardly be compared. Hence, this study was aimed to detect, quantify, and estimate MP contamination in commercially important mussels originating from 12 different countries distributed worldwide. All mussels were obtained from supermarkets and were intended for human consumption. Using a combinatorial approach of focal plane array (FPA)-based micro- Fourier-transform infrared (FTIR) spectroscopy and micro-Raman spectroscopy allowed the detection and characterization of MP down to a size of 3 µm in the investigated mussels. Further, a gentle sample purification method based on enzymes has been modified in order to optimize the digestion of organic material in mussels. A random forest classification (RFC) approach, which allows a rapid discrimination between different polymer types and thus fast generation of data on MP abundance and size distributions with high accuracy, was implemented in the analytical pipeline for IR spectra. Additionally, for the first time we also applied a RFC approach for the automated characterization of Raman spectra of MPs.

Invasive zebra mussel (Dreissena polymorpha) threatens an exceptionally large population of the depressed river mussel (Pseudanodonta complanata) in a postglacial lake.

Freshwater mussels are in decline worldwide, with the depressed river mussel Pseudanodonta complanata being one of the rarest and most endangered species in Europe. Invasive mussels are suspected to be an important factor of decline, but there is little information on their interaction with native species.This study analyzed densities, depth distribution, and individual sizes and weights in one of the largest known populations of P. complanata in Europe in relation to the co-occurring invasive zebra mussel Dreissena polymorpha and other mussel species, using a systematic transect analysis. Pseudanodonta complanata was the dominant unionid species in Lake Siecino reaching densities of up to 26 ind/m2, with half of the specimens found at a water depth of 2.0-4.0 m. Densities were highest on sandy substrates in areas of underwater currents. In contrast, 67% of native Unio tumidus were found at depths < 1 m, indicating different habitat preference.In the study area, 91% of P. complanata, 92% of U. tumidus, and all Anodonta individuals were fouled by D. polymorpha. The dreissenid:unionid mass ratio (mean ± SD; maximum) was 0.43 ± 0.56; 4.22 and 0.86 ± 1.87; 8.76 in P. complanata and U. tumidus, respectively. Pseudanodonta complanata fouled with D. polymorpha were impaired in their anchoring capability and had shell deformations potentially affecting shell closing and filtration activity. Fouling intensity was negatively correlated with unionid density, potentially leading to accelerated population declines.The observed adverse effects of invasive zebra mussels on the depressed river mussel and the difficulties in eradicating established populations of invasive mussels suggest that D. polymorpha should be considered a serious threat to P. complanata. Therefore, the further spread of zebra mussels into habitats with native unionids needs to be avoided by all means.

Modulation of PAH toxicity on the freshwater organism G. roeseli by microparticles.

Polycyclic aromatic hydrocarbons are widespread and environmentally persistent chemicals that readily bind to particles in air, soil and sediment. Plastic particles, which are also an ubiquitous global contamination problem, may thus modulate their environmental fate and ecotoxicity. First, the acute aqueous toxicity of phenanthrene in adult Gammarus roeseli was determined with a LC50 of 471 µg/L after 24 h and 441 µg/L after 48 h. Second, considering lethal and sublethal endpoints, effects of phenanthrene concentration on G. roeseli were assessed in relation to the presence of anthropogenic and natural particles. The exposure of gammarids in presence of either particle type with phenanthrene resulted after 24 and 48 h in reduced effect size. Particle exposure alone did not result in any effects. The observed reduction of phenanthrene toxicity by polyamide contradicts the discussion of microplastics acting as a vector or synergistically. Especially, no difference in modulation by plastic particles and naturally occurring sediment particles was measured. These findings can most likely be explained by the similar adsorption of phenanthrene to both particle types resulting in reduced bioavailability.

Multi-temporal surveys for microplastic particles enabled by a novel and fast application of SWIR imaging spectroscopy - Study of an urban watercourse traversing the city of Berlin, Germany.

Following the widespread assumption that a majority of ubiquitous marine microplastic particles originate from land-based sources, recent studies identify rivers as important pathways for microplastic particles (MPP) to the oceans. Yet a detailed understanding of the underlying processes and dominant sources is difficult to obtain with the existing accurate but extremely time-consuming methods available for the identification of MPP. Thus in the presented study, a novel approach applying short-wave infrared imaging spectroscopy for the quick and semi-automated identification of MPP is applied in combination with a multitemporal survey concept. Volume-reduced surface water samples were taken from transects at ten points along a major watercourse running through the South of Berlin, Germany, on six dates. After laboratory treatment, the samples were filtered onto glass fiber filters, scanned with an imaging spectrometer and analyzed by image processing. The presented method allows to count MPP, classify the plastic types and determine particle sizes. At the present stage of development particles larger than 450 µm in diameter can be identified and a visual validation showed that the results are reliable after a subsequent visual final check of certain typical error types. Therefore, the method has the potential to accelerate microplastic identification by complementing FTIR and Raman microspectroscopy. Technical advancements (e.g. new lens) will allow lower detection limits and a higher grade of automatization in the near future. The resulting microplastic concentrations in the water samples are discussed in a spatio-temporal context with respect to the influence (i) of urban areas, (ii) of effluents of three major Berlin wastewater treatment plants discharging into the canal and (iii) of precipitation events. Microplastic concentrations were higher downstream of the urban area and after precipitation. An increase in microplastic concentrations was discernible for the wastewater treatment plant located furthest upstream though not for the other two.

Variation in plastic abundance at different lake beach zones - A case study.

Plastic particles in marine and freshwater environments span from macroscopic to microscopic size classes. Each may have a different impact on individuals, populations and ecosystems, but still the wide variety of methods used in beach sediment sampling inhibit comparisons among studies and therefore hampers a risk assessment. A large portion of the uncertainties is due to differing sampling strategies. By quantifying the alongshore distribution of macro- and microplastic particles within five beaches of Lake Garda, we aim to shed light on the accumulation behavior of microplastic particles at an exemplary lake which might give indications for potential sampling zones. The identification of plastic at the single particle level with a spatial resolution down to 1µm was performed by Raman microspectroscopy. Given the time consuming approach we reduced the number of samples in the field but increased the spatial area where a single sample was taken, by utilizing a transect approach in combination with sediment cores (5cm depth). The study revealed that, in comparison to the water line and the high-water line, the drift line of all five beaches always contained plastic particles. Since the drift line accumulate particulate matter on a relatively distinct zone, it will enable a comparable sampling of microplastic particles. The applied sampling approach provided a representative method for quantifying microplastic down to 1µm on a shore consisting of pebbles and sand. Hence, as first step towards a harmonization of beach sediment sampling we suggest to perform sampling at the drift line, although further methodological improvements are still necessary.

Do microplastic particles affect Daphnia magna at the morphological, life history and molecular level?

Microplastic particles are ubiquitous not only in marine but also in freshwater ecosystems. However, the impacts of microplastics, consisting of a large variety of synthetic polymers, on freshwater organisms remains poorly understood. We examined the effects of two polymer mixtures on the morphology, life history and on the molecular level of the waterflea Daphnia magna (three different clones). Microplastic particles of ~40 µm were supplied at a low concentration (1% of the food particles) leading to an average of ~30 particles in the digestive tract which reflects a high microplastic contamination but still resembles a natural situation. Neither increased mortality nor changes on the morphological (body length, width and tail spine length) or reproductive parameters were observed for adult Daphnia. The analyses of juvenile Daphnia revealed a variety of small and rather subtle responses of morphological traits (body length, width and tail spine length). For adult Daphnia, alterations in expression of genes related to stress responses (i.e. HSP60, HSP70 & GST) as well as of other genes involved in body function and body composition (i.e. SERCA) were observed already 48h after exposure. We anticipate that the adverse effects of microplastic might be influenced by many additional factors like size, shape, type and even age of the particles and that the rather weak effects, as detected in a laboratory, may lead to reduced fitness in a natural multi-stressor environment.

Enzymatic Purification of Microplastics in Environmental Samples.

Micro-Fourier transform infrared (micro-FTIR) spectroscopy and Raman spectroscopy enable the reliable identification and quantification of microplastics (MPs) in the lower micron range. Since concentrations of MPs in the environment are usually low, the large sample volumes required for these techniques lead to an excess of coenriched organic or inorganic materials. While inorganic materials can be separated from MPs using density separation, the organic fraction impedes the ability to conduct reliable analyses. Hence, the purification of MPs from organic materials is crucial prior to conducting an identification via spectroscopic techniques. Strong acidic or alkaline treatments bear the danger of degrading sensitive synthetic polymers. We suggest an alternative method, which uses a series of technical grade enzymes for purifying MPs in environmental samples. A basic enzymatic purification protocol (BEPP) proved to be efficient while reducing 98.3 ± 0.1% of the sample matrix in surface water samples. After showing a high recovery rate (84.5 ± 3.3%), the BEPP was successfully applied to environmental samples from the North Sea where numbers of MPs range from 0.05 to 4.42 items m-3. Experiences with different environmental sample matrices were considered in an improved and universally applicable version of the BEPP, which is suitable for focal plane array detector (FPA)-based micro-FTIR analyses of water, wastewater, sediment, biota, and food samples.

Spatial and temporal variation of macro-, meso- and microplastic abundance on a remote coral island of the Maldives, Indian Ocean.

Plastic debris is ubiquitous in the marine environment and the world's shores represent a major sink. However, knowledge about plastic abundance in remote areas is scarce. Therefore, plastic abundance was investigated on a small island of the Maldives. Plastic debris (>1mm) was sampled once in natural long-term accumulation zones at the north shore and at the high tide drift line of the south shore on seven consecutive days to quantify daily plastic accumulation. Reliable identification of plastic debris was ensured by FTIR spectroscopy. Despite the remoteness of the island a considerable amount of plastic debris was present. At both sites a high variability in plastic abundance on a spatial and temporal scale was observed, which may be best explained by environmental factors. In addition, our results show that snapshot sampling may deliver biased results and indicate that future monitoring programs should consider spatial and temporal variation of plastic deposition.

Hazardous or not - Are adult and juvenile individuals of Potamopyrgus antipodarum affected by non-buoyant microplastic particles?

Microplastic has been ubiquitously detected in freshwater ecosystems. A variety of freshwater organisms were shown to ingest microplastic particles, while a high potential for adverse effects are expected. However, studies addressing the effect of microplastic in freshwater species are still scarce compared to studies on marine organisms. In order to gain further insights into possible adverse effects of microplastic particles on freshwater invertebrates and to set the base for further experiments we exposed the mud snail (Potampoyrgus antipodarum) to a large range of common and environmentally relevant non-buoyant polymers (polyamide, polyethylene terephthalate, polycarbonate, polystyrene, polyvinylchloride). The impact of these polymers was tested by performing two exposure experiments with irregular shaped microplastic particles with a broad size distribution in a low (30%) and a high microplastic dose (70%) in the food. First, possible effects on adult P. antipodarum were assessed by morphological and life-history parameters. Second, the effect of the same mixture on the development of juvenile P. antipodarum until maturity was analyzed. Adult P. antipodarum showed no morphological changes after the exposure to the microplastic particles, even if supplied in a high dose. Moreover, although P. antipodarum is an established model organism and reacts especially sensitive to endocrine active substances no effects on embryogenesis were detected. Similarly, the juvenile development until maturity was not affected. Considering, that most studies showing effects on marine and freshwater invertebrates mostly exposed their experimental organisms to very small (≤20 µm) polystyrene microbeads, we anticipate that these effects may be highly dependent on the chemical composition of the polymer itself and the size and shape of the particles. Therefore, more studies are necessary to enable the identification of harmful synthetic polymers as some of them may be problematic and should be declared as hazardous whereas others may have relatively moderate or no effects.

Pigments and plastic in limnetic ecosystems: A qualitative and quantitative study on microparticles of different size classes.

Recently, macroplastic (>5 mm) and especially microplastic (<5 mm) particles have been reported as emerging contaminants in marine and limnetic ecosystems. Their coloration is gained by the addition of pigments to the polymer blend which is the major component of the respective product. However, color is also a feature of paint and coatings whereby the pigment is the major component. Once abraded from a surface, paint particles may enter the environment via similar pathways as microplastic particles. So far no detailed studies of microplastic particles (pigmented and non-pigmented) as well as paint particles have been performed focusing on very small microparticles (1-50 µm), in either marine or limnetic ecosystems. Using Raman microspectroscopy with a spatial resolution down to 1 µm, we report a remarkable increase in the occurrence of (pigmented) microplastic particles below 500 µm. Among those, most particles were found at a size of ∼130 µm in a freshwater ecosystem (subalpine Lake Garda, Italy). Moreover, our qualitative and quantitative analyses revealed that the number of paint microparticles significantly increased below the size range of 50 µm due to their brittleness (the smallest detected paint particle had a size of 4 µm). Inductively coupled plasma mass spectrometry measurements showed that both colored particles found in nature as well as virgin particles contain a high variety of metals such as cadmium, lead and copper. These additives may elicit adverse effects in biota ingesting these microparticles, thus paints and associated compounds may act as formerly overlooked contaminants in freshwater ecosystems.

BSH-CP based 3D solid-state NMR experiments for protein resonance assignment.

We have recently presented band-selective homonuclear cross-polarization (BSH-CP) as an efficient method for CO-CA transfer in deuterated as well as protonated solid proteins. Here we show how the BSH-CP CO-CA transfer block can be incorporated in a set of three-dimensional (3D) solid-state NMR (ssNMR) pulse schemes tailored for resonance assignment of proteins at high static magnetic fields and moderate magic-angle spinning rates. Due to the achieved excellent transfer efficiency of 33 % for BSH-CP, a complete set of 3D spectra needed for unambiguous resonance assignment could be rapidly recorded within 1 week for the model protein ubiquitin. Thus we expect that BSH-CP could replace the typically used CO-CA transfer schemes in well-established 3D ssNMR approaches for resonance assignment of solid biomolecules.

Practitioner review: evidence-based practice guidelines on alcohol and drug misuse among adolescents: a systematic review.

BACKGROUND: Context-specific evidence-based guidelines on how to prevent and treat substance misuse among adolescents are currently lacking in many countries. Due to the time consuming nature of de novo guideline development, the ADAPTE collaboration introduced a methodology to adapt existing guidelines to a local context. An important step in this method is a systematic review to identify relevant high-quality evidence-based guidelines. This study describes the results of this step for the development of guidelines on adolescent alcohol and drug misuse in Belgium. METHODS: Rigorous systematic review methodology was used. This included searches of electronic databases (Medline, Embase, Cinahl, PsychInfo, and ERIC in June 2011), websites of relevant organizations, and reference lists of key publications. Experts in the field were also contacted. Included were Dutch, English, French, or German evidence-based practice guidelines from 2006 or later on the prevention, screening, assessment, or treatment of alcohol or illicit drug misuse in persons aged 12-18 years. Two independent reviewers assessed the quality of the guidelines using the AGREE II (Appraisal of Guidelines for Research and Evaluation) instrument. SCOPE: This overview provides a framework of current knowledge in adolescent alcohol and drug misuse prevention and treatment. RESULTS: This systematic review identified 32 relevant evidence-based guidelines on substance misuse among adolescents. Nine guidelines were judged to be of high quality; of which four had recommendations specifically on adolescents: one on school-based prevention, one on substance misuse prevention in vulnerable young people and two on alcohol misuse with specific sections for the adolescent population. There were few commonalities as guidelines focused on different target groups, professional disciplines and type and level of substance misuse. Evidence to support the recommendations was sparse, and many recommendations were based on expert consensus or on studies among adults. Also, the link between evidence and recommendations was often unclear. CONCLUSIONS: There are a substantial number of guidelines addressing substance misuse in adolescents. However, only four high-quality guidelines included recommendations specific for adolescents. The current level of evidence that underpins the recommendations in these high-quality guidelines is low.

Obstacles to implementing evidence-based practice in Belgium: a context-specific qualitative evidence synthesis including findings from different health care disciplines.

A number of barriers to the implementation of evidence-based practice have already been inventoried. However, little attention has been given to their context-specific nature. This qualitative evidence synthesis examines commonalities in the obstacles perceived by different groups of health care practitioners working in the Belgian health care system and sets out to discuss potential strategies to bridge some of these barriers. We actively searched for primary studies addressing our topic of interest in international and national databases (1990 to May 2008), consulted experts and screened references of retrieved studies. We opted for the meta-aggregative approach, developed by the Joanna Briggs Institute, to analyse our findings. The findings indicate that (1) evidence might have a limited role in decision-making processes; (2) aspects other than quality of care steer the evidence-based practice agenda; (3) some health care providers benefit less from evidence-based practice than others and (4) there is a lack of competences to put the evidence-based principles in practice. Belgian policy makers might consider health care system characteristics from and strategies developed or suggested by others to respond to country-specific obstacles. Examples include but are not limited to; (a) providing incentives for patient-centred care coordination and patient communication, (b) supporting practitioners interested in applying research-related activities, (c) considering direct access systems and interprofessional learning to respond to the demand for autonomous decision-making from satellite professional groups, (d) systematically involving allied health professionals in important governmental advisory boards, (e) considering pharmaceutical companies perceived as 'the enemy' an ally in filling in research gaps, (f) embedding the evaluation of evidence-based knowledge and skills in examinations (g) moving from (in)formative learning to transformative learning and (h) organizing high quality catch-up programs for those who missed out on evidence-based medicine in their curriculum.

[Preliminary results of a focus-group-based research project on the problems of implementing evidence-based practice in Belgium (Flanders). Do psychiatrists differ from other health care practitioners?]. / Preliminaire bevindingen van focusgroeponderzoek over hinderpalen bij implementatie van evidence-based praktijkvoering in Vlaanderen. Zijn psychiaters anders dan andere zorgverleners?

BACKGROUND: The impact of evidence-based practice (EBP) has increased substantially in recent years. However, health care practitioners are experiencing difficulties in implementing EBP. AIM: The specific task was to find out what problems are encountered by Flemish (Belgian, Dutch-speaking) health care practitioners. method In order to explore this problem, we adopted a qualitative research strategy and set up 25 focus groups, 5 of which consisted solely of psychiatrists. results Psychiatrists shared with other health care disciplines some concerns about the characteristics of 'evidence' and about the influential role played by their 'partners' in the health care system, namely by government, commercial firms and patients. Psychiatrists perceived their discipline to be much more complex than other disciplines, particularly in areas such as research design, patients' problems, psychiatric diagnosis and therapeutic psychiatrist-patient relationships. The literature and the preliminary results of ongoing research revealed that other disciplines too are confronted with similar complexities. CONCLUSION: There seems to be no justification for ruling out the possibility of implementing EBP on the basis of discipline-related barriers.

Implementing and optimising an Electronic Library of Health Care in Belgium: results of a pilot study.

Health care practitioners are expected to incorporate results from the best available, scientific information into their daily clinical decision-making process. Useful formats of evidence for practitioners include selected reviews, abstracts in which research results are discussed, "quick answer", evidence-based website including for example diagnostic and therapeutic algorithms, drugs prescription and non-drug therapy. An increasing amount of practitioners has access to the World Wide Web, either at home or at the office. However, easy and cheap access to objective and high quality research results is limited. Many practitioners lack the skills to efficiently navigate complicated medical databases. In 2003 an 'Electronic Library of Health Care' was introduced in Belgium. The main goal of the electronic library is to provide a gateway to scientific evidence to Belgian health care practitioners from different disciplines. This paper presents the results of a pilot project to implement the library in the field. It also describes recent developments and adjustments that increased the efficacy of this gateway to evidence.

['Evidence-based medicine' in the Dutch and Flemish psychiatric, psychological and psychotherapeutic specialist literature: widely used?]. / 'Evidence-based medicine' in de Nederlandstalige psychiatrische, psychologische en psychotherapeutische vakliteratuur: opvallend aanwezig?

The expression 'evidence-based medicine' was first used in medical journals in the 1990's. Recent research has shown that the expression appears very frequently in international medical publications. Until recently, however, there were no research data concerning the frequency with which the expression is used in the titles and summaries in Dutch and Flemish specialist journals in the field of psychiatry, psychology and psychotherapy. In our systematic review of the Dutch and Flemish specialist medical literature published between 1990 and 2003 we found that the use of the expression increased markedly as from 1997.

[Evidence-based medicine: a discussion of the most frequently occurring criticisms]. / Evidence-based medicine: een bespreking van de meest voorkomende kritiek.

Since the introduction of evidence-based medicine (EBM) into the field of health care in the early nineties some major criticisms have appeared in scientific literature. One of the most commonly heard objections to EBM is loss of therapeutic freedom. However even with the advent of EBM the physician continues to look for solutions that are tailored to the patient. The available evidence is often inadequate, there are many inconsistencies and contradictions in the research material and the published outcomes are distorted by publication bias. There is resistance to the opinion that randomized clinical trials (RCTs) provide the best foundations on which to build clinical policies. There must always be room for views expressed in other types of study. EBM is primarily for academics and does not take clinical expertise into account. However as the results of scientific research are becoming increasingly available to a wider public, patients are able to challenge the decisions made by their health-care practitioners and push them to provide the motivation for their decisions. Many health-care practitioners have commented that they always have to take the results of scientific research into account. One strength of EBM in this is the transparent manner in which the overview of the literature develops and the systematic approach to results from scientific study. After all, there is insufficient evidence that the EBM process works effectively and that it therefore improves patient care. It is true to say that patients who receive treatment of which the efficacy has been proven experience better treatment results than other patients. Setting up a definitive randomized study to answer this question would be difficult if not impossible. EBM is an aid to support clinical decision making. The development of principles on which to base this way of thinking and acting and the quest for suitable research designs and the most objective research results in order to be able to answer all the questions posed by caregivers, is not yet complete. EBM is just one of the weapons in the armoury of the caregiver in the battle for the optimal provision.