We performed a mixture risk assessment (MRA) case study of dietary exposure to the food contaminants lead, methylmercury, inorganic arsenic (iAs), fluoride, non-dioxin-like polychlorinated biphenyls (NDL-PCBs) and polybrominated diphenyl ethers (PBDEs), all substances associated with declines in cognitive abilities measured as IQ loss. Most of these chemicals are frequently measured in human biomonitoring studies. A component-based, personalised modified reference point index (mRPI) approach, in which we expressed the exposures and potencies of our chosen substances as lead equivalent values, was applied to perform a MRA for dietary exposures. We conducted the assessment for four different age groups (toddlers, children, adolescents, and women aged 18-45 years) in nine European countries. Populations in all countries considered exceeded combined tolerable levels at median exposure levels. NDL-PCBs in fish, other seafood and dairy, lead in grains and fruits, methylmercury in fish and other seafoods, and fluoride in water contributed most to the combined exposure. We identified uncertainties for the likelihood of co-exposure, assessment group membership, endpoint-specific reference values (ESRVs) based on epidemiological (lead, methylmercury, iAs, fluoride and NDL-PCBs) and animal data (PBDE), and exposure data. Those uncertainties lead to a complex pattern of under- and overestimations, which would require probabilistic modelling based on expert knowledge elicitation for integration of the identified uncertainties into an overall uncertainty estimate. In addition, the identified uncertainties could be used to refine future MRA for cognitive decline.
- MeSH
- Arsenic * MeSH
- Dioxins * MeSH
- Fluorides MeSH
- Halogenated Diphenyl Ethers MeSH
- Humans MeSH
- Methylmercury Compounds * MeSH
- Adolescent MeSH
- Lead MeSH
- Polybrominated Biphenyls * MeSH
- Polychlorinated Biphenyls * MeSH
- Polychlorinated Dibenzodioxins * MeSH
- Mercury * MeSH
- Animals MeSH
- Check Tag
- Humans MeSH
- Adolescent MeSH
- Female MeSH
- Animals MeSH
- Publication type
- Journal Article MeSH
Ryby, rybí výrobky a mořští živočichové jsou důležitou součástí zdravé výživy, významným dietárním zdrojem jodu, ale také dalších látek, které pozitivně působí na lidský organismus. Na druhé straně jsou v nich obsaženy kontaminanty (především rtuť/methylrtuť), jejichž toxické vlastnosti ovlivňují bezpečnost potravin. Na základě výsledků monitorování dietární expozice a specializovaných studií Státního zdravotního ústavu – Centra zdraví, výživy a potravin i mezinárodních aktivit lze konstatovat, že z hlediska lidského zdraví je při konzumaci produktů rybolovu zřejmý přínos. Na zahrnutí těchto produktů do jídelníčku by měly dbát zejména ženy a děti. Obsah rtuti/methylrtuti je v běžných výrobcích v Česku pod kontrolou a hodnoty koncentrace jsou prakticky pod legislativními limity. Pozor je třeba dát na ryby a výrobky z nich, kde může docházet ke kumulaci rtuti. Odpovídající je reakce Evropské komise, která aktuálně apeluje právě na to, aby byly přezkoumány maximální přípustné limity pro rtuť/methylrtuť u různých druhů ryb. Tím by se dalo přispět ještě k dalšímu snížení dietární expozice rtuti v potravinách a podpořit konzumaci ryb.
Fish, fish products and seafood are an important part of a healthy diet. They make an important contribution as a dietary source of iodine, but also of other substances that have a positive effect on the human body. On the other hand, they contain contaminants (especially mercury/methylmercury) whose toxic properties affect food safety. Based on the results of dietary exposure monitoring and specialised studies by the National Institute of Health – Centre for Health, Nutrition and Food and international activities it can be concluded that there are clear benefits in terms of human health from the consumption of fishery products. Women and children should take care to include these products in their diets. The mercury/methylmercury content of common products in the Czech Republic is under control and the concentration levels are practically below the legislative limits. Care should be taken with fish and fish products where mercury may accumulate. The response of the European Commission, which is currently calling for a review of the maximum permissible limits for mercury/methylmercury in various fish species, is appropriate. This could help to further reduce dietary exposure to mercury in food and encourage fish consumption.
- MeSH
- Food Analysis MeSH
- Iodine analysis MeSH
- Food Contamination MeSH
- Food Inspection * MeSH
- Humans MeSH
- Mercury analysis MeSH
- Fish Products * analysis adverse effects MeSH
- Fishes MeSH
- Check Tag
- Humans MeSH
- Publication type
- Research Support, Non-U.S. Gov't MeSH
- Review MeSH
Methyl mercury (MeHg) is an organic highly toxic compound that is transported efficiently via the human placenta. Our previous data suggest that MeHg is taken up into placental cells by amino acid transporters while mercury export from placental cells mainly involves ATP binding cassette (ABC) transporters. We hypothesized that the ABC transporter multidrug resistance-associated protein (MRP)1 (ABCC1) plays an essential role in mercury export from the human placenta. Transwell transport studies with MRP1-overexpressing Madin-Darby Canine Kidney (MDCK)II cells confirmed the function of MRP1 in polarized mercury efflux. Consistent with this, siRNA-mediated MRP1 gene knockdown in the human placental cell line HTR-8/SVneo resulted in intracellular mercury accumulation, which was associated with reduced cell viability, accompanied by increased cytotoxicity, apoptosis, and oxidative stress as determined via the glutathione (GSH) status. In addition, the many sources claiming different localization of MRP1 in the placenta required a re-evaluation of its localization in placental tissue sections by immunofluorescence microscopy using an MRP1-specific antibody that was validated in-house. Taken together, our results show that (1) MRP1 preferentially mediates apical-to-basolateral mercury transport in epithelial cells, (2) MRP1 regulates the GSH status of placental cells, (3) MRP1 function has a decisive influence on the viability of placental cells exposed to low MeHg concentrations, and (4) the in situ localization of MRP1 corresponds to mercury transport from maternal circulation to the placenta and fetus. We conclude that MRP1 protects placental cells from MeHg-induced oxidative stress by exporting the toxic metal and by maintaining the placental cells' GSH status in equilibrium.
- MeSH
- ATP-Binding Cassette Transporters metabolism MeSH
- Apoptosis drug effects MeSH
- Cell Line MeSH
- Madin Darby Canine Kidney Cells MeSH
- Endothelial Cells MeSH
- Gene Knockdown Techniques MeSH
- Glutathione metabolism MeSH
- Immunohistochemistry MeSH
- Cells, Cultured MeSH
- Humans MeSH
- Methylmercury Compounds adverse effects metabolism MeSH
- Oxidative Stress * MeSH
- Placenta metabolism MeSH
- Multidrug Resistance-Associated Proteins physiology MeSH
- Dogs MeSH
- Pregnancy MeSH
- Amino Acid Transport Systems metabolism MeSH
- Cell Survival drug effects MeSH
- Animals MeSH
- Check Tag
- Humans MeSH
- Dogs MeSH
- Pregnancy MeSH
- Female MeSH
- Animals MeSH
- Publication type
- Journal Article MeSH
- Research Support, Non-U.S. Gov't MeSH
Large-scale studies are needed to identify the drivers of total mercury (THg) and monomethyl-mercury (MeHg) concentrations in aquatic ecosystems. Studies attempting to link dissolved organic matter (DOM) to levels of THg or MeHg are few and geographically constrained. Additionally, stream and river systems have been understudied as compared to lakes. Hence, the aim of this study was to examine the influence of DOM concentration and composition, morphological descriptors, land uses and water chemistry on THg and MeHg concentrations and the percentage of THg as MeHg (%MeHg) in 29 streams across Europe spanning from 41°N to 64 °N. THg concentrations (0.06-2.78 ng L-1) were highest in streams characterized by DOM with a high terrestrial soil signature and low nutrient content. MeHg concentrations (7.8-159 pg L-1) varied non-systematically across systems. Relationships between DOM bulk characteristics and THg and MeHg suggest that while soil derived DOM inputs control THg concentrations, autochthonous DOM (aquatically produced) and the availability of electron acceptors for Hg methylating microorganisms (e.g. sulfate) drive %MeHg and potentially MeHg concentration. Overall, these results highlight the large spatial variability in THg and MeHg concentrations at the European scale, and underscore the importance of DOM composition on mercury cycling in fluvial systems.
- MeSH
- Water Pollutants, Chemical analysis chemistry MeSH
- Ecosystem MeSH
- Lakes chemistry MeSH
- Methylmercury Compounds analysis chemistry MeSH
- Environmental Monitoring methods MeSH
- Soil chemistry MeSH
- Rivers chemistry MeSH
- Mercury analysis chemistry MeSH
- Publication type
- Journal Article MeSH
- Research Support, Non-U.S. Gov't MeSH
- Geographicals
- Europe MeSH
Concentrations and fluxes of total and methylmercury were determined in surface sediments and associated with settling particles at two sites in Lake Geneva to evaluate the sources and dynamics of this toxic contaminant. Total mercury concentrations measured in settling particles were different throughout the seasons and were greatly influenced by the Rhone River particulate inputs. Total mercury concentrations closer to shore (NG2) ranged between 0.073 ± 0.001 and 0.27 ± 0.01 μg/g, and between 0.038 ± 0.001 and 0.214 ± 0.008 μg/g at a site deeper in the lake (NG3). Total mercury fluxes ranged between 0.144 ± 0.002 and 3.0 ± 0.1 μg/m2/day at NG2, and between 0.102 ± 0.008 and 1.32 ± 0.08 μg/m2/day at NG3. Combined results of concentrations and fluxes showed that total mercury concentrations in settling particles are related to the season and particle inputs from the Rhone River. Despite an observed decrease in total mercury fluxes from the coastal zone towards the open lake, NG3 (~ 3 km from the shoreline) was still affected by the coastal boundary, as compared to distal sites at the center of the lake. Thus, sediment focusing is not efficient enough to redistribute contaminant inputs originating from the coastal zones, to the lake center. Methylmercury concentrations in settling particles largely exceeded the concentrations found in sediments, and their fluxes did not show significant differences with relation to the distance from shore. The methylmercury found associated with settling particles would be related to the lake's internal production rather than the effect of transport from sediment resuspension.
- MeSH
- Water Pollutants, Chemical analysis MeSH
- Geologic Sediments analysis MeSH
- Lakes analysis chemistry MeSH
- Methylmercury Compounds analysis MeSH
- Environmental Monitoring MeSH
- Rivers MeSH
- Seasons MeSH
- Mercury analysis MeSH
- Publication type
- Journal Article MeSH
- Geographicals
- Switzerland MeSH
More than 400 seal mummies and skeletons are now mapped in the northern part of James Ross Island, Antarctica. Decomposing carcasses represent a rare source of both organic matter and associated elements for the soil. Owing to their high trophic position, seals are known to carry a significant mercury body burden. This work focuses on the extent of the mercury input from seal carcasses and shows that such carcasses represent locally significant sources of mercury and methylmercury for the environment. Mercury contents in soil samples from the surrounding areas were determined using a single-purpose AAS mercury analyzer. For the determination of methylmercury, an ultra-sensitive isotopic dilution HPLC-ICP-MS technique was used. In the soils lying directly under seal carcasses, mercury contents were higher, with levels reaching almost 40 μg/kg dry weight of which methylmercury formed up to 2.8 % of the total. The spatial distribution implies rather slow vertical transport to the lower soil layers instead of a horizontal spread. For comparison, the background level of mercury in soils of the investigated area was found to be 8 μg/kg dry weight, with methylmercury accounting for less than 0.1 %. Apart from the direct mercury input, an enhanced level of nutrients in the vicinity of carcasses enables the growth of lichens and mosses with accumulative ability with respect to metals. The enhanced capacity of soil to retain mercury is also anticipated due to the high content of total organic carbon (from 1.6 to 7.5 %). According to the results, seal remains represent a clear source of mercury in the observed area.
The distribution of mercury in surface water and in sediment from Deûle River in Northern France was studied by application of conventional sampling methods and by diffusive gradients in thin films technique (DGT). Concentration of total dissolved mercury in surface water was 20.8 ± 0.8 ng l(-1). The particulate mercury concentration was 6.2 ± 0.6 µg g(-1). The particulate mercury was accumulated in sediment (9.9 ± 2.3 mg kg(-1)), and it was transformed by methylating bacteria to methylmercury, mainly in the first 2-cm layer of the sediment. Total dissolved concentration of mercury in sediment pore water obtained by application of centrifugation extraction was 17.6 ± 4.1 ng l(-1), and it was comparable with total dissolved pore water mercury concentration measured by DGT probe containing Duolite GT-73 resin gel (18.2 ± 4.3 ng l(-1)), taking the sediment heterogeneity and different principles of the applied methods into account. By application of two DGT probes with different resin gels specific for mercury, it was found that approximately 30% of total dissolved mercury in sediment pore water was present in labile forms easy available for biota. The resolution of mercury DGT depth profiles was 0.5 cm, which allows, unlike conventional techniques, to study the connection of the geochemical cycle of mercury with geochemical cycles of iron and manganese.
- MeSH
- Water Pollutants, Chemical analysis MeSH
- Environmental Monitoring methods MeSH
- Mercury analysis MeSH
- Publication type
- Journal Article MeSH
- Research Support, Non-U.S. Gov't MeSH
- Geographicals
- France MeSH
The precise characterization of the behavior of individual microorganisms in the presence of increased mercury contents in soil is necessary for better elucidation of the fate of mercury in the soil environment. In our investigation, resistant bacterial strains isolated from two mercury contaminated soils, represented by Paenibacillus alginolyticus, Burkholderia glathei, Burkholderia sp., and Pseudomonas sp., were used. Two differently contaminated soils (0.5 and 7 mg kg(-1) total mercury) were chosen. Preliminary soil analysis showed the presence of methylmercury and phenylmercury with the higher soil mercury level. Modified rhizobox experiments were performed to assess the ability of mercury accumulating strains to deplete the mobile and mobilizable mercury portions in the soil by modification; microbial agar cultures were used rather than the plant root zone. A sequential extraction procedure was performed to release the following mercury fractions: water soluble, extracted in acidic conditions, bound to humic substances, elemental, and bound to complexes, HgS and residual. Inductively coupled plasma mass spectrometry (ICP-MS) and a single-purpose atomic absorption spectrometer (AMA-254) were applied for mercury determination in the samples and extracts. Gas chromatography coupled to atomic fluorescence spectrometry (GC-AFS) was used for the determination of organomercury compounds. The analysis of the microbial community at the end of the experiment showed a 42% abundance of Paenibacillus sp. followed by Acetivibrio sp., Brevibacillus sp., Cohnella sp., Lysinibacillus sp., and Clostridium sp. not exceeding 2% abundance. The results suggest importance of Paenibacillus sp. in Hg transformation processes. This genus should be tested for potential bioremediation use in further research.
- MeSH
- Bacteria metabolism MeSH
- Biodegradation, Environmental MeSH
- Chromatography, Gas MeSH
- Spectrometry, Fluorescence MeSH
- Soil Pollutants analysis chemistry MeSH
- Methylmercury Compounds analysis chemistry MeSH
- Environmental Monitoring methods MeSH
- Soil Microbiology * MeSH
- Mercury analysis chemistry MeSH
- Mercury Compounds analysis chemistry MeSH
- Spectrophotometry, Atomic MeSH
- Environmental Pollution analysis MeSH
- Publication type
- Journal Article MeSH
- Research Support, Non-U.S. Gov't MeSH
Potentially carcinogenic compounds may cause cancer through direct DNA damage or through indirect cellular or physiological effects. To study possible carcinogens, the fields of endocrinology, genetics, epigenetics, medicine, environmental health, toxicology, pharmacology and oncology must be considered. Disruptive chemicals may also contribute to multiple stages of tumor development through effects on the tumor microenvironment. In turn, the tumor microenvironment consists of a complex interaction among blood vessels that feed the tumor, the extracellular matrix that provides structural and biochemical support, signaling molecules that send messages and soluble factors such as cytokines. The tumor microenvironment also consists of many host cellular effectors including multipotent stromal cells/mesenchymal stem cells, fibroblasts, endothelial cell precursors, antigen-presenting cells, lymphocytes and innate immune cells. Carcinogens can influence the tumor microenvironment through effects on epithelial cells, the most common origin of cancer, as well as on stromal cells, extracellular matrix components and immune cells. Here, we review how environmental exposures can perturb the tumor microenvironment. We suggest a role for disrupting chemicals such as nickel chloride, Bisphenol A, butyltins, methylmercury and paraquat as well as more traditional carcinogens, such as radiation, and pharmaceuticals, such as diabetes medications, in the disruption of the tumor microenvironment. Further studies interrogating the role of chemicals and their mixtures in dose-dependent effects on the tumor microenvironment could have important general mechanistic implications for the etiology and prevention of tumorigenesis.
- MeSH
- Carcinogenesis chemically induced MeSH
- Humans MeSH
- Tumor Microenvironment drug effects MeSH
- Neoplasms chemically induced MeSH
- Hazardous Substances adverse effects MeSH
- Environmental Exposure adverse effects MeSH
- Animals MeSH
- Check Tag
- Humans MeSH
- Animals MeSH
- Publication type
- Journal Article MeSH
- Research Support, Non-U.S. Gov't MeSH
- Review MeSH
- Research Support, N.I.H., Extramural MeSH
Total mercury (Hg) concentrations in hair and urine are often used as biomarkers of exposure to fish-derived methylmercury (MeHg) and gaseous elemental Hg, respectively. We used Hg stable isotopes to assess the validity of these biomarkers among small-scale gold mining populations in Ghana and Indonesia. Urine from Ghanaian miners displayed similar Δ(199)Hg values to Hg derived from ore deposits (mean urine Δ(199)Hg=0.01‰, n=6). This suggests that urine total Hg concentrations accurately reflect exposure to inorganic Hg among this population. Hair samples from Ghanaian miners displayed low positive Δ(199)Hg values (0.23-0.55‰, n=6) and low percentages of total Hg as MeHg (7.6-29%, n=7). These data suggest that the majority of the Hg in these miners' hair samples is exogenously adsorbed inorganic Hg and not fish-derived MeHg. Hair samples from Indonesian gold miners who eat fish daily displayed a wider range of positive Δ(199)Hg values (0.21-1.32‰, n=5) and percentages of total Hg as MeHg (32-72%, n=4). This suggests that total Hg in the hair samples from Indonesian gold miners is likely a mixture of ingested fish MeHg and exogenously adsorbed inorganic Hg. Based on data from both populations, we suggest that total Hg concentrations in hair samples from small-scale gold miners likely overestimate exposure to MeHg from fish consumption.
- MeSH
- Biomarkers analysis metabolism urine MeSH
- Adult MeSH
- Mass Spectrometry MeSH
- Mining * MeSH
- Mercury Isotopes analysis metabolism urine MeSH
- Soil Pollutants analysis metabolism urine MeSH
- Middle Aged MeSH
- Humans MeSH
- Methylmercury Compounds analysis metabolism urine MeSH
- Adolescent MeSH
- Young Adult MeSH
- Environmental Monitoring MeSH
- Occupational Exposure * MeSH
- Mercury analysis metabolism urine MeSH
- Fishes metabolism MeSH
- Hair chemistry MeSH
- Animals MeSH
- Check Tag
- Adult MeSH
- Middle Aged MeSH
- Humans MeSH
- Adolescent MeSH
- Young Adult MeSH
- Male MeSH
- Female MeSH
- Animals MeSH
- Publication type
- Journal Article MeSH
- Research Support, Non-U.S. Gov't MeSH
- Geographicals
- Ghana MeSH
- Indonesia MeSH
