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Plastics of the future? The impact of biodegradable polymers on the environment and on society

Author: Haider, T.; Völker, C.; Kramm, J.; Landfester, K.; Wurm, F.R.
Year of Publication: 2018
Published: Angewandte Chemie International Edition

Abstract:
We are living in a plastic age. For most of us, life without polymers and plastics is unthinkable. However, in recent years the littering of plastics and the problems related to their persistence in the environment have become a major focus in both research and the news. Biodegradable polymers like poly(lactic acid) are seen as a suitable alternative to commodity plastics in order to minimize the impact of plastics on the environment after disposal. However, poly(lactic acid) is basically non‐degradable in seawater. Similarly, the degradation rate of other biodegradable polymers also crucially depends on the environments they end up in, such as soil or marine water, or when used in biomedical devices. In this review, we show that biodegradation tests carried out in artificial environments lack transferability to real conditions and, therefore, highlight the necessity of environmentally authentic and relevant field‐testing conditions. In addition, we focus on ecotoxicological implications of biodegradable polymers: Are there any possible adverse effects on biota caused by degradation products of the polymers? We also consider the social aspects and ask how biodegradable polymers influence consumer behavior and municipal waste management. Taken together, this study is intended as a contribution towards evaluating the potential of biodegradable polymers as alternative materials to commodity plastics.

Keywords:
Microplastics, Polyester, Ppolylactic Acid, Degradation, Polymers

Citation:
Haider, T.; Völker, C.; Kramm, J.; Landfester, K.; Wurm, F.R. (2018): Plastics of the future? The impact of biodegradable polymers on the environment and on society. In: Angewandte Chemie International Edition, https://doi.org/10.1002/anie.201805766.

Link:
https://doi.org/10.1002/anie.201805766

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Microplastics in freshwater ecosystems: what we know and what we need to know

Author: Martin Wagner, Christian Scherer, Diana Alvarez-Muñoz, Nicole Brennholt, Xavier Bourrain, Sebastian Buchinger, Elke Fries, Cécile Grosbois, Jörg Klasmeier, Teresa Marti, Sara Rodriguez-Mozaz, Ralph Urbatzka, A. Dick Vethaak, Margrethe Winther-Nielsen & Georg Reifferscheid
Year of Publication: 2014
Published:

Abstract:
Background
While the use of plastic materials has generated huge societal benefits, the ‘plastic age’ comes with downsides: One issue of emerging concern is the accumulation of plastics in the aquatic environment. Here, so-called microplastics (MP), fragments smaller than 5 mm, are of special concern because they can be ingested throughout the food web more readily than larger particles. Focusing on freshwater MP, we briefly review the state of the science to identify gaps of knowledge and deduce research needs.

State of the science
Environmental scientists started investigating marine (micro)plastics in the early 2000s. Today, a wealth of studies demonstrates that MP have ubiquitously permeated the marine ecosystem, including the polar regions and the deep sea. MP ingestion has been documented for an increasing number of marine species. However, to date, only few studies investigate their biological effects.

The majority of marine plastics are considered to originate from land-based sources, including surface waters. Although they may be important transport pathways of MP, data from freshwater ecosystems is scarce. So far, only few studies provide evidence for the presence of MP in rivers and lakes. Data on MP uptake by freshwater invertebrates and fish is very limited.

Knowledge gaps
While the research on marine MP is more advanced, there are immense gaps of knowledge regarding freshwater MP. Data on their abundance is fragmentary for large and absent for small surface waters. Likewise, relevant sources and the environmental fate remain to be investigated. Data on the biological effects of MP in freshwater species is completely lacking. The accumulation of other freshwater contaminants on MP is of special interest because ingestion might increase the chemical exposure. Again, data is unavailable on this important issue.

Conclusions
MP represent freshwater contaminants of emerging concern. However, to assess the environmental risk associated with MP, comprehensive data on their abundance, fate, sources, and biological effects in freshwater ecosystems are needed. Establishing such data critically depends on a collaborative effort by environmental scientists from diverse disciplines (chemistry, hydrology, ecotoxicology, etc.) and, unsurprisingly, on the allocation of sufficient public funding.

Keywords:
Chemistry, Ecotoxicology, Environmental  quality, Litter, Microplastics, Monitoring, Plastics, Polymers, Review, Water framework directive

Citation:
Martin Wagner, Christian Scherer, Diana Alvarez-Muñoz, Nicole Brennholt, Xavier Bourrain, Sebastian Buchinger, Elke Fries, Cécile Grosbois, Jörg Klasmeier, Teresa Marti, Sara Rodriguez-Mozaz, Ralph Urbatzka, A. Dick Vethaak, Margrethe Winther-Nielsen & Georg Reifferscheid (2014): Microplastics in freshwater ecosystems: what we know and what we need to know. Environmental Sciences Europe 26:12.

http://www.enveurope.com/content/26/1/12/abstract

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Interactions of microplastics with freshwater biota. In: Martin Wagner & Scott Lambert (Eds.): Freshwater microplastics: Emerging environmental contaminants?

Author: Christian Scherer, Annkatrin Weber, Scott Lambert, Martin Wagner
Year of Publication: 2017
Published: Martin Wagner & Scott Lambert (Eds.): Freshwater microplastics: Emerging environmental contaminants? The Handbook of Environmental Chemistry. Springer-Verlag.

Abstract:
The ubiquitous detection of microplastics in aquatic ecosystems promotes the concern for adverse impacts on freshwater ecosystems. The wide variety of material types, sizes, shapes, and physicochemical properties renders interactions with biota via multiple pathways probable.

So far, our knowledge about the uptake and biological effects of microplastics comes from laboratory studies, applying simplified exposure regimes (e.g., one polymer and size, spherical shape, high concentrations) often with limited environmental relevance. However, the available data illustrates species- and material-related interactions and highlights that microplastics represent a multifaceted stressor. Particle-related toxicities will be driven by polymer type, size, and shape. Chemical toxicity is driven by the adsorption-desorption kinetics of additives and pollutants. In addition, microbial colonization, the formation of hetero-aggregates, and the evolutionary adaptations of the biological receptor further increase the complexity of microplastics as stressors. Therefore, the aim of this chapter is to synthesize and critically revisit these aspects based on the state of the science in freshwater research. Where unavailable we supplement this with data on marine biota. This provides an insight into the direction of future research.

In this regard, the challenge is to understand the complex interactions of biota and plastic materials and to identify the toxicologically most relevant characteristics of the plethora of microplastics. Importantly, as the direct biological impacts of natural particles may be similar, future research needs to benchmark synthetic against natural materials. Finally, given the scale of the research question, we need a multidisciplinary approach to understand the role of microplastics in a multiple-particle world.

Keywords:
Autecology, Feeding types, Microplastic-biota interaction, Polymers, Suspended solids, Vector 

Citation:
Christian Scherer, Annkatrin Weber, Scott Lambert, Martin Wagner (2017): Interactions of microplastics with freshwater biota. In: Martin Wagner & Scott Lambert (Eds.): Freshwater microplastics: Emerging environmental contaminants? The Handbook of Environmental Chemistry. Springer-Verlag.

https://www.springer.com/de/book/9783319616148

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PET microplastics do not negatively affect the survival, development, metabolism and feeding activity of the freshwater invertebrate Gammarus pulex

Author: Annkatrin Weber, Christian Scherer, Nicole Brennholt, Georg Reifferscheid, Martin Wagner
Year of Publication: 2018
Published: Environmental Pollution 234: 181-189

Abstract:
Over the past decade, microscopic plastic debris, known as microplastics, emerged as a contaminant of concern in marine and freshwater ecosystems. Although regularly detected in aquatic environments, the toxicity of those synthetic particles is not well understood. To address this, we investigated whether the exposure to microplastics adversely affects the amphipod Gammarus pulex, a key freshwater invertebrate.

Juvenile (6–9 mm) and adult (12–17 mm) individuals were exposed to irregular, fluorescent polyethylene terephthalate fragments (PET, 10–150 μm; 0.8–4,000 particles mL−1) for 24 h. Results show that body burden after 24 h depends on the dose and age of G. pulex with juveniles ingesting more microplastics than adults. After chronic exposure over 48 d, microplastics did not significantly affect survival, development (molting), metabolism (glycogen, lipid storage) and feeding activity of G. pulex.

This demonstrates that even high concentrations of PET particles did not negatively interfere with the analyzed endpoints. These results contradict previous research on marine crustaceans. Differences may result from variations in the exposure regimes (e.g., duration, particle concentrations), plastic characteristics (e.g., type, size, shape, additives) as well as the species-specific morphological, physiological and behavioral traits. As a detritivorous shredder G. pulex is adapted to feed on non-digestible materials and might, therefore, be less sensitive towards exposure to synthetic particles. Accordingly, we argue that the autecology needs to be taken into account and that research should focus on identifying traits that render species susceptible to microplastic exposure.

Keywords:
Amphipods, Body burden, Ecotoxicology, Effects, Polymers, Toxicity

Citation:
Annkatrin Weber, Christian Scherer, Nicole Brennholt, Georg Reifferscheid, Martin Wagner (2018): PET microplastics do not negatively affect the survival, development, metabolism and feeding activity of the freshwater invertebrate Gammarus pulex. Environmental Pollution 234: 181-189

https://doi.org/10.1016/j.envpol.2017.11.014