Due to the widespread use and durability of synthetic polymers, plastic debris occurs in the environment worldwide. In the present work, information on sources and fate of microplastic particles in the aquatic and terrestrial environment, and on their uptake and effects, mainly in aquatic organisms, is reviewed. Microplastics in the environment originate from a variety of sources. Quantitative information on the relevance of these sources is generally lacking, but first estimates indicate that abrasion and fragmentation of larger plastic items and materials containing synthetic polymers are likely to be most relevant. Microplastics are ingested and, mostly, excreted rapidly by numerous aquatic organisms. So far, there is no clear evidence of bioaccumulation or biomagnification. In laboratory studies, the ingestion of large amounts of microplastics mainly led to a lower food uptake and, consequently, reduced energy reserves and effects on other physiological functions. Based on the evaluated data, the lowest microplastic concentrations affecting marine organisms exposed via water are much higher than levels measured in marine water. In lugworms exposed via sediment, effects were observed at microplastic levels that were higher than those in subtidal sediments but in the same range as maximum levels in beach sediments. Hydrophobic contaminants are enriched on microplastics, but the available experimental results and modelling approaches indicate that the transfer of sorbed pollutants by microplastics is not likely to contribute significantly to bioaccumulation of these pollutants. Prior to being able to comprehensively assess possible environmental risks caused by microplastics a number of knowledge gaps need to be filled. However, in view of the persistence of microplastics in the environment, the high concentrations measured at some environmental sites and the prospective of strongly increasing concentrations, the release of plastics into the environment should be reduced in a broad and global effort regardless of a proof of an environmental risk.Electronic supplementary materialThe online version of this article (doi:10.1186/s12302-015-0069-y) contains supplementary material, which is available to authorised users.

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The veterinary parasiticide ivermectin was selected as a case study compound within the project ERAPharm (Environmental Risk Assessment of Pharmaceuticals). Based on experimental data generated within ERAPharm and additional literature data, an environmental risk assessment (ERA) was performed mainly according to international and European guidelines. For the environmental compartments surface water, sediment, and dung, a risk was indicated at all levels of the tiered assessment approach. Only for soil was no risk indicated after the lower tier assessment. However, the use of effects data from additional 2-species and multispecies studies resulted in a risk indication for collembolans. Although previously performed ERAs for ivermectin revealed no concern for the aquatic compartment, and transient effects on dung-insect populations were not considered as relevant, the present ERA clearly demonstrates unacceptable risks for all investigated environmental compartments and hence suggests the necessity of reassessing ivermectin-containing products. Based on this case study, several gaps in the existing guidelines for ERA of pharmaceuticals were shown and improvements have been suggested. The action limit at the start of the ERA, for example, is not protective for substances such as ivermectin when used on intensively reared animals. Furthermore, initial predicted environmental concentrations (PECs) of ivermectin in soil were estimated to be lower than refined PECs, indicating that the currently used tiered approach for exposure assessment is not appropriate for substances with potential for accumulation in soil. In addition, guidance is lacking for the assessment of effects at higher tiers of the ERA, e.g., for field studies or a tiered effects assessment in the dung compartment.

β-Adrenergic receptor blockers (β-blockers) are applied to treat high blood pressure, ischemic heart disease, and heart rhythm disturbances. Due to their widespread use and limited human metabolism, β-blockers are widely detected in sewage effluents and surface waters. β-Adrenergic receptors have been characterized in fish and other aquatic animals, so it can be expected that physiological processes regulated by these receptors in wild animals may be affected by the presence of β-blockers. Because ecotoxicological data on β-blockers are scarce, it was decided to choose the β-blocker atenolol as a case study pharmaceutical within the project ERAPharm. A starting point for the assessment of potential environmental risks was the European guideline on the environmental risk assessment of medicinal products for human use. In Phase I of the risk assessment, the initial predicted environmental concentration (PEC) of atenolol in surface water (500 ng L−1) exceeded the action limit of 10 ng L−1. Thus, a Phase II risk assessment was conducted showing acceptable risks for surface water, for groundwater, and for aquatic microorganisms. Furthermore, atenolol showed a low potential for bioaccumulation as indicated by its low lipophilicity (log KOW = 0.16), a low potential for exposure of the terrestrial compartment via sludge (log KOC = 2.17), and a low affinity for sorption to the sediment. Thus, the risk assessment according to Phase II-Tier A did not reveal any unacceptable risk for atenolol. Beyond the requirements of the guideline, additional data on effects and fate were generated within ERAPharm. A 2-generation reproduction test with the waterflea Daphnia magna resulted in the most sensitive no-observed-effect concentration (NOEC) of 1.8 mg L−1. However, even with this NOEC, a risk quotient of 0.003 was calculated, which is still well below the risk threshold limit of 1. Additional studies confirm the outcome of the environmental risk assessment according to EMEA/CHMP (2006). However, atenolol should not be considered as representative for other β-blockers, such as metoprolol, oxprenolol, and propranolol, some of which show significantly different physicochemical characteristics and varying toxicological profiles in mammalian studies.

Because of their usually high molecular weight, polymers are generally considered as being of low environmental concern and are, therefore, exempted from registration and evaluation within REACH. This exemption is currently being reviewed by the European Commission. Against this background, data on the environmental fate and effects of selected water-soluble synthetic organic polymers used in cosmetic products were evaluated. The considered polymers include non-ionic polyethylene glycols (PEGs), anionic homo- and copolymers of acrylic acid (AA-P&CoPs), and cationic polyquaterniums (PQs). The PEGs are more amenable to biodegradation than the AA-P&CoPs and the PQs, which biodegrade slowly. In wastewater treatment plants, sorption and precipitation are expected to lead to an effective removal of the considered polymers from the wastewater. Uptake and bioaccumulation in aquatic organisms are limited by the large molecular size and, for AA-P&CoPs and PQs, the ionic charge of the polymers. In aquatic ecotoxicity tests, the PEGs and the AA-P&CoPs showed generally no to low toxicity. Effects of AA-P&CoPs on algae and crustaceans are attributed to the chelation of cationic nutrients in soft water, with toxicity being mitigated at higher water hardness. Toxicity of the cationic PQs to aquatic organisms ranged from absent to high, depending on the polymer structure, charge density and molecular weight, as well as on the test organism and test conditions. The observed effects most likely result from interactions with the organisms’ surfaces. Aquatic toxicity of the PQs is reduced by dissolved organic carbon, suspended solids, sediments minerals, and at higher water hardness, representative of natural conditions. Results from toxicity tests with sediment and soil organisms were only identified for homopolymers of acrylic acid, showing no toxicity. The evaluation of the available ecotoxicity data suggests that test methods may need to be adapted to the respective polymer type, and further standardised to improve reproducibility. Based on the identified data, the considered polymers are likely to be of low environmental concern. However, this conclusion must be seen as preliminary, since environmental concentrations could not be estimated, and further ecotoxicity data are required, e.g., for sediment and soil organisms.

The incorporation of the quinolone antibacterials oxohnic acid and sarafloxacin into Artemia fransciscana and subsequently into turbot, Scophthalmus maximus (L.), was quantified, and the therapeutic efficacy of the bioencapsulated drugs against challenge with Vibrio anguillarum 8587 was investigated. Five-wcek-oid turbot were fed for 10 days with Artemia enriched with either oxolinic acid or sarafloxaein. Therapeutic concentrations were reached with both drugs (11-8^/g oxolinic acid per gram fresh weight: lK/^g sarafloxacin per gram fresh weight). Both treatments proved effective against challenge, with V. anguillaritmspeeific mortality rates of 6 and 14% in the oxolinic acid and sarafloxaein treated groups, respectively, compared with 75% in the infected control. However, incorporation of the drug by brine shrimp was extremely low (<1%), and therefore, bioencapsulation cannot be considered as an appropriate method to reduce impact on the environment.Correspondence; K. Duis, Fleitberg 2, 23619 Heilshoop. Germany.

Based on the hypothesis that analysis of gene expression could be used to predict chronic fish toxicity, the zebrafish (Danio rerio) embryo test (DarT), developed as a replacement method for the acute fish test, was expanded to a gene expression D. rerio embryo test (Gene-DarT). The effects of 14 substances on lethal and sublethal endpoints of the DarT and on expression of potential marker genes were investigated: the aryl hydrocarbon receptor 2, cytochrome P450 1A (cypla), heat shock protein 70, fizzy-related protein 1, the transcription factors v-maf musculoaponeurotic fibrosarcoma oncogene family protein g (avian) 1 and NF-E2-p45-related factor, and heme oxygenase 1 (hmox1). After exposure of zebrafish embryos for 48 h, differential gene expression was evaluated using reverse transcriptase-polymerase chain reaction, gel electrophoresis, and densitometric analysis of the gels. All tested compounds significantly affected the expression of at least one potential marker gene, with cyp1a and hmox1 being most sensitive. Lowest-observed-effect concentrations (LOECs) for gene expression were below concentrations resulting in 10% lethal effects in the DarT. For 10 (3,4- and 3,5-dichloroaniline, 1,4-dichlorobenzene, 2,4-dinitrophenol, atrazine, parathion-ethyl, chlorotoluron, genistein, 4-nitroquinoline-1-oxide, and cadmium) out of the 14 tested substances, LOEC values derived with the Gene-DarT differ by a factor of less than 10 from LOEC values of fish early life stage tests with zebrafish. For pentachloroaniline and pentachlorobenzene, the Gene-DarT showed a 23- and 153-fold higher sensitivity, respectively, while for lindane, it showed a 13-fold lower sensitivity. For ivermectin, the Gene-DarT was by a factor of more than 1,000 less sensitive than the acute fish test. The results of the present study indicate that gene expression analysis in zebrafish embryos could principally be used to predict effect concentrations in the fish early life stage test.

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