Additives in polypropylene and polylactic acid food packaging: Chemical analysis and bioassays provide complementary tools for risk assessment

Additives in bioplastics: Chemical characterization, migration in water and effects on photosynthetic organisms

The potential release in the environment and biological effects of chemicals like additives and non-intentionally added substances present in conventional plastics and bioplastics is an issue that could occur if these materials are not properly disposed of. Herein, seven leachates of biobased and biodegradable plastics made of polylactic acid (PLA), polybutylene succinate (PBS)/PLA blends, and starch-based blends (SB) were characterized and compared for the inorganic and organic additives present in the source materials. The main inorganic elements found in the leachates were Na, Mg, K, and Ca (0.1-100 mg L-1), corresponding to the main elements present in the bioplastics. Also trace elements such as Ba, Zn, Sr, B, Fe, Ti, Al, Mn, Cu, and Sn occurred in leachates with concentrations between 1 and 1000 μg L-1. In contrast, most of the organic additives found in the bioplastics did not migrate in water and the few organic compounds detected and identified were not of concern. The lowest tested concentration of PBS/PLA- and SB-leachates (0.5 % of the corresponding initial leachate) induced a significant algal growth inhibition (corresponding to bioplastic concentrations in water of 0.4 g L-1). Conversely, PLA-based materials were less toxic (LOEC corresponding to 10 % of the leachates or >75 %). No effect on seed germination nor the development of roots and shoots of cress was observed for any leachate prepared from PLA and PBS/PLA materials. Leachates prepared from SB bags inhibited the growth of roots and shoots at the concentrations of 25 and 50 %, while they induced hormesis at 10 % concentration promoting a growth higher than the control.

Morphometric characteristics and spatiotemporal heterogeneity of microplastics on the north-east coast of India

The study analysed microplastics (MPs) in surface waters along the north-east coast of India and focused on the spatiotemporal distribution and morphometric characteristics of 800 particles for environmental insights. The MPs were consistently present in all water masses, with an average abundance of 0.67 ± 0.66 particles/m3 during the monsoon and 0.12 ± 0.08 particles/m3 post-monsoon. Fragments and fibers were dominant in both seasons, comprising over 83 % and 12 %, respectively. In terms of colours, blue was significantly dominant during the post-monsoon (H, χ2 (5) = 15.38, p < 0.01); however, such variation was absent during the monsoon. Spatially, significant variance in abundance (F4, 34 = 8.542; p < 0.01) and across colours and forms during the monsoon was correlated with land-based inputs from the Hooghly River. FTIR analysis revealed ten polymer types, predominantly polyethylene (44 %). SEM observations indicated that 80 % of particles exhibited polymer ageing from oxidative weathering. The size distribution of MPs varied notably, with a higher proportion of < 0.3 mm (16.7 %) during the monsoon, possibly due to increased particle disintegration. The study noted MPs had low to moderate circularity, with increased irregularity during the monsoon due to heavy precipitation and river flushing. An initial risk assessment of MP pollution in surface waters on the north-east coast revealed a low-risk state. Acrylonitrile butadiene styrene (ABS) was identified as the most hazardous MP polymer. A wide range of toxic trace elements were found in MPs in these waters. The findings from the study deepen our knowledge of MPs and their fate in the pelagic zone, which supports the development of science-based policies that effectively reduce MP pollution.

Advances in the enhancement of mechanical and hydrophobic properties of nanocellulose-based packaging materials: A review

As environmental issues are hotly debated worldwide, finding suitable materials to replace petroleum-based materials as the next-generation packaging materials has become a research hotspot. Nanocellulose, as a biomass material widely available in nature, is favored for application in green packaging materials due to its environmentally friendly and bio-friendly characteristics. However, the unstable mechanical properties and strong hydrophilicity of nanocellulose limit its practical application in packaging materials. This paper starts with a discussion of nanocellulose-based packaging materials and focuses on methods to improve their mechanical and hydrophobic properties. The discussion on mechanical properties focuses on the contribution of carbon nanomaterials, which is then combined with hydrophobic modifications (including plant polyphenol modification, esterification, acetylation, in situ polymerization, etc.) to illustrate the impact on the performance of packaging materials in use. The relationship between the hydrophobic characteristics of packaging materials derived from nanocellulose and their comprehensive mechanical properties is meticulously elucidated. Furthermore, a theoretical framework is proposed, positing that enhancing the hydrophobicity of these materials can indirectly augment their mechanical attributes. This insight offers pivotal guidance for the advancement of next-generation, high-performance packaging materials based on nanocellulose.

Chemical toxicity of leachates from synthetic and natural-based spat collectors on the embryo-larval development of the pearl oyster, Pinctada margaritifera

In French Polynesia, the pearl farming industry relies entirely on collecting natural spat using a shade-mesh collector, which is reported to contribute to both plastic pollution and the release of toxic chemicals. With the aim of identifying more environment-friendly collectors, this study investigates the chemical toxicity of shade-mesh (SM) and alternative materials, including reusable plates (P), a newly developed biomaterial (BioM) and Coconut coir geotextile (Coco), on the embryo-larval development of Pinctada margaritifera. Embryos were exposed during 48 h to four concentrations (0, 0.1, 10 and 100 g L-1) of leachates produced from materials. Chemical screening of raw materials and leachates was performed to assess potential relationships with the toxicity observed on D-larvae development. Compared to the other tested materials, results demonstrated lower levels of chemical pollutants in BioM and no toxic effects of its leachates at 10 g L-1. No toxicity was observed at the lowest tested concentration (0.1 g L-1). These findings offer valuable insights for promoting safer spat collector alternatives such as BioM and contribute to the sustainable development of pearl farming.

Carboxymethyl cellulose-based multifunctional film integrated with polyphenol-rich extract and carbon dots from coffee husk waste for active food packaging applications

Sustainable carboxymethyl cellulose (CMC)-based active composite films were developed through the addition of polyphenol-rich extract from coffee husk (CHE) and carbon dots (CDs) prepared using the biowaste residue of CHE extraction. The influences of various CDs contents on the physicochemical and functional characteristics of composite films have been researched. The 6% (w/w) CHE and 3% (w/w) CDs were uniformly dispersed within the CMC matrix to produce a homogenous film with enhanced mechanical properties. The CMC/CHE/CDs3% film exhibited outstanding UV-light blocking, improved water and gas barriers, potent antioxidant activity with above 95% DPPH and ABTS scavenging rates, and effective antibacterial capabilities against L. monocytogenes and E. coli. The food packaging experiment demonstrated that this active composite film slowed the rotting of fresh-cut apples and extended their shelf-life to 7 days at 4 °C storage. Therefore, the obtained multifunctional film showed promise as an environmentally friendly food packaging material.

Preparation of Green Silver Nanoparticles and Eco-Friendly Polymer-AgNPs Nanocomposites: A Study of Toxic Properties across Multiple Organisms

This article focuses on the eco-friendly (green) synthesis of silver nanoparticles (AgNPs) and their incorporation into a polymer matrix. For AgNPs synthesis, Lavandula angustifolia (lavender) leaf extract was used as a reducing and stabilizing agent, and as a silver precursor, AgNO3 solution with different concentrations of silver (50, 100, 250, and 500 mg/L) was used. Prepared AgNPs colloids were characterized using UV-vis spectrophotometry, transmission electron microscopy (TEM), and X-ray diffraction (XRD). The spherical morphology of AgNPs with an average size of 20 nm was confirmed across all samples. Further, the antimicrobial properties of the AgNPs were evaluated using the disk diffusion method on algae (Chlorella kessleri) and the well diffusion method on bacteria (Staphylococcus chromogenes, Staphylococcus aureus, and Streptococcus uberis), along with root growth inhibition tests on white mustard (Sinapis alba). Polymer composite (PVA-AgNPs) was prepared by incorporation of AgNPs into the polymer matrix. Subsequently, non-woven textiles and thin foils were prepared. The distribution of AgNPs within the nanocomposites was observed by scanning electron microscopy (SEM). Antibacterial properties of PVA-AgNPs composites were analyzed on bacteria Streptococcus uberis. It was found that not only AgNPs showed good antimicrobial properties, but toxic properties were also transferred to the PVA-AgNPs nanocomposite.

Carbon Fiber Reinforced Recycled Polypropylene/Polyolefin Elastomer Composites with High Mechanical Properties

The treatment of waste plastics has gradually become a hot topic in the current scientific community. In response to the needs for high-impact performance R-PP-based composites, carbon fiber (CF)-reinforced polyolefin elastomer (POE)/recycled polypropylene (R-PP) composite (CF/POE/R-PP) was prepared by the mechanical blending method, and its mechanical and thermal properties were systematically studied. It was found that the CF could effectively improve the bending and notch impact strength as well as enhance the thermal stability of POE/R-PP. Furthermore, a stable and dispersed composite interface formed by the combination of maleic anhydride-grafted polypropylene (PP-g-MAH) with the surface of CF and the fusion alkyl chains in R-PP and POE further enhanced the CF's reinforcing effect. As a result, the addition of 9 wt.% CF successfully improved the heat resistance of the composite material, and the residual carbon content increased by 97.84% after sintering. The composite toughening of POE and CF effectively improved the impact strength of the composite material, with a maximum increase of over 1000%. This study ultimately resulted in a high-impact-resistant composite material.

Dissolution-precipitation method concatenated sodium alginate/MOF-derived magnetic multistage pore carbon magnetic solid phase extraction for determination of antioxidants and ultraviolet stabilizers in polylactic acid food contact plastics

Antioxidants and UV stabilizers have some endocrine disrupting effects and liver toxicity. Both types of additives are still widely used in food contact plastics to improve the durability of plastic products. However, efficient and rapid detection of antioxidants and UV stabilizers has been a challenge due to the complexity of the plastic matrix and the low content of antioxidants and UV stabilizers. In this study, a sodium alginate/MOF-derived magnetic multistage pore carbon material (MIL-101(Fe)/SA-CAs) was developed, having the merits of abundant multistage pore structure, large specific surface area, and good magnetic separation properties. Thus, this material was selected as the sorbent for magnetic solid-phase extraction combined with a dissolution-precipitation method for the extraction and purification of antioxidants and UV stabilizers from polylactic acid food contact plastics. The extraction parameters such as sorbent type, sorbent dosage, sample solution pH, ionic strength, sorption time, elution solution type, volume, and time were investigated. Under the optimized conditions, all the analytes determined by UPLC-MS/MS showed good linear range (r > 0.99), detection limit (0.023-3.105 ng g-1), accuracy (70.6-102.3 %), and reproducibility (RSD<9.8 %). Further, the developed method was applied to determine the antioxidants and UV stabilizers in polylactic acid lunch boxes and straws, showing excellent applicability. The results showed that the antioxidants and UV stabilizers were detected in some of the samples, with a maximum detection of antioxidant 1010 at 7297 ng g-1. This study provided a sensitive, efficient, and environmentally friendly method for antioxidants and UV stabilizers in polylactic acid food contact plastics. The ideas for the design of environmentally friendly metal-organic frameworks and biomass composite multifunctional materials would promise in the sample pretreatment field for the emerging contaminants.

A global review on the abundance and threats of microplastics in soils to terrestrial ecosystem and human health

Soil is the source and sink of microplastics (MPs), which is more polluted than water and air. In this paper, the pollution levels of MPs in the agriculture, roadside, urban and landfill soils were reviewed, and the influence of MPs on soil ecosystem, including soil properties, microorganisms, animals and plants, was discussed. According to the results of in vivo and in vitro experiments, the possible risks of MPs to soil ecosystem and human health were predicted. Finally, in light of the current status of MPs research, several prospects are provided for future research directions to better evaluate the ecological risk and human health risk of MPs. MPs concentrations in global agricultural soils, roadside soils, urban soils and landfill soils had a great variance in different studies and locations. The participation of MPs has an impact on all aspects of terrestrial ecosystems. For soil properties, pH value, bulk density, pore space and evapotranspiration can be changed by MPs. For microorganisms, MPs can alter the diversity and abundance of microbiome, and different MPs have different effects on bacteria and fungi differently. For plants, MPs may interfere with their biochemical and physiological conditions and produce a wide range of toxic effects, such as inhibiting plant growth, delaying or reducing seed germination, reducing biological and fruit yield, and interfering with photosynthesis. For soil animals, MPs can affect their mobility, growth rate and reproductive capacity. At present epidemiological evidences regarding MPs exposure and negative human health effects are unavailable, but in vitro and in vivo data suggest that they pose various threats to human health, including respiratory system, digestive system, urinary system, endocrine system, nervous system, and circulation system. In conclusion, the existence and danger of MPs cannot be ignored and requires a global effort.

A vision for safer food contact materials: Public health concerns as drivers for improved testing

Food contact materials (FCMs) and food contact articles are ubiquitous in today's globalized food system. Chemicals migrate from FCMs into foodstuffs, so called food contact chemicals (FCCs), but current regulatory requirements do not sufficiently protect public health from hazardous FCCs because only individual substances used to make FCMs are tested and mostly only for genotoxicity while endocrine disruption and other hazard properties are disregarded. Indeed, FCMs are a known source of a wide range of hazardous chemicals, and they likely contribute to highly prevalent non-communicable diseases. FCMs can also include non-intentionally added substances (NIAS), which often are unknown and therefore not subject to risk assessment. To address these important shortcomings, we outline how the safety of FCMs may be improved by (1) testing the overall migrate, including (unknown) NIAS, of finished food contact articles, and (2) expanding toxicological testing beyond genotoxicity to multiple endpoints associated with non-communicable diseases relevant to human health. To identify mechanistic endpoints for testing, we group chronic health outcomes associated with chemical exposure into Six Clusters of Disease (SCOD) and we propose that finished food contact articles should be tested for their impacts on these SCOD. Research should focus on developing robust, relevant, and sensitive in-vitro assays based on mechanistic information linked to the SCOD, e.g., through Adverse Outcome Pathways (AOPs) or Key Characteristics of Toxicants. Implementing this vision will improve prevention of chronic diseases that are associated with hazardous chemical exposures, including from FCMs.

Mechanical, chemical, and bio-recycling of biodegradable plastics: A review

The extensive use of petroleum-based non-biodegradable plastics for various applications has led to global concerns regarding the severe environmental issues associated with them. However, biodegradable plastics are emerging as green alternatives to petroleum-based non-biodegradable plastics. Biodegradable plastics, which include bio-based and petroleum-based biodegradable polymers, exhibit advantageous properties such as renewability, biocompatibility, and non-toxicity. Furthermore, certain biodegradable plastics are compatible with existing recycling streams intended for conventional plastics and are biodegradable in controlled and/or predicted environments. Recycling biodegradable plastics before their end-of-life (EOL) degradation further enhances their sustainability and reduces their carbon footprint. Since the production of biodegradable plastic is increasing and these materials will coexist with conventional plastics for many years to come, it is essential to identify the optimal recycling options for each of the most prevalent biodegradable plastics. The substitution of virgin biodegradable plastics by their recyclates leads to higher savings in the primary energy demand and reduces global warming impact. This review covers the current state of the mechanical, chemical, and bio-recycling of post-industrial and post-consumer waste of biodegradable plastics and their related composites. The effects of recycling on the chemical structure and thermomechanical properties of biodegradable plastics are also reported. Additionally, the improvement of biodegradable plastics by blending them with other polymers and nanoparticles is comprehensively discussed. Finally, the status of bioplastic usage, life cycle assessment, EOL management, bioplastic market, and the challenges associated with the recyclability of biodegradable plastics are addressed. This review gives comprehensive insights into the recycling processes that may be employed for the recycling of biodegradable plastics.