Plastic Food Packaging from Five Countries Contains Endocrine- and Metabolism-Disrupting Chemicals

Biodegradation of commercial polyester polyurethane by a soil-borne bacterium Bacillus velezensis MB01B: Efficiency, degradation pathway, and in-situ remediation in landfill soil

Polyurethane (PU), a widely used and durable plastic, persists in the environment, resulting in significant waste management challenges. Therefore, developing eco-friendly degradation technologies, such as screening for efficient biodegrading microorganism strains, is urgently needed to address this issue. Bacillus velezensis MB01B, an efficient polyester PU-degrading bacterium, was isolated from landfill soil and demonstrated the ability to degrade 91.4% of 0.75% Impranil DLN within 24 h under the optimal conditions (30.5 °C and initial pH 6.5). To assess the degradation capability of MB01B, three PU substrates of increasing complexity-Impranil DLN film, polyester thermoplastic polyurethane (TPU) film, and commercial PU desk mat-were tested; after 30 days, weight losses of 24.8%, 18.3%, and 5.4% were observed, respectively. In addition, SEM images showed significant morphological changes on the surface of these PU materials after treatment with MB01B. FTIR analysis of Impranil DLN films following degradation showed reductions in key functional groups (ester and urethane); and the identification of neopentyl glycol and 1,6-hexanediol as degradation intermediates suggested MB01B possesses the capability to hydrolyze ester and urethane bonds. Concurrently, genome sequencing combined with RT-qPCR identified several enzymes, including urethanases and esterases/lipases, involved in PU degradation. Based on these results, the pathway for MB01B to degrade Impranil DLN was inferred. Finally, MB01B was successfully formulated into a solid microbial inoculum with favorable storage properties and used for in-situ degradation of the commercial PU materials (Impranil DLN films, TPU films and PU desk mats) in landfill soil, underscoring its potential for the in-situ biological treatment of PU plastic wastes.

Beyond plastic pollution: Unveiling chemical release from plastic debris in river water and seawater using non-target screening

Oceans and rivers are predominant sinks, reservoirs, and carriers of plastic debris that are proposed to be long term sources of a variety of contaminants in the environments. This research unveiled kinetics of chemical releases from plastic debris in freshwater and marine environment via artificial river water (ARW) and seawater (ASW) in combination of nontarget screening. Chemical leaching from PVC cord particles in the ARW and ASW basically followed the first order kinetics, reaching pseudo-equilibrium in 30d and 14d, respectively, associated with both particle surface - water partitioning and inner-particle diffusion of chemicals. Dissolved organic carbon, finer size, and weathering of plastic particles might enhance whereas metal ions potentially hinder chemical releases from plastic debris in waters, respectively. Salinity and pH showed moderate effects on chemical leaching. In addition, chemicals' physiochemical properties might also affect their leaching behavior. Hundreds to thousands of chemicals would be released from plastic debris in days once entering waters, among which > 80% were unknown with rare or no information about eco-toxicity and environmental fate, posing unpredicted risks to the environment. Furthermore, new chemicals may keep being released with increasing weathering and extending retention time of plastics in waters, leading to increases in both numbers and complexities of released chemicals. Chemical leaching from plastics showed product-dependence and certain differences in freshwater and seawater. Large numbers of unknown chemicals potentially released from plastic debris in rivers, lakes, and oceans and subsequent environmental risks warrant in-depth research.

Rapid Generation of Microplastics and Plastic-Derived Dissolved Organic Matter from Food Packaging Films under Simulated Aging Conditions

In this study, we show that low-density polyethylene films, a prevalent choice for food packaging in everyday life, generated high numbers of microplastics (MPs) and hundreds to thousands of plastic-derived dissolved organic matter (DOM) substances under simulated food preparation and storage conditions. Specifically, the plastic film generated 66-2034 MPs/cm2 (size range 10-5000 μm) under simulated aging conditions involving microwave irradiation, heating, steaming, UV irradiation, refrigeration, freezing, and freeze-thaw cycling alongside contact with water, which were 15-453 times that of the control (plastic film immersed in water without aging). We also noticed a substantial release of plastic-derived DOM. Using ultrahigh-resolution mass spectrometry, we identified 321-1414 analytes with molecular weights ranging from 200 to 800 Da, representing plastic-derived DOM containing C, H, and O. The DOM substances included both degradation products of polyethylene (including oxidized forms of oligomers) and toxic plastic additives. Interestingly, although no apparent oxidation was observed for the plastic film under aging conditions, plastic-derived DOM was more oxidized (average O/C increased by 27-46%) following aging with a higher state of carbon saturation and higher polarity. These findings highlight the future need to assess risks associated with MP and DOM release from plastic wraps.

A multidisciplinary perspective on the role of plastic pollution in the triple planetary crisis

In this perspective paper, we discuss the negative impacts of plastics and associated chemicals on the triple planetary crisis of environmental pollution, climate change and biodiversity loss from a multidisciplinary perspective. Plastics are part of the pollution crisis, threatening ecosystems and human health. They also impact climate change and accelerate biodiversity loss; in this, they aggravate the triple planetary crisis. We analyze the scientific state-of-the-art to identify critical knowledge gaps regarding the life cycle, release, fate, exposure, hazard and governance of plastics and associated chemicals, as well as links to climate change and biodiversity loss. Based on the outcome, we derive key research needs for a comprehensive hazard assessment of plastics and associated chemicals, amongst others, to address the largely missing regulation of plastic additives and in-use plastics. We offer a holistic perspective bridging disciplinary expertise from natural and social sciences to achieve effective plastic governance and risk management of plastics and associated chemicals that protect the Earth, its ecosystems and human health from the plastics crisis.

Twenty years of microplastic pollution research-what have we learned?

Twenty years after the first publication that used the term microplastic, we review current understanding, refine definitions, and consider future prospects. Microplastics arise from multiple sources, including tires, textiles, cosmetics, paint, and the fragmentation of larger items. They are widely distributed throughout the natural environment, with evidence of harm at multiple levels of biological organization. They are pervasive in food and drink and have been detected throughout the human body, with emerging evidence of negative effects. Environmental contamination could double by 2040, and wide-scale harm has been predicted. Public concern is increasing, and diverse measures to address microplastic pollution are being considered in international negotiations. Clear evidence on the efficacy of potential solutions is now needed to address the issue and to minimize the risks of unintended consequences.

Leveraging integrative toxicogenomic approach towards development of stressor-centric adverse outcome pathway networks for plastic additives

Plastics are widespread pollutants found in atmospheric, terrestrial and aquatic ecosystems due to their extensive usage and environmental persistence. Plastic additives, that are intentionally added to achieve specific functionality in plastics, leach into the environment upon plastic degradation and pose considerable risk to ecological and human health. Limited knowledge concerning the presence of plastic additives throughout plastic life cycle has hindered their effective regulation, thereby posing risks to product safety. In this study, we leveraged the adverse outcome pathway (AOP) framework to understand the mechanisms underlying plastic additives-induced toxicities. We first identified an exhaustive list of 6470 plastic additives from chemicals documented in plastics. Next, we leveraged heterogenous toxicogenomics and biological endpoints data from five exposome-relevant resources, and identified associations between 1287 plastic additives and 322 complete and high quality AOPs within AOP-Wiki. Based on these plastic additive-AOP associations, we constructed a stressor-centric AOP network, wherein the stressors are categorized into ten priority use sectors and AOPs are linked to 27 disease categories. We visualized the plastic additives-AOP network for each of the 1287 plastic additives and made them available in a dedicated website: https://cb.imsc.res.in/saopadditives/ . Finally, we showed the utility of the constructed plastic additives-AOP network by identifying highly relevant AOPs associated with benzo[a]pyrene (B[a]P), bisphenol A (BPA), and bis(2-ethylhexyl) phthalate (DEHP) and thereafter, explored the associated toxicity pathways in humans and aquatic species. Overall, the constructed plastic additives-AOP network will assist regulatory risk assessment of plastic additives, thereby contributing towards a toxic-free circular economy for plastics.

Potential mammary carcinogens used in food contact articles: implications for policy, enforcement, and prevention

Many nations have food contact material (FCM) legislation purporting to protect citizens from hazardous chemicals, often specifically by regulating genotoxic carcinogens. Despite such regulations, cancers that are associated with harmful chemical exposures are highly prevalent, especially breast cancer. Using the novel Key Characteristics of Toxicants framework, Kay et al. found 921 substances that are potential mammary carcinogens. By comparing Kay et al.'s chemicals list with our own Database on migrating and extractable food contact chemicals (FCCmigex), we found that 189 (21%) of the potential mammary carcinogens have been measured in FCMs. When limiting these results to migration studies published in 2020-2022, 76 potential mammary carcinogens have been detected to migrate from FCMs sold in markets across the globe, under realistic conditions of use. This implies that chronic exposure of the entire population to potential mammary carcinogens from FCMs is the norm and highlights an important, but currently underappreciated opportunity for prevention. Reducing population-wide exposure to potential mammary carcinogens can be achieved by science-based policy amendments addressing the assessment and management of food contact chemicals.

Moldable Plastics (Polycaprolactone) can be Acutely Toxic to Developing Zebrafish and Activate Nuclear Receptors in Mammalian Cells

Popularized on social media, hand-moldable plastics are formed by consumers into tools, trinkets, and dental prosthetics. Despite the anticipated dermal and oral contact, manufacturers share little information with consumers about these materials, which are typically sold as microplastic-sized resin pellets. Inherent to their function, moldable plastics pose a risk of dermal and oral exposure to unknown leachable substances. We analyzed 12 moldable plastics advertised for modeling and dental applications and determined them to be polycaprolactone (PCL) or thermoplastic polyurethane (TPU). The bioactivities of the most popular brands advertised for modeling applications of each type of polymer were evaluated using a zebrafish embryo bioassay. While water-borne exposure to the TPU pellets did not affect the targeted developmental end points at any concentration tested, the PCL pellets were acutely toxic above 1 pellet/mL. The aqueous leachates of the PCL pellets demonstrated similar toxicity. Methanolic extracts from the PCL pellets were assayed for their bioactivity using the Attagene FACTORIAL platform. Of the 69 measured end points, the extracts activated nuclear receptors and transcription factors for xenobiotic metabolism (pregnane X receptor, PXR), lipid metabolism (peroxisome proliferator-activated receptor γ, PPARγ), and oxidative stress (nuclear factor erythroid 2-related factor 2, NRF2). By nontargeted high-resolution comprehensive two-dimensional gas chromatography (GC × GC-HRT), we tentatively identified several compounds in the methanolic extracts, including PCL oligomers, a phenolic antioxidant, and residues of suspected antihydrolysis and cross-linking additives. In a follow-up zebrafish embryo bioassay, because of its stated high purity, biomedical grade PCL was tested to mitigate any confounding effects due to chemical additives in the PCL pellets; it elicited comparable acute toxicity. From these orthogonal and complementary experiments, we suggest that the toxicity was due to oligomers and nanoplastics released from the PCL rather than chemical additives. These results challenge the perceived and assumed inertness of plastics and highlight their multiple sources of toxicity.

Migration of endocrine and metabolism disrupting chemicals from plastic food packaging

Plastics constitute a vast array of substances, with over 16000 known plastic chemicals, including intentionally and non-intentionally added substances. Thousands of chemicals, including toxic ones, are extractable from plastics, however, the extent to which these compounds migrate from everyday products into food or water remains poorly understood. This study aims to characterize the endocrine and metabolism disrupting activity, as well as the chemical composition of migrates from plastic food contact articles (FCAs) from four countries as significant sources of human exposure. Fourteen plastic FCAs covering seven polymer types with high global market shares were migrated into water and a water-ethanol mixture as food simulants according to European regulations. The migrates were analyzed using reporter gene assays for nuclear receptors relevant to human health and non-target chemical analysis to characterize the chemical composition. Chemicals migrating from each FCA interfered with at least two nuclear receptors, predominantly targeting pregnane X receptor (24/28 migrates). Moreover, peroxisome proliferator receptor gamma was activated by 19 out of 28 migrates, though mostly with lower potencies. Estrogenic and antiandrogenic activity was detected in eight and seven migrates, respectively. Fewer chemicals and less toxicity migrated into water compared to the water-ethanol mixture. However, 73 % of the 15 430 extractable chemical features also transferred into food simulants, and the water-ethanol migrates exhibited a similar toxicity prevalence compared to methanol extracts. The chemical complexity differed largely between FCAs, with 8 to 10631 chemical features migrating into food simulants. Using stepwise partial least squares regressions, we successfully narrowed down the list of potential active chemicals, identified known endocrine disrupting chemicals, such as triphenyl phosphate, and prioritized chemical features for further identification. This study demonstrates the migration of endocrine and metabolism disrupting chemicals from plastic FCAs into food simulants, rendering a migration of these compounds into food and beverages probable.

Occurrence and Prioritization of Human Androgen Receptor Disruptors in Sewage Sludges Across China

The global practice of reusing sewage sludge in agriculture and its landfill disposal reintroduces environmental contaminants, posing risks to human and ecological health. This study screened sewage sludge from 30 Chinese cities for androgen receptor (AR) disruptors, utilizing a disruptor list from the Toxicology in the 21st Century program (Tox21), and identified 25 agonists and 33 antagonists across diverse use categories. Predominantly, natural products 5α-dihydrotestosterone and thymidine emerged as agonists, whereas the industrial intermediate caprolactam was the principal antagonist. In-house bioassays for identified disruptors displayed good alignment with Tox21 potency data, validating employing Tox21 toxicity data for theoretical toxicity estimations. Potency calculations revealed 5α-dihydrotestosterone and two pharmaceuticals (17β-trenbolone and testosterone isocaproate) as the most potent AR agonists and three dyes (rhodamine 6G, Victoria blue BO, and gentian violet) as antagonists. Theoretical effect contribution evaluations prioritized 5α-dihydrotestosterone and testosterone isocaproate as high-risk AR agonists and caprolactam, rhodamine 6G, and 8-hydroxyquinoline (as a biocide and a preservative) as key antagonists. Notably, 16 agonists and 20 antagonists were newly reported in the sludge, many exhibiting significant detection frequencies, concentrations, and/or toxicities, demanding future scrutiny. Our study presents an efficient strategy for estimating environmental sample toxicity and identifying key toxicants, thereby supporting the development of appropriate sludge management strategies.

Beyond the Nucleus: Plastic Chemicals Activate G Protein-Coupled Receptors

G protein-coupled receptors (GPCRs) are central mediators of cell signaling and physiological function. Despite their biological significance, GPCRs have not been widely studied in the field of toxicology. Herein, we investigated these receptors as novel targets of plastic chemicals using a high-throughput drug screening assay with 126 human non-olfactory GPCRs. In a first-pass screen, we tested the activity of triphenol phosphate, bisphenol A, and diethyl phthalate, as well as three real-world mixtures of chemicals extracted from plastic food packaging covering all major polymer types. We found 11 GPCR-chemical interactions, of which the chemical mixtures exhibited the most robust activity at adenosine receptor 1 (ADORA1) and melatonin receptor 1 (MTNR1A). We further confirm that polyvinyl chloride and polyurethane products contain ADORA1 or MTNRA1 agonists using a confirmatory secondary screen and pharmacological knockdown experiments. Finally, an analysis of the associated gene ontology terms suggests that ADORA1 and MTNR1A activation may be linked to downstream effects on circadian and metabolic processes. This work highlights that signaling disruption caused by plastic chemicals is broader than that previously believed and demonstrates the relevance of nongenomic pathways, which have, thus far, remained unexplored.