Polychlorinated Naphthalenes in Foods from the French Market: Occurrence, Dietary Exposure, and Evaluation of Relative Contributions to Dioxin-like Contaminants.

Despite the growing interest in PCNs and the dioxin-like toxicity exhibited by a number of congeners, a comprehensive assessment of their contribution to the cocktail of dioxin-like contaminants is still lacking. To address such a shortcoming, this study investigated the PCN contamination in foodstuffs recently acquired in France, together with that of the regulatory polychlorinated dibenzodioxins/furans (PCDD/Fs) and polychlorinated biphenyls (PCBs). PCNs were ubiquitous at levels (∑70 PCNs = 2.5-150 pg g-1 wet weight) similar to those reported in other countries, with maximum concentrations observed in fish and fishery products from the North-East Atlantic Ocean. Their congener patterns further suggested unintentional releases of PCNs, while those of the other foodstuffs were correlated to the historical PCN profiles. Low risk from dietary exposure was estimated (∑70 PCNs-EDIs of 60-360 pg kg-1 bw d-1, ∑24 PCNs-TEQ-EDIs of 8 × 10-3-2.2 × 10-2 pg TEQ kg-1 bw d-1), with milk and dairy products being the highest contributors, followed by meat and meat products. Finally, the rather high contributions of PCNs to the total PCNs+PCDD/Fs+PCBs concentrations (0.9-50%, average of 9%) and the toxic equivalents (0.2-24%, average of 5%) show that these substances are not minor components of the PCNs+PCDD/Fs+PCBs cocktail.

Dibenzofurans from nature: Biosynthesis, structural diversity, sources, and bioactivities.

Dibenzofurans are a small class of natural products with versatile biological activities that used to be thought to come mainly from lichens and ascomycetes. In fact, they are also distributed widely in higher plants, especially in the families Rosaceae and Myrtaceae. Dibenzofurans and derivatives from lichens and ascomycetes have been well reviewed, but dibenzofurans from all biological sources in nature have not been reviewed. In this review, dibenzofurans from all natural sources have been comprehensively reviewed, and a total of 211 dibenzofurans isolated and identified from organisms between 1843 and March 2023 are categorized and discussed, including their biosynthesis, structural diversity, sources, and bioactivities.

Occurrence, physicochemical properties and environmental behavior of polychlorinated dibenzothiophenes: A comprehensive review and future perspectives.

Polychlorinated dibenzothiophenes (PCDTs) are a form of emerging pollutant that has attracted great attention due to their structural resemblance to dioxins, which cast detrimental influence on the ecosystem and human health. This review shows the current status of research on PCDTs, focusing on their environmental occurrence, physicochemical properties, environmental behavior, and toxicity. Studies have suggested that the steps leading to the formation of PCDTs resemble those generating polychlorinated dibenzo-p-dioxin/dibenzofurans (PCDD/Fs), indicating their probable origin from the same sources. Furthermore, they may undergo a dechlorination process as a result of their photodegradation in the environment and metabolic reaction occurring within organisms, which could result in the conversion of these substances into additional pollutants like dibenzothiophene. PCDTs exist widely in the environmental media and have high logKOW values (>4.0), indicating their tendency to bioaccumulate. Moreover, the prediction results of EPI (Estimation Program Interface) Suite demonstrated a strong accumulation capacity for tetra-CDTs in fish compared to other chlorinated PCDTs. The biotransformation half-life of PCDTs would prolong with an increasing number of substituted Cl atoms in fish. A limited number of studies have also suggested that PCDTs can cause damage to the liver and immune system in living organisms, and the toxicity of PCDTs depends on the number and position of substituted Cl atoms. Future studies should be conducted on processes causing PCDT toxicity as well as their behavior and fate in actual environments.

The 2022 world health organization reevaluation of human and mammalian toxic equivalency factors for polychlorinated dioxins, dibenzofurans and biphenyls.

In October 2022, the World Health Organization (WHO) convened an expert panel in Lisbon, Portugal in which the 2005 WHO TEFs for chlorinated dioxin-like compounds were reevaluated. In contrast to earlier panels that employed expert judgement and consensus-based assignment of TEF values, the present effort employed an update to the 2006 REP database, a consensus-based weighting scheme, a Bayesian dose response modeling and meta-analysis to derive "Best-Estimate" TEFs. The updated database contains almost double the number of datasets from the earlier version and includes metadata that informs the weighting scheme. The Bayesian analysis of this dataset results in an unbiased quantitative assessment of the congener-specific potencies with uncertainty estimates. The "Best-Estimate" TEF derived from the model was used to assign 2022 WHO-TEFs for almost all congeners and these values were not rounded to half-logs as was done previously. The exception was for the mono-ortho PCBs, for which the panel agreed to retain their 2005 WHO-TEFs due to limited and heterogenous data available for these compounds. Applying these new TEFs to a limited set of dioxin-like chemical concentrations measured in human milk and seafood indicates that the total toxic equivalents will tend to be lower than when using the 2005 TEFs.

Probabilistic human health risk assessment of PCDD/Fs near municipal solid-waste incinerator using Monte Carlo analysis coupled with triangular fuzzy numbers.

PCDD/Fs are dioxins produced by waste incineration and pose risks to human health. We aimed to detail the health risks of airborne and soil PCDD/Fs near a municipal solid-waste incinerator (MSWI) for the surrounding population and develop a new model that improves upon existing methods. Thus, we conducted field sampling and then investigated a MSWI in the Pearl River Delta (2016-2018). Our results showed that the carcinogenic and non-carcinogenic risk values of PCDD/Fs exposed to residents in nearby areas were acceptable, with hazard index (HI) values lower than 1.0 and a total carcinogenic risk lower than 1.0E-6. Notably, the results raised concerns regarding higher non-carcinogenic risks in children than in adults. Comparative analysis of the frequency accumulation diagram, accumulated probability risk, and the absolute value of error (δ) between the 95% confidence interval (CI) and the 90% CI of the Monte Carlo stochastic simulation-triangular fuzzy number (MCSS-TFN) and the MCSS model, respectively, demonstrated that the MCSS-TFN exhibited less uncertainty than the MCSS model, regardless of the health risk value of PCDD/Fs in ambient air or in soil. This observation underscores the superiority of the MCSS-TFN model over other models in assessing the health risks associated with PCDD/Fs in situations with limited data. Our new method overcomes the limited dataset size and high uncertainty in assessing the health risks of dioxin substances, providing a more comprehensive understanding of their associated health risks than MCSS models.

Contaminants from dredged sediments alter the transcriptome of Manila clam and induce shifts in microbiota composition.

BACKGROUND: The reuse of dredged sediments in ports and lagoons is a big issue as it should not affect the quality and the equilibrium of ecosystems. In the lagoon of Venice, sediment management is of crucial importance as sediments are often utilized to built-up structures necessary to limit erosion. However, the impact of sediment reuse on organisms inhabiting this delicate area is poorly known. The Manila clam is a filter-feeding species of high economic and ecological value for the Venice lagoon experiencing a drastic decline in the last decades. In order to define the molecular mechanisms behind sediment toxicity, we exposed clams to sediments sampled from different sites within one of the Venice lagoon navigable canals close to the industrial area. Moreover, we investigated the impacts of dredged sediments on clam's microbial communities. RESULTS: Concentrations of the trace elements and organic chemicals showed increasing concentrations from the city of Venice to sites close to the industrial area of Porto Marghera, where PCDD/Fs and PCBs concentrations were up to 120 times higher than the southern lagoon. While bioaccumulation of organic contaminants of industrial origin reflected sediments' chemical concentrations, metal bioaccumulation was not consistent with metal concentrations measured in sediments probably due to the activation of ABC transporters. At the transcriptional level, we found a persistent activation of the mTORC1 signalling pathway, which is central in the coordination of cellular responses to chemical stress. Microbiota characterization showed the over-representation of potential opportunistic pathogens following exposure to the most contaminated sediments, leading to host immune response activation. Despite the limited acquisition of new microbial species from sediments, the latter play an important role in shaping Manila clam microbial communities. CONCLUSIONS: Sediment management in the Venice lagoon will increase in the next years to maintain and create new canals as well as to allow the operation of the new mobile gates at the three Venice lagoon inlets. Our data reveal important transcriptional and microbial changes of Manila clams after exposure to sediments, therefore reuse of dredged sediments represents a potential risk for the conservation of this species and possibly for other organisms inhabiting the Venice lagoon.

Ensuring safety standards in sewage sludge-derived biochar: Impact of pyrolysis process temperature and carrier gas on micropollutant removal.

The application of sewage sludge to agricultural land is facing increasing restrictions due to concerns about various micropollutants, including polycyclic aromatic hydrocarbons (PAHs), dioxins and furans (PCDD/Fs), polychlorinated biphenyls (PCBs), per- and poly-fluoroalkyl substances (PFAS), and heavy metals (HMs). As an alternative approach to manage this residue, the use of pyrolysis, a process that transforms sludge into biochar, a carbon-rich solid material, is being explored. Despite the potential benefits of pyrolysis, there is limited data on its effectiveness in removing micropollutants and the potential presence of harmful elements in the resulting biochar. This study aims to evaluate the impact of the temperature and the use of a carrier gas (N2) during a two-stage pyrolysis and cooling on micropollutant removal. Pilot-scale tests showed that a higher temperature (650 °C) and the use of a carrier gas (0.4 L/min N2) during the pyrolysis and the cooling process led to a reduction of PAHs, PCDD/Fs, PCBs and PFAS below their detection limits. As such, the generated biochar aligns with the guidelines set by the International Biochar Initiative (IBI) and the European Biochar Certificate (EBC) for all micropollutants, except for zinc and copper. Additional investigation is required to determine whether the micropollutants undergo destruction or transition into other pyrolysis end-products, such as the gas or liquid phase.

Biphenyls and dibenzofurans of the rosaceous subtribe Malinae and their role as phytoalexins.

MAIN CONCLUSION: Biphenyl and dibenzofuran phytoalexins are differentially distributed among species of the rosaceous subtribe Malinae, which includes apple and pear, and exhibit varying inhibitory activity against phytopathogenic microorganisms. Biphenyls and dibenzofurans are specialized metabolites, which are formed in species of the rosaceous subtribe Malinae upon elicitation by biotic and abiotic inducers. The subtribe Malinae (previously Pyrinae) comprises approximately 1000 species, which include economically important fruit trees such as apple and pear. The present review summarizes the current status of knowledge of biphenyls and dibenzofurans in the Malinae, mainly focusing on their role as phytoalexins. To date, 46 biphenyls and 41 dibenzofurans have been detected in 44 Malinae species. Structurally, 54 simple molecules, 23 glycosidic compounds and 10 miscellaneous structures were identified. Functionally, 21 biphenyls and 21 dibenzofurans were demonstrated to be phytoalexins. Furthermore, their distribution in species of the Malinae, inhibitory activities against phytopathogens, and structure-activity relationships were studied. The most widely distributed phytoalexins of the Malinae are the three biphenyls aucuparin (3), 2'-methoxyaucuparin (7), and 4'-methoxyaucuparin (9) and the three dibenzofurans α-cotonefuran (47), γ-cotonefuran (49), and eriobofuran (53). The formation of biphenyl and dibenzofuran phytoalexins appears to be an essential defense weapon of the Malinae against various stresses. Manipulating phytoalexin formation may enhance the disease resistance in economically important fruit trees. However, this approach requires an extensive understanding of how the compounds are formed. Although the biosynthesis of biphenyls was partially elucidated, formation of dibenzofurans remains largely unclear. Thus, further efforts have to be made to gain deeper insight into the distribution, function, and metabolism of biphenyls and dibenzofurans in the Malinae.

Synthesis of Benzofuropyridines and Dibenzofurans by a Metalation/Negishi Cross-Coupling/SNAr Reaction Sequence.

An efficient methodology for the synthesis of benzofuropyridines and dibenzofurans from fluoropyridines or fluoroarenes and 2-bromophenyl acetates is reported. This streamlined one-pot procedure consists of a four-step directed ortho-lithiation, zincation, Negishi cross-coupling, and intramolecular nucleophilic aromatic substitution, allowing for the facile assembly of a diverse set of fused benzofuro heterocycles.

Framework of the Integrated Approach to Formation Mechanisms of Typical Combustion Byproducts─Polyhalogenated Dibenzo-p-dioxins/Dibenzofurans (PXDD/Fs).

Understanding the mechanisms through which persistent organic pollutants (POPs) form during combustion processes is critical for controlling emissions of POPs, but the mechanisms through which most POPs form are poorly understood. Polyhalogenated dibenzo-p-dioxins and dibenzofurans (PXDD/Fs) are typical toxic POPs, and the formation mechanisms of PXDD/Fs are better understood than the mechanisms through which other POPs form. In this study, a framework for identifying detailed PXDD/Fs formation mechanisms was developed and reviewed. The latest laboratory studies in which organic free radical intermediates of PXDD/Fs have been detected in situ and isotope labeling methods have been used to trace transformation pathways were reviewed. These studies provided direct evidence for PXDD/Fs formation pathways. Quantum chemical calculations were performed to determine the rationality of proposed PXDD/Fs formation pathways involving different elementary reactions. Many field studies have been performed, and the PXDD/Fs congener patterns found were compared with PXDD/Fs congener patterns obtained in laboratory simulation studies and theoretical studies to mutually verify the dominant PXDD/Fs formation mechanisms. The integrated method involving laboratory simulation studies, theoretical calculations, and field studies described and reviewed here can be used to clarify the mechanisms involved in PXDD/Fs formation. This review brings together information about PXDD/Fs formation mechanisms and provides a methodological framework for investigating PXDD/Fs and other POPs formation mechanisms during combustion processes, which will help in the development of strategies for controlling POPs emissions.

Occurrence and Formation Mechanism of PCDD/Fs and SCCPs in Chlorinated Paraffin Products.

Polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/Fs) and short-chain chlorinated paraffins (SCCPs) can be formed during the production of chlorinated paraffins (CPs). Detection and accurate quantification of PCDD/Fs in CPs are challenging because of their matrix complexity. Therefore, the occurrence and formation mechanisms of PCDD/Fs from CPs have not been studied extensively in the past. In this study, 15 commercial samples including solid and liquid CPs were collected in 2022 from China. The average ΣSCCP concentrations detected in the solid and liquid CPs were 158 and 137 mg/g, respectively. The average International Toxic Equivalent (I-TEQ) values of 2,3,7,8-PCDD/F in solid and liquid CPs were 15.8 pg I-TEQ/g and 15.0 pg I-TEQ/g, respectively. The solid and liquid CPs had different predominant congener groups for SCCPs and PCDD/Fs. Possible formation routes for the generation of PCDD/Fs were analyzed by screening precursors in paraffin and laboratory-scale thermochemical experiments of CPs. The transformation between 2,3,7,8-PCDD/Fs and non-2,3,7,8-PCDD/Fs was recognized by calculating the successive chlorination preference. The first reported occurrence of PCDD/Fs in CP commercial products indicated that exposure to CPs and downstream products might be an assignable source of PCDD/F emission, which is of great significance to further explore the control factors of PCDD/Fs in the whole life cycle of CPs.

Unexpected Dioxin Formation During Digestion of Soil with Oxidizing Acids.

Dioxins, such as polychlorinated dibenzo-p-dioxins and polychlorinated dibenzofurans (PCDD/Fs), are among the most toxic unintentionally produced persistent organic pollutants, and their emission is of great concern. Herein, we discovered abundant dioxin formation in soil and various organic carbon-containing matrices after digestion with aqua regia. Σ17PCDD/Fs concentrations were in the range of 66.6-142,834 pg/g dw (5.6-17,021 pg WHO2005-TEQ/g dw) in 19 soil samples after digestion with aqua regia for 6 h. Σ17PCDD/Fs concentration was significantly and positively correlated with soil organic carbon content (R2 = 0.89; p < 0.01). Compared with cellulose and lignin, humic acid served as an important organic matter component that was converted to PCDD/Fs during soil digestion. Strong oxidation and production of reactive chlorine by aqua regia may be the key factors in the formation of PCDD/Fs. The yearly emission of PCDD/Fs due to digestion with strong acids by the inspection and testing industry was estimated to be 83.8 g TEQ in China in 2021 based on the highest level, which was ∼0.9% of the total dioxin inventory in China. Great attention should be paid to unexpected dioxin formation during digestion processes considering the potential risk of release from laboratories and enterprises.

Formation and Inventory of Polychlorinated Dibenzo-p-dioxins and Dibenzofurans and Other Byproducts along Manufacturing Processes of Chlorobenzene and Chloroethylene.

Chlorinated organic chemicals are produced and used extensively worldwide, and their risks to the biology and environment are of increasing concern. However, chlorinated byproducts [e.g., polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/Fs)] formed during the commercial manufacturing processes and present in organochlorine products are rarely reported. The knowledge on the occurrences and fate of unintentional persistent organic chemicals in the manufacturing of organochlorine chemical is necessary for accurate assessment of the risks of commercial chemicals and their production. Here, PCDD/Fs were tracked throughout chlorobenzene and chloroethylene production processes (from raw materials to final products) by target analysis. Other byproducts that can further transform into PCDD/Fs were also identified by performing non-target screening. As a result, the PCDD/F concentrations were mostly the highest in bottom residues, and the octachlorinated congeners were dominant. Alkali/water washing stages may cause the formation of oxygen-containing byproducts including PCDD/Fs and acyl-containing compounds, so more attention should be paid to these stages. PCDD/Fs were of 0.17 and 0.21-1.2 ng/mL in monochlorobenzene and chloroethylene products, respectively. Annual PCDD/F emissions (17 g toxic equivalent in 2018) during chlorobenzene and chloroethylene production were estimated using PCDD/F emission factors. The results can contribute to the improvement of PCDD/F inventories for the analyzed commercial chemicals.

Characterization of PCDD/F and dl-PCB levels in air in Gipuzkoa (Basque Country, Spain).

This research examines the levels and trends of pollutants, specifically 17 congeners of PCDD/Fs and 12 dl-PCBs, in the air measured in the province of Gipuzkoa (Basque Country, Spain). The study used PCDD/Fs, dl-PCB, and the sum of dioxin-like compounds as separate response variables. A total of 113 air samples were collected and analyzed using the method described in the European Standard (EN-1948:2006) from two industrial areas. The results were analyzed using non-parametric test to assess the variability of these pollutants based on different factors (year, season and day of the week) and General Linear Models to assess the weight of each factor. The study found that the toxic equivalents (TEQs) for PCDD/Fs were 12.29 fg TEQm-3 and for dl-PCBs were 1.63 fg TEQm-3, which were in a similar range or lower than those observed in other national and international studies in industrial areas. The results showed temporal variations, with higher levels of PCDD/Fs in autumn-winter than in spring-summer and higher levels of PCDD/Fs and dl-PCBs during weekdays than on weekends. The industrial area where the energy recovery plant (ERP) will be located had higher levels of air pollutants due to the presence of two PCDD/Fs emitting industries nearby, as indicated by the Spanish Registry of Polluting Emission Sources. Both industrial areas showed similar profiles of PCDD/Fs and dl-PCBs, with the PCDD/F profiles dominated by OCDD, 1,2,3,4,6,7,8-HpCDD, and 1,2,3,4,6,7,8-HpCDF in terms of concentrations and 1,2,3,7,8-PeCDD, 2,3,4,7,8-PeCDF, and 2,3,7,8-TCDD in terms of TEQs. The dl-PCB profiles were dominated by PCB 118, PCB 105, and PCB 77 in terms of concentrations and PCB 126 in terms of TEQs. The findings of this study can serve as an indicator of the potential impact of ERP on the health of the resident population and the environment.

Trace elements, dioxins and PCBs in different fish species and marine regions: Importance of the taxon and regional features.

Chemical contaminant concentrations in wild organisms are used to assess environmental status under the European Marine Strategy Framework Directive. However, this approach is challenged by the complex intra- and inter-species variability, and the different regional features. In this study, concentrations in trace elements (As, Cd, Hg and Pb), polychlorinated biphenyls (PCBs), polychlorodibenzo-para-dioxines (PCDDs) and polychlorodibenzofuranes (PCDFs) were monitored in 8 fish species sampled on the continental shelf of three French regions: the Eastern English Channel (EEC) and Bay of Biscay (BoB) in the Northeast Atlantic Ocean, and the Gulf of Lions (GoL) in Western Mediterranean Sea. Our objectives were to identify species or regions more likely to be contaminated and to assess how to take this variability into account in environmental assessment. While concentrations were higher in benthic and demersal piscivores, PCB and PCDD/F concentrations (lipid-weight) were similar in most teleost species. For Cd, Hg and Pb, the trophic group accumulating the highest concentrations depended on the contaminant and region. Concentrations in Hg, PCBs and PCDD/Fs were higher in the EEC and/or GoL than in BoB. Cadmium and Pb concentrations were highest in the BoB. Lipid content accounted for 35%-84% of organic contaminant variability. Lipid normalisation was employed to enhance robustness in the identification of spatial patterns. Contaminant patterns in chondrichthyans clearly differed from that in teleosts. In addition, trophic levels accounted for ≤1% and ≤33% of the contaminant variability in teleost fishes in the EEC and BoB, respectively. Therefore, developing taxa-specific thresholds might be a more practical way forward for environmental assessment than normalisation to trophic levels.

Dietary intake of polychlorinated dibenzo-p-dioxins and furans, adiposity and obesity status.

INTRODUCTION: The principal source of exposure to Polychlorinated dibenzo-p-dioxins and polychlorinated dibenzo-p-furans (PCDD/Fs) in humans comes from food intake. PCDD/Fs, are a family of potential endocrine disruptors and have been associated with different chronic diseases such as diabetes and hypertension. However, studies assessing the relationship between dietary exposure to PCDD/Fs and adiposity or obesity status in a middle-aged population are limited. OBJECTIVE: To assess cross-sectionally and longitudinally the associations between estimated dietary intake (DI) of PCDD/Fs and body mass index (BMI), waist circumference, and the prevalence/incidence of obesity and abdominal obesity in a middle-aged population. METHODS: In 5899 participants aged 55-75 years (48% women) living with overweight/obesity from the PREDIMED-plus cohort, PCDD/Fs DI was estimated using a 143-item validated food-frequency questionnaire, and the levels of food PCDD/F expressed as Toxic Equivalents (TEQ). Consequently, cross-sectional and prospective associations between baseline PCDD/Fs DI (in pgTEQ/week) and adiposity or obesity status were assessed at baseline and after 1-year follow-up using multivariable cox, logistic or linear regression models. RESULTS: Compared to participants in the first PCDD/F DI tertile, those in the highest tertile presented a higher BMI (ß-coefficient [confidence interval]) (0.43kg/m2 [0.22; 0.64]; P-trend <0.001), a higher waist circumference (1.11 cm [0.55; 1.66]; P-trend <0.001), and a higher prevalence of obesity and abdominal obesity (1.05 [1.01; 1.09] and 1.02 [1.00; 1.03]; P-trend = 0.09 and 0.027, respectively). In the prospective analysis, participants in the top PCDD/F DI baseline tertile showed an increase in waist circumference compared with those in the first tertile after 1-year of follow-up (ß-coefficient 0.37 cm [0.06; 0.70]; P-trend = 0.015). CONCLUSION: Higher DI of PCDD/Fs was positively associated with adiposity parameters and obesity status at baseline and with changes in waist circumference after 1-year of follow-up in subjects living with overweight/obesity. Further large prospective studies using a different population with longer follow-up periods are warranted in the future to strengthen our results.

Serum levels of polychlorinated dibenzo-p-dioxins and polychlorinated dibenzofurans in a sample of Lebanese pregnant women: The role of dietary, anthropometric, and environmental factors.

Polychlorinated dibenzo-p-dioxins (PCDDs) and polychlorinated dibenzofurans (PCDFs) are unintentionally produced, toxic environmental chemicals that persist for long years and bioaccumulate along the food chain, contaminating humans through diet. A particularly critical population subgroup is pregnant women given the adverse health effects on fetuses and newborns. Several anthropogenic sources of exposure to PCDD/Fs exist in Lebanon. Therefore, the aim of the present cross-sectional study is to measure the levels of PCDD/Fs in a sample of pregnant women in Lebanon and to explore potential associated factors. In this study, we measured serum concentrations of seven dioxins and ten furans, among 423 pregnant women recruited at delivery, using gas chromatography MS/MS. Among 269 participants, maternal sociodemographic information was collected including vicinity to landfills, incineration, pesticide use, industrial activity, and smoking. Anthropometric data were registered regarding pre-pregnancy body mass index (BMI), pre-pregnancy weight loss from restrictive diet, and gestational weight gain. Intake of major food groups generally related to PCDD/Fs was reported (fish, red meat, poultry, and dairy). Bivariate and multivariate analyses were performed to identify associations. PCDD/Fs were detected in 0 to 56.1% of the sample. Geometric mean concentrations were 75.5 (2.35) pg/g lipid and 2.25 (1.39) TEQ2005 pg/g lipid for total dioxins, and 2.66 (1.76) pg/g lipid and 0.34 (1.78) TEQ2005 pg/g lipid for total furans. Levels were relatively lower than levels previously observed in France, Germany, Mexico, Ghana, and Japan. Red meat consumption was the most consistently associated factor with a 2.38-2.57 fold increase in PCDD/F levels. Pre-pregnancy weight loss showed inverse associations with PCDD/F congeners. Vicinity to illegal incineration was also associated with a 2.32-2.43 fold increase in PCDD/F levels. In conclusion, results showed the importance of dietary, anthropometric, and environmental factors in the present sample's exposure to PCDD/Fs, in a region that contains anthropogenic sources of contamination.

Transfer of polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/Fs) and polychlorinated biphenyls (PCBs) from oral exposure into cow's milk - Part I: state of knowledge and uncertainties.

Polychlorinated dibenzo-para-dioxins (PCDDs) and dibenzofurans (PCDFs) (collectively and colloquially referred to as 'dioxins') as well as polychlorinated biphenyls (PCBs) are persistent and ubiquitous environmental contaminants that may unintentionally enter and accumulate along the food chain. Owing to their chronic toxic effects in humans and bioaccumulative properties, their presence in feed and food requires particular attention. One important exposure pathway for consumers is consumption of milk and dairy products. Their transfer from feed to milk has been studied for the past 50 years to quantify the uptake and elimination kinetics. We extracted transfer parameters (transfer rate, transfer factor, biotransfer factor and elimination half-lives) in a machine-readable format from seventy-six primary and twenty-nine secondary literature items. Kinetic data for some toxicologically relevant dioxin congeners and the elimination half-lives of dioxin-like PCBs are still not available. A well-defined selection of transfer parameters from literature was statistically analysed and shown to display high variability. To understand this variability, we discuss the data with an emphasis on influencing factors, such as experimental conditions, cow performance parameters and metabolic state. While no universal interpretation could be derived, a tendency for increased transfer into milk is apparently connected to an increase in milk yield and milk fat yield as well as during times of body fat mobilisation, for example during the negative energy balance after calving. Over the past decades, milk yield has increased to over 40 kg/d during high lactation, so more research is needed on how this impacts feed to food transfer for PCDD/Fs and PCBs.

Transfer of polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/Fs) and polychlorinated biphenyls (PCBs) from oral exposure into cow's milk - part II: toxicokinetic predictive models for risk assessment.

Understanding the transfer of polychlorinated dibenzo-p-dioxins (PCDDs) and dibenzofurans (PCDFs) as well as polychlorinated biphenyls (PCBs) from oral exposure into cow's milk is not purely an experimental endeavour, as it has produced a large corpus of theoretical work. This work consists of a variety of predictive toxicokinetic models in the realms of health and environmental risk assessment and risk management. Their purpose is to provide mathematical predictive tools to organise and integrate knowledge on the absorption, distribution, metabolism and excretion processes. Toxicokinetic models are based on more than 50 years of transfer studies summarised in part I of this review series. Here in part II, several of these models are described and systematically classified with a focus on their applicability to risk analysis as well as their limitations. This part of the review highlights the opportunities and challenges along the way towards accurate, congener-specific predictive models applicable to changing animal breeds and husbandry conditions.

Effects of the Dibenzofuran, Usnic Acid, on Inhibition of Ocular Biofilm Formation Due to Coagulase-Negative Staphylococci.

BACKGROUND Coagulase-negative staphylococci (CoNS) are gram-positive, aerobic, commensal bacteria found on the skin and mucus membranes, including the conjunctiva. Usnic acid (UA) is a dibenzofuran derivative isolated from lichens. This study aimed to investigate the effects of usnic acid on inhibition of ocular biofilm formation due to CoNS. MATERIAL AND METHODS Nine Staphylococcus epidermidis isolates, 5 Staphylococcus hominis isolates, 2 Staphylococcus saprophyticus isolates, and 1 Staphylococcus capitis and Staphylococcus lentus isolates were taken as test bacteria. They were inoculated into brain heart infusion broth and incubated for 24 hours at 35°C and activated. Antibiotic susceptibility was investigated by Kirby-Bauer disc diffusion method. Biofilm production was determined using the microtiter plate method and optical densitometry was measured at 570 nm using an automated microplate reader. Anti-biofilm activity of UA was determined by microtitration method and biofilm removal percentage was calculated. RESULTS All tested bacteria were found as high biofilm-producer strains; they were generally resistant to methicillin, but susceptible to vancomycin. UA inhibited the biofilm formation of S. epidermidis isolates, ranging from 5.7% to 81.5%. It inhibited the biofilm formation of S. saprophyticus and S. lentus by 73.3% and 74.3%, respectively. There was no effect of UA on mature biofilms of S. epidermidis 17.7H, S. epidermidis 15.41, S. hominis 9.3, S. hominis 17.2H, S. saprophyticus, and S. lentus. CONCLUSIONS It was determined that UA exerted anti-biofilm activity on some CoNS isolated from the ocular surface. Anti-biofilm activity was found to be higher even in strains that did not show antibacterial activity.