Adsorption of bio-organic eco-corona molecules reduces the toxic response to metallic nanoparticles in <i>Daphnia magna</i>

As the use of engineered nanomaterials increases, so does the risk of them spreading to natural ecosystems. Hitherto, knowledge regarding the toxic properties of nanoparticles (NP’s) and their potential interactions with natural bio-organic molecules adsorbed to them, and thereby forming surface coronas, is limited. However, we show here that the toxic effect of NPs of tungsten carbide cobalt (WC–Co) and cobalt (Co) on the crustacean Daphnia magna is postponed in the presence of natural biological degradation products (eco-corona biomolecules). For Daphnia exposed to WC–Co NPs the survival time increased with 20–25% and for Co NPs with 30–47% after mixing the particles with a solution of eco-corona biomolecules before exposure. This suggests that an eco-corona, composed of biomolecules always present in natural ecosystems, reduces the toxic potency of both studied NPs. Further, the eco-coronas did not affect the particle uptake, suggesting that the reduction in toxicity was related to the particle-organism interaction after eco-corona formation. In a broader context, this implies that although the increasing use and production of NPs may constitute a novel, global environmental threat, the acute toxicity and long-term effects of some NPs will, at least under certain conditions, be reduced as they enter natural ecosystems

On the missing link in ecology: improving communication between modellers and experimentalists

Collaboration between modellers and experimentalists is essential in ecological research, however, different obstacles linking both camps often hinder scientific progress. In this commentary, we discuss several issues of the current state of affairs in this research loop. Backed by an online survey amongst fellow ecologists, modellers and experimentalists alike, we identify two major areas that need to be mended. Firstly, differences in language and jargon lead to a lack of exchange of ideas and to unrealistic mutual expectations. And secondly, constraint data sharing, accessibility and quality limit the usage of empirical data and thereby the impact of ecological studies. We discuss ways to advance collaboration; how to improve communication and the design of experiments; and the sharing of data. We hope to start a much-needed conversation between modellers and experimentalists, to further future research collaboration and to increase the impact of single ecological studies alike

Workshop on Environmental Nanosafety: Biological Interactions of Plastic Nanoparticles

The one-hour workshop, containing both a demonstration and hands-on experiments on the topic of nanosafety, is based on current science on a topic of general interest. The workshop aims to provide a deeper knowledge and understanding of nanoparticles. The participants get an introduction to what nanoparticles are, why nanosized materials are interesting, how nanomaterials interact with biological molecules, and potential risks associated with nanoparticles. Furthermore, by participating in the workshop the audience gains insights into how research about nanoparticles is conducted. The participants carry out experiments to demonstrate that daily-used plastic products can be disintegrated into particles in the nanometer size range, which may have important implications for the environment

Environmental impact of nanoplastics from fragmentized consumer plastics : Final project reportMikael

Misplaced plastics is an ongoing environmental problem. The breakdown of plasticsinto smaller pieces, microplastics, likely cause additional environmental burdensas they affect animals and plants at the beginning of the food chain. This may beeven more true for the smallest of microplastics: the nanoplastics as they will behavedifferentlyin nature and interact in new ways with organisms and potentially be takenup by the organisms and affect internal organs. The small size of nanoplasticsandtheir chemical resemblance with the surrounding environment makes them difficultto find, isolate and study. Most of what is known about nanoplastics behaviourinnature and their effect on nature derives from studies using commercially availablepolystyrene nanoparticles. These are probably different in many ways, such as structure,surface chemistry, and size distribution, compared to nanoplastics brokendownin nature from plastic debris. Despite this, we have used polystyrene nanoparticlestostudy knowledge gaps. The toxicity to zooplankton Daphnia magna (D. magna) of smallpositively charged amine-modified polystyrene nanoparticles is not affected byprotein-induced aggregation. All tested polystyrene nanoparticles were toxic toD. magna regardless of their toxicity in acute tests. Proteins bound to polystyrenenanoparticles after filtrationby D. magna were different on acutely and non-acutelytoxic particles which may imply different mechanisms behind the toxicity. In orderto study the effect of nanoplastics that resemble what can be expected in nature wehave mechanically broken down 8 different plastics and rubbers from 14 differentconsumer products and isolated the nanoplastics. Careful characterization shows thatthe nanoplastics are irregular in shape, have a slightly negative surface charge, andoften have a strongly oxidized surface compared to the starting material. The nanosizedfractions are not toxic to D. magna in the used concentrations. In contrary, forat least two plastics High Density Polyethylene (HDPE) and Polylactic acid (PLA) thenanoplastics increase the lifetime of the D. magna probably because the nanoplasticscan 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 polystyrenenanoparticles.The bacterial growth and the UV breakdown may imply that the nanoplastics breakdown faster than believed in nature and that they with time may disappear

Prolonged survival time of Daphnia magna exposed to polylactic acid breakdown nanoplastics

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

The forgotten tonsils—does the immune active organ absorb nanoplastics?

Nanoplastics are defined as plastic particles broken down to extremely small sizes (1–100 nm) with unknown effects to the human body and immune system. Air and food exposure scenarios involving blood, lungs and intestine are considered in the literature. The fact that plastics also needs to pass the nose, oral cavity, and throat is so far ignored in the literature. The tonsils are immunologically important tissue in the oral cavity in which ingested and inhaled agents are incorporated through crypts with the capacity to capture agents and start early immunologic reactions. We argue that the tonsil is a very important tissue to study in regard to micro and nanoplastic human exposure and immunologic response. Nano-sized particles are known to be able to travel through the natural barriers and have different effects on biology compared to larger particle and the bulk material. It is therefore, although difficult, important to develop experimental methods to detect and identify nanoplastics in the tonsils. In preliminary experiments we have optimized the breakdown of tonsil tissues and tried to retrieve added polystyrene nanoparticles using density-based separation and concentration. The polystyrene was followed by FTIR spectrometry and could be detected in micro- and nano-size, in the tissue breakdown solution but not after density-based separation. When nanoplastics are incorporated in the human body, it is possible that the small plastic pieces can be detected in the tonsil tissue, in the lymph system and it is of importance for future studies to reveal the immunological effects for humans

Environmental impact of nanoplastics from fragmentized consumer plastics : Final project reportMikael

Misplaced plastics is an ongoing environmental problem. The breakdown of plasticsinto smaller pieces, microplastics, likely cause additional environmental burdensas they affect animals and plants at the beginning of the food chain. This may beeven more true for the smallest of microplastics: the nanoplastics as they will behavedifferentlyin nature and interact in new ways with organisms and potentially be takenup by the organisms and affect internal organs. The small size of nanoplasticsandtheir chemical resemblance with the surrounding environment makes them difficultto find, isolate and study. Most of what is known about nanoplastics behaviourinnature and their effect on nature derives from studies using commercially availablepolystyrene nanoparticles. These are probably different in many ways, such as structure,surface chemistry, and size distribution, compared to nanoplastics brokendownin nature from plastic debris. Despite this, we have used polystyrene nanoparticlestostudy knowledge gaps. The toxicity to zooplankton Daphnia magna (D. magna) of smallpositively charged amine-modified polystyrene nanoparticles is not affected byprotein-induced aggregation. All tested polystyrene nanoparticles were toxic toD. magna regardless of their toxicity in acute tests. Proteins bound to polystyrenenanoparticles after filtrationby D. magna were different on acutely and non-acutelytoxic particles which may imply different mechanisms behind the toxicity. In orderto study the effect of nanoplastics that resemble what can be expected in nature wehave mechanically broken down 8 different plastics and rubbers from 14 differentconsumer products and isolated the nanoplastics. Careful characterization shows thatthe nanoplastics are irregular in shape, have a slightly negative surface charge, andoften have a strongly oxidized surface compared to the starting material. The nanosizedfractions are not toxic to D. magna in the used concentrations. In contrary, forat least two plastics High Density Polyethylene (HDPE) and Polylactic acid (PLA) thenanoplastics increase the lifetime of the D. magna probably because the nanoplasticscan 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 polystyrenenanoparticles.The bacterial growth and the UV breakdown may imply that the nanoplastics breakdown faster than believed in nature and that they with time may disappear

Experimental evidence for a mismatch between insect emergence and waterfowl hatching under increased spring temperatures

By combining a large-scale experimental assessment on timing of insect emergence with longtermmonitoring of waterfowl hatching date, we here show that insect emergence is mainly driven bytemperature, whereas there is only a weak effect of increasing spring temperatures on inter-annualvariability in observations of waterfowl chicks. Hence, a change in timing of the mass-emergence of insectsfrom lakes and wetlands, which is the crucial food source for waterfowl chicks, will likely result in aconsumer/resource mismatch in a future climate change perspective. Specifically, we experimentally showthat a moderate increase in temperature of 38C above ambient, expected to occur within 25–75 years, leadsto a considerably (2 weeks) earlier, and more pronounced, peak in insect emergence (Chironomus sp).Moreover, by utilizing long-term Citizen Science databases, ranging over several decades, we also showthat common waterfowl species are unable to significantly adjust their reproduction to fit futuretemperature increase. Hence, based on our data we predict a future mismatch between insect emergenceand waterfowl species basing their reproduction on temperature. This will have a profound impact onreproductive success and population dynamics of many aquatic birds, as well as on freshwaterbiodiversity

Controlled protein mediated aggregation of polystyrene nanoplastics does not reduce toxicity towards Daphnia magna

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

Long-term exposure to nanoplastics reduces life-time in Daphnia magna

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