Comparative in vitro hepatic clearances of commonly used antidepressants, antipsychotics, and anti-inflammatory agents in rainbow trout liver S9 fractions.

Residues of human pharmaceuticals are widely detected in surface waters and can be taken up by and bioaccumulate in aquatic organisms, especially fish. One of the key challenges in assessing the bioaccumulation potential of ionizable organic compounds, such as the pharmaceuticals, is the lack of empirical data for biotransformation. In the present study, we assessed the in vitro intrinsic clearances (CLINT) of twelve pharmaceuticals, individually and some additionally as mixtures, in rainbow trout (Oncorhynchus mykiss) liver S9 fractions (RT-S9) adhering to the OECD test guidance 319B. The test substances included four anti-inflammatory agents (diclofenac, ibuprofen, ketoprofen, naproxen), seven antidepressants/antipsychotics (citalopram, haloperidol, levomepromazine, mirtazapine, risperidone, sertraline, venlafaxine) and the O-desmethyl metabolite of venlafaxine. Quantifiable intrinsic clearances were detected for diclofenac, ibuprofen, naproxen, levomepromazine, and sertraline. Apart from diclofenac, the in vitro clearances of the other four pharmaceuticals were shown to be critically dependent on the cytochrome P450 (CYP) metabolism. Therefore, we also determined the half-maximal inhibitory concentrations (IC50) of the same twelve pharmaceuticals toward CYP1A-like (7-ethoxyresorufin-O-deethylation, EROD) and CYP3A-like (benzyloxy-4-trifluoromethylcoumarin-O-debenzyloxylation, BFCOD) activities in RT-S9 using IC50 shift assay. As a result, levomepromazine and sertraline were identified as the most potent inhibitors of both EROD and BFCOD activity (unbound IC50 < 10 µM each), followed by citalopram and haloperidol (10 µM < IC50 < 100 µM). Additionally, mirtazapine was a selective EROD inhibitor (IC50 ∼ 30 µM). The inhibitory impacts of haloperidol and sertraline were indicatively time dependent. Finally, we carried out intrinsic clearance assays with mixtures of diclofenac, ibuprofen, naproxen, levomepromazine, and sertraline to examine the impacts of EROD and BFCOD inhibitions on their in vitro CLINT in RT-S9. Our in vitro data suggests that the intrinsic clearances of ibuprofen, levomepromazine, and sertraline in rainbow trout can be significantly reduced as the result of P450 inhibition by pharmaceutical mixtures, whereas the clearances of diclofenac and naproxen are less impacted.

Independent and joint associations of multiple metals exposure with vital capacity index: a cross-sectional study in Chinese children and adolescents.

OBJECTIVE: The current study aimed to explore the relationships between urinary metals and vital capacity index (VCI) in 380 children and adolescents in Northeast China using a variety of statistical methods. METHODS: A cross-sectional survey was conducted among 380 children and adolescents in Liaoning Province, China. To assess the relationships between urinary metals and VCI, Elastic-net (ENET) regression, multivariate linear regression, weighted quantile sum (WQS), bayesian kernel machine regression (BKMR) and quantile-based g computation (qgcomp) were adopted. RESULTS: The ENET model selected magnesium (Mg), vanadium (V), manganese (Mn), arsenic (As), tin (Sn) and lead (Pb) as crucial elements. In multiple linear regression, we observed urinary Pb, Mn was negatively correlated with VCI individually in both total study population and adolescents (all p values < 0.05) in the adjustment model. The WQS indices were negatively related with VCI in total study population (ß=-3.19, 95%CI: -6.07, -0.30) and adolescents (ß=-3.46, 95%CI: -6.58, -0.35). The highest weight in total study population was Pb (38.80%), in adolescents was Mn (35.10%). In the qgcomp, Pb (31.90%), Mn (27.20%) were the major negative contributors to the association in the total population (ß=-3.51, 95%CI: -6.29, -0.74). As (42.50%), Mn (39.90%) were the main negative contributors (ß=-3.95, 95% CI: -6.68, -1.22) among adolescents. The results of BKMR were basically consistent with WQS and qgcomp analyses. CONCLUSIONS: Our results indicated that Pb and Mn were priority toxic materials on VCI. The cumulative effect of metals was negatively related to VCI, and this relationship was more pronounced in adolescents.

The Growing Complexity of Human Bitter Taste Perception.

Human bitter perception is important for the identification of potentially harmful substances in food. For quite some years, research focused on the identification of activators for ∼25 human bitter taste receptors. The discovery of antagonists as well as increasing knowledge about agonists of different efficacies has substantially added to the intricacy of bitter taste perception. This article seeks to raise awareness for an underestimated new level of complexity when compound mixtures or even whole food items are assessed for their bitter taste.

The exposure to UV filters: Prevalence, effects, possible molecular mechanisms of action and interactions within mixtures.

Substances that can absorb sunlight and harmful UV radiation such as organic UV filters are widely used in cosmetics and other personal care products. Since humans use a wide variety of chemicals for multiple purposes it is common for UV filters to co-occur with other substances either in human originating specimens or in the environment. There is increasing interest in understanding such co-occurrence in form of potential synergy, antagonist, or additive effects of biological systems. This review focuses on the collection of data about the simultaneous occurrence of UV filters oxybenzone (OXYB), ethylexyl-methoxycinnamate (EMC) and 4-methylbenzylidene camphor (4-MBC) as well as other classes of chemicals (such as pesticides, bisphenols, and parabens) to understand better any such interactions considering synergy, additive effect and antagonism. Our analysis identified >20 different confirmed synergies in 11 papers involving 16 compounds. We also highlight pathways (such as transcriptional activation of estrogen receptor, promotion of estradiol synthesis, hypothalamic-pituitary-gonadal (HPG) axis, and upregulation of thyroid-hormone synthesis) and proteins (such as Membrane Associated Progesterone Receptor (MAPR), cytochrome P450, and heat shock protein 70 (Hsp70)) that can act as important key nodes for such potential interactions. This article aims to provide insight into the molecular mechanisms on how commonly used UV filters act and may interact with other chemicals.

Prenatal exposure to mixtures of per- and polyfluoroalkyl substances and organochlorines affects cognition in adolescence independent of postnatal exposure.

BACKGROUND: Studies on cognitive and neurodevelopmental outcomes have shown inconsistent results regarding the association with prenatal exposure to perfluoroalkyl substance (PFAS) and organochlorines. Assessment of mixture effects of correlated chemical exposures that persist in later life may contribute to the unbiased evaluation and understanding of dose-response associations in real-life exposures. METHODS: For a subset of the 4th Flemish Environment and Health Study (FLEHS), concentrations of four PFAS and six organochlorines were measured in respectively 99 and 153-160 cord plasma samples and 15 years later in adolescents' peripheral serum by Ultra Performance Liquid Chromatography-Tandem Mass Spectrometry (UPLC-MS/MS). Sustained and selective attention were measured at 14-15 years with the Continuous Performance Test (CPT) and Stroop Test as indicators of potential neurodevelopmental deficits. Quantile g-computation was applied to assess the joint associations between prenatal exposure to separate and combined groups of PFAS and organochlorines and performance in the CPT and Stroop Test at adolescence. Subsequently, individual effects of each chemical compound were analyzed in mixed effects models with two sets of covariates. Analytical data at birth and at the time of cognitive assessment allowed for off-setting postnatal exposure. RESULTS: In mixtures analysis, a simultaneous one-quantile increase in the natural log-transformed values of PFAS and organochlorines combined was associated with a decrease in the mean reaction time (RT) and the reaction time variability (RTV) in the CPT (ß = -15.54, 95% CI:-29.64, -1.45, and ß = -7.82, 95% CI: -14.97, -0.67 respectively) and for the mixture of PFAS alone with RT (ß = -11.94, 95% CI: -23.29, -0.60). In the single pollutant models, these results were confirmed for the association between perfluorohexanesulfonate (PFHxS) with RT (ß = -17.95, 95% CI = -33.35, -2.69) and hexachlorobenzene with RTV in the CPT (ß = -5.78, 95% CI: -10.39, -0.76). Furthermore, the participants with prenatal exposure above the limit of quantification for perfluorononanoic acid (PFNA) had a significantly shorter RT and RTV in the CPT (ß = -23.38, 95% CI: -41.55, -5.94, and ß = -9.54, 95% CI: -19.75, -0.43, respectively). CONCLUSION: Higher prenatal exposure to a PFAS mixture and a mixture of PFAS and organochlorines combined was associated with better sustained and selective attention during adolescence. The associations seemed to be driven by PFHxS and were not linked to exposure levels at the time of assessment.

Environmental exposure to per- and polyfluoroalkyl substances mixture and asthma in adolescents.

BACKGROUND: Previous epidemiological studies about the relationship between per- and polyfluoroalkyl substances (PFAS) concentrations and adolescent asthma have typically examined single PFAS, without considering the mixtures effects of PFAS. METHODS: Using data from the 2013-2018 National Health and Nutrition Examination Survey (NHANES), 886 adolescents aged 12-19 years were included in this study. We explored the association between PFAS mixture concentrations and adolescent asthma using weighted quantile sum (WQS) regression and Bayesian kernel machine regression (BKMR) models, respectively. RESULTS: After adjusting for confounders, the results of the WQS regression and BKMR models were consistent, with mixed exposure to the five PFAS not significantly associated with asthma in all adolescents. The association remained nonsignificant in the subgroup analysis by sex. CONCLUSIONS: Our study demonstrated no significant association between mixed exposure to PFAS and adolescent asthma, and more large cohort studies are needed to confirm this in the future.

Impact of perfluoroalkyl substances (PFAS) and PFAS mixtures on lipid metabolism in differentiated HepaRG cells as a model for human hepatocytes.

Per- and polyfluoroalkyl substances (PFAS) are environmental contaminants with various adverse health effects in humans including disruption of lipid metabolism. Aim of the present study was to elucidate the molecular mechanisms of PFAS-mediated effects on lipid metabolism in human cells. Here, we examined the impact of a number of PFAS (PFOS, PFOA, PFNA, PFDA, PFHxA, PFBA, PFHxS, PFBS, HFPO-DA, and PMPP) and of some exposure-relevant PFAS mixtures being composed of PFOS, PFOA, PFNA and PFHxS on lipid metabolism in human HepaRG cells, an in vitro model for human hepatocytes. At near cytotoxic concentrations, the selected PFAS and PFAS mixtures induced triglyceride accumulation in HepaRG cells and consistently affected the expression of marker genes for steatosis, as well as PPARα target genes and genes related to lipid and cholesterol metabolism, pointing to common molecular mechanisms of PFAS in disrupting cellular lipid and cholesterol homeostasis. PPARα activation was examined by a transactivation assay in HEK293T cells, and synergistic effects were observed for the selected PFAS mixtures at sum concentrations higher than 25 µM, whereas additivity was observed at sum concentrations lower than 25 µM. Of note, any effect observed in the in vitro assays occurred at PFAS concentrations that were at least four to five magnitudes above real-life internal exposure levels of the general population.

Prediction and assessment of xenoestrogens mixture effects using the in vitro ERα-CALUX assay.

Introduction: Many natural or synthetic compounds used in foods, dietary supplements, and food contact materials (FCMs) are suspected endocrine disruptors (EDs). Currently, scientific evidence to predict the impacts on biological systems of ED mixtures is lacking. In this study, three classes of substances were considered: i) phytoestrogens, ii) plant protection products (PPP) and iii) substances related to FCMs. Fourteen compounds were selected based on their potential endocrine activity and their presence in food and FCMs. Methods: These compounds were evaluated using an in vitro gene expression assay, the ERα-CALUX, to characterize their responses on the estrogen receptor alpha. Cells were exposed to fixed ratio mixtures and non-equipotent mixtures of full and partial agonists. The concentration-response curves measured for the three classes of compounds were characterized by variable geometric parameters in terms of maximum response (efficacy), sensitivity (slope) and potency (median effective concentration EC50). To account for these variations, a generic response addition (GRA) model was derived from mass action kinetics. Results: Although GRA does not allow us to clearly separate the concentration addition (CA) and independent action (IA) models, it was possible to determine in a statistically robust way whether the combined action of the chemicals in the mixture acted by interaction (synergy and antagonism) or by additive behavior. This distinction is crucial for assessing the risks associated with exposure to xenoestrogens. A benchmark dose approach was used to compare the response of phytoestrogen blends in the presence and absence of the hormone estradiol (E2). At the same time, 12 mixtures of 2-5 constituents including phytoestrogens, phthalates and PPPs in proportions close to those found in food products were tested. In 95% of cases, the response pattern observed showed a joint and independent effect of the chemicals on ER. Discussion: Overall, these results validate a risk assessment approach based on an additive effects model modulated by intrinsic toxicity factors. Here, the CA and IA approaches cannot be distinguished solely based on the shape of the concentration response curves. However, the optimized GRA model is more robust than CA when the efficacy, potency, and sensitivity of individual chemical agonists show large variations.

Exposure to parabens and semen quality in reproductive-aged men.

BACKGROUND: Parabens are common preservatives in personal care products, cosmetics, and medical goods. In the past few years, animal studies showed the male reproductive toxicity associated with some parabens. Yet, epidemiological studies have generated inconsistent findings and research rarely has focused on the mixture effects of the parabens. We aimed to explore the associations between individual paraben exposure as well as the mixture and semen quality parameters. METHODS: A total of 795 male partners from preconception couples were included in the study. Their urine samples were analyzed for the concentrations of six parabens, namely methyl paraben (MeP), ethyl paraben (EtP), propyl paraben (PrP), butyl paraben (BuP), benzyl paraben (BzP) and heptyl paraben (HeP). Multiple linear regression models and weighted quantile sum regression (WQS) models were utilized to assess the relationships between individual paraben exposure and paraben mixture with semen quality parameters, respectively. RESULTS: After adjusting for covariates, exposure to a paraben mixture was significantly associated with declining sperm concentration, total sperm count, and progressive motility, among which BuP was identified as the main contributor to sperm concentration and total sperm count while MeP to progressive motility. Results from multiple linear regression models were generally in line with the WQS analysis. CONCLUSIONS: Our results suggest negative associations between paraben mixture and sperm concentration, total sperm count, and sperm motility among reproductive-aged men.

The effects of N-addition on litter mixture effects depend on decomposition time: A case from mixed-litter decomposition in the Gurbantunggut Desert.

Changes in nitrogen (N) deposition and litter mixtures have been shown to influence ecosystem processes such as litter decomposition. However, the interactive effects of litter mixing and N-deposition on decomposition process in desert regions remain poorly identified. We assessed the simultaneous effects of both N addition and litter mixture on mass loss in a litterbag decomposition experiment using six native plants in single-species samples with diverse quality and 14-species combinations in the Gurbantunggut Desert under two N addition treatments (control and N addition). The N addition had no significant effect on decomposition rate of single-species litter (expect Haloxylon ammodendron), whereas litter mass loss and decomposition rate differed significantly among species, with variations positively correlated with initial phosphorus concentration and negatively correlated with initial lignin concentration. After 18 months, the average mass loss across litter mixtures did not overall differ from those predicted from single species either in control or N addition treatments, that is, mixing of different species had no non-additive effects on decomposition. The N addition, however, did modify the direction of mixture effects and interacted with incubation time. Added N transformed synergistic effects of litter mixtures to antagonistic effects on mass loss after 1 month of decomposition, while transforming neutral effects of litter mixture to synergistic effects after 6 months of decomposition. Our results demonstrated that initial chemical properties played an important role in litter decomposition, while no effects of litter mixture on decomposition process in this desert region. The N addition altered the litter mixture effects on mass loss with incubation time, implying that increased N deposition in the future may have profound effects on carbon turnover to a greater extent than previously thought in desert ecosystems.

Effects of mixtures of polychlorinated biphenyls (PCBs) and three organochlorine pesticides on cognitive function differ between older Mohawks at Akwesasne and older adults in NHANES.

BACKGROUND: Akwesasne Mohawks has been exposed to high concentrations of polychlorinated biphenyls (PCBs) and background levels of organochlorine pesticides, hexachlorobenzene (HCB), dichlorodiphenyl dichloroethylene (DDE), and mirex. We have previously reported relative contributions to the mixture of low- and high-chlorinated PCBs, HCB, and DDE on cognitive decrements in Mohawks of various ages. OBJECTIVE: This study examines differences in the mixture effects of PCB congener groups, HCB, DDE, and mirex on cognitive function in older Mohawks and less PCB-exposed older adults from the National Health and Nutrition Examination Survey (NHANES) 1999-2002 cycles. METHODS: We used Bayesian kernel machine regression (BKMR) to evaluate the mixture effects of different PCB congener groups, HCB, DDE, and mirex on cognitive function in both populations. Models were adjusted for age, sex, education levels, and race/ethnicity focusing on individuals 60 years and older. RESULTS: Older Mohawks had 3-fold higher mean total PCB concentrations and 1.8-fold higher mirex, but slightly lower mean DDE and HCB levels than NHANES older adults. Higher mixture concentrations were significantly associated with greater cognitive decline. In older Mohawks, low- and high-chlorinated PCBs, HCB, and DDE contributed to the cognitive score decline. In contrast, score decline in older NHANES adults were primarily from high-chlorinated PCBs and DDE with a threshold dose of approximately 2.08-2.27 ng/g and 2.02-2.40 ng/g, respectively. CONCLUSION: Mixtures of PCBs and organochlorine pesticides increase the risk of cognitive decline in both older Mohawks and NHANES older adults. However, contributions to these mixture effects show significant differences. In older Mohawks, high- and low-chlorinated PCBs, DDE, and HCB are the primary contributors, while high-chlorinated PCBs and DDE are important contributors in NHANES older adults. Due to chronic heavy exposures to PCBs, older Mohawks had a significantly increased risk of cognitive decline compared to general older adults from NHANES.

The effects of the IM1-12Br ionic liquid and the oxytetracycline mixture on selected marine and brackish microorganisms.

The number of applications and commercialized processes utilizing ionic liquids has been increasing, and it is anticipated that this trend will persist and even intensify in the future. Ionic liquids possess desirable characteristics, such as low vapor pressure, good water solubility, amphiphilicity, and stability. Nevertheless, these properties can influence their environmental behavior, resulting in resistance to biotic and abiotic degradation and subsequent water contamination with more harmful derivatives. However, there is a notable scarcity of data regarding the impact of mixtures comprising ionic liquids and other micropollutants. Identifying potential potentiation of ionic liquids (Ils) toxicity in the presence of other xenobiotics is a proactive risk assessment measure. Therefore, the study aims to fill an important knowledge gap and identify possible interactions between imidazolium-based ionic liquid (IM1-12Br) and the common antibiotic oxytetracycline (OXTC). During 11-day experiments, selected marine, brackish and freshwater microorganisms (diatom Phaeodactylum tricornutum, cyanobacterium Microcystis aeruginosa and green algae Chlorella vulgaris) were exposed to binary mixtures of target substances. The assessed responses encompassed chlorophyll a kinetic parameters related to photosynthesis efficiency, as well as pigment concentrations, specifically phycobilin content. Additionally, the impact on the luminescent marine bacterium Aliivibrio fischeri has been evaluated. Significant effects on the growth, photosynthetic processes, and pigment content were observed in all the targeted microorganisms. The concentration addition (CA) and independent action (IA) mathematical models followed by the Model Deviation Ratio (MDR) evaluation enabled the identification of mainly synergistic interactions in the studied mixtures. The findings of present study offer valuable insights into the impacts of ionic liquids and other organic micropollutants.

Ecotoxicity of single and mixture of perfluoroalkyl substances (PFOS and PFOA) in soils to the earthworm Aporrectodea caliginosa.

Per and polyfluoroalkyl substances (PFAS) are persistent compounds that are massively used in industry, consumer goods and fire-fighting foams. Soil contamination by PFAS is a major environmental concern, and there is a lack of knowledge on both their ecotoxicological mechanisms and the concentrations that induce adverse effects especially to non-target organisms, particularly in the case of PFAS mixtures. This study contributes to filling these gaps by assessing and modelling the effects of PFAS (in single and in mixtures for PFOS and PFOA at different environmental doses) on juvenile endogeic earthworms of a common species in European soils (Aporrectodea caliginosa) at different levels of biological organization (sub-individual and individual). The results showed for the first time combined strong ecotoxicological effects of PFAS on earthworm survival, integumental integrity, growth, sexual maturity and on genomic stability notably with the induction of DNA breaks associated with no abnormal oxidative DNA-lesion levels. Our results demonstrated significant effects at 0.3 mg kg-1 and additive effects in case of mixtures.

Bioanalytical and chemical characterization of organic micropollutant mixtures in long-term exposed passive samplers from the Joint Danube Survey 4: Setting a baseline for water quality monitoring.

Monitoring methodologies reflecting the long-term quality and contamination of surface waters are needed to obtain a representative picture of pollution and identify risk drivers. This study sets a baseline for characterizing chemical pollution in the Danube River using an innovative approach, combining continuous three-months use of passive sampling technology with comprehensive chemical (747 chemicals) and bioanalytical (seven in vitro bioassays) assessment during the Joint Danube Survey (JDS4). This is one of the world's largest investigative surface-water monitoring efforts in the longest river in the European Union, which water after riverbank filtration is broadly used for drinking water production. Two types of passive samplers, silicone rubber (SR) sheets for hydrophobic compounds and AttractSPETM HLB disks for hydrophilic compounds, were deployed at nine sites for approximately 100 days. The Danube River pollution was dominated by industrial compounds in SR samplers and by industrial compounds together with pharmaceuticals and personal care products in HLB samplers. Comparison of the Estimated Environmental Concentrations with Predicted No-Effect Concentrations revealed that at the studied sites, at least one (SR) and 4-7 (HLB) compound(s) exceeded the risk quotient of 1. We also detected AhR-mediated activity, oxidative stress response, peroxisome proliferator-activated receptor gamma-mediated activity, estrogenic, androgenic, and anti-androgenic activities using in vitro bioassays. A significant portion of the AhR-mediated and estrogenic activities could be explained by detected analytes at several sites, while for the other bioassays and other sites, much of the activity remained unexplained. The effect-based trigger values for estrogenic and anti-androgenic activities were exceeded at some sites. The identified drivers of mixture in vitro effects deserve further attention in ecotoxicological and environmental pollution research. This novel approach using long-term passive sampling provides a representative benchmark of pollution and effect potentials of chemical mixtures for future water quality monitoring of the Danube River and other large water bodies.

Recruitment, mortality and growth in semi-arid conifer-eucalypt forest: Small trees insure against fire and drought.

Aim: Well-managed semi-arid forests help offset global change by storing significant amounts of carbon above- and belowground and maintaining hydrological cycles. Larger trees have been the focus of many studies due to their carbon storage and habitat quality, yet recruitment and small trees are important components of ecosystem resilience and recovery. Here, we study the impacts of disturbances (including harvesting) on recruitment, mortality and growth for a mixed conifer-broadleaf semi-arid forest type using long-term data. Location: Pilliga Forest in New South Wales, inland eastern Australia. Taxon: Callitris-Eucalyptus forests. Methods: We used data from permanent sample plots (PSPs) spanning 55 years, calculated stand structure, gains and losses and determined reasons for tree death (harvesting, fire, wind, drought and other effects). We extracted climate and fire data for the PSP locations using spatial analysis. Results: Stocking of studied forests remained stable (modest increase in basal area and stem density), despite harvesting and wildfires over 6 decades. Compared to stands in the 1940s and prior to European settlement, current forests are composed of more trees per unit area, and these trees have smaller diameters. Recruitment and sustained presence of small trees have buffered impacts of recurring drought, fire and harvesting. Fires are a common feature of the studied ecosystems and fire impacts have increased in the past 20 years, especially in unmanaged stands, where fires have reduced tree carbon by >50%. Main conclusions: Recruitment and growth of small trees are critical to offset carbon losses due to fire, drought and harvesting. All size classes have important ecological values in semi-arid forests and must be included in long-term monitoring programmes. Long-term data offer unique insights into combined effects of climate change, management and disturbances, especially for fire-prone ecosystems, where small trees are often susceptible to fire.

Toxicokinetic and toxicodynamic mixture effects of plant protection products: A case study.

Authorisation of ready to use plant protection products (PPPs) usually relies on the testing of acute and local toxicity only. This is in stark contrast to the situation for active substances where the mandatory data set comprises a most comprehensive set of studies. While the combination of certain active ingredients and co-formulants may nevertheless result in increased toxicity of the final product such combinations have never been evaluated systematically for complex and long-term toxicological endpoints. We therefore investigated the effect of three frequently used co-formulants on the toxicokinetic and toxicodynamic of the representative active substance combination of tebuconazol (Teb) and prothioconazol (Pro) or of cypermethrin (Cpm) and piperonyl butoxide (Pip), respectively. With all four active substances being potential liver steatogens, cytotoxicity and triglyceride accumulation in HepaRG were used as primary endpoints. Concomitantly transcriptomics and biochemical studies were applied to interrogate for effects on gene expression or inhibition of CYP3A4 as key enzyme for functionalization. Some of the tested combinations clearly showed more than additive effects, partly due to CYP3A4 enzyme inhibition. Other effects comprised the modulation of the expression and activity of steatosis-related nuclear key receptors. Altogether, the findings highlight the need for a more systematic consideration of toxicodynamic and toxicokinetic mixture effects during assessment of PPPs.

Mixture effects of co-formulants and two plant protection products in a liver cell line.

Plant protection products (PPPs) consist of one or more active substances and several co-formulants. Active substances provide the functionality of the PPP and are consequently evaluated according to standard test methods set by legal data requirements before approval, whereas co-formulants' toxicity is not as comprehensively assessed. However, in some cases mixture effects of active substances and co-formulants might result in increased or different forms of toxicity. In a proof-of-concept study we hence built on previously published results of Zahn et al. (2018[38]) on the mixture toxicity of Priori Xtra® and Adexar® to specifically investigate the influence of co-formulants on the toxicity of these commonly used fungicides. Products, their respective active substances in combination as well as some co-formulants were applied to human hepatoma cell line (HepaRG) in several dilutions. Cell viability analysis, mRNA expression, abundance of xenobiotic metabolizing enzymes and intracellular concentrations of active substances determined by LC-MS/MS analyses demonstrated that the toxicity of the PPPs is influenced by the presence of co-formulants in vitro. PPPs were more cytotoxic than the mix of their active substances. Gene expression profiles of cells treated with the PPPs were similar to those treated with their respective mixture combinations with marked differences. Co-formulants can cause gene expression changes on their own. LC-MS/MS analyses revealed higher intracellular concentrations of active substances in cells treated with PPPs compared to those treated with the respective active substances' mix. Proteomic data showed co-formulants can induce ABC transporters and CYP enzymes. Co-formulants can contribute to the observed increased toxicity of PPPs compared to their active substances in combination due to kinetic interactions, necessitating a more comprehensive evaluation approach.

Mixture Effects of Polychlorinated Biphenyls (PCBs) and Three Organochlorine Pesticides on Cognitive Function in Mohawk Adults at Akwesasne.

The Mohawks at Akwesasne have been highly exposed to polychlorinated biphenyls (PCBs), via releases from three aluminum foundries located near the reserve. They are also exposed to organochlorine pesticides, namely hexachlorobenzene (HCB), dichlorodiphenyldichloroethylene (DDE), and mirex. Previous studies have demonstrated reduced cognition in relation to total PCBs, but the effects of the mixtures of different PCB congener groups, HCB, DDE, and mirex on cognitive function have not been studied. Therefore, cognitive performance for executive function, scored via the digit symbol substitution test (DSST), in Mohawk adults aged 17-79 years (n = 301), was assessed in relation to serum concentrations of low-chlorinated PCBs, high-chlorinated PCBs, total PCBs, HCB, DDE, and mirex. We used mixture models employing the quantile-based g-computation method. The mixture effects of low-chlorinated PCBs, high-chlorinated PCBs, HCB, DDE, and mirex were significantly associated with 4.01 DSST scores decrements in the oldest age group, 47-79 years old. There were important contributions to mixture effects from low-chlorinated PCBs, high-chlorinated PCBs, and total PCBs, with smaller contributions of HCB and DDE. Our findings indicate that exposures to both low- and high-chlorinated PCBs increase the risk of cognitive decline in older adults, while DDE and HCB have less effect.

Investigating the surfactant antagonism with the Open Source Reconstructed Epidermis (OS-Rep) model.

Under the current EU chemicals legislation, in vitro test methods became the preferred methods to identify and classify the skin irritation potential of chemicals and mixtures. Among these, especially in vitro skin models are widely used. For surfactants, a well-known group of typically irritating chemicals, it is a long-standing experience that the irritation potential of a mixture of surfactants is typically lower than the irritation potential of the single surfactants, an effect usually described as surfactant antagonism. In order to evaluate if this effect can be observed in skin model systems as well, the irritation potential of the surfactants and of their mixtures was determined in the Open Source Reconstructed Epidermis (OS-REp) models. Combinations of sodium dodecyl sulfate or linear alkylbenzene sulfonate with cocoamidopropyl betain and alkyl polyglycosid, respectively, resulted in a clear decrease of the irritation potential compared to the irritation exerted by the single surfactants. The effect appeared to be primarily driven by the mixture's lower ability to damage the skin model's barrier, as shown by a reduced fluorescein permeation.

Exposure to metals and the disruption of sex hormones in 6-19 years old children: An exploration of mixture effects.

BACKGROUND: Individual metals have been linked to sex hormones disruption, but the associations of metals mixture are rarely examined among children. METHODS: A total of 1060 participants of 6-19-year-old who participated in the National Health and Nutrition Examination Survey (2013-2016) were included. Eighteen metals were quantified in the whole blood and urine. Sex hormones were measured in serum, including total testosterone (TT), estradiol (E2), and sex hormone binding globulin (SHBG). In addition, free androgen index (FAI) and the ratio of TT to E2 were calculated. Bayesian kernel machine regression and latent class analysis were performed to assess the associations of metals mixture and exposure patterns of metals at varied levels with sex hormones while adjusting for selected covariates. All analyses were conducted by sex-age and sex-puberty groups to explore the potential sex-dimorphic effects. RESULTS: Exposure to metals mixture was associated with elevated levels of FAI and E2 among 12-19 years old girls. Moreover, the exposure pattern of metals that was characterized by high levels of blood and urinary cadmium, blood manganese, and urinary cobalt was associated with elevated E2 and reduced TT/E2 levels among girls of 12-19 years old. However, the associations of metals mixture with sex hormones were overall nonsignificant among boys. Nevertheless, metals exposure pattern that was characterized by high levels of blood lead, urinary barium, strontium, and lead but comparatively low levels of the other metals was consistently associated with reduced levels of FAI and E2 but elevated levels of TT/E2 and SHBG among boys of 12-19 years old. CONCLUSION: Metals mixture and exposure patterns that were dominated by high levels of certain metals were associated with sex hormones imbalance among 12-19 years old children in a sex-dimorphic pattern, with the identified individual metals that drove the associations of metals mixture varied by sex.