Characterization of ecotoxicological risks from unintentional mixture exposures calculated from European freshwater monitoring data: Forwarding prospective chemical risk management

Current regulatory chemical safety assessments do not acknowledge that ambient exposures are to multiple chemicals at the same time. As a result, potentially harmful exposures to unintentional mixtures may occur, leading to potential insufficient protection of the environment. The present study describes cumulative environmental risk assessment results for European fresh water ecosystems, based on the NORMAN chemical surface water monitoring database (1998-2016). It aims to characterize the magnitude of the mixture problem and the relative contribution of chemicals to the mixture risk, and evaluates how cumulative risks reduce when the acceptable risk per single chemical is fractionally lowered. Available monitoring data were curated and aggregated to 26,631 place-time combinations with at least two chemicals, of which 376 place-time combinations had at least 25 chemicals identified above the Limit of Detection. Various risk metrics were based on measured environmental concentrations (MECs). Mixture risk characterization ratio's (ΣRCRs) ≥ 1 were found for 39% of the place-time combinations, with few chemicals dominating the ΣRCR. Analyses of mixture toxic pressures, expressed as multi-substance Potentially Affected Fractions of species based on No Observed Effect Concentrations (msPAF_NOEC), showed similar outcomes. Small fractional reductions of the ambient chemical concentrations give a steep increase of the percentage of sufficiently protected water bodies (i.e. ΣRCR < 1 and msPAF_NOEC < 5%). Scientific and regulatory aspects of these results are discussed, especially with reference to the representativeness of the monitoring data for characterizing ambient mixtures, the robustness of the findings, and the possible regulatory implementation of the concept of a Mixture Allocation Factor (MAF) for prospective chemicals risk management. Although the monitoring data do not represent the full spectrum of ambient mixture exposures in Europe, results show the need for adapting policies to reach European Union goals for a toxic-free environment and underpin the utility and possible magnitude of a MAF.

Role of the Synergistic Interactions of Environmental Pollutants in the Development of Cancer

There is a growing awareness that the large number of environmental pollutants we are exposed to on a daily basis are causing major health problems. Compared to traditional studies that focus on individual pollutants, there are relatively few studies on how pollutants mixtures interact. Several studies have reported a relationship between environmental pollutants and the development of cancer, even when pollutant levels are below toxicity reference values. The possibility of synergistic interactions between different pollutants could explain how even low concentrations can cause major health problems. These intricate that molecular interactions can occur through a wide variety of mechanisms, and our understanding of the physiological effects of mixtures is still limited. The purpose of this paper is to discuss recent reports that address possible synergistic interactions between different types of environmental pollutants that could promote cancer development. Our literature studies suggest that key biological pathways are frequently implicated in such processes. These include increased production of reactive oxygen species, activation by cytochrome P450, and aryl hydrocarbon receptor signaling, among others. We discuss the need to understand individual pathological vulnerability not only in relation to basic genetics and gene expression, but also in terms of measurable exposure to contaminants. We also mention the need for significant improvements in future studies using a multitude of disciplines, such as the development of high-throughput study models, better tools for quantifying pollutants in cancer patients, innovative pharmacological and toxicological studies, and high-efficiency computer analysis, which allow us to analyze the molecular mechanisms of mixtures.

Integrating Selection and Risk Assessment of Chemical Mixtures: A Novel Approach Applied to a Breast Milk Survey

BACKGROUND

One of the main challenges of modern risk assessment is to account for combined exposure to the multitude of various substances present in food and the environment.

OBJECTIVE

The present work proposes a methodological approach to perform chemical risk assessment of contaminant mixtures across regulatory silos regarding an extensive range of substances and to do so when comprehensive relevant data concerning the specific effects and modes of action of the mixture components are not available.

METHODS

We developed a complete step-by-step approach using statistical methods to prioritize substances involved in combined exposure, and we used a component-based approach to cumulate the risk using dose additivity. The most relevant toxicological end point and the associated reference point were selected from the literature to construct a toxicological threshold for each substance.

DISCUSSION

By applying the proposed method to contaminants in breast milk, we observed that among the 19 substances comprising the selected mixture, ∑DDT, ∑PCBi, and arsenic were main joint contributors to the risk of neurodevelopmental and thyroid effects for infants. In addition, ∑PCCD/F contributed to the thyroid effect and ∑aldrin-dieldrin to the neurodevelopmental effect. Our case study on contaminants in breast milk demonstrated the importance of crossing regulatory silos when studying mixtures and the importance of identifying risk drivers to regulate the risk related to environmental contamination. Applying this method to another set of data, such as human biomonitoring or in ecotoxicology, will reinforce its relevance for risk assessment. https://doi.org/10.1289/EHP8262.

One planet: one health. A call to support the initiative on a global science-policy body on chemicals and waste

The chemical pollution crisis severely threatens human and environmental health globally. To tackle this challenge the establishment of an overarching international science-policy body has recently been suggested. We strongly support this initiative based on the awareness that humanity has already likely left the safe operating space within planetary boundaries for novel entities including chemical pollution. Immediate action is essential and needs to be informed by sound scientific knowledge and data compiled and critically evaluated by an overarching science-policy interface body. Major challenges for such a body are (i) to foster global knowledge production on exposure, impacts and governance going beyond data-rich regions (e.g., Europe and North America), (ii) to cover the entirety of hazardous chemicals, mixtures and wastes, (iii) to follow a one-health perspective considering the risks posed by chemicals and waste on ecosystem and human health, and (iv) to strive for solution-oriented assessments based on systems thinking. Based on multiple evidence on urgent action on a global scale, we call scientists and practitioners to mobilize their scientific networks and to intensify science-policy interaction with national governments to support the negotiations on the establishment of an intergovernmental body based on scientific knowledge explaining the anticipated benefit for human and environmental health.

The Eco-Exposome Concept: Supporting an Integrated Assessment of Mixtures of Environmental Chemicals

Organisms are exposed to ever-changing complex mixtures of chemicals over the course of their lifetime. The need to more comprehensively describe this exposure and relate it to adverse health effects has led to formulation of the exposome concept in human toxicology. Whether this concept has utility in the context of environmental hazard and risk assessment has not been discussed in detail. In this Critical Perspective, we propose-by analogy to the human exposome-to define the eco-exposome as the totality of the internal exposure (anthropogenic and natural chemicals, their biotransformation products or adducts, and endogenous signaling molecules that may be sensitive to an anthropogenic chemical exposure) over the lifetime of an ecologically relevant organism. We describe how targeted and nontargeted chemical analyses and bioassays can be employed to characterize this exposure and discuss how the adverse outcome pathway concept could be used to link this exposure to adverse effects. Available methods, their limitations, and/or requirement for improvements for practical application of the eco-exposome concept are discussed. Even though analysis of the eco-exposome can be resource-intensive and challenging, new approaches and technologies make this assessment increasingly feasible. Furthermore, an improved understanding of mechanistic relationships between external chemical exposure(s), internal chemical exposure(s), and biological effects could result in the development of proxies, that is, relatively simple chemical and biological measurements that could be used to complement internal exposure assessment or infer the internal exposure when it is difficult to measure. Environ Toxicol Chem 2022;41:30-45. © 2021 The Authors. Environmental Toxicology and Chemistry published by Wiley Periodicals LLC on behalf of SETAC.

First Attempt to Couple Proteomics with the AhR Reporter Gene Bioassay in Soil Pollution Monitoring and Assessment

A topsoil sample obtained from a highly industrialized area (Taranto, Italy) was tested on the DR-CALUX^® cell line and the exposed cells processed with proteomic and bioinformatics analyses. The presence of polyhalogenated compounds in the topsoil extracts was confirmed by GC-MS/MS analysis. Proteomic analysis of the cells exposed to the topsoil extracts identified 43 differential proteins. Enrichment analysis highlighted biological processes, such as the cellular response to a chemical stimulus, stress, and inorganic substances; regulation of translation; regulation of apoptotic process; and the response to organonitrogen compounds in light of particular drugs and compounds, extrapolated by bioinformatics all linked to the identified protein modifications. Our results confirm and reflect the complex epidemiological situation occurring among Taranto inhabitants and underline the need to further investigate the presence and sources of inferred chemicals in soils. The combination of bioassays and proteomics reveals a more complex scenario of chemicals able to affect cellular pathways and leading to toxicities rather than those identified by only bioassays and related chemical analysis. This combined approach turns out to be a promising tool for soil risk assessment and deserves further investigation and developments for soil monitoring and risk assessment.

Metabolic Syndrome and Endocrine Disrupting Chemicals: An Overview of Exposure and Health Effects

Increasing prevalence of metabolic syndrome (MetS) is causing a significant health burden among the European population. Current knowledge supports the notion that endocrine-disrupting chemicals (EDCs) interfere with human metabolism and hormonal balance, contributing to the conventionally recognized lifestyle-related MetS risk factors. This review aims to identify epidemiological studies focusing on the association between MetS or its individual components (e.g., obesity, insulin resistance, diabetes, dyslipidemia and hypertension) and eight HBM4EU priority substances (bisphenol A (BPA), per- and polyfluoroalkyl substances (PFASs), phthalates, polycyclic aromatic hydrocarbons (PAHs), pesticides and heavy metals (cadmium, arsenic and mercury)). Thus far, human biomonitoring (HBM) studies have presented evidence supporting the role of EDC exposures on the development of individual MetS components. The strength of the association varies between the components and EDCs. Current evidence on metabolic disturbances and EDCs is still limited and heterogeneous, and mainly represent studies from North America and Asia, highlighting the need for well-conducted and harmonized HBM programmes among the European population. Rigorous and ongoing HBM in combination with health monitoring can help to identify the most concerning EDC exposures, to guide future risk assessment and policy actions.

Protracted Impairment of Maternal Metabolic Health in Mouse Dams Following Pregnancy Exposure to a Mixture of Low Dose Endocrine-Disrupting Chemicals, a Pilot Study

Pregnancy, a period of increased metabolic demands coordinated by fluctuating steroid hormones, is an understudied critical window of disease susceptibility for later-life maternal metabolic health. Epidemiological studies have identified associations between exposures to various endocrine-disrupting chemicals (EDCs) with an increased risk for metabolic syndrome, obesity, and diabetes. Whether such adverse outcomes would be heightened by concurrent exposures to multiple EDCs during pregnancy, consistent with the reality that human exposures are to EDC mixtures, was examined in the current pilot study. Mouse dams were orally exposed to relatively low doses of four EDCs: (atrazine (10 mg/kg), bisphenol-A (50 µg/kg), perfluorooctanoic acid (0.1 mg/kg), 2,3,7,8-tetrachlorodibenzo-p-dioxin (0.036 µg/kg)), or the combination (MIX), from gestational day 7 until birth or for an equivalent 12 days in non-pregnant females. Glucose intolerance, serum lipids, weight, and visceral adiposity were assessed six months later. MIX-exposed dams exhibited hyperglycemia with a persistent elevation in blood glucose two hours after glucose administration in a glucose tolerance test, whereas no such effects were observed in MIX-exposed non-pregnant females. Correspondingly, MIX dams showed elevated serum low-density lipoprotein (LDL). There were no statistically significant differences in weight or visceral adipose; MIX dams showed an average visceral adipose volume to body volume ratio of 0.09, while the vehicle dams had an average ratio of 0.07. Collectively, these findings provide biological plausibility for the epidemiological associations observed between EDC exposures during pregnancy and subsequent maternal metabolic dyshomeostasis, and proof of concept data that highlight the importance of considering complex EDC mixtures based of off common health outcomes, e.g., for increased risk for later-life maternal metabolic effects following pregnancy.

A mixture of 15 phthalates and pesticides below individual chemical no observed adverse effect levels (NOAELs) produces reproductive tract malformations in the male rat

Humans carry residues of multiple synthetic chemicals at any given point in time. Research has demonstrated that compounds with varying molecular initiating events (MIE) that disrupt common key events can act in concert to produce cumulative adverse effects. Congenital defects of the male reproductive tract are some of the most frequently diagnosed malformations in humans and chemical exposures in utero can produce these effects in laboratory animals and humans. Here, we hypothesized that in utero exposure to a mixture of pesticides and phthalates, each of which produce male reproductive tract defects individually, would produce cumulative effects even when each chemical is present at a no observed adverse effect level (NOAEL) specific for male reproductive effects. Pregnant Sprague-Dawley rats were exposed via oral gavage to a fixed-ratio dilution mixture of 5 pesticides (vinclozolin, linuron, procymidone, prochloraz, pyrifluquinazon), 1 pesticide metabolite (dichlorodiphenyldichloroethylene (DDE)), and 9 phthalates (dipentyl, dicyclohexyl, di-2-ethylhexyl, dibutyl, benzyl butyl, diisobutyl, diisoheptyl, dihexyl, and diheptyl) during the critical window of rat fetal masculinization (gestation day 14-18). The top dose (100% dose) contained each compound at a concentration 2-fold greater than the individual chemical NOAEL followed by a dilution series that represented each chemical at NOAEL, NOAEL/2, NOAEL/4, NOAEL/8, NOAEL/15, NOAEL/100, NOAEL/1000. Reduced fetal testis gene expression occurred at NOAEL/15, reduced fetal testis testosterone production occurred at NOAEL/8, reduced anogenital distance, increased nipple retention, and delayed puberty occurred at NOAEL/4, and severe effects including genital malformations and weight reductions in numerous reproductive tissues occurred at NOAEL/2. This study demonstrates that these phthalates and pesticides acted cumulatively to produce adverse effects at doses below which any individual chemical had been shown to produce an effect alone and even though they have different MIEs.

Bioavailability for organic chemical bioaccumulation follows the power law

Despite the importance of bioavailability for organic chemical bioaccumulation by terrestrial and benthic invertebrates, the principles of bioavailability for organic chemical bioaccumulation remain poorly understood. Here we use large-scale databases with contrasting geographic, compound and organism coverage (from 925 sites, 446 compounds and 184 invertebrate species), and report that bioavailability for organic chemical bioaccumulation follows the power law. It represents that the internal concentration of organic chemicals is the composite power function of the lipid fraction of invertebrates, bulk site concentration of compounds, and organic carbon content of soils/sediments. This law directly links environmental exposures and body burdens of organic chemicals in contaminated sites, and provides a method for enabling case-specific risk assessments of a vast number of organic chemicals and contaminated sites. Our findings may pave the way for translating bioavailability knowledge into risk-oriented regulation of organic chemicals and contaminated sites.

Recognition and Selectivity Analysis Monitoring of Multicomponent Steroid Estrogen Mixtures in Complex Systems Using a Group-Targeting Environmental Sensor

The same class of steroid estrogen mixtures, coexisting in the environment of 17β-estradiol, estrone (E1), and ethinyl estradiol (EE2), have strong ability to disrupt the human endocrine system and are seriously prejudicial to the health of the organism and environmental safety. Herein, a highly sensitive and group-targeting environmental monitoring sensor was fabricated for a comprehensive analysis of multicomponent steroid estrogens (multi-SEs) in complex systems. This breakthrough was based on the highly sensitive photoelectrochemical response composite material CdSe NPs-TiO₂ nanotube and highly group-specific aptamers. The optimized procedure exhibited not only high sensitivity in a wide range of concentrations from 0.1 to 50 nM, indeed, the minimum detection limit was 33 pM, but also strong resistance to interference. The affinity and consistent action pockets of this sensor enable selective detection of multi-SEs in complex systems. It subsequently was applied for the analysis of multi-SEs from three real samples in the environment including medical wastewater, river water, and tap water to provide a means to clarify the fate of multi-SEs in the process of migration and transformation. This monitoring sensor has a brilliant application prospect for the identification and monitoring of the same class of endocrine-disrupting chemical mixtures in environmental complex systems.

The European Human Biomonitoring Initiative (HBM4EU): Human biomonitoring guidance values (HBM-GVs) for the aprotic solvents N-methyl-2-pyrrolidone (NMP) and N-ethyl-2-pyrrolidone (NEP)

Toxicologically and/or epidemiologically derived guidance values referring to the internal exposure of humans are a prerequisite for an easy to use health-based interpretation of human biomonitoring (HBM) results. The European Joint Programme HBM4EU derives such values, named human biomonitoring guidance values (HBM-GVs), for priority substances which could be of regulatory relevance for policy makers and have been identified by experts of the participating countries, ministries, agencies and stakeholders at EU and national level. NMP and NEP are such substances for which unresolved policy relevant issues should be clarified by targeted research. Since widespread exposure of the general population in Germany to NMP and NEP was shown for the age groups 3–17 years and 20–29 years, further investigations on exposure to NMP and NEP in other European countries are warranted. The HBM-GVs derived for both solvents focus on developmental toxicity as decisive endpoint. They amount for the sum of the two specific urinary NMP metabolites 5-HNMP and 2-HMSI and likewise of the two specific urinary NEP metabolites 5-HNEP and 2-HESI to 10 mg/L for children and 15 mg/L for adolescents/adults. The values were determined following a consultation process on the value proposals within HBM4EU. A health-based risk assessment was performed using the newly derived HBM-GV_GenPop and exposure data from two recent studies from Germany. The risk assessment revealed that even when considering the combined exposure to both substances by applying the Hazard Index approach, the measured concentrations are below the HBM-GV_GenPop in all cases investigated (i.e., children, adolescents and young adults).

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HBM-GVs are a prerequisite for an easy to use health-based risk assessment of human biomonitoring results.

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For NMP and NEP metabolites in urine, respectively, HBM-GVs were set for children and adolescents/adults.

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First HBM exposure data indicate widespread exposure of German children, adolescents and young adults to NMP and NEP.

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The Hazard Index approach revealed that even when combined exposure to both solvents is assessed, HBM-GVs are not exceeded.

β-cyclodextrin-containing polymer based on renewable cellulose resources for effective removal of ionic and non-ionic toxic organic pollutants from water

A novel, bio-derived cyclodextrin-based trifunctional adsorbent has been successfully synthesized for efficient, rapid and simultaneous removal of a broad-spectrum of toxic ionic (anionic and cationic dyes) and non-ionic organic pollutants from water. The composition, morphology and the presence of functional groups in the obtained sorption material were characterized by elemental analysis, XRD, SEM, and FTIR spectroscopy. The adsorption results were represented by cationic dye (crystal violet, CV) and endocrine disrupting compound (bisphenol A, BPA) as an adsorbate. The sorption processes of the model pollutants were studied with both kinetic and equilibrium models. The results showed that the sorption was rapid (less than 1 min) and the time evolution could be fitted using a pseudo-second order model. According to Langmuir isotherm model, the maximum adsorption capacities were found at 113.64 and 43.10 mg g^-1 for BPA and CV, respectively. The adsorption ability of β-CDPs was kept nearly on the same level after five regeneration cycles. Furthermore, almost complete removal of the pollutants was observed during the treatment of real effluents samples thus the bio-derived, cheap and reusable BAN-EPI-CDP has a promising potential for practical applications.

Dosing the Coast: Leaking Sewage Infrastructure Delivers Large Annual Doses and Dynamic Mixtures of Pharmaceuticals to Urban Rivers

Pharmaceuticals are commonly detected at low concentrations in surface waters, where they disrupt biological and ecological processes. Despite their ubiquity, the annual mass of pharmaceuticals exported from watersheds is rarely quantified. We used liquid chromatography-mass spectroscopy to screen for 92 pharmaceuticals in weekly samples from an urban stream network in Baltimore, MD, USA, that lacks wastewater treatment effluents. Across the network, we detected 37 unique compounds, with higher concentrations and more compounds in streams with higher population densities. We also used concentrations and stream discharge to calculate annual pharmaceutical loads at the watershed outlet, which range from less than 1 kg to ∼15 kg and are equivalent to tens of thousands of human doses. By calculating annual watershed mass balances for eight compounds, we show that ∼0.05 to ∼42% of the pharmaceuticals consumed by humans in this watershed are released to surface waters, with the importance of different pathways (leaking sewage vs treated wastewater effluent) differing among compounds. These results demonstrate the importance of developing, maintaining, and improving sewage infrastructure to protect water resources from pharmaceutical contamination.

Short-Term and Long-Term Carcinogenic Effects of Food Contaminants (4-Hydroxynonenal and Pesticides) on Colorectal Human Cells: Involvement of Genotoxic and Non-Genomic Mechanisms

Simple Summary

One’s environment, including diet, play a major role in the occurrence and the development of colorectal cancer (CRC). In this study, we are interested in two western diet associated food contaminants: 4-hydroxynonenal (HNE), a major lipid peroxidation product neoformed during digestion, and a mixture of pesticides to which we are commonly exposed to via fruit and vegetable consumption. The aim of this study was to analyse the impact of acute and long-term exposure to these contaminants, alone or in combination, on colorectal carcinogenesis. We used in vitro models of human colonic cells, either exhibiting or not different genetic susceptibilities to CRC. After acute exposure, we did not observe major alteration. However, long-term exposure to contaminants induce malignant transformation with different cellular mechanisms, depending on genetic susceptibility and contaminants alone or in mixtures.

Abstract

To investigate environmental impacts upon colorectal carcinogenesis (CRC) by diet, we assessed two western diet food contaminants: 4-hydroxynonenal (HNE), a major lipid peroxidation product neoformed during digestion, and a mixture of pesticides. We used human colonic cell lines ectopically eliciting varied genetic susceptibilities to CRC: the non-transformed human epithelial colonic cells (HCECs) and their five isogenic cell lines with the loss of APC (Adenomatous polyposis coli) and TP53 (Tumor protein 53) and/or ectopic expression of mutated KRAS (Kristen-ras). These cell lines have been exposed for either for a short time (2–24 h) or for a long period (3 weeks) to 1 µM HNE and/or 10 µM pesticides. After acute exposure, we did not observe any cytotoxicity or major DNA damage. However, long-term exposure to pesticides alone and in mixture with HNE induced clonogenic transformation in normal HCECs, as well as in cells representing later stages of carcinogenesis. It was associated with genotoxic and non-genomic mechanisms (cell growth, metabolic reprogramming, cell mobility and epithelial-mesenchymal transition) depending on genetic susceptibility. This study demonstrated a potential initiating and promoting effect of food contaminants on CRC after long-term exposure. It supports that these contaminants can accelerate carcinogenesis when mutations in oncogenes or tumor suppressor genes occur.

Optimised ICP-MS quantification method for using animal faeces as a measure of protected area ecosystem health

Pollution is a key threat to biodiversity and ecosystem health within protected areas. Using a non-invasive, multi-matrix approach, sediment, vegetation and faecal material from lion (Panthera leo) and giraffe (Giraffa camelopardalis) were collected and assessed for the simultaneous quantification of 20 trace elements using an optimised method for Inductively Coupled Plasma--Mass Spectrometry (ICP-MS). Method Linearity was confirmed over an analytical range of 0.1-50 mg/kg for aluminium (Al) and iron (Fe); 0.4-400 µg/kg for vanadium (V), cobalt (Co), molybdenum (Mo), and cadmium (Cd); 0.5-5 µg/kg for mercury (Hg); and 1-1 000 µg/kg for elements arsenic (As), boron (B), barium (Ba), chromium (Cr), copper (Cu), manganese (Mn), nickel (Ni), lead (Pb), antimony (Sb), selenium (Se), tin (Sn), strontium (Sr) and zinc (Zn). Coefficient of determination (R²) was above 0.99 for all elements. Accuracy (% recovery) and precision (% RSD) of replicate measurements for certified reference material controls fell within 20% of expected value at lower concentrations and 15% at higher concentrations for all elements except Al. Results for instrument and method limit of detections (LOD), method limit of quantification (LOQ) and expanded uncertainty were satisfactory. Preliminary data indicate As, Cd, Cr, Cu, Hg, Ni, Pb, Se, and Zn were present in all matrices evaluated. This raises concerns regarding the combined action of multiple elements at concentrations that can adversely affect ecosystem and wildlife integrity.•Sample quantity is reduced due to the power and sensitivity of ICP-MS.•The optimised method is capable of detecting differences in trace element concentrations over large orders of magnitude in animal faeces containing different amounts of organic content.•The method can be applied to the quantification of essential and potentially toxic elements in faeces across a wide range of terrestrial species.

Environmental risk assessment and bioaccumulation of pharmaceuticals in a large urbanized estuary

We screened for the presence of 66 different pharmaceutical residues in surface waters and in multiple invertebrate and fish species of the Tejo estuary to produce an environmental risk assessment of individual pharmaceuticals and their mixtures, as well as evaluate the bioaccumulation of pharmaceuticals in one of Europe's largest estuarine systems. Sixteen pharmaceutical residues, from seven therapeutic classes, were detected in estuarine waters, with environmental mixture concentrations ranging from 42 to 1762 ng/L. Environmental risk assessment via the determination of risk quotients, demonstrated high ecological risk for the antibiotic amoxicillin and angiotensin II receptor blockers irbesartan and losartan. Moderate risk was estimated for antidepressants, antiepileptics, anxiolytics and beta-blockers, but the risk quotient of the accumulated mixture of compounds was over 380-fold higher than the no risk threshold, driven by antibiotics and angiotensin II receptor blockers. In biota, higher risk therapeutic groups were found in higher concentrations, with nine pharmaceutical residues detected, including six antibiotics and two neuroactive compounds, and maximum tissue concentrations up to 250 μg/kg. Bioaccumulation was species- and compound-specific, with only two compounds found simultaneously in water and biota, likely a result of the complex dynamics and fate of pharmaceuticals in estuarine waters. Nonetheless, higher detection frequencies were observed in species living directly on or just above the substrate (i.e. benthic and demersal species), underpinning the importance of habitat use, as well the potential role of sediment and diet based routes for pharmaceutical uptake. Ultimately, results support urgent action on managing the impact of pharmaceuticals in coastal environments, striving for improved monitoring schemes tailored to the dynamic nature and ecological diversity of estuaries and coastal ecosystems.

Risk Characterization of Environmental Samples Using In Vitro Bioactivity and Polycyclic Aromatic Hydrocarbon Concentrations Data

Methods to assess environmental exposure to hazardous chemicals have primarily focused on quantification of individual chemicals, although chemicals often occur in mixtures, presenting challenges to the traditional risk characterization framework. Sampling sites in a defined geographic region provide an opportunity to characterize chemical contaminants, with spatial interpolation as a tool to provide estimates for non-sampled sites. At the same time, the use of in vitro bioactivity measurements has been shown to be informative for rapid risk-based decisions. In this study, we measured in vitro bioactivity in 39 surface soil samples collected immediately after flooding associated with Hurricane Harvey in Texas in a residential area known to be inundated with polycyclic aromatic hydrocarbon (PAH) contaminants. Bioactivity data were from a number of functional and toxicity assays in 5 human cell types, such as induced pluripotent stem cell-derived hepatocytes, cardiomyocytes, neurons, and endothelial cells, as well as human umbilical vein endothelial cells. Data on concentrations of PAH in these samples were also available and the combination of data sources offered a unique opportunity to assess the joint spatial variation of PAH components and bioactivity. We found significant evidence of spatial correlation of a subset of PAH contaminants and of cell-based phenotypes. In addition, we show that the cell-based bioactivity data can be used to predict environmental concentrations for several PAH contaminants, as well as overall PAH summaries and cancer risk. This study's impact lies in its demonstration that cell-based profiling can be used for rapid hazard screening of environmental samples by anchoring the bioassays to concentrations of PAH. This work sets the stage for identification of the areas of concern and direct quantitative risk characterization based on bioactivity data, thereby providing an important supplement to traditional individual chemical analyses by shedding light on constituents that may be missed from targeted chemical monitoring.

Long-Range Transport, Trophic Transfer, and Ecological Risks of Organophosphate Esters in Remote Areas

Organophosphate esters (OPEs) have been a focus in the field of environmental science due to their large volume production, wide range of applications, ubiquitous occurrence, potential bioaccumulation, and worrisome ecological and health risks. Varied physicochemical properties among OPE analogues represent an outstanding scientific challenge in studying the environmental fate of OPEs in recent years. There is an increasing number of studies focusing on the long-range transport, trophic transfer, and ecological risks of OPEs. Therefore, it is necessary to conclude the OPE pollution status on a global scale, especially in the remote areas with vulnerable and fragile ecosystems. The present review links together the source, fate, and environmental behavior of OPEs in remote areas, integrates the occurrence and profile data, summarizes their bioaccumulation, trophic transfer, and ecological risks, and finally points out the predominant pollution burden of OPEs among organic pollutants in remote areas. Given the relatively high contamination level and bioaccumulation/biomagnification behavior of OPEs, in combination with the sensitivity of endemic species in remote areas, more attention should be paid to the potential ecological risks of OPEs.

Commentary: Novel strategies and new tools to curtail the health effects of pesticides

BACKGROUND

Flaws in the science supporting pesticide risk assessment and regulation stand in the way of progress in mitigating the human health impacts of pesticides. Critical problems include the scope of regulatory testing protocols, the near-total focus on pure active ingredients rather than formulated products, lack of publicly accessible information on co-formulants, excessive reliance on industry-supported studies coupled with reticence to incorporate published results in the risk assessment process, and failure to take advantage of new scientific opportunities and advances, e.g. biomonitoring and "omics" technologies.

RECOMMENDED ACTIONS

Problems in pesticide risk assessment are identified and linked to study design, data, and methodological shortcomings. Steps and strategies are presented that have potential to deepen scientific knowledge of pesticide toxicity, exposures, and risks. We propose four solutions: (1) End near-sole reliance in regulatory decision-making on industry-supported studies by supporting and relying more heavily on independent science, especially for core toxicology studies. The cost of conducting core toxicology studies at labs not affiliated with or funded directly by pesticide registrants should be covered via fees paid by manufacturers to public agencies. (2) Regulators should place more weight on mechanistic data and low-dose studies within the range of contemporary exposures. (3) Regulators, public health agencies, and funders should increase the share of exposure-assessment resources that produce direct measures of concentrations in bodily fluids and tissues. Human biomonitoring is vital in order to quickly identify rising exposures among vulnerable populations including applicators, pregnant women, and children. (4) Scientific tools across disciplines can accelerate progress in risk assessments if integrated more effectively. New genetic and metabolomic markers of adverse health impacts and heritable epigenetic impacts are emerging and should be included more routinely in risk assessment to effectively prevent disease.

CONCLUSIONS

Preventing adverse public health outcomes triggered or made worse by exposure to pesticides will require changes in policy and risk assessment procedures, more science free of industry influence, and innovative strategies that blend traditional methods with new tools and mechanistic insights.

The challenge of micropollutants in surface water of the Yangtze River

The Yangtze River, the third largest river and supporting nearly one-third of Chinese population, has been severely polluted in recent decades. Among the numerous pollutants, organic micropollutants, as one kind of important emerging contaminants, are currently key contaminants of concern. However, few studies have focused on their mixture environmental impacts, especially for the complex environmental mixtures. In the current study, four categories of organic micropollutants, including 16 polycyclic aromatic hydrocarbons (PAHs), 32 polychlorinated biphenyls (PCBs), 27 organochlorine pesticides (OCPs) and 20 pharmaceutical and personal care products (PPCPs) are analyzed in 10 study sites on the Yangtze River. Subsequently, comprehensive risk assessment for micropollutant mixtures was conducted by risk quotient based on the sum of PEC/PNEC values (RQ_MEC/PNEC) and risk quotient based on the toxic units (RQ_STU). The mixture risk evaluation based on the detected environmental concentrations indicates that micropollutant mixtures in surface water of the Yangtze River exhibited relative high risks for aquatic organisms. The observed results revealed that mixture risk assessments have to consider the complexity of environmental samples; PCBs dominated main mixture risks in the upper stream; PAHs contributed major comprehensive risks in the middle stream; and OCPs were the key micropollutants in the downstream. The outcomes of the present study here can serve for pollution control in the Yangtze River, which provide the scientific underpinnings and regulatory reference for risk management and river protection.

Novel polar AhR-active chemicals detected in sediments of an industrial area using effect-directed analysis based on in vitro bioassays with full-scan high resolution mass spectrometric screening

Studies investigating aryl hydrocarbon receptor (AhR)-active compounds in the environment typically focus on non- and mid-polar substances, such as PAHs; while, information on polar AhR agonists remains limited. Here, we identified polar AhR agonists in sediments collected from the inland creeks of an industrialized area (Lake Sihwa, Korea) using effect-directed analysis combined with full-scan screening analysis (FSA; using LC-QTOFMS). Strong AhR-mediated potencies were observed for the polar and latter fractions of RP-HPLC (F3.5-F3.8) from sediment organic extracts in the H4IIE-luc in vitro bioassays. FSA was performed on the corresponding fractions. Twenty-eight tentative AhR agonists were chosen using a five-step process. Toxicological confirmation using bioassay revealed that canrenone, rutaecarpine, ciprofloxacin, mepanipyrim, genistein, protopine, hydrocortisone, and medroxyprogesterone were significantly active. The relative potencies of these AhR-active compounds compared to that of benzo[a]pyrene ranged from 0.00002 to 2.0. Potency balance analysis showed that polar AhR agonists explained, on average, ~6% of total AhR-mediated potencies in samples. Some novel polar AhR agonists also exhibited endocrine-disrupting potentials capable of binding to estrogen and glucocorticoid receptors, as identified by QSAR modeling. In conclusion, the focused studies on distributions, sources, fate, and ecotoxicological effects of novel polar AhR agonists in the environment are necessary.

Exposure to a low concentration of mixed organochlorine pesticides impairs glucose metabolism and mitochondrial function in L6 myotubes and zebrafish

More realistic effects on glucose metabolic dysfunction can be evaluated by applying organochlorine (OCP) mixtures than individual OCPs. We formulated an equal ratio mixture of five OCPs (chlordane, heptachlor, p,p'-dichlorodiphenyltrichloroethane, β-hexachlorocyclohexane, and hexachlorobenzene) and treated L6 myotubes with this OCP mixture to investigate effects on glucose uptake and the underlying mechanism. Exposure to the OCP mixture reduced 2-NBDG staining, representing glucose uptake, and stimulated the excessive production of reactive oxygen species (ROS). Reduced 2-NBDG uptake and ROS overproduction were compensated by insulin treatment. The expression of proteins such as IRβ, PI3K, and AKT was downregulated, indicating that ROS overproduction contributed to the inhibition of insulin-dependent glucose uptake. Reduction in mitochondria quantity and decreased expression levels of PGC-1α, PDH, and GLUT4 proteins were observed, suggesting that mitochondrial dysfunction played a causative role in the disruption of glucose uptake. The inhibition of glucose uptake and ROS overproduction caused by the OCP mixture were also found in zebrafish as an in vivo model. We demonstrated that exposure to the OCP mixture, even at the lowest concentration, perturbed glucose uptake, which was associated with mitochondrial dysfunction, suggesting that an OCP mixture could be a potential environmental factor in type 2 diabetes-related effects on skeletal muscles.

Parental preconception exposure to phenol and phthalate mixtures and the risk of preterm birth

BACKGROUND

Parental preconception exposure to select phenols and phthalates was previously associated with increased risk of preterm birth in single chemical analyses. However, the joint effect of phenol and phthalate mixtures on preterm birth is unknown.

METHODS

We included 384 female and 211 male (203 couples) participants seeking infertility treatment in the Environment and Reproductive Health (EARTH) Study who gave birth to 384 singleton infants between 2005 and 2018. Mean preconception urinary concentrations of bisphenol A (BPA), parabens, and eleven phthalate biomarkers, including di(2-ethylhexyl) phthalate (DEHP) metabolites, were examined. We used principal component analysis (PCA) with log-Poisson regression and Probit Bayesian Kernel Machine Regression (BKMR) with hierarchical variable selection to examine maternal and paternal phenol and phthalate mixtures in relation to preterm birth. Couple-based BKMR model was fit to assess couples' joint mixtures in relation to preterm birth.

RESULTS

PCA identified the same four factors for maternal and paternal preconception mixtures. Each unit increase in PCA scores of maternal (adjusted Risk Ratio (aRR): 1.36, 95%CI: 1.00, 1.84) and paternal (aRR: 1.47, 95%CI: 0.90, 2.42) preconception DEHP-BPA factor was positively associated with preterm birth. Maternal and paternal BKMR models consistently presented the DEHP-BPA factor with the highest group Posterior Inclusion Probability (PIP). BKMR models further showed that maternal preconception BPA and mono(2-ethyl-5-hydroxyhexyl) phthalate, and paternal preconception mono(2-ethylhexyl) phthalate were positively associated with preterm birth when the remaining mixture components were held at their median concentrations. Couple-based BKMR models showed a similar relative contribution of paternal (PIP: 61%) and maternal (PIP: 77%) preconception mixtures on preterm birth. We found a positive joint effect on preterm birth across increasing quantiles of couples' total mixture concentrations.

CONCLUSION

In this prospective cohort of subfertile couples, maternal BPA and DEHP, and paternal DEHP exposure before conception were positively associated with preterm birth. Both parental windows jointly contributed to the outcome. These results suggest that preterm birth may be a couple-based pregnancy outcome.

Differential mitochondrial dysregulation by exposure to individual organochlorine pesticides (OCPs) and their mixture in zebrafish embryos

Organochlorine pesticides (OCPs) have been reported to cause mitochondrial dysfunction. However, most studies reported its mitochondrial toxicity with respect to a single form, which is far from the environmentally relevant conditions. In this study, we exposed zebrafish embryos to five OCPs: chlordane, heptachlor, p,p'-dichlorodiphenyltrichloroethane (p,p'-DDT), β-hexachlorocyclohexane (β-HCH), and hexachlorobenzene (HCB), as well as an equal ratio mixture of these OCPs. We evaluated mitochondrial function, including oxygen consumption, the activity of mitochondrial complexes, antioxidant reactions, and expression of genes involved in mitochondrial metabolism. Oxygen consumption rate was reduced by exposure to chlordane, and β-HCH, linking to the increased activity of specific mitochondrial complex I and III, and decreased GSH level. We found that these mitochondrial dysfunctions were more significant in the exposure to the OCP mixture than the individual OCPs. On the mRNA transcription level, the individual OCPs mainly dysregulated the metabolic cycle (i.e., cs and acadm), whereas the OCP mixture disrupted the genes related to mitochondrial oxidative phosphorylation (i.e., sdha). Consequently, we demonstrate that the OCP mixture disrupts mitochondrial metabolism by a different molecular mechanism than the individual OCPs, which warrants further study to evaluate mitochondrial dysregulation by chronic exposure to the OCP mixture.

Profile of exposures and lung function in adults with asthma: An exposome approach in the EGEA study

BACKGROUND

Environmental research on multifactorial health outcomes calls for exposome approaches able to assess the joint effect of multiple exposures.

OBJECTIVE

Our aim was to identify profiles of exposure to lifestyle/environmental factors associated with lung function in adults with asthma using a cluster-based approach.

METHODS

We used data from 599 adults of the Epidemiological study on the Genetics and Environment of Asthma, bronchial hyperresponsiveness and atopy (EGEA) (mean age 39.0 years, 52% men) who ever had asthma. Exposures to 53 lifestyle/environmental factors were assessed by questionnaires or geographic information systems-based models. A two-step approach was developed: 1) exposome dimension reduction by selecting factors showing association with forced expiratory volume in 1 s (FEV₁) (p < 0.20) in an exposome-wide association study (ExWAS), 2) clustering analysis using the supervised Bayesian Profile Regression (sBPR) to group individuals according to FEV₁ level and to their profile of exposure to a reduced set of uncorrelated exposures (each paired correlation<0.70) identified in step 1.

RESULTS

The ExWAS identified 21 factors showing suggestive association with FEV₁ (none significant when controlling for multiple tests). The sBPR conducted on 15 uncorrelated exposures identified in step 1, revealed 3 clusters composed of 30, 115 and 454 individuals with a mean ± SD FEV₁(%pred) of 79% ± 21, 90% ± 19 and 93% ± 16, respectively. Cluster 1 was composed of individuals with heavy smoking, poor diet, higher outdoor humidity and proximity to traffic, while cluster 2 and 3 included individuals with moderate/low levels of exposure to these factors.

DISCUSSION

This exposome study identified a specific profile of joint lifestyle and environmental factors, associated with a low FEV₁ in adults with asthma. None of the exposures revealed significant association when considered independently.

Chemical Mixture Calculator - A novel tool for mixture risk assessment

Humans are continuously exposed to complex chemical mixtures from foods and the environment. Experimental models in vivo and in vitro have increased our knowledge on how we can predict mixture effects. To accommodate a need for tools for efficient mixture risk assessment across different chemical classes and exposure sources, we have developed fit-for-purpose criteria for grouping of chemicals and a web-based tool for mixture risk assessment. The Chemical Mixture Calculator (available at www.chemicalmixturecalculator.dk) can be used for mixture risk assessment or identification of main drivers of risk. The underlying database includes hazard and exposure estimates for more than 200 chemicals in foods and environment. We present a range of cumulative assessment groups for effects on haematological system, kidney, liver, nervous system, developmental and reproductive system, and thyroid. These cumulative assessment groups are useful for grouping of chemicals at several levels of refinement depending on the question addressed. We present a mixture risk assessment case for phthalates, evaluated with and without contributions from other chemicals with similar effects. This case study shows the usefulness of the tool as a starting point for mixture risk assessment by the risk assessor, and emphasizes that solid scientific insight regarding underlying assumptions and uncertainties is crucial for result interpretation.

Joint toxicity of imidacloprid and azoxystrobin to Chironomus dilutus at organism, cell, and gene levels

Pesticides occur in the environment as mixtures, yet the joint toxicity of pesticide mixtures remains largely under-explored and is usually overlooked in ecological risk assessment. In the current study, joint toxicity of a neonicotinoid insecticide (imidacloprid, IMI) and a strobilurin fungicide (azoxystrobin, AZO) was investigated with Chironomus dilutus over a wide range of concentrations and at different effect levels (organism, cell, and gene levels). The two pesticides, both individually and in combination, were found to induce oxidative stress and cause lethality in C. dilutus. Median lethal concentrations for IMI and AZO were 3.98 ± 1.17 and 52.9 ± 1.1 μg/L, respectively. Mixtures of the two pesticides presented synergetic effects at environmentally relevant concentrations whilst antagonistic effects at high concentrations, showing concentration-dependent joint toxicity. Investigation on the expressions of 12 genes (cyt b, coi, cox1, cyp4, cyp12m1, cyp9au1, cyp6fv1, cyp315, gst, Zn/Cu-sod, Mn-sod, and cat) revealed that the two pesticides impaired mitochondrial respiration, detoxification, and antioxidant system of C. dilutus, and the joint effects of the two pesticides were likely due to an interplay between their respective influences on these physiological processes. Collectively, the synergistic effects of the two pesticides at environmentally relevant concentrations highlight the importance to incorporate combined toxicity studies into ecological risk assessment of pesticides.

Tackling the toxics in plastics packaging

The widespread use of plastic packaging for storing, transporting, and conveniently preparing or serving foodstuffs is significantly contributing to the global plastic pollution crisis. This has led to many efforts directed toward amending plastic packaging’s end of life, such as recycling, or alternative material approaches, like increasingly using paper for food packaging. But these approaches often neglect the critical issue of chemical migration: When contacting foodstuffs, chemicals that are present in packaging transfer into food and thus unwittingly become part of the human diet. Hazardous chemicals, such as endocrine disrupters, carcinogens, or substances that bioaccumulate, are collectively referred to as “chemicals of concern.” They can transfer from plastic packaging into food, together with other unknown or toxicologically uncharacterized chemicals. This chemical transfer is scientifically undisputed and makes plastic packaging a known, and avoidable, source of human exposure to synthetic, hazardous, and untested chemicals. Here, I discuss this issue and highlight aspects in need of improvement, namely the way that chemicals present in food packaging are assessed for toxicity. Further, I provide an outlook on how chemical contamination from food packaging could be addressed in the future. Robust innovations must attempt systemic change and tackle the issue of plastic pollution and chemical migration in a way that integrates all existing knowledge.

The widespread use of plastic packaging for storing, transporting, and conveniently preparing or serving foodstuffs is significantly contributing to the global plastic pollution crisis. This Essay exhorts us to change the conversation about plastic packaging and address the chemicals that migrate into food.

Imidacloprid dominates the combined toxicities of neonicotinoid mixtures to stream mayfly nymphs

Contamination of the environment with toxic chemicals such as pesticides has become a global problem. Understanding the role of chemical contaminants as stressors in ecological systems is therefore an important research need in the 21st century. In surface freshwaters, mixtures of neonicotinoid insecticides are being detected around the world as more monitoring data become available. Combinations of imidacloprid, clothianidin and thiamethoxam are commonly found, but studies testing their combined toxicities to freshwater invertebrates are rare. Taking a multiple-stressor approach, we employed a full-factorial design to investigate the individual and combined chronic toxicities of these three neonicotinoids in a 28-day laboratory experiment using Deleatidium spp. mayfly nymphs. Imidacloprid (1.2 μg/L achieved concentration) reduced mayfly survival (by 50% on Day 28) and mobility (~100%) more than clothianidin (1.1 μg/L, affecting about 25% of individuals across the responses measured) and thiamethoxam (2.9 μg/L, affecting 12%). Imidacloprid interacted with the other two neonicotinoids to cause a greater-than-additive negative effect when combined until 25 days of exposure, after which the strong negative overall effects of imidacloprid prevented these interactions from being observed. Our findings represent a novel contribution to multiple-stressor research by demonstrating the combined effects of chronic exposure to environmentally relevant neonicotinoid concentrations on an ecologically important stream insect taxon. These results emphasise the higher toxicity of imidacloprid to non-target freshwater insects compared to clothianidin and thiamethoxam, implying that stricter regulation to control the use of imidacloprid may need to be prioritised to protect vulnerable aquatic insect populations that provide key links to terrestrial food webs. Finally, our study provides an ecological, multiple-stressor comparison for related ecotoxicological investigations indicating neonicotinoid mixtures can deviate from additive toxicity.

Moving from Protection to Prosperity: Evolving the U.S. Environmental Protection Agency for the next 50 years

The people of the United States and the world owe the United States Environmental Protection Agency (U.S. EPA) a debt of gratitude for preserving, protecting, and defending human health and the environment for the past half century. As we celebrate the 50th anniversary of the founding of the U.S. EPA, there are two truths about the agency that are difficult to deny: (1) U.S. EPA and its people constitute a renowned agency that has greatly improved both environmental and public health in the United States, and has served as the leading model for nations around the world; and (2) the approaches, tools, structures, and legal frameworks that created the achievements of the U.S. EPA must evolve-and grow-to deal with the issues facing the country and the planet in the next 50 years. Building on the creativity, innovation, and brilliance of individuals and groups working at the U.S. EPA over the course of the last half century, we present 10 recommendations organized in three areas: organization, paradigms, and strategies and tools. Underlying these recommendations are the frameworks of sustainability and systems thinking and guiding these recommendations is the goal of evolving the Environmental Protection Agency to the Environmental Prosperity Agency.

Investigation on Combined Inhalation Exposure Scenarios to Biocidal Mixtures: Biocidal and Household Chemical Products in South Korea

Global regulations of biocides have been continuously enhanced for protecting human health and the environment from potentially harmful biocidal products. Such regulations consider the combined toxicity caused by mixture components in a biocidal product of which approval and authorization are to be enhanced. Although the combined exposure scenarios of components in mixtures are firstly needed to conduct the mixture risk assessment, systematic combined exposure scenarios are still lacking. In this study, combined inhalation exposure scenarios of biocides in household chemical and biocidal products marketed in South Korea were investigated based on the European Union (EU) and Korean chemical product databases and various data sources integration. The information of 1058 biocidal products and 675 household chemical products that are likely to cause inhalation exposure with two or more biocides was collected, and mixture combination patterns were investigated. Binary mixtures occupied 72% in biocidal products. The most frequently appearing binary mixture was phthalthrin and d-phenothrin. Based on the frequency of use, we suggested a priority list of biocide mixture combinations which need to be firstly evaluated for identifying their combined toxicity for the mixture risk assessment. This study highlights that the derived combined inhalation exposure scenarios can support and facilitate further studies on priority settings for mixture risk assessment and management of potentially inhalable biocides.

Comprehensive supramolecular solvent-based sample treatment platform for evaluation of combined exposure to mixtures of bisphenols and derivatives by liquid chromatography-tandem mass spectrometry

The growing demand for a better understanding of the effects of chemical mixtures on human health has fostered the need for extensive estimation of uptake rates from identified sources and/or biomonitoring, which has encouraged the development of analyte- and matrix-independent analytical methods. In this paper, we report a comprehensive sample treatment platform for the efficient extraction and interference removal in the determination of twenty-one bisphenols and derivatives (log K_ow from 1.254 to 6.564) in a variety of human exposure sources and biological fluids. Treatment of both liquid (canned beverages, urine and serum) and solid (canned food, dust) samples was based on the use of low volumes (190-200 μL) of a hexanol-based supramolecular solvent having properties of restricted access materials. The efficient extraction of bisphenol and derivatives (absolute recoveries 70-114%) was due to the mixed-mode mechanisms (hydrogen bonding, polar and dispersion interactions) and the huge number of binding sites offered by the supramolecular solvent with properties of restricted access materials for solute solubilization. Signal suppression or enhancement (SSE) values kept in the range 78-116% for samples encompassing a wide range of macromolecules content (e.g. protein, fat, carbohydrates, etc.). Quantification was carried out by liquid chromatography, electrospray tandem mass spectrometry using external calibration. Method quantitation limits for bisphenols in liquid and solid samples were in the interval 0.019-0.19 μg L^-1 and 0.06-0.81 μg kg^-1. The method was applied to the determination of bisphenols and derivatives in thirteen human exposure sources and biological fluids. Only four bisphenols out of twenty-one were not found in the analyzed samples. This supramolecular solvent-based bisphenol- and matrix-independent method constitutes a valuable strategy in terms of analytical and operational characteristics for the assessment of human exposure to mixtures of bisphenols and derivatives.

Assessment of chemical mixtures using biomarkers of combined biological activity: A screening study in human placentas

Humans are simultaneously exposed to complex mixtures of chemicals with limited knowledge on potential health effects, therefore improved tools for assessing these mixtures are needed. As part of the Human Biomonitoring for Europe (HBM4EU) Project, we aimed to examine the combined biological activity of chemical mixtures extracted from human placentas using one in vivo and four in vitro bioassays, also known as biomarkers of combined effect. Relevant endocrine activities (proliferative and/or reporter gene assays) and four endpoints were tested: the estrogen receptor (ER), androgen receptor (AR), and aryl hydrocarbon receptor (AhR) activities, as well as thyroid hormone (TH) signaling. Correlations among bioassays and their functional shapes were evaluated. Results showed that all placental extracts agonized or antagonized at least three of the abovementioned endpoints. Most placentas induced ER-mediated transactivation and ER-dependent cell proliferation, together with a strong inhibition of TH signaling and the AR transactivity; while the induction of the AhR was found in only one placental extract. The effects in the two estrogenic bioassays were positively and significantly correlated and the AR-antagonism activity showed a positive borderline-significant correlation with both estrogenic bioassay activities. However, the in vivo anti-thyroid activities of placental extracts were not correlated with any of the tested in vitro assays. Findings highlight the importance of comprehensively mapping the biological effects of "real-world" chemical mixtures present in human samples, through a battery of in vitro and in vivo bioassays. This approach should be a complementary tool for epidemiological studies to further elucidate the combined biological fingerprint triggered by chemical mixtures.

Risk Characterization and Probabilistic Concentration-Response Modeling of Complex Environmental Mixtures Using New Approach Methodologies (NAMs) Data from Organotypic in Vitro Human Stem Cell Assays

BACKGROUND

Risk assessment of chemical mixtures or complex substances remains a major methodological challenge due to lack of available hazard or exposure data. Therefore, risk assessors usually infer hazard or risk from data on the subset of constituents with available toxicity values.

OBJECTIVES

We evaluated the validity of the widely used traditional mixtures risk assessment paradigms, Independent Action (IA) and Concentration Addition (CA), with new approach methodologies (NAMs) data from human cell-based in vitro assays.

METHODS

A diverse set of 42 chemicals was tested both individually and as mixtures for functional and cytotoxic effects in vitro. A panel of induced pluripotent stem cell (iPSCs)-derived models (hepatocytes, cardiomyocytes, endothelial, and neurons) and one primary cell type (HUVEC) were used. Bayesian concentration-response modeling of individual chemicals or their mixtures was performed for a total of 47 phenotypes to derive point-of-departure (POD) values. Probabilistic IA or CA was conducted to estimate the mixture effects based on the bioactivity profiles from the individual chemicals and compared with mixture bioactivity.

RESULTS

All mixtures showed significant bioactivity, even though some were constructed using individual chemical concentrations considered "low" or "safe." Even though CA is much more accurate as a predictor of mixture effects in comparison with IA, with CA-based POD typically within an order of magnitude of the actual mixture, in some cases, the bioactivity of the mixtures appeared to be much greater than that of their components under either additivity assumption.

DISCUSSION

These results suggest that CA is a preferred first approximation for predicting mixture toxicity when data for all constituents are available. However, because the accuracy of additivity assumptions varies greatly across phenotypes, we posit that mixtures and complex substances need to be directly tested for their hazard potential. NAMs provide a practical solution that rapidly yields highly informative data for mixtures risk assessment. https://doi.org/10.1289/EHP7600.

Ten years of research on synergisms and antagonisms in chemical mixtures: A systematic review and quantitative reappraisal of mixture studies

BACKGROUND

Several reviews of synergisms and antagonisms in chemical mixtures have concluded that synergisms are relatively rare. However, these reviews focused on mixtures composed of specific groups of chemicals, such as pesticides or metals and on toxicity endpoints mostly relevant to ecotoxicology. Doubts remain whether these findings can be generalised. A systematic review not restricted to specific chemical mixtures and including mammalian and human toxicity endpoints is missing.

OBJECTIVES

We conducted a systematic review and quantitative reappraisal of 10 years' of experimental mixture studies to investigate the frequency and reliability of evaluations of mixture effects as synergistic or antagonistic. Unlike previous reviews, we did not limit our efforts to certain groups of chemicals or specific toxicity outcomes and covered mixture studies relevant to ecotoxicology and human/mammalian toxicology published between 2007 and 2017.

DATA SOURCES, ELIGIBILITY CRITERIA

We undertook searches for peer-reviewed articles in PubMed, Web of Science, Scopus, GreenFile, ScienceDirect and Toxline and included studies of controlled exposures of environmental chemical pollutants, defined as unintentional exposures leading to unintended effects. Studies with viruses, prions or therapeutic agents were excluded, as were records with missing details on chemicals' identities, toxicities, doses, or concentrations.

STUDY APPRAISAL AND SYNTHESIS METHODS

To examine the internal validity of studies we developed a risk-of-bias tool tailored to mixture toxicology. For a subset of 388 entries that claimed synergisms or antagonisms, we conducted a quantitative reappraisal of authors' evaluations by deriving ratios of predicted and observed effective mixture doses (concentrations).

RESULTS

Our searches produced an inventory of 1220 mixture experiments which we subjected to subgroup analyses. Approximately two thirds of studies did not incorporate more than 2 components. Most experiments relied on low-cost assays with readily quantifiable endpoints. Important toxicity outcomes of relevance for human risk assessment (e.g. carcinogenicity, genotoxicity, reproductive toxicity, immunotoxicity, neurotoxicity) were rarely addressed. The proportion of studies that declared additivity, synergism or antagonisms was approximately equal (one quarter each); the remaining quarter arrived at different evaluations. About half of the 1220 entries were rated as "definitely" or "probably" low risk of bias. Strikingly, relatively few claims of synergistic or antagonistic effects stood up to scrutiny in terms of deviations from expected additivity that exceed the boundaries of acceptable between-study variability. In most cases, the observed mixture doses were not more than two-fold higher or lower than the predicted additive doses. Twenty percent of the entries (N = 78) reported synergisms in excess of that degree of deviation. Our efforts of pinpointing specific factors that predispose to synergistic interactions confirmed previous concerns about the synergistic potential of combinations of triazine, azole and pyrethroid pesticides at environmentally relevant doses. New evidence of synergisms with endocrine disrupting chemicals and metal compounds such as chromium (VI) and nickel in combination with cadmium has emerged.

CONCLUSIONS, LIMITATIONS AND IMPLICATIONS

These specific cases of synergisms apart, our results confirm the utility of default application of the dose (concentration) addition concept for predictive assessments of simultaneous exposures to multiple chemicals. However, this strategy must be complemented by an awareness of the synergistic potential of specific classes of chemicals. Our conclusions only apply to the chemical space captured in published mixture studies which is biased towards relatively well-researched chemicals.

SYSTEMATIC REVIEW REGISTRATION NUMBER

The final protocol was published on the open-access repository Zenodo and attributed the following digital object identifier, doi: https://doi.org//10.5281/zenodo.1319759 (https://zenodo.org/record/1319759#.XXIzdy7dsqM).

A two-step gas chromatography-tandem mass spectrometry method for measurement of multiple environmental pollutants in human plasma

Individuals are exposed to a wide variety of chemicals over their lifetime, yet current understanding of mixture toxicology is still limited. We present a two-step analytical method using a gas chromatograph-triple quadrupole mass spectrometer that requires less than 1 mL of sample. The method is applied to 183 plasma samples from a study population of children with autism spectrum disorder, their parents, and unrelated neurotypical children. We selected 156 environmental chemical compounds and ruled out chemicals with detection rates less than 20% of our study cohort (n = 61), as well as ones not amenable to the selected extraction and analytical methods (n = 34). The targeted method then focused on remaining chemicals (n = 61) plus 8 additional polychlorinated biphenyls (PCBs). Persistent pollutants, such as p,p'-dichlorodiphenyldichloroethylene (p,p'-DDE) and PCB congeners 118 and 180, were detected at high frequencies and several previously unreported chemicals, including 2,4,6-trichlorophenol, isosafrole, and hexachlorobutadiene, were frequently detected in our study cohort. This work highlights the benefits of employing a multi-step analytical method in exposure studies and demonstrates the efficacy of such methods for reporting novel information on previously unstudied pollutant exposures.

Exploring the Concepts of Concentration Addition and Independent Action Using a Linear Low-Effect Mixture Model

Chemicals emitted into the environment are typically present at low concentrations but may act together in mixtures. Concentration-response curves of in vitro bioassays were often linear for effect levels <30%, and the predictions for concentration addition (CA) of similarly acting chemicals and for independent action (IA) of dissimilarly acting chemicals overlapped. We derived a joint CA/IA mixture model for the low-effect level portion of concentration-response curves. In a first case study, we evaluated the cytotoxicity of over 200 mixtures of up to 17 components that were mixed in concentration ratios as they occurred in river water. The predictions of the full IA model were indistinguishable from the predictions of the full CA model up to 10% effect, confirming the applicability of the joint CA/IA mixture model at low effect levels. In a second case study, we evaluated if environmental concentrations trigger effects at levels low enough for the joint CA/IA mixture model to apply. The detected concentrations were scaled by their toxic potencies to estimate the mixture effect of the detected chemicals in a complex mixture. In 86% of 156 samples the effects fell in the validity range of the joint CA/IA mixture model (<10% effect level), confirming the CA assumption for toxic unit summation. The joint CA/IA mixture model is not suitable for testing specific mixture hypotheses and interactions of chemicals in mixtures, where more refined models are required; but it is helpful for the interpretation of effects of complex (multicomponent) environmental mixtures, especially for water samples with relatively low effect level. Environ Toxicol Chem 2020;39:2552-2559. © 2020 The Authors. Environmental Toxicology and Chemistry published by Wiley Periodicals LLC on behalf of SETAC.

A chemical, microbiological and (eco)toxicological scheme to understand the efficiency of UV-C/H2O2 oxidation on antibiotic-related microcontaminants in treated urban wastewater

An assessment comprising chemical, microbiological and (eco)toxicological parameters of antibiotic-related microcontaminants, during the application of UV-C/H₂O₂ oxidation in secondary-treated urban wastewater, is presented. The process was investigated at bench scale under different oxidant doses (0-50 mg L^-1) with regard to its capacity to degrade a mixture of antibiotics (i.e. ampicillin, clarithromycin, erythromycin, ofloxacin, sulfamethoxazole, tetracycline and trimethoprim) with an initial individual concentration of 100 μg L^-1. The process was optimized with respect to the oxidant dose. Under the optimum conditions, the inactivation of selected bacteria and antibiotic resistant bacteria (ARB) (i.e. faecal coliforms, Enterococcus spp., Pseudomonasaeruginosa and total heterotrophs), and the reduction of the abundance of selected antibiotic resistance genes (ARGs) (e.g. bla_OXA, qnrS, sul1, tetM) were investigated. Also, phytotoxicity against three plant species, ecotoxicity against Daphnia magna, genotoxicity, oxidative stress and cytotoxicity were assessed. Apart from chemical actinometry, computational fluid dynamics (CFD) modelling was applied to estimate the fluence rate. For the given wastewater quality and photoreactor type used, 40 mg L^-1 H₂O₂ were required for the complete degradation of the studied antibiotics after 18.9 J cm^-2. Total bacteria and ARB inactivation was observed at UV doses <1.5 J cm^-2 with no bacterial regrowth being observed after 24 h. The abundance of most ARGs was reduced at 16 J cm^-2. The process produced a final effluent with lower phytotoxicity compared to the untreated wastewater. The toxicity against Daphnia magna was shown to increase during the chemical oxidation. Although genotoxicity and oxidative stress fluctuated during the treatment, the latter led to the removal of these effects. Overall, it was made apparent from the high UV fluence required, that the particular reactor although extensively used in similar studies, it does not utilize efficiently the incident radiation and thus, seems not to be suitable for this kind of studies.

In Silico Assessment of Acute Oral Toxicity for Mixtures

While exposure of humans to environmental hazards often occurs with complex chemical mixtures, the majority of existing toxicity data are for single compounds. The Globally Harmonized System of chemical classification (GHS) developed by the Organization for Economic Cooperation and Development uses the additivity formula for acute oral toxicity classification of mixtures, which is based on the acute toxicity estimate of individual ingredients. We evaluated the prediction of GHS category classifications for mixtures using toxicological data collected in the Integrated Chemical Environment (ICE) developed by the National Toxicology Program (United States Department of Health and Human Services). The ICE database contains in vivo acute oral toxicity data for ∼10,000 chemicals and for 582 mixtures with one or multiple active ingredients. By using the available experimental data for individual ingredients, we were able to calculate a GHS category for only half of the mixtures. To expand a set of components with acute oral toxicity data, we used the Collaborative Acute Toxicity Modeling Suite (CATMoS) implemented in the Open Structure-Activity/Property Relationship App to make predictions for active ingredients without available experimental data. As a result, we were able to make predictions for 503 mixtures/formulations with 72% accuracy for the GHS classification. For 186 mixtures with two or more active ingredients, the accuracy rate was 76%. The structure-based analysis of the misclassified mixtures did not reveal any specific structural features associated with the mispredictions. Our results demonstrate that CATMoS together with an additivity formula can be used to predict the GHS category for chemical mixtures.

Joint toxic impacts of cadmium and three pesticides on embryonic development of rare minnow (Gobiocypris rarus)

Although rare minnow (Gobiocypris rarus) has been employed in many toxicological investigations, most of them have only assessed the impacts of single chemical. In our current work, we investigated the single and joint toxic impacts of heavy metal cadmium (Cd) and three pesticides (thiamethoxam, bifenthrin, and tebuconazole) on G. rarus embryos. Results from the 96-h semi-static toxicity assay exhibited that bifenthrin possessed the highest intrinsic toxic effect on rare minnows with an LC₅₀ value of 1.86 mg L^-1, followed by tebuconazole with LC₅₀ values of 4.07 mg L^-1. Contrarily, thiamethoxam elicited the least toxic effect with an LC₅₀ value of 351.9 mg L^-1. Seven chemical mixtures (four binary mixtures of Cd-bifenthrin, thiamethoxam-bifenthrin, thiamethoxam-tebuconazole, and bifenthrin-tebuconazole, two ternary mixtures of Cd-thiamethoxam-tebuconazole and thiamethoxam-bifenthrin-tebuconazole, and one quaternary mixture of Cd-thiamethoxam-bifenthrin-tebuconazole) displayed synergistic impacts with equivalent concentration and equitoxic ratio on G. rarus. Our results offered valuable insights into ecological risk assessment of these chemical combinations to aquatic vertebrates. The simultaneous existence of a few chemicals in the aquatic ecosystem might result in elevated toxicity, leading to severe harm to the non-target organisms compared with single compound. The observed synergistic interactions underlined the necessity to revise water quality standards, in which the detrimental joint effects of these chemicals are likely to be underestimated.

Thresholds and Endocrine Disruptors: An Endocrine Society Policy Perspective

The concept of a threshold of adversity in toxicology is neither provable nor disprovable. As such, it is not a scientific question but a theoretical one. Yet, the belief in thresholds has led to traditional ways of interpreting data derived from regulatory guideline studies of the toxicity of chemicals. This includes, for example, the use of standard "uncertainty factors" when a "No Adverse Effect Level" (or similar "benchmark dose") is either observed, or not observed. In the context of endocrine-disrupting chemicals (EDCs), this approach is demonstrably inappropriate. First, the efficacy of a hormone on different endpoints can vary by several orders of magnitude. This feature of hormone action also applies to EDCs that can interfere with that hormone. For this reason, we argue that the choice of endpoint for use in regulation is critical, but note that guideline studies were not designed with this in mind. Second, the biological events controlled by hormones in development not only change as development proceeds but are different from events controlled by hormones in the adult. Again, guideline endpoints were also not designed with this in mind, especially since the events controlled by hormones can be both temporally and spatially specific. The Endocrine Society has laid out this logic over several years and in several publications. Rather than being extreme views, they represent what is known about hormones and the chemicals that can interfere with them.

Effect of the Albumin Corona on the Toxicity of Combined Graphene Oxide and Cadmium to Daphnia magna and Integration of the Datasets into the NanoCommons Knowledge Base

In this work, we evaluated the effect of protein corona formation on graphene oxide (GO) mixture toxicity testing (i.e., co-exposure) using the Daphnia magna model and assessing acute toxicity determined as immobilisation. Cadmium (Cd2+) and bovine serum albumin (BSA) were selected as co-pollutant and protein model system, respectively. Albumin corona formation on GO dramatically increased its colloidal stability (ca. 60%) and Cd2+ adsorption capacity (ca. 4.5 times) in reconstituted water (Daphnia medium). The acute toxicity values (48 h-EC50) observed were 0.18 mg L-1 for Cd2+-only and 0.29 and 0.61 mg L-1 following co-exposure of Cd2+ with GO and BSA@GO materials, respectively, at a fixed non-toxic concentration of 1.0 mg L-1. After coronation of GO with BSA, a reduction in cadmium toxicity of 110 % and 238% was achieved when compared to bare GO and Cd2+-only, respectively. Integration of datasets associated with graphene-based materials, heavy metals and mixture toxicity is essential to enable re-use of the data and facilitate nanoinformatics approaches for design of safer nanomaterials for water quality monitoring and remediation technologies. Hence, all data from this work were annotated and integrated into the NanoCommons Knowledge Base, connecting the experimental data to nanoinformatics platforms under the FAIR data principles and making them interoperable with similar datasets.

Chemical pollution imposes limitations to the ecological status of European surface waters

Aquatic ecosystems are affected by man-made pressures, often causing combined impacts. The analysis of the impacts of chemical pollution is however commonly separate from that of other pressures and their impacts. This evolved from differences in the data available for applied ecology vis-à-vis applied ecotoxicology, which are field gradients and laboratory toxicity tests, respectively. With this study, we demonstrate that the current approach of chemical impact assessment, consisting of comparing measured concentrations to protective environmental quality standards for individual chemicals, is not optimal. In reply, and preparing for a method that would enable the comprehensive assessment and management of water quality pressures, we evaluate various quantitative chemical pollution pressure metrics for mixtures of chemicals in a case study with 24 priority substances of Europe-wide concern. We demonstrate why current methods are sub-optimal for water quality management prioritization and that chemical pollution currently imposes limitations to the ecological status of European surface waters. We discuss why management efforts may currently fail to restore a good ecological status, given that to date only 0.2% of the compounds in trade are considered in European water quality assessment and management.