Originally posted on the IEAM blog on 17 August
This post is the last in our series of updates from the SETAC Brussels meeting. We hope you enjoyed our coverage of toxicology research from the meeting!
What are microplastics and why should we care about them?
Microplastics are pieces of plastic or polymer debris that are very small in size, ranging from a shard as narrow as the width of a hair to a piece as large as a marble. Microplastics include pieces of plastic that are broken down from larger items, such as single-use water bottles, or ‘microbeads’ that are added to certain soaps and exfoliators.
Even though microplastics are small, there are concerns they can cause serious damage. Animals that confuse microplastics for food can end up with internal lacerations, inflammation, and nutrient deficiency caused by eating too much inedible material. Microplastics are also widely spread across the globe—scientists calculated that up to 90% of marine birds have ingested microplastics.
Plastic waste can be found everywhere. Coupled with predictions that plastic production could increase to 33 billion tons each year by 2050, it appears that microplastics are not going away anytime soon. Major news outlets regularly highlight the pervasive nature of this waste, including the story of the recent discovery of over 37 million pieces of plastic garbage on a South Pacific island.
Environmental toxicology researchers at the SETAC Brussels meeting (May 2017) presented a range of studies exploring the impacts of microplastics and addressing the challenges that we face in combating this pervasive, persistent, and tiny pollutant. In this post we highlight some of the findings presented during the sessions “Challenges and best practices in monitoring of micro- and nanoplastic abundance and environmental distribution” and “Microplastics, nanoplastics and co-contaminants: Fate, effects, and risk assessment for biota, the environment and human health.”
Microplastic monitoring: Where does it come from and where does it go?
One of the challenges for researchers is that microplastics comprise a large and diverse group of materials, including various sizes, shapes, materials, and sources. Some microplastics are formed by the breakdown of larger materials, while others are added into household products (e.g., microbeads), so it’s difficult to trace the fate of these materials.
Beate Baensch-Baltruschat from the German Federal Institute of Hydrology conducted a survey of plastic monitoring in European freshwater ecosystems. She found that rivers and streams are important for following the movement of plastics since these waterways are a major route for microplastics on their journey to the ocean. The survey looked at active sampling efforts by ten countries across Western and Central Europe. Monitoring data collected by these surveys revealed that there is a wide range of microplastic sizes, with larger particles (0.1 mm to 10 mm) more prevalent in surface waters and smaller particles found primarily in sediments.
Jes Vollertsen (Aalborg University) noted the problem of how the transport of microplastics during stormwater runoff events was not well-understood. To explore the issue, his research group sampled water and sediment from stormwater retention ponds in Denmark to examine microplastic levels. Their survey found that stormwater can hold up to 10 micrograms of microplastics per liter, and that nearly half of this plastic waste builds up in the sediment while the other half slowly discharges out of the pond water over time. Both Vollertsen and Baensch-Baltruschat’s work highlight the importance of monitoring and tracking microplastic movement in different types of environments.
Fabienne Lagarde from the Institute of Molecules and Materials studied how mussels were impacted by microplastic contamination along the Atlantic coast of France. Lagarde and her team identified 73 microplastics across all of the mussels they sampled over two sites, seasons, and habitats (wild caught versus cultivated environments). Eighty-five percent of the particles were polyethylene and polypropylene. Polyethylene is primarily found in single-use plastics such as bags and bottles, while polypropylene is made for more durable materials like plastic pipes and furniture. While microplastic levels did not differ significantly between seasons, sampling sites, or habitats, Lagarde’s results highlight the pervasive nature of microplastic contamination. Over 140,000 tons of mussels are produced in France every year, so studies like this are crucial for understanding potential risk to seafood consumers.
Some microplastics are in the form of fibers, shed from synthetic clothing during laundering. When these plastic microfibers enter the waste stream, pieces that are too small to be filtered out (microfibers) are discharged into the environment. Imogen Napper (Plymouth University) measured microfibers released from wash cycles with synthetic materials and found that a typical 6-kg wash of polyester-cotton blend clothing releases 137,000 fibers into wastewater. Even more microfibers are released from polyester materials (nearly 500,000) and acrylic clothing (728,000 fibers). Napper proposed a straightforward solution of including filters on washing machines to collect microfibers in order to reduce the large number of them that are discharged into the environment.
Microplastic effects: Are microplastics harmful to marine wildlife?
Inger Lise Nerland from NIVA discussed her work examining the impacts of polyethylene microbead exposure on Mediterranean mussels. Nerland exposed mussels to microbeads isolated from toothpaste for 3 weeks. The study was designed to reflect what happens in an actual environmental exposure by weathering the microbeads (allowing the material to break down naturally in seawater) before the exposure started. Nerland and her group found that not only did mussels ingest the microbeads, but that mussels with plastic particles had a higher number of blood cells in their gills, thinner gill tissues, and clumps of blood cells in their digestive system. This study provides more support for the hypothesis that microbead exposure can cause damage to the wildlife they come in contact with.
Theresee Karlsson (University of Gothenburg) looked at how single-use polyethylene bags break down in seawater. These single-use bags are very lightweight, yet somehow scientists find polyethylene deep in ocean sediments. Karlsson cut single-use bags into pieces of various sizes and placed the bags in stainless steel cages. Karlsson’s study showed that the amount of time that plastic pieces were left to degrade influenced the growth of microorganisms, or biofilms, on the plastic. The presence of biofilms changed the density of the plastic waste due to a build-up of calcium and silica. The example of how polyethylene bags change in density when they are bound by biofilms demonstrates how plastic waste cannot be classified in any broad, all-encompassing manner—even waste that starts off as the same material can have a completely different fate based on how it interacts with the environment.
Adam Porter from the University of Exeter highlighted his work demonstrating the importance of marine snow—organic matter, such as decaying animal and plant material, that falls from the surface levels of the ocean into the deep sea. This ‘snow’ is responsible for moving nutrients from the ocean’s surface down to the organisms living in the depths of the ocean. Porter’s work provides evidence on how marine snow affects the movement of microplastics. Porter measured microplastic sinking rates in artificial water columns both with and without artificial marine snow and also measured the difference in microplastic uptake in mussels. This study found that marine snow can bring lightweight microplastics to lower parts of the water column, and that mussels consumed more microplastics if marine snow was present. Porter’s work highlights the importance of considering deep sea organisms studying effects of microplastics in the marine environment.
Ricardo Beiras (University of Vigo) described how microplastics can bind other chemicals, becoming inadvertent vehicles for chemical exposure. Polymers and plastics contain many additives that can absorb other chemicals, so animals who consume microplastics might accidentally also be eating toxic chemicals. Beiras exposed sea urchin larvae to microplastics that were incubated with a toxic chemical (nonylphenol). While the plastic particles did absorb nonylphenol and the larvae did eat the plastic particles, Beiras did not find any evidence that nonylphenol was transferred to the larvae through the microplastics.
There is still a lot of work to be done to gain a better understanding the environmental fate and impacts of microplastics. Several sessions held at SETAC Brussels brought together researchers from numerous fields to share their work. This post represents just a small part of the global effort to understand and mediate the impacts of plastic pollution for both environmental and human health.
For those who want to help in the effort to reduce microplastics, you can start by using your own shopping bag instead of a single-use bag at the grocery store and look for alternatives to cleaning products containing microbeads.
Originally posted on the IEAM blog on 15 August as part of our SETAC Brussels session summaries series.
Circular economy, LCA, and the environment
As we consumers become more aware of how the products we buy and use impact the health of the environment, companies are also looking for ways to make more sustainable products using materials with a more positive environmental impact. Life cycle analysis (LCA) is a way for environmental scientists to clarify the environmental impacts of a material or product. A circular economy is a system of production and consumption that is powered by renewable energy. A clean circular economy also focuses on eliminating toxic chemicals and closing material loops through better design, maintenance, repair, reuse, refurbishing, and recycling.
An LCA includes everything that goes into the creation of a consumer product: gathering raw materials (like wood, coal, or metal), manufacturing the product (the type of factory used, what energy goes into production), how the product is used (single use versus multiple uses), and what happens to the product when it is no longer needed (what components are disposed or recycled). An LCA is completed using three steps: 1) inventory analysis (identify all inputs and outputs, where materials come from, where they end up, and the energy inputs and outputs related to the creation of the product), 2) impact analysis (a value known as an ‘impact score’ indicates the impact of each step in the manufacturing process), and 3) improvement analysis (finding places in the process that can be improved to reduce the impact score, like using less energy).
LCA helps companies understand what they can do to make products more sustainable, reduce negative impacts on the environment, and produce less toxic by-products. Product manufacturing is extremely complex however: raw materials are sourced from around the world, all of which are obtained in different ways depending on the country of origin and the type of material. Companies are constantly looking for better ways to determine the sustainability of new products.
At the SETAC Brussels meeting held in May 2017, researchers presented the latest advancements within LCA towards solving real-world problems in sustainability. Here we highlight the findings from the special session “Think-Outside-The-Box-Session: Clean circular economy: recycling while eliminating legacy toxics” organized by Dr. Niels Jonkers (Ecochain) and Dr. Heather Leslie (VU Amsterdam). We also highlight a selection of platform presentations from the “Advancements in life cycle impact assessment and footprint method development” session chaired by Serenella Sala (Joint Research Centre).
Creating a clean circular economy
Sicco Brandsma from VU Amsterdam highlighted the science behind recent health concerns on the use of recycled tires and rubber for recreational fields. Nearly 90% of all artificial soccer fields in countries like the Netherlands are made of recycled rubber granules, and a single playing field can use up to 20,000 recycled tires. EU regulations currently limit the amount toxic chemicals, such as polycyclicaromatic hydrocarbons (PAHs) that can be found in recycled rubber on playing fields to 100 mg of chemical per kg of rubber material. But Brandsma pointed out that regulations for other rubber products, such as children’s toys and rubber playground flooring require much lower maximum concentrations of PAHs, closer to the 1 mg/kg range. Brandsma highlighted the need for further research in this area that can address the concerns consumers have about the presence of rubber in places that people come into contact with on a regular basis.
Jane Muncke (Food Packaging Forum Foundation) gave a perspective from the food packaging industry on the future of the circular economy. Food consumption makes up close to one third of all human-induced environmental impacts across the world. Part of this impact is due to waste from food packaging, and the industry is attempting to address these challenges while making sure that chemicals used in food packaging are not toxic. There are currently 8,000 chemicals regulated by the EU in food packaging materials, but Muncke said that monitoring all 8,000 chemicals and understanding how the manufacturing process impacts chemical composition remains a challenge.
Muncke highlighted the importance of food package recycling in order to achieve a complete circular economy but stressed that material recycling should not be done in a way that increases human contact with potentially hazardous chemicals. Proposed solutions include ensuring that food containers are recycled but then reused in a manner consistent with their original purpose, such as reusing cold food containers to hold cold food again and not hot food (where the heat could cause some of the chemicals to leech out).
Giorgia Faraca (Technical University of Denmark) talked about on finding safe ways to recycle and reuse wood products. The challenge in this area is the presence of impurities in wood, such as metals, plastics, and chemical additives including paints and oils. There are EU regulations in place to prevent contact with hazardous materials in recycled wood, but Faraca stated that these regulations also make it a challenge to ensure that high-quality wood materials can be reused instead of simply thrown away. Faraca and her team found that some chemical impurities could be removed completely before recycling. She commented that while some impurities may still occur in recycled wood materials, low enough levels ensure that the material could still be used safely by consumers.
Arthur Haarman from EMPA Technology and Society Lab discussed work on electronic waste. Electronic waste (e-waste) is a fast-growing waste stream in the developing world that includes materials such as used computers and television sets. This waste stream is attractive to recyclers because it contains valuable minerals like copper. However, this waste stream also includes highly toxic materials such as flame retardants and heavy metals. Haarman said that of the 42 million tons of e-waste generated in 2014, only 15% of materials entered a formal and proper recycling and waste treatment process. Haarman then discussed e-waste in India, where informal regulations and cultural perspectives can lead to unsafe handling of hazardous materials. There are ways for recyclers in India to handle plastic contaminated with toxic chemicals, but Haarman reported that the initiatives for recyclers to undergo additional separation steps are not working. Haarman and his group studied the trends of e-waste recycling in India and developed a strategy, coupled with easy-to-use testing methods, that provides greater incentives for removing toxic chemicals from e-waste.
New advances in LCA
Caroline Catalan (I Care & Consult) presented new LCA methods for measuring a product’s impacts on biodiversity. Once finalized, this new LCA method will be able to measure how different versions of a product relate to measures of ecological richness. This method will provide a way to calculate the total ecological footprint of a product, providing a new way for companies to use LCA to ensure that their products are sustainable. Catalan also hopes that the results of this project will provide a connection between ecologists and LCA researchers that is both scientifically and economically sound.
Mathilde Vlieg (Evah Institute) discussed a case study aimed at calculating carbon credits from wood products. Vlieg emphasized the importance of accounting for carbon storage during LCA because of the ability for timber products to uptake carbon before harvest. This carbon remains stored if the materials are recycled, and carbon is released back into the environment if they are burned or allowed to decompose. Vlieg presented data from suppliers and manufacturers, with endpoints including forest age and fire history to calculate carbon sequestration. Long-term models developed for this LCA showed that up to 90% recovery of wood materials is possible even after 60 years of use. These results provide further support to the study of carbon sequestration potential of wood materials and their application in LCA.
Karoline Wowra (TU Darmstadt) discussed the importance of nitrogen in LCA. An over-abundance of nitrogen from agricultural or fossil fuel production can lead to eutrophication, algal blooms, and oxygen depletion in freshwater ecosystems. Many LCA models already account for nitrogen levels but there are many regional differences in nitrogen levels and cycles. Wowra’s group compared different LCA methods to see if nitrogen levels were being incorporated accurately. She found that the specific nitrogen compounds studied and the geography of the region influenced how applicable the existing LCA methods were for a particular area under consideration. Wowra suggested that researchers select LCA methods depending on the goal or scope of the study, for example, an LCA focused on agricultural impacts should include more accurate measurements of specific nitrogen compounds relative to agricultural soil.
Bernard De Caevel at RDC Environment examined using a resource’s market price as a basis for its value within LCA. This project focused on the use of a non-renewable resource’s monetary value as a proxy for that resource’s environmental value. De Caevel and his team found that a material’s market price can be a valid substitute for determining value, but that social and market forces on a resource’s price still needs to be taken into account. His group will continue to develop other ways to determine the value of minerals and fossil reserves for completing LCAs on products which use those non-renewable resources.
What’s next for life cycle analysis, circular economy, and SETAC?
LCA is just one way that science is helping companies make greener products for consumers looking for safe and sustainable products. The SETAC Brussels meeting provided a forum for these researchers to discuss the challenges and considerations needed to apply these methods to address real-world challenges. SETAC will continue to play a role in the future of LCA as a place for researchers in the field to work together towards making the vision of a clean circular economy a reality.