Derivation and validation of thresholds of cadmium, chromium, lead, mercury and arsenic for safe rice production in paddy soil.

Cadmium (Cd), chromium (Cr), lead (Pb), mercury (Hg) and arsenic (As) are potent toxicants to human health via dietary intake. It is imperative to establish accurate soil thresholds based on soil-plant transfer models and food safety standards for safe agricultural production. This study takes rice genotypes and soil properties into account to derive soil thresholds for five heavy metal(loid)s using the bioconcentration factors (BCF) and species sensitivity distribution (SSD) based on the food safety standard. The BCF generated from two paddy soils was calculated to investigate the sensitivity of heavy metal accumulation in nine rice cultivars in a greenhouse pot experiment. Then, empirical soil-plant transfer models were developed from a middle-sensitivity rice cultivar (Denong 2000, one selected from nine rice) grown in nineteen paddy soils with various soil properties under a proper exogenously metal(loid)s concentration gradient. After normalization, hazardous concentrations from the fifth percentile (HC5) were calculated from the SSD curves, and the derived soil thresholds were obtained from HC5 prediction models that based on the combination of pH and organic carbon (OC) or cation exchange capacity (CEC). The soil Cd threshold derived based on pH and organic carbon (pH < 7.5, OC ≥ 20 g kg-1) was 1.3-fold of those only considering pH, whereas the Pb threshold (pH > 6, CEC ≥ 20 cmolc kg-1) was 3.1 times lower than the current threshold. The derived thresholds for five elements were validated to be reliable through literature data and field experiments. The results suggested that deriving soil heavy metal(loid)s threshold using SSD method and local food safety standards is feasible and also applicable to other crops as well as other regions with potential health risks of toxic elements contamination in agricultural production.

Potato (Solanum tuberosum L.) can be grown safety on human consumption in slight Hg-contaminated soils across China mainland.

Mercury (Hg) exposure poses serious health risks to humans, resulting in extensive investigations examining Hg accumulation, biotransformation and uptake in crops. In this investigation, Hg accumulation in potato tubers due to bioaccumulation processes was determined and bioconcentration factors affecting bioaccumulation were identified using a greenhouse experiment. Our results showed that the percentage of available Hg concentrations from total Hg in soil samples were less than 1.2%, indicating that soils used in our experiment exhibited a high binding strength for Hg, with alkaline soil recording the lowest available Hg/total Hg ratio. Results indicated that soil type and Hg treatment, as well as their interactions, significantly affected Hg accumulation in potato tubers (P < 0.01). Importantly, our results also indicated that potatoes grown in soil with a Hg concentration two times higher than the Chinese Environmental Quality Standard exhibited no obvious toxic effects on humans; Bioconcentration factors (BCF) values (<0.04) suggested that potatoes can be considered as a low Hg accumulating species and suitable for human consumption. Potato yields in acidic soil were lower than those in neutral or alkaline soils, making this medium unsuitable for growth.

Avaliação da concentração de mercúrio em rações caninas comercializadas em Niterói, Rio de Janeiro / Evaluation of the mercury concentration in canine feeds sold in Niterói, Rio de Janeiro

Dentre os metais pesados de maior preocupação para saúde humana e animal, tem-se o mercúrio, cuja forma orgânica é a mais agressiva aos sistemas. A fonte mais comum de adquirir tal metal é através do consumo de pescado e seus derivados, sendo que para os pets (animais de companhia) a ingestão é via rações formuladas com tal matriz alimentar. Logo, foram feitas análises através do DMA 80 de tal elemento em distintas rações comerciais no município de Niterói para avaliar a qualidade do produto ofertado. Os resultados para as rações úmidas de peixe apresentaram 80% em desacordo com a legislação vigente para alimentos humanos, sendo necessário mais estudos e uma legislação específica para mercúrio para alimentação animal.

Concentração de mercúrio total em atum enlatado comercializado no município do Rio de Janeiro: risco potencial à saúde? / Concentration of total mercury in canned tuna marketed in the city of Rio de Janeiro

Este estudo determinou o teor total de mercúrio (HgT) em 69 atuns em conserva de 13 marcas comercializadas no sudoeste do Brasil. Todos os valores são reportados em µg.g-1 de peso úmido. O potencial de risco para a saúde foi estimado com base na concentração de mercúrio e consumo médio (175 g / semana) de peixes no Brasil em comparação com ISPT de 1,6 µg.kg-1 (FAO / WHO, 2010). Uma grande variação na concentração de mercúrio em diferentes espécies foi observada. A concentração média de mercúrio foi de 0,256 ± 0,215 µg.g-1 com maior valor de 1,060 µg.g-1 em uma única lata. Em geral, a concentração média foi inferior à legislação de 1,0 µg.g-1 para espécies predadoras (BRASIL, 2014). A ingestão semanal estimada (EIS) variou de 0,2 a 1,7 µg.kg-1. Para as marcas analisadas de consumo de peixe no Brasil, não há ocorrência de risco à saúde humana. No entanto, uma marca foi superior a ISPT de 1,6 µg.kg-1, não mostrando segurança para o grupo de risco específico. Serão necessários mais estudos, incluindo dados específicos sobre o consumo de atum em conserva em populações específicas, bem como o tipo de peixe, tamanho e local de pesca.

Total Mercury Determination in Muscle and Liver Tissue Samples from Brazilian Amazon Fish Using Slurry Sampling.

This paper presents a slurry sampling method for total mercury determination by graphite furnace atomic absorption spectrometry (GFAAS) in tissue of fish from the Amazon. The tissue samples were lyophilized and macerated, and then the slurry samples were prepared by putting 20 mg of tissue, added to a solution containing Triton X-100, Suprapur HNO3, and zirconium nitrate directly in sampling vials of a spectrometer. Mercury standard solutions were prepared under the same conditions as the slurry samples. The slurry samples and the mercury standard solutions were sonicated for 20 s. Twenty microliters of slurry samples were injected into the graphite tube, which contained an internal wall lined with tungsten carbide. Under these conditions, it was possible to thermally stabilize the mercury up to an atomization temperature of 1700 °C. The method was validated by mercury determination in reference materials DORM-4 and DOLT-4. The LOD and LOQ were 0.014 and 0.045 mg kg-1, respectively, and recovery percentages in relation to the concentration values were certified in the order of 98%.

Development of a Common Procedure for the Determination of Methylmercury, Ethylmercury, and Inorganic Mercury in Human Whole Blood, Hair, and Urine by Triple Spike Species-Specific Isotope Dilution Mass Spectrometry.

We report the first common methodology for the simultaneous determination of methylmercury (MeHg), ethylmercury (EtHg), and inorganic mercury (Hg(II)) in human blood hair and urine. With the exception of the initial sample mass (0.15 g for blood, 0.5 g for urine, and 0.1 g for hair), the same sample preparation and gas chromatography-inductively coupled plasma mass spectrometry (GC-ICPMS) measurement conditions are employed for the three matrixes providing experimental values in agreement with the certified values in the analysis of NIST SRM 955c (Caprine Blood) Level 3 and the certified human hairs IAEA 085 and IAEA 086. Also, the method provides quantitative recoveries for the three Hg species in the analysis of fortified human urine samples at 1, 2, and 5 ng Hg g-1. Mercury species concentrations for levels 2 and 4 of SRM 955c are reported here for the first time. A systematic interconversion of EtHg into Hg(II) was obtained for all matrixes reaching values up to 95% in blood, 29% in hair, and 11% in urine. MeHg dealkylation was also observed in a lesser extent in blood and hair analyses, but it was not observed when analyzing urine samples. Hg methylation was not observed in any matrix. The amount of NaBPr4 added for derivatization has been found to be the main factor responsible for Hg species interconversion. This work demonstrates for the first time that experimental conditions optimized for SRM 955c (caprine blood) are not valid for human blood samples as the optimum initial sample amount for a real sample is more than 3 times lower than that for SRM 955c.

Temporal variability of blood lead, mercury, and cadmium levels in elderly panel study (2008-2014).

BACKGROUND: Biological measurements have been employed as useful biomarkers for exposure. Because of its property of reflecting toxicokinetic differences, however, within-subject variability leads to biased results in epidemiologic studies. METHOD: We examined the variability of lead (Pb), mercury (Hg), and cadmium (Cd) levels in blood samples from 1429 participants among 1677 elderly individuals aged over 60 years who lived in an urban area from August 2008 to April 2015. RESULTS: The geometric means of blood Pb, Hg, Cd were 1.92µg/dL, 2.48µg/L, and 1.33µg/L, and the intra-class correlations (ICCs) were 0.81, 0.71, and 0.83, respectively. The mean values of Pb and Hg levels in this study were lower than the results from single spot samples in other national biomonitoring surveys in Korea, with the exception of Cd was higher than those in other studies. Moreover, the predicted exceedances over the guidance levels for Pb, Hg, and Cd were 1.9%, 4.2%, and 0.3%, respectively. CONCLUSION: Korean elderly were exposed to high levels of Pb, Hg and Cd. Especially, those who had high levels of Cd were continuously exposed to Cd during study period with the 6 collection intervals. Therefore, factors affecting environmental Cd exposure should be further studied in the future.

On the use of certified reference materials for assuring the quality of results for the determination of mercury in environmental samples.

This work focused on the development and validation of methodologies for the accurate determination of mercury in environmental samples and its further application for the preparation and certification of new reference materials (RMs). Two certified RMs ERM-CC580 (inorganic matrix) and ERM-CE464 (organic matrix) were used for the evaluation of digestion conditions assuring the quantitative recovery of mercury. These conditions were then used for the digestion of new candidates for the environmental RMs: bottom sediment (M_2 BotSed), herring tissue (M_3 HerTis), cormorant tissue (M_4 CormTis), and codfish muscle (M_5 CodTis). Cold vapor atomic absorption spectrometry (CV AAS) and inductively coupled plasma mass spectrometry (ICP MS) were used for the measurement of mercury concentration in all RMs. In order to validate and assure the accuracy of results, isotope dilution mass spectrometry (IDMS) was applied as a primary method of measurement, assuring the traceability of obtained values to the SI units: the mole, the kilogram, and the second. Results obtained by IDMS using n(200Hg)/n(202Hg) ratio, with estimated combined uncertainty, were as follows: (916 ± 41)/[4.5 %] ng g-1 (M_2 BotSed), (236 ± 14)/[5.9 %] ng g-1 (M_3 HerTis), (2252 ± 54)/[2.4 %] ng g-1 (M_4 CormTis), and (303 ± 15)/[4.9 %] ng g-1 (M_CodTis), respectively. Different types of detection techniques and quantification (external calibration, standard addition, isotope dilution) were applied in order to improve the quality of the analytical results. The good agreement (within less than 2.5 %) between obtained results and those derived from the Inter-laboratory Comparison, executed by the Institute of Nuclear Chemistry and Technology (Warsaw, Poland) on the same sample matrices, further validated the analytical procedures developed in this study, as well as the concentration of mercury in all four new RMs. Although the developed protocol enabling the metrological certification of the reference value was exemplified by the determination of mercury in environmental samples, it could be considered as valid for any certification procedure required whenever new certified RMs are introduced.

[The approach to the regulation of mercury according to the content of its termoforms in soils and bed loads].

The article contains the results of the ecological and hygienic diagnostics of conditions of lands of areas of different sizes and varying degrees of urbanization, located in different agro-climatic conditions of European Russia (the southern Astrakhan region, he city of Moscow). Assessments of the state of territories use a new approach to rationing of Hg according to quantitative ratios of the content of its thermoforms in soils, grounds and alluvium (in litho substrate). The method of diagnostics is based on known properties of Hg forms: their geochemical activity (migration mobility) and toxicity decline along with the increment of the Hg temperature threshold of the release in the process of continuous warming up of the litho substrate sample (up to 1100°C). Thermoforms are not tied to specific minerals or chemicals and are conditionally designated as FR (Free: <180°C), CL (Chloride: 180-250°C), FS and CS (physically and chemically sorbed: 250-400°C), SU (Sulfide: 400-500°C) IS (isomorphic: >500°C) Hg forms. Among forms, also conditionally according to complexes of low, medium and high temperature variations(FR + CL, FS + CS and SU + IZ, respectively, there are selected groups of «mobile¼, «sustainable¼ and «inert¼ forms. For technogenic Hg there is characterized the predominance in the sample of «mobile¼ and to lesser extent degree - «stable¼ thermoforms. The more intensive this predominance is, the higher is environmental hazard. The natural accumulation is diagnosed by the presence and prevalence of the sum of moderate - and high-temperature inert forms of Hg. According to the ratios of Hg content, its forms and groups, as well as the density of correlationships between them, 6 indices of the conditions of soils and alluvium were developed by ourselves.Main coefficients out of indices on informativeness of results of diagnostics are the following factors: Endogenous input, Geochemical activity and Hg mobility. With regard to the combination of variability in indices, the total amount of Hg, the genesis and intensity of its accumulation (natural or anthropogenic), there were also developed ranking scales of the ecological and hygienic condition of the land areas and surface water bodies. As a result, on the base of such approach to the regulation of Hg the information value of assessments of mercury contamination of land significantly increased. At the objects of assessments there were identified following areas: foci of the manifestation of Hg hypolimnetic emanations on the landscape surface - dispersion halos in the areas of the Earth crust fracture (the dome of the Astrakhan gas condensate field); environmentally dangerous (sometimes even at a low total content of Hg) parts of cities, towns, their districts, as well as beds of watercourses and water reservoirs bottom (the Volga river valley and delta, the Lefortovo quarter in Moscow). There was also diagnosed the threshold of the background distribution of gross Hg content detected = 0.2-0.3 mg/kg. Its magnitude is consistent with domestic and abroad safe levels of Hg accumulation in soils = 0.3-0.4 mg/kg. The approach provides the differentiation of the environmental hazard lands. Technology of the approach can be used in the development of normative Document for the diagnosis of environmental and sanitary condition of territories in the system of Classifications of hazard of waste, in decontamination of territories, water areas and land zoning according to the criteria of natural or anthropogenic Hg accumulation.

Critical perspectives on mercury toxicity reference values for protection of fish.

Environmental management decisions at mercury-contaminated sediment sites are predicated on the understanding of risks to various receptors, including fish. Toxicity reference values (TRVs) for interpreting risks to fish have been developed to assess mercury concentrations in fish or fish prey. These TRVs were systematically evaluated based on several lines of evidence. First, their conceptual basis and specific derivation were evaluated, including a close review of underlying toxicity studies. Second, case studies were reviewed to investigate whether TRVs are predictive of effects on fish populations in the field. Third, TRVs were compared with available information regarding preindustrial and present-day background concentrations of mercury in fish. The findings show that existing TRVs are highly uncertain, because they were developed using limited data from studies not designed for TRV derivation. Although field studies also entail uncertainty, several case studies indicate no evidence of adverse effects despite mercury exposures that exceed the available TRVs. Some TRVs also fall within the range of background mercury concentrations in predatory or prey fish. Lack of information on the selenium status of mercury-exposed fish is a critical confounding factor, and the form of methylmercury used in toxicity testing may also contribute to differences between TRV-based predictions and field observations of mercury effects on fish. On balance, the available information indicates that several of the TRVs reviewed are lower than necessary to protect fish populations. The 20% effect concentration from a previously published dose-response analysis appears closer to an effect threshold, based on available laboratory data. Additional research is needed to provide a stronger basis to establish dose-response relationships for mercury effects on fish.

Potential health consequences of applying mercury-containing skin-lightening creams during pregnancy and lactation periods.

Many studies have highlighted the widespread use of skin-lightening creams containing mercury by women during and after pregnancy to remove dark spots. Women, especially pregnant and lactating mothers using these products are at risk of mercury poisoning because sometimes it has no clinical symptoms, particularly during early exposure. Studies have shown that prenatal and postnatal mercury exposure can cause permanent neurological damage in children. Furthermore, mercury can cause women infertility and birth defects. Even though several studies have examined the reproductive and/or developmental consequences of gestational and lactational mercury exposure from fish consumption and/or dental amalgam, no studies have assessed the possible effects of the long-term use of mercury-containing skin-lightening products by women of childbearing age on their pregnancy outcome and children's health. This commentary aims to collate information on the popular use of mercury-containing skin-lightening creams and sheds the light to the readers about the limitations of the available data on its impact during a prenatal and/or postnatal period. There is an urgent need to assess the adverse health effects of applying these products during pregnancy or lactation on child growth and development through birth cohort studies. Until data from these studies are available, women should be advised not to use topical skin-lightening creams during pregnancy and lactation.

Dietary intake of trace elements by the population of Catalonia (Spain): results from a total diet study.

This study aimed to analyse the concentrations of Al, Ba, Bi, Cu, Cr, Ge, Mn, Mo, Ni, Sb, Se, Sr and Zn in food samples collected in 2008 in Catalonia (Spain). The dietary intake of these 13 trace elements was subsequently estimated by different age-gender groups of the population: children, adolescents, adults and seniors. In general terms, fish and shellfish, cereals, and pulses were the food groups showing the highest levels for most elements. Higher dietary intakes were associated with male groups (adolescents, adults and seniors). However, none exceeded the tolerable levels. When exposure was estimated based on body weight, children were the group with the highest dietary intake. Notwithstanding, only the weekly intake of Al by children exceeded the recommendations of the European Food Safety Authority (EFSA). It is a consequence of the higher intake of cereals in relation to their respective body weights. In addition to the periodical food surveillance of toxic metals (As, Cd, Hg and Pb), it is also important to determine the levels of other trace elements in order to ensure that the dietary exposure by the Catalan population is under control.

The heavy metals cadmium, lead and mercury in raw materials of animal origin: evaluation of data from practice.

Raw materials from animal origin are widely used in homoeopathy. Due to the lack of dedicated limits, the quality requirements for herbal drugs of the European Pharmacopoeia (Ph. Eur.) and/or the German Homoeopathic Pharmacopoeia (Homöopathisches Arzneibuch, HAB), including limits for heavy metals such as cadmium, lead and mercury, have been applied. A recent database evaluation shows that for some raw materials of animal origin the Ph. Eur. limits for herbal drugs cannot be met in practice. For this reason proposals for new limits for cadmium, lead and mercury are made based on recent experiences from the companies' daily practice. These specific limits are suggested to be included in the individual monographs of the Ph. Eur. or at least the German HAB, respectively, for Ambra grisea, Euspongia officinalis, Formica rufa and Sepia officinalis.

Determination of methylmercury in marine sediment samples: method validation and occurrence data.

The determination of methylmercury (MeHg) in sediment samples is a difficult task due to the extremely low MeHg/THg (total mercury) ratio and species interconversion. Here, we present the method validation of a cost-effective fit-for-purpose analytical procedure for the measurement of MeHg in sediments, which is based on aqueous phase ethylation, followed by purge and trap and hyphenated gas chromatography-pyrolysis-atomic fluorescence spectrometry (GC-Py-AFS) separation and detection. Four different extraction techniques, namely acid and alkaline leaching followed by solvent extraction and evaporation, microwave-assisted extraction with 2-mercaptoethanol, and acid leaching, solvent extraction and back extraction into sodium thiosulfate, were examined regarding their potential to selectively extract MeHg from estuarine sediment IAEA-405 certified reference material (CRM). The procedure based on acid leaching with HNO3/CuSO4, solvent extraction and back extraction into Na2S2O3 yielded the highest extraction recovery, i.e., 94±3% and offered the possibility to perform the extraction of a large number of samples in a short time, by eliminating the evaporation step. The artifact formation of MeHg was evaluated by high performance liquid chromatography coupled to inductively coupled plasma mass spectrometry (HPLC-ICP-MS), using isotopically enriched Me(201)Hg and (202)Hg and it was found to be nonexistent. A full validation approach in line with ISO 17025 and Eurachem guidelines was followed. With this in mind, blanks, selectivity, working range (1-800 pg), linearity (0.9995), recovery (94-96%), repeatability (3%), intermediate precision (4%), limit of detection (0.45 pg) and limit of quantification (0.85 pg) were systematically assessed with CRM IAEA-405. The uncertainty budget was calculated and the major contribution to the combined uncertainty (16.24%, k=2) was found to arise from the uncertainty associated with recovery (74.1%). Demonstration of traceability of measurement results is also presented. The validated measurement procedure was applied to the determination of MeHg incurred in sediments from a highly polluted and scarcely studied area in the Caribbean region.

New science challenges old notion that mercury dental amalgam is safe.

Mercury dental amalgam has a long history of ostensibly safe use despite its continuous release of mercury vapor. Two key studies known as the Children's Amalgam Trials are widely cited as evidence of safety. However, four recent reanalyses of one of these trials now suggest harm, particularly to boys with common genetic variants. These and other studies suggest that susceptibility to mercury toxicity differs among individuals based on multiple genes, not all of which have been identified. These studies further suggest that the levels of exposure to mercury vapor from dental amalgams may be unsafe for certain subpopulations. Moreover, a simple comparison of typical exposures versus regulatory safety standards suggests that many people receive unsafe exposures. Chronic mercury toxicity is especially insidious because symptoms are variable and nonspecific, diagnostic tests are often misunderstood, and treatments are speculative at best. Throughout the world, efforts are underway to phase down or eliminate the use of mercury dental amalgam.

A baseline study of levels of mercury, arsenic, cadmium and lead in Northeast Arctic cod (Gadus morhua) from different parts of the Barents Sea.

This study is one of several baseline studies that will provide basic and reliable information about the content of undesirable substances in important species of fish caught in Norwegian waters. Concentrations of metals in the muscle and liver of more than 800 Northeast Arctic cod caught at 32 sites in the Barents Sea are reported. The highest concentration of both mercury in the muscle and cadmium in the liver was found in cod caught in the western part of the Barents Sea, while the highest concentration of total arsenic was found in cod from the eastern part. The arsenic concentrations varied greatly among individual fish, ranging from 0.3 to 170 mg kg(-1) wet weight in the muscle. Such high levels of total arsenic have never previously been reported in any fish, and the primary factor for these high concentrations is likely to be the shrimp in the cod diet.

Control strategies of atmospheric mercury emissions from coal-fired power plants in China.

Atmospheric mercury (Hg) emission from coal is one of the primary sources of anthropogenic discharge and pollution. China is one of the few countries in the world whose coal consumption constitutes about 70% of total primary energy, and over half of coals are burned directly for electricity generation. Atmospheric emissions of Hg and its speciation from coal-fired power plants are of great concern owing to their negative impacts on regional human health and ecosystem risks, as well as long-distance transport. In this paper, recent trends of atmospheric Hg emissions and its species split from coal-fired power plants in China during the period of 2000-2007 are evaluated, by integrating each plant's coal consumption and emission factors, which are classified by different subcategories of boilers, particulate matter (PM) and sulfur dioxide (SO2) control devices. Our results show that the total Hg emissions from coal-fired power plants have begun to decrease from the peak value of 139.19 t in 2005 to 134.55 t in 2007, though coal consumption growing steadily from 1213.8 to 1532.4 Mt, which can be mainly attributed to the co-benefit Hg reduction by electrostatic precipitators/fabric filters (ESPs/FFs) and wet flue gas desulfurization (WFGD), especially the sharp growth in installation of WFGD both in the new and existing power plants since 2005. In the coming 12th five-year-plan, more and more plants will be mandated to install De-NO(x) (nitrogen oxides) systems (mainly selective catalytic reduction [SCR] and selective noncatalytic reduction [SNCR]) for minimizing NO(x) emission, thus the specific Hg emission rate per ton of coal will decline further owing to the much higher co-benefit removal efficiency by the combination of SCR + ESPs/FFs + WFGD systems. Consequently, SCR + ESPs/FFs + WFGD configuration will be the main path to abate Hg discharge from coal-fired power plants in China in the near future. However advanced specific Hg removal technologies are necessary for further reduction of elemental Hg discharge in the long-term.