Nanoscale Coloristic Pigments: Upper Limits on Releases from Pigmented Plastic during Environmental Aging, In Food Contact, and by Leaching

Characterization of Inorganic Additives in and Photochemically Liberated from Consumer Plastics: Implications for Global and Local Biogeochemical Cycles

The composition and environmental impacts of inorganic additives in consumer plastics have received little attention within the plastic pollution discipline relative to organic additives. In this work, X-ray florescence spectroscopy, loss-on-ignition, and inductively coupled plasma mass spectrometry were used to qualitatively and quantitatively characterize inorganic additives from up to 80 consumer plastic items. On average, consumer plastic goods contained ∼8% inorganic additives by mass. Concentrations of each element often varied by orders of magnitude. The most common elements detected were from the alkali metal, alkaline earth metal, and first-row transition metal groups, with Ca, Ti, and Al being most abundant. The diversity and abundance of inorganic additives was notably higher in consumer-grade plastics than in standard plastics routinely used to assess the fate and impacts of plastic pollution. Sunlight exposure readily liberated most elements from consumer plastics, typically in the <10 and <1 μm fractions. However, the relative percent of photochemical liberation varied considerably across element and plastic articles, suggesting that formulation is a key control of their liberation from consumer plastics. Compared to average upper continental crust concentrations, Sb and Zn were most enriched, with median enrichment factors of 2 and 1 orders of magnitude, respectfully. Mass balance calculations indicate that plastic pollution may represent a substantial proportion of natural riverine elemental fluxes, particularly for Sb and Zn, which could reach ∼13% and ∼4% of the global natural riverine fluxes by 2060, respectively. Localized impacts in many small, highly polluted rivers could be even larger. However, such impacts are highly dependent on the riverine plastic loading rate to the ocean. Overall, these findings highlight the need for increased consideration of inorganic additives when assessing the fate and impacts of consumer plastics leaking into the environment.

Valorization of Fruit and Vegetable Waste: An Approach to Focusing on Extraction of Natural Pigments

The increasing demand for functional foods has spurred interest in bioactive compounds, particularly their role in health promotion and disease prevention. This review comprehensively explores the bioavailability, mechanisms of action, and potential applications of bioactive compounds derived from natural food sources. We have systematically compiled and synthesized data from the recent scientific literature, including peer-reviewed journal articles, clinical studies, and meta-analyses, to present an in-depth evaluation of these compounds' physicochemical properties, stability, and interactions within food matrices. Furthermore, this review discusses advanced delivery systems, such as nanoencapsulation and emulsification, for enhancing bioavailability and targeted release. By addressing critical gaps in the understanding of the functional and technological aspects of bioactive compounds, this review underscores their relevance in formulating novel nutraceuticals and functional foods. The insights presented herein provide a foundation for future research and practical applications in the food industry, ultimately contributing to improving human health and well-being. Although recovering bioactive compounds from food waste is a sustainable way to reduce waste and use resources, additional research is required to make these procedures more efficient for use on an industrial scale.

Microplastic in upper Himalayan Ganga river: Occurrence, seasonal dynamics and ecological risk

Ganga river supports about 500 million population in the Gangetic Plain. Still, the occurrence of toxic pollutants in the Ganga river is an emerging concern, questioning its ecological health. This study is the first to quantify the microplastic (MP) and its characteristics, seasonal dynamics (pre-monsoon and post-monsoon), and environmental risk in the 19 sites (sample size, n = 228) in the upper Himalayan stretch of Ganga (Devprayag, Zone-I; Rishikesh, Zone-II; Haridwar, Zone-III) with multiples sampling (6 months). Average MP particles were found in the range of 100-1550 particles/L in water and 50-1300 particles/kg in sediment samples. MP flux showed an increased trend (Zone-I < Zone-II < Zone-III) while the river flows from the foothills of the Himalayas to densely populated bank cities. MP-sized 500 μm to 5 mm were dominant in sediment (45.68 %) and water (52.73 %) during pre-monsoon. MP-sized 500 μm to 5 mm, 250 μm to 500 μm, and 50 μm to 250 μm were found to be 45.68 %, 27.57 %, and 26.75 % in water and 52.73 %, 23.03 %, and 24.24 % in sediments, respectively with abundance during post-monsoon. μATR-FTIR analysis revealed polyethylene, polyamides and polystyrene as dominant polymers and no drastic change occurred in polymer types between studied seasons. The fibers were the predominant particle type, followed by fragments and films across the studied stretch of the Ganga river. The pollution load index suggested that Zone-I and Zone-II fall under hazard category 1 while Zone-III in category 2. Polymer hazard index and potential ecological risk index data suggested an extreme pollution level of MP in a studied stretch of the Ganga river. This study emphasizes the adverse impacts of beach activities, tourist accommodations, and open waste disposals on river health, highlighting the urgent action required for effective plastic waste management. We urged a comprehensive study on MPs in the Ganga river basin, which serves as pathways and sinks for these particles into the ocean.

Comprehensive Multidimensional Analysis of Metal(loid)-Containing Dust in Plastic Sports Facilities: Insights into the Potential Sources and Health Risks

Dust released from widely established plastic sports courts and synthetic turf poses potential environmental and health risks. Herein, we systematically investigate the metal(loid) characteristics, potential sources, and health risks of 162 dust samples from 17 campuses in Beijing, using complementary analytical techniques. Bulk analysis revealed higher levels of Zn, Pb, Cu, Sb, Cd, and Cr than background values, suggesting excessive anthropogenic contamination. Pb and Cr in plastic basketball court and track dust and Zn and Sb in synthetic turf dust were higher than those in other sports facilities. Multielement single-particle inductively coupled plasma time-of-flight mass spectrometry (spICP-TOF-MS) revealed more Fe-, Al-, Si-, Ti-, and Pb-containing particles in the dust. At least 92% toxic Pb-containing particles were composed of multiple elements. The significant correlations between Pb and Cr contents on individual dust particles support their common potential source from inorganic pigments (crocoite, PbCrO4). Pb, Sb, As, and Cr in the dust pose higher health risks through intake. The risks were estimated to be approximately 3-5 times higher for children than for adults. Additionally, highly toxic Cr(VI) and As(III) species were observed in the sweat and gastric juice leachate of dust, highlighting severe threats of the metal(loid)s to human health.

A comprehensive review of microplastic aging: Laboratory simulations, physicochemical properties, adsorption mechanisms, and environmental impacts

As a new type of ecological environment problem, microplastic pollution is a severe challenge faced by the world, and its threat and potential risk to the ecosystem have become a hot research spot in the current environmental field. Microplastics (MPs) in the natural environment will experience aging effect, aging will change the physical and chemical properties of MPs and affect the adsorption behavior. Recently reported characterization techniques of MPs and laboratory simulation of aging are reviewed. The aging mechanism between MPs and different pollutants and the intervention mechanism of environmental factors (MPs, pollutants and water quality environment) were revealed. In addition, to further understand the potential ecological toxicity of MPs after aging, the release and harm of additives during aging, produce the environmentally persistent free radicals, and the mechanism of reactive oxygen species (ROS) removal of pollutants adsorbed on the surface of MPs were summarized. Future research efforts should focus more on bridging the disparity between laboratory aging simulations and natural environmental conditions to enhance the authenticity and ecological relevance of such studies. The ROS production mechanism of MPs provides a reference direction for removing pollutants adsorbed by aged MPs.

Presence of microplastics during high rainfall events in the Cauvery River (South India): Ecological risk and cultural practices

Rivers directly support the development of a region/country; however, globally, these aquatic regions are impacted by recent human activity. During a rainfall event, we monitored the baseline information on the spatial variability of microplastics (MPs) in the Cauvery River in South India. Forty surface water samples from two selected sites were collected between 27 September and 16 October 2022 during the commencement of monsoon which indicates 69 and 43 pieces L-1 of MPs, respectively. SEM and FTIR analysis on the surface morphotypes (cracks, grooves, pits) and elemental (Si, Ti, Mg, Cu, Ta) presence/adsorption of these elements' (in particle) surface indicates surface deformation of fibers, which is mainly due to external input/forces. Fragments of polymers establish a high degree of deterioration indicating its longer trajectory in the aquatic environment. The origin of extended fiber ranges between 631.65 and 5639.9 µm, which is being associated with laundry activities for textiles, household items, and fishing gear. Toxicity and ecological risk assessment suggest significant degree of weathered MPs due to photo-oxidation process and aging owing to exposition of intense UV light. This research serves as a strong illustration of the multiple pressures from urban development and cultural practices that have a bigger influence on the river ecosystem like Cauvery River and regular monitoring.

Differential photoaging behaviors of different colored commercial polyethylene microplastics in water: The important role of color characteristics

Upon entering the environment, plastics would undergo photoaging and forming microplastics (MPs). However, information on the photoaging behavior of colored MPs and how the color characteristics (wavelength, lightness, and saturation) influence their photoaging process is still lacking. Thus, attention was paid to comparing the photoaging process of transparent and five-colored MPs. To reveal the degree of photodegradation and photooxidation, physicochemical changes (e.g., surface morphology, functional groups, and the leaching of intermediates) of transparent and five-colored MPs were explored. Photodegradation rates and photooxidation degrees ranked transparent > yellow > red ≈ orange > green > blue. However, transparent and five-colored MPs exhibited a different photoaging sequence and eluted different photodegradation products from each other. Pearson correlation analysis was used to describe the relationships between color characteristics (wavelength, lightness, and saturation) and their photoaging properties, and the results indicated that MPs (yellow, red, and orange) with longer color wavelength, higher lightness, and lower saturation are more susceptible to UV light than MPs with shorter color wavelength, lower lightness and higher saturation (green and blue). The findings demonstrate that the photoaging process of colored MPs is correlated to their color characteristics, highlighting the important role of color in MPs' environmental fate.

Mechanical recycling of printed flexible plastic packaging: The role of binders and pigments

Low-density polyethylene (LDPE), extensively employed in flexible plastic packaging, often undergoes printing with inks. However, during the mechanical recycling of post-consumer waste, these inks act as contaminants, subsequently compromising the quality and usability of recycled material. To understand better exactly which ink components cause which effects, this study comprehensively assesses the thermal behavior of three organic pigments and two commonly utilised binders, correlated with the impact on the mechanical recycling of LDPE-based flexible plastic packaging. In this regard, the study focuses on four pivotal factors: processability, mechanical properties, aesthetic attributes, and volatile organic compound profiles. The results indicate that nitrocellulose, used as a binder, degrades during reprocessing, resulting in film discoloration and the emission of potentially odorous compounds. Conversely, pigments are found to be dispersed within droplets of polyurethane binder in LDPE recyclates, whilst reprocessing printed samples detrimentally affects film properties, notably dart drop impact resistance, strain at break, and the number of inclusions. Additionally, it is shown that both inks comprise components that emit volatile compounds during reprocessing: non-thermally stable components, nitrocellulose and pigment yellow PY13, as well as low-molecular weight molecules from polyurethane and by-products from wax, plasticisers, and additives.

Everything falls apart: How solids degrade and release nanomaterials, composite fragments, and microplastics

To ensure the safe use of materials, one must assess the identity and quantity of exposure. Solid materials, such as plastics, metals, coatings and cements, degrade to some extent during their life cycle, and releases can occur during manufacturing, use and end-of-life. Releases (e.g., what is released, how does release happen, and how much material is released) depend on the composition and internal (nano)structures of the material as well as the applied stresses during the lifecycle. We consider, in some depth, releases from mechanical, weathering and thermal stresses and specifically address the use cases of fused-filament 3D printing, dermal contact, food contact and textile washing. Solid materials can release embedded nanomaterials, composite fragments, or micro- and nanoplastics, as well as volatile organics, ions and dissolved organics. The identity of the release is often a heterogenous mixture and requires adapted strategies for sampling and analysis, with suitable quality control measures. Control materials enhance robustness by enabling comparative testing, but reference materials are not always available as yet. The quantity of releases is typically described by time-dependent rates that are modulated by the nature and intensity of the applied stress, the chemical identity of the polymer or other solid matrix, and the chemical identity and compatibility of embedded engineered nanomaterials (ENMs) or other additives. Standardization of methods and the documentation of metadata, including all the above descriptors of the tested material, applied stresses, sampling and analytics, are identified as important needs to advance the field and to generate robust, comparable assessments. In this regard, there are strong methodological synergies between the study of all solid materials, including the study of micro- and nanoplastics. From an outlook perspective, we review the hazard of the released entities, and show how this informs risk assessment. We also address the transfer of methods to related issues such as tyre wear, advanced materials and advanced manufacturing, biodegradable polymers, and non-solid matrices. As the consideration of released entities will become more routine in industry via lifecycle assessment in Safe-and-Sustainable-by-Design practices, release assessments will require careful design of the study with quality controls, the use of agreed-on test materials and standardized methods where these exist and the adoption of clearly defined data reporting practices that enable data reuse, meta-analyses, and comparative studies.

The extent of microplastic pollution along the eastern coast of India: Focussing on marine waters, beach sand, and fish

In this study, for the first time, we evaluated microplastic contamination in water, beach sand, and fish samples collected from the seven most famous and crowded beaches of the eastern coast of India, which cover around 1200 km. The average number of microplastics found was 80 ± 33 microplastics/m3 and 4 ± 2 microplastics/kg dry weight with a numerical abundance of polyethylene and polystyrene for water and sand samples, respectively. The polymer hazard index score, which represents the severity of the microplastics scenario in the studied locations, depicts that this coastline falls under hazard levels IV and V (most hazardous) for water and sand samples, respectively. The study revealed that approximately 30 % of the commercially important fishes collected from the locations contained microplastics with polyethylene terephthalate and polypropylene being the most abundant types. Rastrelliger kanagurta and Sardinella gibbosa were identified as the most polluted species.

Microplastic pollution in the Himalayas: Occurrence, distribution, accumulation and environmental impacts

Microplastics have been reported from various ecosystems including lakes, ponds, wetlands, mountains, and forests globally. Recent research works showed microplastic deposition and accumulation in the Himalayan mountains and adjoining ecosystems, rivers and streams. Fine particles of microplastic originating from different anthropogenic sources can travel long distances, even upwards (altitudinally) through atmospheric transport and can pollute remote and pristine locations situated in the Himalayas. Precipitation also plays a vital role in influencing deposition and fallout of microplastics in the Himalayas. Microplastics can be trapped in the snow in glaciers for a long time and can be released into freshwater rivers by snow melting. Microplastic pollution in Himalayan rivers such as the Ganga, Indus, Brahmaputra, Alaknanda, and Kosi has been researched on both the upper and lower catchments. Additionally, Himalayan region draws many domestic and international tourists throughout the year, resulting in generation of massive and unmanageable volume of plastics wastes and finally ending up in the open landscapes covering forests, river streams and valley. Fragmentation of these plastic wastes can lead to microplastic formation and accumulation in the Himalayas. This paper discusses and explains occurrence and distribution of microplastics in the Himalayan landscapes, possible adverse effects of microplastic on local ecosystems and human population and policy intervention needed to mitigate microplastic pollution in the Himalayas. A knowledge gap was noticed regarding the fate of microplastics in the freshwater ecosystems and their control mechanisms in the Indian Himalayas. Regulatory approaches for microplastics management in the Himalayas sit within the broader plastics/solid waste management and can be implemented effectively by following integrated approaches.

Characteristics and behaviors of microplastics undergoing photoaging and Advanced Oxidation Processes (AOPs) initiated aging

The fact that 94% of microplastics (MPs) ubiquitous in the environment are subject to natural weathering makes the aging study currently a research hotspot. This review summarized the physicochemical characteristics of MPs undergoing natural and artificial aging and evaluated current analytical methods used in aging studies. Besides, the differences in photoaging and aging induced by advanced oxidation processes (AOPs) were discussed, leading to a conclusion that AOPs composed of oxidant and ultraviolet (UV) irradiation can better facilitate the alteration of MPs compared to UV irradiation alone. In addition, the environmental behavior of aged MPs was outlined and their adsorption properties for organics and metals were highlighted as a result of combined effects of hydrophobic, π-π, diffusion, and hydrogen bond interaction. Furthermore, the mechanisms of photoaging and AOPs-initiated aging were analyzed, mainly the role of reactive oxygen species (ROS) and environmentally persistent free radicals (EPFRs). Finally, the applications of two-dimensional correlation spectroscopy (2D-COS) and three-dimensional fluorescence spectra using excitation emission matrix-parallel factor analysis (EEM-PARAFAC) were discussed for the aging process analysis. This overview plays an important role in explaining the aging characteristics of MPs and provides a theoretical foundation for further investigations into their toxicity and removal.

Valorization of agro-industrial biowaste to green nanomaterials for wastewater treatment: Approaching green chemistry and circular economy principles

Water pollution is one of the most critical issues worldwide and is a priority in all scientific agendas. Green nanotechnology presents a plethora of promising avenues for wastewater treatment. This review discusses the current trends in the valorization of zero-cost, biodegradable, and readily available agro-industrial biowaste to produce green bio-nanocatalysts and bio-nanosorbents for wastewater treatment. The promising roles of green bio-nanocatalysts and bio-nanosorbents in removing organic and inorganic water contaminants are discussed. The potent antimicrobial activity of bio-derived nanodisinfectants against water-borne pathogenic microbes is reviewed. The bioactive molecules involved in the chelation and tailoring of green synthesized nanomaterials are highlighted along with the mechanisms involved. Furthermore, this review emphasizes how the valorization of agro-industrial biowaste to green nanomaterials for wastewater treatment adheres to the fundamental principles of green chemistry, circular economy, nexus thinking, and zero-waste manufacturing. The potential economic, environmental, and health impacts of valorizing agro-industrial biowaste to green nanomaterials are highlighted. The challenges and future outlooks for the management of agro-industrial biowaste and safe application of green nanomaterials for wastewater treatment are summarized.

Non-Negligible Effects of UV Irradiation on Transformation and Environmental Risks of Microplastics in the Water Environment

Microplastics (MPs) are ubiquitous in environmental media, and their harmful effects on MPs on the ecosystem have attracted more and more attention. Once released into the environment, MPs can trigger oxidative degradation through ultraviolet (UV) to cause photoaging. Photoaging significantly affects the properties of MPs, which leads to changing their environmental behaviors and increasing environmental risks. In this review, the generation of MPs under UV irradiation and the influence of environmental factors on the photoaging of MPs were discussed. Photoaging of MPs is an important process affecting the migration, transformation and interaction of pollutants in water and soil. In order to fully predict the fate and environmental interaction of MPs, more researches are needed in the future to explore the photoaging behavior of different types of MPs under natural environmental conditions.

Simulation of natural aging property of microplastics in Yangtze River water samples via a rooftop exposure protocol

Due to low aging rate, the environmental behavior of naturally weathered microplastics (MPs) are not fully understood. Here, we systematically investigated the surface property and adsorption behavior of polypropylene (PP), polyethylene (PE) and polystyrene (PS) MPs during outdoor exposure in Yangtze River water for 18 months, and compared their difference from those in laboratory process. Results showed that compared to PE and PS MPs, PP underwent higher changes in surface aging properties such as rapid fragmentation and surface oxidation. Outdoor exposure exhibited different effects on adsorption property of MPs for metal ions, where adsorption capacities of PE and PS MPs for Co(II) were increased with aging degrees, while few change occurred on different aged PP MPs. As for Cr(VI), aging process further decreased the overall adsorption on PP, PE and PS MPs. The difference was mainly ascribed to the surface property (e.g. oxygen-containing groups and size) and the adhered biofilm and charged minerals. We further validated that similar types of oxidation products were formed between natural and laboratory aging of MPs, whereas the reaction order of these products, fragmentation rate and the change in adsorption property of aged MPs might be different in both processes. The findings provide essential information to assess real environmental behavior of MP samples.

Review of the artificially-accelerated aging technology and ecological risk of microplastics

After being discarded into the environment, the microplastics (MPs) will undergo weathering effects. However, the low degradation rate of MPs in natural processes greatly limits the understanding of long-term aging behavior. By critically reviewing 82 articles in Web of Science from 2015 to 2020, the paper summarized different laboratory technologies including light irradiation, chemical oxidation, heat treatment and γ-ray irradiation to simulate and accelerate the aging of MPs, and evaluated the feasibility by comparison with natural processes. The advantages of laboratory technologies are that aging conditions can be artificially controlled and that the labor and time costs can be saved, whereas the laboratory system is too simple to simulate complex aging processes in the environment. We further reviewed the potential impacts of aging process on the risks of MPs (i.e. physical injury, combined toxicity with external pollutants and chemical risk of additives and low-molecular products). The overall risks are seemingly enhanced by aging process due to the high ingestion by organisms, the strong interaction with pollutants and the release of MP-derived organic compounds. Further studies on the aging behavior of MPs should be focused on the laboratory techniques that can simulate multiple processes of natural aging, the long-term fragmentation behavior of MPs, the effect of aging on growth rate of biofilm in MPs and ingestion property by organisms, and the relationship between aging property of MPs and release rate of chemicals in leachates.

Plastic pollution - A case study with Enchytraeus crypticus - From micro-to nanoplastics

The concern about microplastic (a group of polymers) in the environment may cause us to overlook a more substantial problem: microplastics will fragment into nanoplastics. This fragmentation will lead to a high number of nanoplastics particles. Such nanoplastic can be taken up by cells, as opposed to microscale particles that are either not or to much less extend taken up. Fragmentation into nano will also release materials previously safely embedded in the polymer. We here present results from 25 OECD/ISO in vivo hazard tests, and beyond, e.g. extended exposure duration, with Enchytraeus crypticus, using pristine nano-scale materials (NMs) [CuO, Fe₂O₃, Organic Pigment, MWCNT], fragmented products (polymers) with these NMs embedded in the matrices (FP_NM), and fragmented polymers without NMs (FP) [covering the 4 major plastic types: Acrylic, Polyethylene, Polypropylene and Epoxy]. For example, MWCNTs induced a highly significant population decrease after extended period of 60 days, despite having no impact after 28 days' exposure, the standard OECD duration. We conclude, that the standard tests were not suitable to evaluate hazards of these plastic fragments, weathering/ageing of materials is recommended, and extension of test duration can add value to the testing of NMs. We must refocus the concern to testing with polymers (not only "plastics"), from micro-to nano-polymers, and from aquatic to terrestrial environments.

Critical effect of iron red pigment on photoaging behavior of polypropylene microplastics in artificial seawater

Microplastics (MPs) containing chemical additives undergo extensive aging in the environment, but the effect of additives on aging behavior of MPs is not fully understood. This study evaluated the effects of iron red pigment on the photoaging behavior of polypropylene (PP) MPs and the release kinetics of Fe(II) and Fe(III) under simulated sunlight. Based on analyses in surface property and aging products of leachate, the incorporated iron red pigment significantly decreased the photoaging rate of PP MPs. The critical effect mainly depended on the light shielding and the competition of pigment for electrons and reactive oxygen species generated from irradiated MPs. Light irradiation also caused the production of homologous series of organic products containing dicarboxylic acid end groups. Moreover, aging of pigmented MPs enhanced the release of Fe ions in leachates, and the types of released iron ions were different between dark and light conditions, where the iron ion in dark system was mainly as Fe(III), while Fe(II) was the dominant form in light irradiation, since the released Fe(III) reacted with MP-derived organic acids and reactive oxygen species in light condition. The findings highlight the critical role of inorganic pigments in the environmental fate and risk of MPs.

Characteristics and spatial distribution of microplastics in the lower Ganga River water and sediment

Although India is one of the major plastic-waste-generating countries, few studies have been conducted on microplastics (MPs) in freshwater systems that are key contributors to oceans. The current study explores MPs in sediments and water that were collected at five major cities across the Ganga River. MPs number and mass density range in sediment were found to be 17 to 36 items/kg dry weight (d.w.) and 10 to 45 mg/kg d.w. of sediments, respectively, while in the water sample, they were 380 to 684 items/1000 m³ and 143 to 340 mg/1000 m³, respectively. Overall, white color and film-shaped MPs were the major contributors in all samples. MPs of 2.5-5 mm size contributed to a greater number and mass as compared to other fractions. Polyethylene was found to be a widely distributed plastic-type reflecting its high usability.

Environmental Risk Assessment of Nanomaterials in the Light of New Obligations Under the REACH Regulation: Which Challenges Remain and How to Approach Them?

Within the European regulation on the Registration, Evaluation, Authorisation and Restriction of Chemicals (REACH, EC No 1907/2006) specific provisions for nanomaterials were included, which have become effective on 1 January 2020. Although knowledge on the peculiarities of testing and assessing fate and effects of nanomaterials in the environment strongly increased in the last years, uncertainties about how to perform a reliable and robust environmental risk assessment for nanomaterials still remain. These uncertainties are of special relevance in a regulatory context, challenging both industry and regulators. The present paper presents current challenges in regulatory hazard and exposure assessment under REACH, as well as classification of nanomaterials, and makes proposals to address them. Still, the nanospecific considerations made here are expected to also be valid for environmental risk assessment approaches in other regulations of chemical safety. Inter alia, these proposals include a way forward to account for exposure concentrations in aquatic toxicity test systems, a discussion of how to account for availability of dissolving nanomaterials in aquatic test systems, and a pragmatic proposal to deduce effect data for soil organisms. Furthermore, it specifies how to potentially deal with nanoforms under the European regulation on Classification, Labelling and Packaging of substances and mixtures (CLP) and outlines the needs for proper exposure assessments of nanomaterials from a regulatory perspective. Integr Environ Assess Manag 2020;16:706-717. © 2020 The Authors. Integrated Environmental Assessment and Management published by Wiley Periodicals LLC on behalf of Society of Environmental Toxicology & Chemistry (SETAC).

Weathering alters surface characteristic of TiO2-pigmented microplastics and particle size distribution of TiO2 released into water

In natural environment, microplastics (MPs) undergo varying degrees of aging. It is believed that aged MPs show different surface properties and leaching behaviors from unaged ones. Here, the effects of aging on surface characteristics of TiO₂-pigmented MPs and particle size distribution of TiO₂ leached from MPs were systematically investigated. Experimental results show that the carbonyl index and color difference of MPs increased after aging. The increased carbonyl content in MPs was due to photo-oxidation, which further caused the fragility of MPs, the loss of TiO₂ pigments and the formation of surface cracks. The decreased weight loss for aged MPs was due to the photo-transformation of LDPE into other compounds. Aged MPs could release more and faster TiO₂ particles than unaged MPs, and aged MPs tended to release more large particles (>5 μm) and fewer small particles (<5 μm) than unaged MPs. Aged MPs released TiO₂ with particle size uniformly distributed in each size fraction, but unaged MPs mainly released small particles (57.6%-86.2%). With increasing leaching time, the proportion of small particles leached from MPs especially aged MPs decreased and the proportion of large particles increased. These findings will help us better understand how aging process impacts the properties and leaching of MPs and the size distribution of particulate additives leached from MPs.

Continued Efforts on Nanomaterial-Environmental Health and Safety Is Critical to Maintain Sustainable Growth of Nanoindustry

Nanotechnology is enjoying an impressive growth and the global nanotechnology industry is expected to exceed US$ 125 billion by 2024. Based on these successes, there are notions that enough is known and efforts on engineered nanomaterial environmental health and safety (nano-EHS) research should be put on the back burner. However, there are recent events showing that it is not the case. The US Food and Drug Administration found ferumoxytol (carbohydrate-coated superparamagnetic iron oxide nanoparticle) for anemia treatment could induce lethal anaphylactic reactions. The European Union will categorize TiO2 as a category 2 carcinogen due to its inhalation hazard and France banned use of TiO2 (E171) in food from January 1, 2020 because of its carcinogenic potential. Although nanoindustry is seemingly in a healthy state, growth could be hindered for the lack of certainty and more nano-EHS research is needed for the sustainable growth of nanoindustry. Herein, the current knowledge gaps and the way forward are elaborated.

Aging of microplastics affects their surface properties, thermal decomposition, additives leaching and interactions in simulated fluids

Most microplastics (MPs) have undergone extensive aging in the environment. Aged MPs exhibit different physical and chemical properties from unaged ones. Here, we studied the effects of accelerated aging on the characteristics and pyrolysis of commercial pigmented MPs, as well as pigments leaching and their interactions in simulated gastric and intestinal fluids of mammals. We report that the carbonyl index, surface area, and color change of MPs increased after aging treatment. Cracks and fragmentation of MPs facilitated the accessibility of light and oxygen to internal layer and therefore accelerated the aging process. TGA/GC-MS analysis showed that the high temperature resistance of MPs decreased after aging. Thermal decomposition of pigments and polyethylene occurred in temperature ranges of 340-406 °C and 406-550 °C, respectively. Mono (di)-alkenes and saturated alkanes were the thermal decomposition products of polyethylene. Aging of MPs also caused an increased release of pigments and prolonged aging time led to more release in simulated fluids. Pigments would result in fluorescence quenching of the enzymes through binding interactions once they were released from MPs into simulated fluids. Charge neutralization and polymer bridging accounted for the formation of pigment-enzyme complexes and flocs. These novel findings will allow us to better assess how aging process affects the characteristics, leaching, and toxicity of MPs.

Evaluating performance, degradation, and release behavior of a nanoform pigmented coating after natural and accelerated weathering

Pigments with nanoscale dimensions are added to exterior coatings to achieve desirable color and gloss properties. The present study compared the performance, degradation, and release behavior of an acrylic coating that was pigmented by a nanoform of Cu-phthalocyanine after both natural (i.e., outdoor) and accelerated weathering. Samples were weathered outdoors in three geographically distinct locations across the United States (Arizona, Colorado, Maryland) continuously for 15 months. Identically prepared samples were also artificially weathered under accelerated conditions (increased ultraviolet (UV) light intensity and elevated temperatures) for three months, in one-month increments. After exposure, both sets of samples were characterized with color, gloss, and infrared spectroscopy measurements, and selectively with surface roughness measurements. Results indicated that UV-driven coating oxidation was the principal degradation pathway for both natural and accelerated weathering samples, with accelerated weathering leading to an increased rate of oxidation without altering the fundamental degradation pathway. The inclusion of the nanoform pigment reduced the rate of coating oxidation, via UV absorption by the pigment, leading to improved coating integrity compared to non-pigmented samples. Release measurements collected during natural weathering studies indicated there was never a period of weathering, in any location, that led to copper material release above background copper measurements. Lab-based release experiments performed on samples weathered naturally and under accelerated conditions found that the release of degraded coating material after each type of exposure was diminished by the inclusion of the nanoform pigment. Release measurements also indicated that the nanoform pigment remained embedded within the coating and did not release after weathering.

Monitoring the Environmental Aging of Nanomaterials: An Opportunity for Mesocosm Testing?

Traditional aging protocols typically examine only the effects of a limited number of stresses, and relatively harsh conditions may trigger degradation mechanisms that are not observed in actual situations. Environmental aging is, in essence, the complex interaction of multiple mechanical, physicochemical and biological stresses. As yet, there is no (pre)standardized procedure that addresses this issue in a satisfactory manner. Mesocosm experiments can be designed to specifically cover the aging of nanomaterials while characterizing the associated exposure and hazard. The scenario of exposure and the life time of the nanomaterial appear as the predominant factors in the design of the experiment, and appropriate precautions need to be taken. This should the subject of guidance that may be divided into product/application categories.

Non-linear release dynamics for a CeO2 nanomaterial embedded in a protective wood stain, due to matrix photo-degradation

The release of CeO₂-bearing residues during the weathering of an acrylic stain enriched with CeO₂ nanomaterial designed for wood protection (Nanobyk brand additive) was studied under two different scenarios: (i) a standard 12-weeks weathering protocol in climate chamber, that combined condensation, water spraying and UV-visible irradiation and (ii) an alternative accelerated 2-weeks leaching batch assay relying on the same weathering factors (water and UV), but with a higher intensity of radiation and immersion phases. Similar Ce released amounts were evidenced for both scenarios following two phases: one related to the removal of loosely bound material with a relatively limited release, and the other resulting from the degradation of the stain, where major release occurred. A non-linear evolution of the release with the UV dose was evidenced for the second phase. No stabilization of Ce emissions was reached at the end of the experiments. The two weathering tests led to different estimates of long-term Ce releases, and different degradations of the stain. Finally, the photo-degradations of the nanocomposite, the pure acrylic stains and the Nanobyk additive were compared. The incorporation of Nanobyk into the acrylic matrix significantly modified the response of the acrylic stain to weathering.

Environmental Impacts by Fragments Released from Nanoenabled Products: A Multiassay, Multimaterial Exploration by the SUN Approach

Nanoenabled products (NEPs) have numerous outdoor uses in construction, transportation or consumer scenarios, and there is evidence that their fragments are released in the environment at low rates. We hypothesized that the lower surface availability of NEPs fragment reduced their environmental effects with respect to pristine nanomaterials. This hypothesis was explored by testing fragments generated by intentional micronisation ("the SUN approach"; Nowack et al. Meeting the Needs for Released Nanomaterials Required for Further Testing: The SUN Approach. Environmental Science & Technology, 2016 (50), 2747). The NEPs were composed of four matrices (epoxy, polyolefin, polyoxymethylene, and cement) with up to 5% content of three nanomaterials (carbon nanotubes, iron oxide, and organic pigment). Regardless of the type of nanomaterial or matrix used, it was observed that nanomaterials were only partially exposed at the NEP fragment surface, indicating that mostly the intrinsic and extrinsic properties of the matrix drove the NEP fragment toxicity. Ecotoxicity in multiple assays was done covering relevant media from terrestrial to aquatic, including sewage treatment plant (biological activity), soil worms (Enchytraeus crypticus), and fish (zebrafish embryo and larvae and trout cell lines). We designed the studies to explore the possible modulation of ecotoxicity by nanomaterial additives in plastics/polymer/cement, finding none. The results support NEPs grouping by the matrix material regarding ecotoxicological effect during the use phase. Furthermore, control results on nanomaterial-free polymer fragments representing microplastic had no significant adverse effects up to the highest concentration tested.