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Although the Southern Ocean is considered a High Nutrient Low Chlorophyll area (HNLC), massive and recurrent blooms are observed over and downstream the Kerguelen Plateau. This mosaic of blooms is triggered by a higher iron supply resulting from the interaction between the Antarctic Circumpolar Current and the local bathymetry. Net primary production, N-uptake (NO3- and NH4+), and nitrification rates were measured at 8 stations in austral spring 2011 (October-November) during the KEOPS2 cruise in the Kerguelen area. Iron fertilization stimulates primary production, with integrated net primary production and growth rates much higher in the fertilized areas (up to 315 mmol Cm-2 d-1 and up to 0.31 d-1, respectively) compared to the HNLC reference site (12 mmol Cm-2 d-1 and 0.06 d-1, respectively). Primary production is mainly sustained by nitrate uptake, with f ratio (corresponding to NO3- uptake/(NO3- uptake + NH4+ uptake)) lying in the upper end of the observations for the Southern Ocean (up to 0.9). Unexpectedly, we report unprecedented rates of nitrification (up to ~ 3mmol Cm-2 d-1, with ~ 90% of them < 1 mmol Cm-2 d-1). It appears that nitrate is assimilated in the upper part of the mixed layer (coinciding with the euphotic layer) and regenerated in the lower parts. We suggest that such high contribution of nitrification to nitrate assimilation is driven by (i) a deep mixed layer, extending well below the euphotic layer, allowing nitrifiers to compete with phytoplankton for the assimilation of ammonium, (ii) extremely high rates of primary production for the Southern Ocean, stimulating the release of dissolved organic matter, and (iii) an efficient food web, allowing the reprocessing of organic N and the retention of nitrogen into the dissolved phase through ammonium, the substrate for nitrification. [ABSTRACT FROM AUTHOR]

Estrogens are contaminants in the Scheldt estuary due to a dense population and intense industrial and anthropogenic activities, but their levels and evolution in this estuary are not well studied. Here we investigated estrogenic activity (EA) in the dissolved, particulate and sediment compartments of the estuary using the Estrogen Receptor (ER)-Chemical Activated Luciferase Gene Expression (CALUX) bioassay, in recent and historical samples. EA ranges between 7-168, 2.16-22.5 and 1.8-38.2 pg E 2 -equivalents g -1 in the dissolved, particulate and sediment phases of the Scheldt, respectively. The partitioning coefficient (K d ) between the particulate and dissolved phases is about 2000 L kg -1 . EA levels in the estuarine sediments decreased during the last 40 years, but the strongest decrease, from 112 to 28 pg E 2 -equivalents g -1 , is observed in the upper estuary. The mass loadings of dissolved and particulate estrogens discharged into the North Sea amount to 7.5 and 1.6 μg s -1 , respectively. Future monitoring of the estrogen levels in various compartments of the Scheldt is necessary considering its strong environmental impact on living organisms and human beings., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier B.V. All rights reserved.)

In this study, hazardous wastes including fluff, dust, and scrubbing sludge were sampled in 2019 from two metal shredding facilities located in Wallonia, Belgium. To assess the extent of the contamination, a global approach combining chemical and biological techniques was used, to better reflect the risks to health and the environment. The samples investigated induced significant in vitro aryl hydrocarbon receptor (AhR) agonistic bioactivities and estrogenic receptor (ERα) (ant)agonistic bioactivities in the respective CALUX (chemical activated luciferase gene expression) bioassays. The mutagenicity of the samples was investigated with the bacterial reverse gene mutation test using the Salmonella typhimurium TA98 and TA100 strains. Except for the sludge sample (site 3), all samples induced a mutagenic response in the TA98 strain (± S9 metabolic fraction) whereas in the TA100 strain (+ S9 metabolic fraction), only the sludge sample (site 2) showed a clear mutagenic effect. The in vivo toxicity/teratogenicity of the shredder wastes was further evaluated with zebrafish embryos. Except for the dust sample (site 2), all samples were found to be teratogenic as they returned teratogenic indexes (TIs) > 1. The high levels of contamination, the mutagenicity, and the teratogenicity of these shredder wastes raise significant concerns about their potential negative impacts on both human health and environment., (© 2024. The Author(s), under exclusive licence to Springer-Verlag GmbH Germany, part of Springer Nature.)

Objectives: Resin composites may release bisphenol A (BPA) due to impurities present in the monomers. However, there is a lack of knowledge regarding the leaching characteristics of BPA from resin composites. Therefore, experimental resin composites were prepared with known amounts of BPA. The objective of this study was (1) to determine which amount of BPA initially present in the material leaches out in the short term and, (2) how this release is influenced by the resin composition., Methods: BPA (0, 0.001, 0.01, or 0.1 wt%) was added to experimental resin composites containing 60 mol% BisGMA, BisEMA(3), or UDMA, respectively, as base monomer and 40 mol% TEGDMA as diluent monomer. Polymerized samples (n = 5) were immersed at 37 °C for 7 days in 1 mL of water, which was collected and refreshed daily. BPA release was quantified with UPLC-MS/MS after derivatization with pyridine-3-sulfonyl chloride., Results: Between 0.47 to 0.67 mol% of the originally added BPA eluted from the resin composites after 7 days. Similar elution trends were observed irrespective of the base monomer. Two-way ANOVA showed a significant effect of the base monomer on BPA release, but the differences were small and not consistent., Significance: The released amount of BPA was directly proportional to the quantity of BPA present in the resin composite as an impurity. BPA release was mainly diffusion-based, while polymer composition seemed to play a minor role. Our results underscore the importance for manufacturers only to use monomers of the highest purity in dental resin composites to avoid unnecessary BPA exposure in patients., (Copyright © 2024 Elsevier Inc. All rights reserved.)

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., Competing Interests: The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest. The handling editor RD declared a past co-authorship with the authors ME and IB., (Copyright © 2023 Elskens, Boonen and Eisenreich.)

Objectives: Dental composites remain under scrutiny regarding their (long-term) safety. In spite of numerous studies on the release of monomers both in vitro and in vivo, only limited quantitative data exist on the in vivo leaching of degradation products from monomers and additives. The aim of this observational study was for the first time to quantitatively and qualitatively monitor the release of parent compounds and their degradation products in saliva from patients undergoing multiple restorations., Materials and Methods: Five patients in need of multiple large composite restorations (minimally 5 up to 28 restorations) due to wear (attrition, abrasion, and erosion) were included in the study, and they received adhesive restorative treatment according to the standard procedures in the university clinic for Restorative Dentistry. Saliva was collected at different time points, starting before the restoration up until 24 h after the treatment with composite restorations. Saliva extracts were analyzed by liquid chromatography-mass spectrometry., Results: Leaching of monomers and degradation products was highest within 30 min after the placement of the restorations. The highest median concentrations of monomers were recorded for UDMA, BisEMA-3, and TEGDMA; yet, besides BisEMA-3 and TEGDMA, no monomers could be detected after 24 h. Mono- and demethacrylated degradation products remained present up to 24 h and concentrations were generally higher than those of monomers. In patients with multiple restorations, degradation products were still present in the sample taken before the next operation, several weeks after the previous operation., Conclusions: Exposure to residual monomers and degradation products occurs in the first hours after restoration. Monomers are present in saliva shortly after restoration, but degradation products can be detected weeks after the restoration confirming a long-term release., Clinical Significance: Future research should focus more on the release of degradation products from monomers and additives from resin-based materials given their prolonged presence in saliva after restoration., (© 2023. The Author(s), under exclusive licence to Springer-Verlag GmbH Germany, part of Springer Nature.)

Increased human activity in the Antarctic Peninsula combined with accelerated melting of its glaciers highlights the importance of monitoring trace element concentrations. Surface sediment samples were collected around King George Island, Hope Bay and in the Bransfield Strait in February 2020 and were analysed by X-ray fluorescence spectroscopy and inductively coupled plasma mass spectrometry. The methods display a good correlation. Our results show clear distinctions between these regions for selected elements with high local heterogeneities. Hope Bay exhibited lower concentrations of Fe, Mn, Co, V, Zn while most stations in the Bransfield Strait and around King George Island showed moderate to significant enrichment in Cu, As and Cd. Twelve stations presented a moderate ecological risk. The consistency of our values supports a natural rather than anthropogenic origin, possibly related to volcanism and the geology of the area. However, our results suggest an increase in Cr that should be further investigated., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2022 Elsevier Ltd. All rights reserved.)

Effluents of sewage treatment plants (STPs) are an important source of estrogenic substances to the receiving water bodies affecting their ecological safety. In this study, steroids, bisphenol A (BPA) and phthalates were assessed in the secondary (SE) and tertiary effluent (TE) of three typical urban STPs in Beijing (China). In addition, the overall estrogenic activity in these effluents was assessed by an in-vitro bioassay (ERE-CALUX). Results showed that the concentrations and activities of estrogenic compounds in TE were lower than those in SE. The residual concentration of 17β-estradiol (E2) was the highest among the detected steroids, accounting for 51.6 ± 5.1% in SE and 57.5 ± 24.8% in TE. The residual level (25.2-41.6 ng/L) of BPA in effluents was significantly higher than that of steroids (0.2-28.8 ng/L). The residual concentration of diethyl phthalate was the highest among the detected phthalates accounting for 47.1 ± 5.1% in SE and 37.6 ± 11.5% in TE. Steroids and BPA had a higher removal rate (83.5% and 96.7%) in secondary and tertiary treatment than phthalates (68.8% and 83.1%). The hydrophobic characteristics of these estrogenic compounds determined the removal mechanism. The removal of steroids, BPA, dimethyl phthalate and diethyl phthalate (LogK ow = 1.61-4.15) mainly occurred through biodegradation in the water phase, while the removal of dibutyl phthalate, butylbenzyl phthalate and di(2-ethylhexyl) phthalate (LogK ow = 4.27-7.50) mainly occurred in the solid phase after adsorption on and sedimentation of the suspended particulate matter. According to ERE-CALUX, the estrogenic activity in the final STP effluents was 3.2-45.6 ng E 2 -equivalents/L, which is higher than reported levels in the effluents of European STPs. Calculation of estrogenic equivalents by using substance specific chemical analysis indicated that the dominant contributor was E2 (56.4-88.4%), followed by 17α-ethinylestradiol (EE2) (4.1-34.8%), both also exerting a moderate risk to the aquatic ecosystem. While the upgrade of treatment processes in STPs has efficiently reduced the emission of estrogenic substances, their ecological risk was not yet phased out., (Copyright © 2022 Elsevier Ltd. All rights reserved.)

The population of the semi-arid areas of the countries in the East African Rift Valley (EARV) is faced with serious problems associated with the availability and the quality of the drinking water. In these areas, the drinking water supply largely relies on groundwater characterised by elevated fluoride concentration (> 1.5 mg/L), resulting from interactions with the surrounding alkaline volcanic rocks. This geochemical anomaly is often associated with the presence of other naturally occurring potentially toxic elements (PTEs), such as As, Mo, U, V, which are known to cause adverse effects on human health. This study reports on the occurrence of such PTEs in the groundwater on the populated flanks of Mt. Meru, an active volcano situated in the EARV. Our results show that the majority of analysed PTEs (Al, As, Ba, Cd, Cr, Cu, Fe, Mn, Ni, Se, Sr, Pb, and Zn) are within the acceptable limits for drinking purpose in samples collected from wells, springs and tap systems, suggesting that there is no immediate health risk associated with these PTEs. However, some of the samples were found to exceed the WHO tolerance limit for U (> 30 μg/L) and Mo (> 70 μg/L). The sample analysis also revealed that in some of the collected samples, the concentrations of total dissolved solids, Na +  and K +  exceed the permissible limits. The concerning levels of major parameters and PTEs were found to be associated with areas covered with debris avalanche deposits on the northeast flank, and volcanic ash and alluvial deposits on the southwest flanks of the volcano. The study highlights the need to extend the range of elements monitored in the regional groundwater and make a more routine measurement of PTEs to ensure drinking water safety and effective water management measures., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2021 The Authors. Published by Elsevier B.V. All rights reserved.)

Objectives: Only little is known about degradation of methacrylate monomers. Therefore, using in vitro chemical and saliva degradation this study aimed to identify the degradation products of organic compounds present in resin-based dental materials., Methods: Ten dental monomers and nine polymerized dental resin-based materials were immersed for 24 h in chemical media (0.1 M HCl, 0.1 M NaOH) and human pooled saliva in order to identify leached monomers and degradation products from chemical and saliva degradation. Samples were analyzed using liquid chromatography coupled to high-resolution mass spectrometry to identify previously unknown degradation products., Results: During in vitro chemical degradation, uncured monomers were rapidly hydrolyzed into mono- and demethacrylated degradation products. During chemical degradation in alkaline conditions of polymerized materials, considered the worst-case scenario, only degradation products could be detected. In acidic conditions, monomers and their degradation products were detected. In addition, different additives such as EDMAB, DMPA and HMBP were present in acidic degradation samples. Degradation in human pooled saliva for 24 h to mimic the in vivo situation, resulted in the identification of both monomers and their degradation products., Clinical Significance: Using state-of-the-art high-resolution mass spectrometry previously unknown degradation products of commonly used monomers were identified for the first time. Results show that patients may be exposed to monomers and their degradation products in the first 24 h after restorative procedures. The results provide a base for further research on the degradation of resin-based dental composites in order to assess their safety using elution and toxicity studies., Competing Interests: Conflicts of interest The authors declare they have no conflict of interest., (Copyright © 2021 The Academy of Dental Materials. Published by Elsevier Inc. All rights reserved.)

Objectives: There is still much debate about the release of bisphenol A (BPA) from resin-based dental materials. Therefore, this study aimed to quantify BPA present as an impurity and to evaluate whether their degradation by salivary, bacterial, and chemical challenges could increase its release., Methods: BPA was determined in three different amounts (300, 400, and 500 µg) of eight unpolymerized resin-based materials (four composites, one fissure sealant, two adhesives and one root canal sealer). Next, polymerized samples (n = 5) of each material were immersed in 1 mL of whole human pooled saliva collected from adults, Streptococcus mutans (2 × 10 7 CFU/mL), and acidic (0.1 M HCl), alkaline (0.1 M NaOH), and control media, respectively. The amount of BPA was quantified using an UPLC-MS/MS method including derivatization of BPA by pyridine-3-sulfonyl chloride., Results: Only the composites contained trace amounts of BPA above the limit of quantification (ranging from 301±32 pg PBA/mg to 1534±62 pg BPA/mg), most likely as impurity from the synthesis of the monomers. The amounts of BPA released from polymerized materials upon salivary and bacterial degradation were too low for accurate quantification, but in water, quantifiable amounts of BPA were released from all materials. In alkaline media, the BPA release from two composites was significantly decreased, while the release from one adhesive was significantly increased, compared to water., Conclusions: BPA already present in unpolymerized resin-based materials may account for the release of BPA after polymerization. There was no clear indication that short-term material degradation leads to increased release of BPA., (Copyright © 2021 Elsevier Ltd. All rights reserved.)

Objective: The biocompatibility of resin based dental composites has not yet been fully characterized even though certain monomers used in these composites are synthesized from Bisphenol A (BPA), a well-known estrogenic endocrine disruptor. As a result, they show structural relationship to BPA and can contain it as an impurity. Therefore, the estrogenic activity of 9 monomers, 2 photoinitiators, one photostabilizer and leachates of 4 commercially available composites was determined., Methods: The ERα-CALUX bioassay was used to determine both agonistic and antagonistic estrogenic activities of the pure compounds (BPA, BisDMA, BisGMA, BisEMA(3), BisEMA(6), BisEMA(10), TEGDMA, TCD-DI-HEA, BADGE, UDMA, HMBP, DMPA, CQ) and the leachates of cured composite disks. The leachates of 4 commercially available composites (Solitaire 2, Ceram.x Spectra ST, G-ænial Posterior and Filtek Supreme XTE) in water and 0.1 M NaOH (pH = 13, 'worst-case scenario') were tested for estrogenic activity (pooled leachates from 10 cured composite disks)., Results: Agonistic estrogenic activity was found for the monomer BisDMA, the photostabilizer HMBP and photoinitiator DMPA. All leachates from the 4 tested composites showed significant agonistic estrogenic activity higher than the DMSO control, and the highest activity (potency and efficacy) was found for Solitaire 2, followed by Ceram.x Spectra ST. Furthermore, antagonistic estrogenic activity was found in the leachates from G-ænial Posterior., Significance: These results show that significant estrogenic activity was found in all leachates of the cured composite disks, and that this estrogenicity is most likely due to a mixture effect of multiple estrogenic compounds (including BPA, HMBP and DMPA). This indicates that further research into the endocrine activity of all the compounds that are present in these composites (even at low quantities) and their possible mixture effect is warranted to guarantee their safe use., (Copyright © 2021 The Academy of Dental Materials. Published by Elsevier Inc. All rights reserved.)

Objectives: BPA release from composites on the short term has been reported in several in-vitro and in-vivo studies. However, it remains unclear whether these materials also leach BPA on the long term. Even though composites may release various (BPA-based) methacrylate monomers up to one year, quantitative data about BPA have not been reported due to the lack of a sensitive method to accurately quantify low levels of BPA. In this context, the aim of the study was to quantify the one-year release of BPA with an optimized analytical method., Methods: Composite disks (n = 6, 6 mm diameter and 2 mm height) from four commercial materials (G-ӕnial Posterior, Venus, Ceram.x mono and Filtek Supreme XTE) were immersed in 1 mL of water or ethanol as extraction solvent and stored in the dark at 37 °C. The extraction solvent was renewed weekly for a period of 52 weeks. Samples were derivatized with pyridine-3-sulfonyl chloride before analysis with ultra-pressure liquid chromatography tandem mass spectrometry (UPLC-MS/MS)., Results: Derivatizing BPA increased the sensitivity of the analytical method and allowed accurate quantification of very low levels of BPA (i.e. 0.78 pmol BPA). BPA eluted continuously in ethanol from all four tested composites over a period of one year. BPA elution was clearly higher when ethanol was used as extraction solution. In water, BPA eluted could be detected up to one year, but levels could not be accurately quantified anymore after several weeks., Significance: Composites can be considered as a potential long-term source of BPA, and thus should not be neglected when assessing the overall exposure to endocrine disrupting chemicals., (Copyright © 2021 The Academy of Dental Materials. Published by Elsevier Inc. All rights reserved.)

Freshly erupted volcanic ash contains a range of soluble elements, some of which can generate harmful effects in living cells and are considered potentially toxic elements (PTEs). This work investigates the leaching dynamics of ash-associated PTEs in order to optimize a method for volcanic ash respiratory hazard assessment. Using three pristine (unaffected by precipitation) ash samples, we quantify the release of PTEs (Al, Cd, Co, Cr, Cu, Fe, Mn, Ni, Pb, V, Zn) and major cations typical of ash leachates (Mg, Na, Ca, K) in multiple simulated lung fluid (SLF) preparations and under varying experimental parameters (contact time and solid to liquid ratio). Data are compared to a standard water leach (WL) to ascertain whether the WL can be used as a simple proxy for SLF leaching. The main findings are: PTE concentrations reach steady-state dissolution by 24 h, and a relatively short contact time (10 min) approximates maximum dissolution; PTE dissolution is comparatively stable at low solid to liquid ratios (1:100 to 1:1000); inclusion of commonly used macromolecules has element-specific effects, and addition of a lung surfactant has little impact on extraction efficiency. These observations indicate that a WL can be used to approximate lung bioaccessible PTEs in an eruption response situation. This is a useful step towards standardizing in vitro methods to determine the soluble-element hazard from inhaled ash., (Copyright © 2021 Elsevier Ltd. All rights reserved.)

Objectives: This study aims to increase the rate of correctly sexed calcined individuals from archaeological and forensic contexts. This is achieved by evaluating sexual dimorphism of commonly used and new skeletal elements via uni- and multi-variate metric trait analyses., Materials and Methods: Twenty-two skeletal traits were evaluated in 86 individuals from the William M. Bass donated cremated collection of known sex and age-at-death. Four different predictive models, logistic regression, random forest, neural network, and calculation of population specific cut-off points, were used to determine the classification accuracy (CA) of each feature and several combinations thereof., Results: An overall CA of ≥ 80% was obtained for 12 out of 22 features (humerus trochlea max., and lunate length, humerus head vertical diameter, humerus head transverse diameter, radius head max., femur head vertical diameter, patella width, patella thickness, and talus trochlea length) using univariate analysis. Multivariate analysis showed an increase of CA (≥ 95%) for certain combinations and models (e.g., humerus trochlea max. and patella thickness). Our study shows metric sexual dimorphism to be well preserved in calcined human remains, despite the changes that occur during burning., Conclusions: Our study demonstrated the potential of machine learning approaches, such as neural networks, for multivariate analyses. Using these statistical methods improves the rate of correct sex estimations in calcined human remains and can be applied to highly fragmented unburnt individuals from both archaeological and forensic contexts., (© 2021 Wiley Periodicals LLC.)

Objective: There is still much debate about the release of bisphenol-A (BPA) from dental materials. Therefore, this study aimed to quantify BPA present as an impurity in both BPA-based and non-BPA-based monomers and to evaluate whether these monomers may degrade to BPA upon salivary, bacterial, and chemical challenges., Methods: BPA was determined in three different amounts (1, 2, and 3 μmol) of each monomer (TEGDMA, UDMA, mUDMA, BisGMA, BisEMA-3, -6, -10, -30, BisPMA, EBPADMA urethane, BADGE, and BisDMA). Next, the monomers (3 μmol) were immersed in whole human pooled saliva collected from adults, Streptococcus mutans (2 × 10 7 CFU/mL), and acidic (0.1 M HCl), alkaline (0.1 M NaOH), and control media. The amount of BPA was quantified using a specific and highly sensitive UPLC-MS/MS method including derivatization of BPA by pyridine-3-sulfonyl chloride., Results: The monomers BisGMA and BisEMA-3 contained trace amounts (0.0006% and 0.0025%, respectively) of BPA as impurities of their synthesis process. BPA concentrations increased when the monomers BisGMA, BisEMA-3, BisEMA-6, BisEMA-10, BisPMA and BADGE were exposed to saliva and S. mutans, indicating degradation of a small amount of monomer into BPA. In addition, BisPMA and BADGE degraded into BPA under alkaline conditions. The conversion rate of the monomers into BPA ranged between 0.0003% and 0.0025%., Significance: Impurities and degradation of BPA-based monomers may account for the release of BPA from resin-based dental materials. Even though the detected amounts of BPA due to monomer impurity were small, manufacturers of dental materials can reduce the BPA content by using only monomers of the highest purity. Considering the overall current trend towards BPA-free materials, it may be recommendable to investigate whether non-BPA based monomers can be used in dental resin-based materials., (Copyright © 2021 The Academy of Dental Materials. Published by Elsevier Inc. All rights reserved.)

In this study, an AhR-responsive reporter-gene cell-based bioassay CALUX was used to assess the biological potency of dioxins and dioxin-like PCBs (dl-PCBs) in top soil samples collected from a former airbase (A-So) and remote regions from urban and agricultural areas in Thua Thien Hue, Vietnam. In top soil collected from A-So airbase, Bioanalytical EQuivalent (BEQ) concentrations of up to 2700 pg 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) per g dry weight (pg BEQ-TCDD g -1 dw) were assessed. Interestingly, while BEQ values for dl-PCBs were found to be up to 13 pg BEQ-TCDD g -1 dw, the dl-PCB activity was not detected in all the hotspot sample extracts. In contrasts, BEQ values for dioxin like compounds from remote regions were much lower and occasionally below the quantification limits of the method. The BEQ activities obtained in this study have a similar trend to the WHO-TEQ results for the samples collected in the A-So airbase. However, BEQ values were higher than those of TEQ, probably reflecting the presence of additional AhR ligands and/or possible non-additive interactions in the sample mixture. This study confirms that after more than 60 years, a strong residual pollution of PCDD/Fs remains on this former air base following the use and storage of Agent Orange during the Vietnam War, raising a health risk for populations exposed in this area because livestock animals graze there., (Copyright © 2021 The Authors. Published by Elsevier Inc. All rights reserved.)

Recently collected dietary exposure data on mineral oil saturated (MOSH) and aromatic (MOAH) hydrocarbons were used to evaluate the risks associated with exposure to mineral oil through food for the Belgian population. For MOSH, the no observed adverse effect level (NOAEL) value of 19 mg kg -1 bw day -1 based on the hepatic inflammation-associated granulomas found in a 90-day oral study in F-344 rats was used as point of departure (PoD). Due to existing toxicological uncertainties, the margin of exposure (MOE) approach was applied. In all investigated scenarios, the MOE values were well above 100, indicating that there is no direct health concern related to MOSH exposure for the Belgian population. Nevertheless, more appropriate risk assessment approaches for MOSH based on adequate PoD are needed. For dietary exposure to MOAH, which are potentially genotoxic and carcinogenic, no MOE values could be calculated due to the lack of adequate dose-response carcinogenicity data. In two investigated worst-case scenarios, a health concern related to MOAH exposure could not be excluded, highlighting that more data are needed to perform an adequate risk assessment. The possibility to use in vitro bioassays to collect such additional toxicological information for MOAH present in food samples was also investigated., (Copyright © 2021 Elsevier Ltd. All rights reserved.)

The thorough understanding of the adsorption mechanism of phosphate on hydrous ferric oxides is necessary to deal with the environmental issues related to high phosphate concentrations in soils and open water. In this work, we consider three different adsorption geometries (monodentate and bidentate chemisorption and physisorption) and calculate the adsorption geometries and related adsorption energies at optPBE-vdW level. Using the Maxwell-Boltzmann distribution, it is estimated that about 83% of the phosphate molecules is in a monodentate chemisorption configuration, while 17% is physisorbed. Furthermore, theoretical infra-red spectra are obtained and compared to equivalent experimental spectra, supporting the conclusion that mainly monodentate chemisorption and physisorption occur. Most interestingly, a weighed infra-red spectrum is then calculated, using the weights from the Maxwell-Boltzmann distribution, showing a very good comparison with the experimental spectra., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2020 Elsevier Ltd. All rights reserved.)

Root canal sealers are commonly used to endodontically treat teeth with periapical infections. Some root canal sealers based on epoxy resin contain bisphenol A diglycidyl ether (BADGE) and bisphenol F diglycidyl ether (BFDGE). The presence of these chemicals is of concern due to the close contact to the blood stream at the apex and the long setting times of up to 24 h. These chemicals, or any of their degradation products or metabolites, can then exert their toxic effects before being excreted. This study aimed to identify the phase I in vitro biotransformation products of BADGE and BFDGE using human liver microsomes. During incubation with microsomal fractions, the epoxides were rapidly hydrolysed in a NADPH independent manner resulting in the formation of BADGE.2H 2 O and BFDGE.2H 2 O. Further, oxidative reactions, such as hydroxylation and carboxylation, generated other BADGE metabolites, such as BADGE.2H 2 O-OH and BADGE.H 2 O.COOH, respectively. For BFDGE, further oxidation of BFDGE.2H 2 O led to the newly reported carboxylic acid, BFDGE.H 2 O.COOH. In total, three specific metabolites have been identified which can serve in future human biomonitoring studies of BADGE and BFDGE., Competing Interests: Declaration of Competing Interest The authors declare they have no conflict of interest., (Copyright © 2020 Elsevier B.V. All rights reserved.)

The adsorption of phosphate on hydrated ferric oxide (HFO) was studied in solutions containing major seawater ions (Na + , Mg 2+ , Cl - , SO 4 2- , Ca 2+ , K + ) at pHs 6.5, 7.5 and 8.5. The presence of these ions promotes phosphate adsorption and the process is electrostatic in nature. Despite this electrostatic force, the precipitation of hydroxyapatite in the presence of Ca 2+ at pH 8.5 also plays an important role in the removal of phosphates from the dissolved phase. Energy dispersive X-ray spectroscopy (EDS) and Fourier transform infrared (FTIR) spectra support that phosphate adsorption on HFO surface can be attributed to inner sphere complexes with the formation of bidentate complexes (FeO) 2 PO 2 in the presence of main seawater ions at pH = 8.5. The results of EDS clearly indicated that Fe-P-Ca complexes, Fe-P-Mg, or other phosphate-bridged ternary complexes were not formed during adsorption in the presence of NaCl, KCl, CaCl 2 , Na 2 SO 4 . This observation differs somewhat from that the typical explanation used to describe the phosphate adsorption mechanism on HFO. The CD-MUSIC model makes it possible to describe this adsorption mechanism of phosphate on HFO in the presence of 0.7 M NaCl, and these outcomes are coherent with the experimental FTIR and EDS results.2 . This observation differs somewhat from that the typical explanation used to describe the phosphate adsorption mechanism on HFO. The CD-MUSIC model makes it possible to describe this adsorption mechanism of phosphate on HFO in the presence of 0.7 M NaCl, and these outcomes are coherent with the experimental FTIR and EDS results., Competing Interests: Declaration of competing interest The authors declare that they have no competing interests., (Copyright © 2020 Elsevier B.V. All rights reserved.)

Recently, presence of mineral oil in numerous foods has been detected. The analysis of mineral oil in food is convoluted since it comprises MOSH (saturated hydrocarbons) and variable amounts of mainly alkylated MOAH (aromatic hydrocarbons). Both fractions have a different toxicological profile and therefore they need to be assessed separately. For Belgium, occurrence data are available comprising concentrations of 217 food samples. These data were used, in combination with the 2014/15 Belgian Food Consumption Survey data, in a lower bound scenario to evaluate the dietary exposure of the Belgian population. Exposure to mineral oil was much lower compared to the results previously reported by EFSA and RIVM. The main contributors in Belgium were similar to previous studies (i.e. cereal products and oils), but an important additional contribution of non-alcoholic drinks was identified due to the presence of mineral oil in coffee. However, the concentration of mineral oil was determined from the dry product by applying a dilution factor with transfer rate of 100%, and not in the prepared coffee.This study gives an account of the dietary exposure of the Belgian population to mineral oil for the first time and reports the associated uncertainties.

Organic-diffusive gradients in thin-film samplers (o-DGT), were developed and applied for accumulation of estrogen and estrogen-like compounds on a XAD18 resin and deployed in situ in the effluents of Beijing Gaobeidian Wastewater Treatment Plant (GWWTP) and Brussels North Wastewater Treatment Plant as well as in several aquatic systems in Belgium, including the Zenne River, the Belgian Oostende Harbor and the North Sea. Estrogenic compounds accumulate on the XAD18 resin and the estrogenic activity of the resin extract was measured with the Estrogen Responsive Elements-Chemically Activated LUciferase gene eXpression (ERE-CALUX) bioassay. With this result and by applying Fick's diffusion law, it is possible to calculate the estrogenic activity in the aquatic system, if the diffusion boundary layer (DBL) is known or negligible compared to the hydrogel diffusive layer thickness. The DBL thickness in our study varied from 0.010 to 0.023 cm and ignoring the DBL thickness would for instance, underestimate the estrogenic activity by 10-20%. Estrogenic activities in the secondary effluent of GWWTP were the highest (29 ± 4 ng E2-equivalents L -1 ), while the lowest level was found at the Belgian Oostende Harbor (0.05 ± 0.01 ng E2-equivalents L -1 ). Comparable estrogenic activities in water samples measured by o-DGT and grab sampling were obtained, confirming that o-DGT can be efficiently used in various aquatic systems. The advantage of our sampling and measuring method is that very low, time averaged estrogenic activities can be determined, with a minimum of sample treatment. The risk of sample contamination is very low as well as the cost of the whole analytical procedure., (Copyright © 2019 The Authors. Published by Elsevier Ltd.. All rights reserved.)

Phosphate adsorption on suspended sediments is largely influenced by the variations in salinity and pH such as is the case in estuaries where freshwater mixes with seawater, exhibiting strong physico-chemical gradients. In this research, the influence of salinity and pH on the adsorption of phosphate on hydrous ferric oxides (HFO) was investigated in NaCl solutions. The adsorption isotherm data at different salinities can be well fitted with the Langmuir-Freundlich model. At pH 8.5 the maximum adsorption capacity increases with increasing salinity, from 22.7 mg PO4/g at salinity 0-78.5 mg PO4/g at salinity 35 PSU (Practical Salinity Unit) with the largest increase occurring in the low salinity range (76.8 mg PO4/g at salinity 5 PSU). Phosphate adsorption is also highly pH dependent and the adsorption capacity decreases with increasing pH. The dependence of phosphate adsorption on salinity could be attributed to the inner-sphere complexation. The presence of Na + modifies the phosphate speciation, which can also facilitate phosphate adsorption. Fourier-transform infrared spectroscopy (FTIR) results show that both bidentate (≡Fe 2 PO 4 ) and monodentate (≡FePO 4 ) complexes are formed during phosphate adsorption on HFO surface. Quantitative relationships between phosphate adsorption and salinity are proposed for the different pHs investigated in this study, which is important for the understanding of the phosphate adsorption dynamics during estuarine mixing., (Copyright © 2019 Elsevier Ltd. All rights reserved.)

Dental resin systems have been in use for several decades. (Meth)acrylic monomers are an important part of the matrix system and are either based on BPA while others lack the BPA core. The degree of conversion during restoration is in general between 50-70 % allowing leaching from unreacted monomers to the oral cavity where they can be taken up through the pulp or gastrointestinal tract after ingestion with subsequent hepatic metabolism. This study identified the in vitro Phase I and Phase II metabolism of the dental resin monomers BisGMA, UDMA, BisPMA and TCD-DI-HEA, using human liver microsomes (HLM) and human liver cytosols. During Phase I incubation with HLM, the (meth)acrylic acid in the monomers was rapidly removed followed by oxidative and hydroxylation pathways. For BisPMA an O-dealkylation pathway occurred resulting in the formation of BPA. The carbamates present in TCD-DI-HEA and UDMA were resistant to biotransformation reactions. Phase II biotransformation products were only observed for BisPMA and included conjugation reactions with sulphate and glucuronic acid. In total 4, 3, 12 and 3 biotransformation products were identified in this study for BisGMA, UDMA, BisPMA and TCD-DI-HEA respectively. Possible human health effects of these biotransformation products remain unclear due to limited data availability., (Copyright © 2019 Elsevier B.V. All rights reserved.)

This is the first study on polychlorinated biphenyls (PCBs) in fish from the Cau Hai lagoon, a part of the largest coastal lagoon in Southeast Asia. Seven selected PCB congeners and organochlorine pesticides in sediments and edible fish tissues were quantified by GC-MS. The sum of ICES-7 PCB and DDTs concentrations in fish species consumed regularly and of economic value were in ranges 26-43 ng g -1 lw and 182-277 ng g -1 lw, respectively. The ratio between the parent DDT compound and the sum of metabolites, DDE and DDD, was most of the time smaller than 1, suggesting primarily an historical contamination of the lagoon. An agglomerative hierarchical clustering indicates sites located in the north-western part of the Cau Hai lagoon were characterized by above-average concentrations of DDE and DDT. Comparing to previous data, a large decrease in ∑DDT residues can be seen over the past 20 years., (Copyright © 2019 Elsevier Ltd. All rights reserved.)

Since 2011, the World Health Organization has encouraged a global phase-down of the use of dental amalgam and actively supported the use of alternative, resin-based dental materials. The resins consist of (meth)acrylate monomers derived from Bisphenol A (BPA), such as Bisphenol A glycidyl methacrylate (BisGMA) and Bisphenol A ethoxylate methacrylate (BisEMA) or triethylene glycol dimethacrylate (TEGDMA) and urethane dimethacrylate (UDMA) which lack the BPA backbone. Besides monomers, other compounds such as photoinitiators and stabilizing agents can be present in the dental resin matrices. The current study consists in the development of an analytical method for the separation and identification of dental material components using LC-QTOF-MS. The developed method was applied on several dental material ingredients, unpolymerized composite resins, and a common dental sealant. The acquired high resolution accurate-mass data was analyzed using suspect screening with an in-house developed library. Next to the main components, various isomers and impurities related to the production of the main component have been detected and identified in the dental material ingredients. In total, 39 chemicals have been identified in the analyzed dental materials. On average 15 chemicals have been identified. Major components, such as BisEMA, BisGMA and TEGDMA were identified although they were not always stated in the material safety data sheets. Minor components included photoinitiators, such as ethyl 4-dimethyl aminobenzoate (EDMAB) and (meth)acrylates impurities originating from production of main ingredients., (Copyright © 2018 Elsevier B.V. All rights reserved.)

Concentrations of Al, As, Bi, Cd, Co, Cr, Cu, Fe, Mn, Mo, Ni, Pb, U, V and Zn were quantified in surface sediments collected from 13 different sampling sites from Cau Hai lagoon in Central Vietnam, and in 8 wild and farmed-fishes involving both pelagic and benthic species. Multivariate analysis shows that these trace elements are mainly associated with lithogenic matter, and are most likely the result of alteration and erosion processes in the lagoon. Enrichment factors and geo-accumulation indices reveal substantial sediment enrichments for both As and Bi with respect to the mean composition in the upper continental crust. As is enriched in the edible portion of fish tissue with values up to 10 times higher than the allowed limits set up by Health Canada. Target hazard quotient and target carcinogenic risk for As were assessed through fish diet and were greater than 1 and 10 -4 , respectively, indicating potential health risks for fish consumers in Cau Hai lagoon., (Copyright © 2018 Elsevier Ltd. All rights reserved.)

Recently, migration of mineral oil components from food contact materials into various foods has been reported. The analysis of mineral oil in food is complicated since it consists of mineral oil saturated hydrocarbons (MOSH) comprising a complex mixture of linear, branched and cyclic compounds and variable amounts of mineral oil aromatic hydrocarbons (MOAH), mainly alkylated. Both MOSH and MOAH form 'humps' of unresolved peaks in the chromatograms with the same range of volatility. Since these two fractions have a different toxicological relevance, it is important to quantify them separately. Occurrence data on mineral oil are available only for a limited number of food groups and only from few countries. In Belgium, data on the contamination of food by mineral oil are lacking. In this contribution, an in-house validated online combination of liquid chromatography with gas chromatography (LC-GC) with flame ionisation detection (FID) was used for the quantification of MOSH and MOAH. Totally, 217 packed food samples were selected using a well-defined sampling strategy that targeted food categories which are highly consumed and categories suspected to contain mineral oil. For 19 samples, the method was not applicable. For the 198 remaining samples, MOSH was detected in 142 samples with concentrations up to 84.82 mg kg -1 . For the MOAH fraction, there are 175 samples with a concentration below the limits of quantification (LOQ), while 23 samples had a higher concentration ranging from 0.6 to 2.24 mg kg -1 . Finally, these results were compared with the action thresholds as proposed by the Scientific Committee (SciCom) of the Belgian Food Safety Agency (FAVV-AFSCA). Only one sample exceeded the threshold for MOSH, while the threshold for MOAH was exceeded in 23 samples. For the samples exceeding the action threshold, further investigation is needed to identify the contamination source.

There is a growing necessity to acquire more profound knowledge on the quantity of eluates from resin-based dental materials, especially with regard to bisphenol A (BPA). The aim of the present study was to develop a highly sensitive method to characterize the short-term release of BPA in saliva with ultra-performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS), using an extraction step and additional derivatization of BPA with pyridine-3-sulfonyl chloride. Light-cured resin-based composites were incubated at 37 °C in 1 mL artificial saliva, which was refreshed daily for one week. The final protocol allows accurate quantification of very low levels of BPA in samples of artificial saliva (i.e. 1.10 pmol BPA/mL or 250 pg/mL). The daily BPA-release from dental composites, ranging from 1.10 to 7.46 pmol BPA/mL, was characterized over a period of 7 days. The highest total amount of BPA was released from Solitaire 2 (24.72 ± 2.86 pmol), followed by G-ænial Posterior (15.51 ± 0.88 pmol) and Filtek Supreme XTE (12.00 ± 1.31 pmol). In contrast, only trace amounts of BPA were released from Ceram.x Universal. This UPLC-MS/MS method might be used for clinical research focusing on the evaluation of the clinical relevance of BPA release from dental materials.