Plastic Products Leach Chemicals That Induce In Vitro Toxicity under Realistic Use Conditions.

Plastic products contain complex mixtures of extractable chemicals that can be toxic. However, humans and wildlife will only be exposed to plastic chemicals that are released under realistic conditions. Thus, we investigated the toxicological and chemical profiles leaching into water from 24 everyday plastic products covering eight polymer types. We performed migration experiments over 10 days at 40 °C and analyzed the migrates using four in vitro bioassays and nontarget high-resolution mass spectrometry (UPLC-QTOF-MSE). All migrates induced baseline toxicity, 22 an oxidative stress response, 13 antiandrogenicity, and one estrogenicity. Overall, between 17 and 8681 relevant chemical features were present in the migrates. In other words, between 1 and 88% of the plastic chemicals associated with one product were migrating. Further, we tentatively identified ∼8% of all detected features implying that most plastic chemicals remain unknown. While low-density polyethylene, polyvinyl chloride, and polyurethane induced most toxicological endpoints, a generalization for other materials is not possible. Our results demonstrate that plastic products readily leach many more chemicals than previously known, some of which are toxic in vitro. This highlights that humans are exposed to many more plastic chemicals than currently considered in public health science and policies.

Benchmarking the in Vitro Toxicity and Chemical Composition of Plastic Consumer Products.

Plastics are known sources of chemical exposure and few, prominent plastic-associated chemicals, such as bisphenol A and phthalates, have been thoroughly studied. However, a comprehensive characterization of the complex chemical mixtures present in plastics is missing. In this study, we benchmark plastic consumer products, covering eight major polymer types, according to their toxicological and chemical signatures using in vitro bioassays and nontarget high-resolution mass spectrometry. Most (74%) of the 34 plastic extracts contained chemicals triggering at least one end point, including baseline toxicity (62%), oxidative stress (41%), cytotoxicity (32%), estrogenicity (12%), and antiandrogenicity (27%). In total, we detected 1411 features, tentatively identified 260, including monomers, additives, and nonintentionally added substances, and prioritized 27 chemicals. Extracts of polyvinyl chloride (PVC) and polyurethane (PUR) induced the highest toxicity, whereas polyethylene terephthalate (PET) and high-density polyethylene (HDPE) caused no or low toxicity. High baseline toxicity was detected in all "bioplastics" made of polylactic acid (PLA). The toxicities of low-density polyethylene (LDPE), polystyrene (PS), and polypropylene (PP) varied. Our study demonstrates that consumer plastics contain compounds that are toxic in vitro but remain largely unidentified. Since the risk of unknown compounds cannot be assessed, this poses a challenge to manufacturers, public health authorities, and researchers alike. However, we also demonstrate that products not inducing toxicity are already on the market.

Plastics of the Future? The Impact of Biodegradable Polymers on the Environment and on Society.

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. 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 Minireview, 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. 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.

The biological effects and possible modes of action of nanosilver.

Novel physicochemical and biological properties have led to a versatile spectrum of applications for nanosized silver particles. Silver nanoparticles are applied primarily for their antimicrobial effects, and may variety of commercially available products have emerged. To better predict and prevent possible environmental impacts from silver nanoparticles that are derived from increasing production volumes and environmental release, more data on the biological effects are needed on appropriate model organisms. We examined the literature that addressed the adverse effects of silver nanoparticles on different levels of biological integration, including in vitro and in vivo test systems. Results of in vitro studies indicate a dose-dependent programmed cell death included by oxidative stress as main possible pathway of toxicity. Furthermore, silver nanoparticles may affect cellular enzymes by interference with free thiol groups and mimicry of endogenous ions. Similar mechanisms may apply for antibacterial effects produced by nonasilver. These effects are primary from the interference nanosilver has with bacterial cell membranes. Few in vivo studies have been performed to evaluated the toxic mode of action of nanosilver or to provide evidence for oxidative stress as an important mechanism of nanosilver toxicity. Organisms that are most acutely sensitive to nanosilver toxicity are the freshwater filter-freeding organisms. Both in vitro and in vivo studies have demonstrated tha silver ions released from nanoparticle surface contribute to the toxicity, and, indeed, some findings indicated a unique nanoparticles effect. For an adequate evaluation of the environmental impact of nanosilver, greater emphasis should be placed on combining mechanistic investigations that are performed in vitro, with results obtained in in vivo test systems. Future in vivo test system studies should emphasize long-term exposure scenarios. Moreover, the dietary uptake of silver nanoparticles and the potential to bioaccumulate through the food web should be examined in detail.

Are bioplastics and plant-based materials safer than conventional plastics? In vitro toxicity and chemical composition.

Plastics contain a complex mixture of known and unknown chemicals; some of which can be toxic. Bioplastics and plant-based materials are marketed as sustainable alternative to conventional plastics. However, little is known with regard to the chemicals they contain and the safety of these compounds. Thus, we extracted 43 everyday bio-based and/or biodegradable products as well as their precursors, covering mostly food contact materials made of nine material types, and characterized these extracts using in vitro bioassays and non-target high-resolution mass spectrometry. Two-third (67%) of the samples induced baseline toxicity, 42% oxidative stress, 23% antiandrogenicity and one sample estrogenicity. In total, we detected 41,395 chemical features with 186-20,965 features present in the individual samples. 80% of the extracts contained >1000 features, most of them unique to one sample. We tentatively identified 343 priority compounds including monomers, oligomers, plastic additives, lubricants and non-intentionally added substances. Extracts from cellulose- and starch-based materials generally triggered a strong in vitro toxicity and contained most chemical features. The toxicological and chemical signatures of polyethylene (Bio-PE), polyethylene terephthalate (Bio-PET), polybutylene adipate terephthalate (PBAT), polybutylene succinate (PBS), polylactic acid (PLA), polyhydroxyalkanoates (PHA) and bamboo-based materials varied with the respective product rather than the material. Toxicity was less prevalent and potent in raw materials than in final products. A comparison with conventional plastics indicates that bioplastics and plant-based materials are similarly toxic. This highlights the need to focus more on aspects of chemical safety when designing truly "better" plastic alternatives.

What are the drivers of microplastic toxicity? Comparing the toxicity of plastic chemicals and particles to Daphnia magna.

Given the ubiquitous presence of microplastics in aquatic environments, an evaluation of their toxicity is essential. Microplastics are a heterogeneous set of materials that differ not only in particle properties, like size and shape, but also in chemical composition, including polymers, additives and side products. Thus far, it remains unknown whether the plastic chemicals or the particle itself are the driving factor for microplastic toxicity. To address this question, we exposed Daphnia magna for 21 days to irregular polyvinyl chloride (PVC), polyurethane (PUR) and polylactic acid (PLA) microplastics as well as to natural kaolin particles in high concentrations (10, 50, 100, 500 mg/L, ≤ 59 µm) and different exposure scenarios, including microplastics and microplastics without extractable chemicals as well as the extracted and migrating chemicals alone. All three microplastic types negatively affected the life-history of D. magna. However, this toxicity depended on the endpoint and the material. While PVC had the largest effect on reproduction, PLA reduced survival most effectively. The latter indicates that bio-based and biodegradable plastics can be as toxic as their conventional counterparts. The natural particle kaolin was less toxic than microplastics when comparing numerical concentrations. Importantly, the contribution of plastic chemicals to the toxicity was also plastic type-specific. While we can attribute effects of PVC to the chemicals used in the material, effects of PUR and PLA plastics were induced by the mere particle. Our study demonstrates that plastic chemicals can drive microplastic toxicity. This highlights the importance of considering the individual chemical composition of plastics when assessing their environmental risks. Our results suggest that less studied polymer types, like PVC and PUR, as well as bioplastics are of particular toxicological relevance and should get a higher priority in ecotoxicological studies.

Seawater-Degradable Polymers-Fighting the Marine Plastic Pollution.

Polymers shape human life but they also have been identified as pollutants in the oceans due to their long lifetime and low degradability. Recently, various researchers have studied the impact of (micro)plastics on marine life, biodiversity, and potential toxicity. Even if the consequences are still heavily discussed, prevention of unnecessary waste is desired. Especially, newly designed polymers that degrade in seawater are discussed as potential alternatives to commodity polymers in certain applications. Biodegradable polymers that degrade in vivo (used for biomedical applications) or during composting often exhibit too slow degradation rates in seawater. To date, no comprehensive summary for the degradation performance of polymers in seawater has been reported, nor are the studies for seawater-degradation following uniform standards. This review summarizes concepts, mechanisms, and other factors affecting the degradation process in seawater of several biodegradable polymers or polymer blends. As most of such materials cannot degrade or degrade too slowly, strategies and innovative routes for the preparation of seawater-degradable polymers with rapid degradation in natural environments are reviewed. It is believed that this selection will help to further understand and drive the development of seawater-degradable polymers.

Using FTIRS as pre-screening method for detection of microplastic in bulk sediment samples.

We present calibration models for the detection of two types of plastic (LDPE, PET) in sediments, developed from analysis of synthetic sediment mixtures and application of Fourier transform infrared spectroscopy (FTIRS) and partial least squares regression (PLSR) modeling. Synthetic sediment mixtures were produced using ground plastic particles mixed with various different sediment matrixes yielding LDPE and PET contents ranging from 0 to 5 wt%. The resulting PLSR calibration models between the FTIRS spectral information and the defined plastic concentration of the synthetic sediment mixtures show strong cross-validated correlations (R2CV = 0.73 and 0.72) as well as low root-mean square errors of cross-validation (RMSECV = 0.72 and 0.61; 14.4% and 12.2% when expressed as % of gradient). Application of the calibration to natural sediments shows that the method can be used to detect the presence of microplastics in sediment. The results are only semi-quantitative and semi-qualitative, and the method is suitable mainly for samples with very high microplastic concentrations (>1%). However the major advantage of this procedure is the time and cost efficiency. For studies with large amounts of samples (e.g. monitoring applications) we recommend this method as a pre-screening tool for selecting samples with plastic content for further analysis.

Toxicity of silver nanoparticles and ionic silver: Comparison of adverse effects and potential toxicity mechanisms in the freshwater clam Sphaerium corneum.

A range of studies has addressed possible environmental impacts of nanosilver, but most focused on acute effects in few species. Moreover, it remains unclear if toxic effects are particle-specific or mediated by released silver ions. We investigated chronic effects of nanosilver and soluble silver (AgNO3) on the freshwater bivalve Sphaerium corneum. Animals were exposed to nanosilver (0-500 µg Ag L(-1)) and AgNO3 (0-318 µg Ag L(-1)) over 28 days, and effects on reproduction and behavioral changes were assessed. To explore toxic mechanisms, we evaluated the effects on intracellular levels of reactive oxygen species (ROS) and the activity of antioxidant enzymes (superoxide dismutase, catalase, glutathione-S-transferase, glutathione peroxidase). We further explored the activity of the sodium-potassium adenosine triphosphatase (Na(+)/K(+)-ATPase). Chronic exposure to nanosilver and AgNO3 resulted in negative effects on reproduction at concentrations of 5 and 3.18 µg Ag L(-1) (LOEC), respectively. ROS levels significantly increased after exposure to nanosilver at 10 µg Ag L(-1) and AgNO3 at 63.5 µg Ag L(-1). Both forms of silver altered the activities of antioxidant enzymes. Nanosilver (500 µg Ag L(-1)) and AgNO3 (318 µg Ag L(-1)) inhibited Na(+)/K(+)-ATPase activity by 82.6 and 78.9%, respectively. Nanoparticulate and soluble silver produced similar effects in S. corneum suggesting that toxicity of nanosilver is mainly mediated by dissolution of nanoparticles in the test media or after uptake by the test organisms.

Combined effects of silver nanoparticles and 17α-ethinylestradiol on the freshwater mudsnail Potamopyrgus antipodarum.

Ecotoxicological studies have shown that nanosilver is among the most toxic nanomaterials to aquatic organisms. However, research has so far focused on the determination of acute effects. Combined effects of nanosilver with other substances have not yet been studied in aquatic organisms. The present study aimed to investigate the chronic toxicity of nanosilver as well as the potential of nanosilver to influence the effects of co-occurring substances on the freshwater mudsnail Potamopyrgus antipodarum. In 28-day chronic toxicity experiments, the effects of nanosilver on the reproduction of P. antipodarum were assessed. In order to evaluate the influence of nanosilver on other substances, 17α-ethinylestradiol (EE2) was chosen as model compound due to the well-characterized effects on P. antipodarum. In addition to effects on reproduction, exposure to nanosilver and EE2 was monitored by determining the expression of estrogen-responsive transcripts (estrogen receptor and vitellogenin encoding genes). Exposure to nanosilver decreased the reproduction of P. antipodarum (EC10: 5.57 µg l(-1); EC50: 15.0 µg l(-1)). Exposure to EE2 significantly stimulated the embryo production at 25 ng l(-1). The presence of nanosilver led to increased EE2 effects at EE2 concentrations that had no influence on reproduction when applied in absence of nanosilver. In contrast, combined exposure to nanosilver decreased EE2 effects at concentrations that stimulated reproduction and the expression of estrogen responsive genes when applied in the absence of nanosilver. This is the first study demonstrating an influence of nanosilver on the effects of co-contaminants on aquatic organisms. The study further highlights the need for chronic experiments to properly assess environmental risks of nanosilver and their effects on co-occurring contaminants.

Long-term effects of nanoscaled titanium dioxide on the cladoceran Daphnia magna over six generations.

We investigated the impact of nanoscaled titanium dioxide (nTiO2) on Daphnia magna populations in a multi-generational study over six generations (F0-F5). Each generation was exposed for 21 days to nTiO2 (AEROXIDE(®) TiO2 P25, primary particle size 21 nm) while mortality, individual growth, reproduction and population growth rates (PGR) were assessed as endpoints. The size distribution of nTiO2 in the single test media was analysed by dynamic light scattering (DLS) and transmission electron microscopy (TEM). nTiO2 concentrations were measured using ICP-MS. Mortality and individual growth of D. magna were significantly affected with increasing exposure duration and concentration. Daphnids demonstrated decreasing reproduction over generations in all treatment groups (1.19-6 mg/L) but not in the control. At concentration levels of 1.78 mg/L chronic exposure resulted in a population collapse after five generations. This study indicates that multi-generational studies are suitable for evaluating long-term effects of nanoparticles since they reflect potential effects more accurately than single generation tests.

Comparative toxicity assessment of nanosilver on three Daphnia species in acute, chronic and multi-generation experiments.

The antibacterial properties of nanosilver have led to a versatile application spectrum including medical purposes and personal care products. However, the increasing use of nanosilver has raised concerns about its environmental impacts. Long-term exposure studies with aquatic invertebrates are essential to assess possible adverse effects on aquatic ecosystems. In the present study, acute (48 h), chronic (21 d) and long-term effects of nanosilver (primary size 15 nm) on five successive generations of three Daphnia species (D. magna, D. pulex, and D. galeata) were investigated. Acute EC50 values of nanosilver were 121 µg Ag L(-1) for D. magna being the least sensitive species and 8.95 and 13.9 µg Ag L(-1) for D. pulex and D. galeata, respectively. Chronic exposure provided EC10 values of 0.92 µg Ag L(-1) for D. magna showing the most sensitive chronic reaction and 2.25 and 3.45 µg Ag L(-1) for D. pulex and D. galeata, respectively. Comparative exposure to AgNO3 revealed a generally higher toxicity of the soluble form of silver. The multi-generation experiments resulted in effects on the population level for all tested species. Exposure of D. magna indicated an increased toxicity of nanosilver in the fifth generation of animals exposed to 10 µg Ag L(-1). Neonates from pre-exposed parental daphnids did not completely recover when transferred into clean water. Exposure of D. pulex and D. galeata revealed not only increasing toxicity in some generations, but also greater tolerance to nanosilver. This study contributes to the assessment of the risk potential of nanosilver on aquatic ecosystems. It shows that effects of nanosilver vary within one genus and change with exposure duration. Therefore, long-term studies considering different aquatic species are needed to better understand the possible effects of nanosilver on aquatic ecosystems.