| 1. |
- Ekvall, Mikael T., et al.
(author)
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Environmental impact of nanoplastics from fragmentized consumer plastics : Final project report
- 2022
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Reports (other academic/artistic)abstract
- Misplaced plastics is an ongoing environmental problem. The breakdown of plastics into smaller pieces, microplastics, likely cause additional environmental burdens as they affect animals and plants at the beginning of the food chain. This may be even more true for the smallest of microplastics: the nano plastics as they will behave differently in nature and interact in new ways with organisms and potentially be taken up by the organisms and affect internal organs. The small size of nano plastics and their chemical resemblance with the surrounding environment makes them difficult to find, isolate and study. Most of what is known about nano plastics behavior in nature and their effect on nature derives from studies using commercially available polystyrene nanoparticles. These are probably different in many ways, such as structure, surface chemistry, and size distribution, compared to nano plastics broken down in nature from plastic debris. Despite this, we have used polystyrene nanoparticles to study knowledge gaps. The toxicity to zooplankton Daphnia magna (D. magna) of small positively charged amine-modified polystyrene nanoparticles is not affected by protein-induced aggregation. All tested polystyrene nanoparticles were toxic to D. magna regardless of their toxicity in acute tests. Proteins bound to polystyrene nanoparticles after filtration by D. magna were different on acutely and non-acutely toxic particles which may imply different mechanisms behind the toxicity. In order to study the effect of nano plastics that resemble what can be expected in nature we have mechanically broken down 8 different plastics and rubbers from 14 different consumer products and isolated the nano plastics. Careful characterization shows that the nano plastics are irregular in shape, have a slightly negative surface charge, and often have a strongly oxidized surface compared to the starting material. The nano sized fractions are not toxic to D. magna in the used concentrations. In contrary, for at least two plastics High Density Polyethylene (HDPE) and Polylactic acid (PLA) thoracoplasties increase the lifetime of the D. magna probably because the nano plastics can be utilized by bacteria which in turn serve as additional food for the zooplankton. However, leached additives and/or smaller polymers from HDPE are toxic to D. magna. We have also seen that UV irradiation further degrade polystyrene nanoparticles. The bacterial growth and the UV breakdown may imply that the nano plastics breakdown faster than believed in nature and that they with time may disappear.
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| 2. |
- Ekvall, Mikael T., et al.
(author)
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Nanoplastics formed during the mechanical breakdown of daily-use polystyrene products
- 2019
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In: Nanoscale Advances. - : Royal Society of Chemistry (RSC). - 2516-0230. ; 1:3, s. 1055-1061
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Journal article (peer-reviewed)abstract
- Large amounts of plastics are released into the environment every day. These released plastics have a clearly documented negative effect on wildlife. Much research attention has been given to large plastic pieces and microplastics. However, if the breakdown of plastics is a continous process, eventually nanoplastics will be produced. Nanoplastics will affect wildlife differently from larger plastic pieces. We have studied the products formed by the mechanical breakdown of two commonly used polystyrene products, takeaway coffee cup lids and expanded polystyrene foam. After breakdown using a food processor, we characterized the breakdown products using seven different methods and found nanosized polystyrene particles with different shapes and negative or nearly neutral surface charges. These results clearly demonstrate that daily-use polystyrene products can break down into nanoparticles. Model polystyrene particles with different sizes and surface modifications have previously been shown to have different negative effects on wildlife. This indicates that breakdown nanoparticles might have the potential to cause cocktail effects in nature.
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| 3. |
- Ekvall, Mikael T., et al.
(author)
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Nanoplastics released from daily used silicone and latex products during mechanical breakdown
- 2023
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In: PLoS ONE. - 1932-6203. ; 18:9
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Journal article (peer-reviewed)abstract
- Waste of polymer products, especially plastics, in nature has become a problem that caught the awareness of the general public during the last decade. The macro- and micro polymers in nature will be broken down by naturally occurring events such as mechanical wear and ultra-violet (UV) radiation which will result in the generation of polymeric particles in the nano-size range. We have recently shown that polystyrene and high-density polyethylene macroplastic can be broken down into nano-sized particles by applying mechanical force from an immersion blender. In this article, we show that particles in the nano-size range are released from silicone and latex pacifiers after the same treatment. Additionally, boiling the pacifiers prior to the mechanical breakdown process results in an increased number of particles released from the silicone but not the latex pacifier. Particles from the latex pacifier are acutely toxic to the freshwater filter feeding zooplankter Daphnia magna.
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| 4. |
- Ekvall, Mikael T, et al.
(author)
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Size fractionation of high-density polyethylene breakdown nanoplastics reveals different toxic response in Daphnia magna
- 2022
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In: Scientific Reports. - : Springer Science and Business Media LLC. - 2045-2322. ; 12, s. 3109-3109
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Journal article (peer-reviewed)abstract
- Plastic litter is a growing environmental problem. Recently, microplastics and nanoplastics, produced during breakdown processes in nature, have been in focus. Although there is a growing knowledge concerning microplastic, little is still known about the effect of nanoplastics. We have showed that mechanical breakdown of high-density polyethylene (HDPE), followed by filtration through 0.8 µm filters, produces material toxic to the freshwater zooplankton Daphnia magna and affected the reproduction in life-time tests. However, further size fractionation and purification reveals that the nanoplastics fraction is non-toxic at these concentrations, whereas the fraction with smaller sizes, below ~ 3 nm, is toxic. The HDPE nanoplastics are highly oxidized and with an average diameter of 110 nm. We conclude that mechanical breakdown of HDPE may cause environmental problems, but that the fraction of leached additives and short chain HDPE are more problematic than HDPE nanoplastics.
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| 5. |
- Frankel, Rebecca, et al.
(author)
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Controlled protein mediated aggregation of polystyrene nanoplastics does not reduce toxicity towards Daphnia magna
- 2020
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In: Environmental Science: Nano. - : Royal Society of Chemistry (RSC). - 2051-8153 .- 2051-8161. ; 7:5, s. 1518-1524
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Journal article (peer-reviewed)abstract
- Microplastics have recently become a growing environmental issue, whereas the smaller fractions, nanoplastics, have received less attention. Due to their small size, nanoplastics may affect organisms differently and potentially more severely than larger microplastics. In natural environments nanoplastics also interact with organic material and form larger aggregates, which may, potentially, reduce their toxicity as they grow in size. We tested the change in toxicity towards Daphnia magna by controlling the size of the aggregates of positively charged 50 nm polystyrene nanoplastics, which are highly toxic as single particles. We show that although 200 to 500 nm nanoplastics are not toxic, aggregates of 50 nm nanoplastics in the same size range are at least as toxic as the free, 50 nm, nanoplastics. Hence, an increase in size through aggregation, a process likely to occur as nanoparticles enter natural ecosystems, does not reduce toxicity. In a broader context this finding provides a firm basis for societal decision making regarding the potency of nanoparticles as they enter natural ecosystems.
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| 6. |
- Kaur, Jasreen, et al.
(author)
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Label-free detection of polystyrene nanoparticles in Daphnia magna using Raman confocal mapping
- 2023
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In: Nanoscale Advances. - : Royal Society of Chemistry. - 2516-0230. ; 5:13, s. 3453-
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Journal article (peer-reviewed)abstract
- Micro- and nanoplastic pollution has emerged as a global environmental problem. Moreover, plastic particles are of increasing concern for human health. However, the detection of so-called nanoplastics in relevant biological compartments remains a challenge. Here we show that Raman confocal spectroscopy-microscopy can be deployed for the non-invasive detection of amine-functionalized and carboxy-functionalized polystyrene (PS) nanoparticles (NPs) in Daphnia magna. The presence of PS NPs in the gastrointestinal (GI) tract of D. magna was confirmed by using transmission electron microscopy. Furthermore, we investigated the ability of NH2-PS NPs and COOH-PS NPs to disrupt the epithelial barrier of the GI tract using the human colon adenocarcinoma cell line HT-29. To this end, the cells were differentiated for 21 days and then exposed to PS NPs followed by cytotoxicity assessment and transepithelial electrical resistance measurements. A minor disruption of barrier integrity was noted for COOH-PS NPs, but not for the NH2-PS NPs, while no overt cytotoxicity was observed for both NPs. This study provides evidence of the feasibility of applying label-free approaches, i.e., confocal Raman mapping, to study PS NPs in a biological system.
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| 7. |
- Kelpsiene, Egle, et al.
(author)
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Long-term exposure to nanoplastics reduces life-time in Daphnia magna
- 2020
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In: Scientific Reports. - : Springer Science and Business Media LLC. - 2045-2322. ; 10
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Journal article (peer-reviewed)abstract
- Plastics are widely used in todays society leading to an accelerating amount of plastic waste entering natural ecosystems. Over time these waste products degrade to micro- and, eventually, nanoplastic particles. Therefore, the break-down of plastics may become a critical threat to aquatic ecosystems and several short term studies have demonstrated acute toxicity of nanoplastics on aquatic organisms. However, our knowledge about effects of chronic or life-time exposure on freshwater invertebrates remains elusive. Here, we demonstrate results from life-time exposure (103 days) of a common freshwater invertebrate, Daphnia magna, exposed to sub-lethal concentrations of polystyrene nanoparticles. 53 nm positively charged aminated polystyrene particles were lethal at concentration of 0.32 mg/L which is two magnitudes lower than previously used concentrations in short-term (24 h) tests. At this concentration the life-time of individuals was shortened almost three times. Negatively charged carboxylated 26 and 62 nm polystyrene particles, previously demonstrated to be non-toxic at 25 and 50 mg/L concentrations in short-term tests, were toxic to D. magna at all concentrations used in our long-term study. Although total reproductive output was not significantly affected at increasing concentrations of polystyrene nanoparticles, there was a decreasing trend in the number of offspring over their life-time. Hence, in order to understand how the potential future environmental problem of nanoplastic particles may affect biota, long-term or life-time studies resembling environmental concentrations should be performed in order to provide information for predictions of future scenarios in natural aquatic environments.
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| 8. |
- Kelpsiene, Egle, et al.
(author)
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Metabolomics-based analysis in Daphnia magna after exposure to low environmental concentrations of polystyrene nanoparticles
- 2023
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In: Environmental Science: Nano. - 2051-8153. ; 10:7, s. 1858-1866
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Journal article (peer-reviewed)abstract
- Larger plastic pieces break down into micro- and eventually nano-sized plastics. This makes nanoplastics ubiquitous in the environment, giving rise to great concern for its effect on biota. Many studies use polystyrene nanoparticles (PS-NPs) as a model for nanoplastics, showing a negative impact on various organisms, but the molecular effects are yet not fully explored. Here we applied 1H nuclear magnetic resonance (NMR) metabolomics to characterize the metabolic changes in Daphnia magna during long-term (37 days) exposure to low concentrations of positively and negatively charged (aminated and carboxylated) PS-NPs. We show that exposure to PS-NPs at concentrations down to 3.2 μg L−1 affected amino acid metabolism and the bacterial metabolite isopropanol in D. magna. These effects were largely independent of particle concentration and surface charge. The results highlight the importance of (1) performing chronic exposures under low concentrations and (2) further investigation of particles with different surface charges.
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| 9. |
- Kelpsiene, Egle, et al.
(author)
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Prolonged survival time of Daphnia magna exposed to polylactic acid breakdown nanoplastics
- 2023
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In: PLoS ONE. - 1932-6203. ; 18:9
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Journal article (peer-reviewed)abstract
- Polylactic acid nanoparticles (PLA NPs) according to food and drug administration are biodegradable and biocompatible polymers that have received a lot of attention due to their natural degradation mechanism. Although there is already available information concerning the effects of PLA microplastic to aquatic organisms, the knowledge about PLA NPs is still vague. In the present study, we analyzed the chemical composition of engineered PLA NPs, daily used PLA items and their breakdown products. We show that PLA breakdown products are oxidized and may contain aldehydes and/or ketones. The breakdown produces nanosized particles, nanoplastics, and possibly other small molecules as lactide or cyclic oligomers. Further, we show that all PLA breakdown nanoplastics extended the survival rate in Daphnia magna in an acute toxicity assay, however, only PLA plastic cup breakdown nanoplastics showed a significant difference compared to a control group.
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| 10. |
- Kelpsiene, Egle, et al.
(author)
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Protein binding on acutely toxic and non-toxic polystyrene nanoparticles during filtration by Daphnia magna
- 2022
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In: Environmental Science: Nano. - : Royal Society of Chemistry (RSC). - 2051-8153 .- 2051-8161.
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Journal article (peer-reviewed)abstract
- Nanomaterials can adsorb biomolecules to their surface and form a protein corona. Here we investigated the protein profile bound to different sizes of aminated and carboxylated polystyrene (PS) nanoparticles after passing through the digestive tract of the freshwater zooplankter Daphnia magna. We found that acutely toxic aminated 53 nm PS nanoparticles bind a different set of proteins compared to other non-toxic PS nanoparticles. The aminated PS nanoparticles bind a higher number of proteins, which are smaller and more acidic, compared to the proteins which bind to the PS nanoparticles that are non-toxic in acute toxicity tests. The proteins bound to toxic nanoparticles can be divided into two groups. One group of proteins which function is related to the digestive system, whereas the other group of proteins can be related to the epithelium, intracellular structures and processes. Finally, we observed that not only proteins bind to the surfaces of the nanoparticles. Triglycerides effectively bind to 200 nm carboxylated PS nanoparticles but not to the other tested nanoparticles. These results provide information about the composition of the corona formed on surfaces of nanoparticles after a short-term incubation with D. magna and give insights to what underlies the acute toxicity caused by nanoparticles.
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