Organic Mercury Levels Research Articles

Chemical threats for the sentinel Pygoscelis adeliae from the Ross Sea (Antarctica): Occurrence and levels of persistent organic pollutants (POPs), perfluoroalkyl substances (PFAS) and mercury within the largest marine protected area worldwide

The Ross Sea Marine Protected Area (RS-MPA) hosts endemic species that have to cope with multiple threats, including chemical contamination. Adèlie penguin is considered a good sentinel species for monitoring pollutants. Here, 23 unhatched eggs, collected from three colonies along the Ross Sea coasts, were analysed to provide updated results on legacy pollutants and establish a baseline for newer ones. Average sum of polychlorinated biphenyls (∑PCBs) at the three colonies ranged 20.9–24.3 ng/g lipid weight (lw) and included PCBs IUPAC nos. 28, 118, 153, 138, 180. PCBs were dominated by hexachlorinated congeners as previously reported. Hexachlorobenzene (HCB) and p,p’-dichlorodiphenyldichloroethylene (p,p’-DDE) ranged between 134 and 166 and 181–228 ng/g lw, respectively. Overall, ∑PCBs was exceeded by pesticides, contrary to previous studies from the Ross Sea. Sum of polybrominated diphenyl ethers (∑PBDEs) ranged between 0.90 and 1.18 ng/g lw and consisted of BDE-47 (that prevailed as expected, representing 60–80 % of the ∑PBDEs) and BDE-85. Sum of perfluoroalkyl substances (∑PFAS) ranged from 1.04 to 1.53 ng/g wet weight and comprised five long-chain perfluorinated carboxylic acids (PFCAs), perfluorooctane sulfonate (PFOS), perfluorohexane sulfonate (PFHxS) and perfluorooctanoic acid (PFOA); perfluorooctane sulfonamide (PFOSA) was also detected. The PFAS profile was dominated by PFCAs as already observed in Arctic seabirds. Mercury ranged from 0.07 to 0.15 mg/kg dry weight similarly to previous studies. Legacy pollutants confirmed their ongoing presence in Antarctic biota and their levels seemed mostly in line with the past, but with minor variations in some cases, likely due to continued input or release from past reservoirs. PFAS were reported for the first time in penguins from the Ross Sea, highlighting their ubiquity. Although further studies would be useful to increase the sample size and accordingly improve our knowledge on spatial and temporal trends, this study provides interesting data for future monitoring programs within the RS-MPA that will be crucial to test its effectiveness against human impacts.

Blood and Urine Inorganic and Organic Mercury Levels in the United States from 1999 to 2016

BackgroundMercury is an environmental hazard. Organic mercury is biologically more toxic than inorganic mercury. Therefore, we studied recent trends in the blood levels of organic and inorganic mercury in the United States. MethodsA total of 56,445 participants that had blood mercury and urine mercury measurements in National Health and Nutrition Examination Survey (NHANES) 1999-2016 were included. The organic mercury level was obtained by subtracting the inorganic mercury level from the total mercury level. Results were analyzed using SPSS complex sample module version 25. Pregnant women, children ages <20 years, and different ethnicities were analyzed as subgroups. ResultsBlood organic mercury level increased from (geometric mean [95% confidence interval]) 0.08 [0.07-0.10] to 0.17 [0.16-0.18] µg/L during 1999-2016. It increased significantly (P <0.001) from 0.03 [0.02-0.03] to 0.07 [0.06-0.07] µg/L in children ages <20 and from 0.14 [0.09-0.21] to 0.36 [0.16-0.83] µg/L in pregnant women in this period (P <0.001). In 2013-2016, non-Hispanic Asians had the highest blood organic mercury level among different ethnicities, 0.93 [0.82-1.05] µg/L (P <0.001). Blood inorganic mercury level decreased from 0.31 [0.31-0.31] in 1999-2000 to 0.21 [0.21-0.22] µg/L in 2015-2016 (P <0.001). Urine mercury level decreased from 0.75 [0.71-0.80] in 1999-2000 to 0.16 [0.16-0.17] µg/L in 2015-2016 (P <0.001). ConclusionBlood organic mercury increased over the period 1999-2016 in the US population, including children and pregnant women, whereas there was a steady decline in both blood inorganic mercury and urine mercury levels.

High pollutant exposure level of the largest European community of bottlenose dolphins in the English Channel

The objective of this study was to assess the levels of persistent organic pollutants (POPs) and mercury (T-Hg) in the blubber and skin, respectively, of the free-ranging bottlenose dolphins, Tursiops truncatus, from the Normanno-Breton Gulf, one of the largest identified coastal population in Europe. Among all the POPs analysed in this study, the ∑NDL-PCBs were the most abundant compounds found in the blubber (mean: 1.33 × 105–0.65 × 105 ng.g−1 lipid weight (lw) for males and females respectively), followed by ∑DDX (1.11 × 104–4.67 × 103 ng.g−1 lw) > ∑DL-PCBs (8.06 × 103–2.62 × 103ng.g−1 lw) > ∑PBDEs (1.95 × 103–0.64 × 103ng.g−1 lw) > dieldrin (1.86 × 103–0.18 × 103 ng.g−1 lw) > ∑endosulfan (405–62 ng.g−1 lw) > HCB (86–52 ng.g−1 lw) > ∑HCHs (47–60 ng.g−1 lw) > ∑chlordane (24–0.97 ng.g−1 lw) > ∑PCDFs (0.3–0.1 ng.g−1 lw) > ∑PCDDs (0.06–0.05 ng.g−1 lw). The T-Hg concentrations were highly variable between individuals (2.45 × 103 ng.g−1 to 21.3 × 103 ng.g−1 dry weight, dw). The reported concentrations are among the highest reported for cetaceans. We strongly recommend that the Normanno-Breton Gulf be a special area of conservation (cSAC) candidate because it contains the last large European population of bottlenose dolphins (rare or threatened within a European context) designated under the EC Habitats Directive.

Spatial variability in total and organic mercury levels in Antarctic krill Euphausia superba across the Scotia Sea

Total and organic mercury concentrations were determined for males, females and juveniles of Euphausia superba collected at three discrete locations in the Scotia Sea (South Orkney Islands, South Georgia and Antarctic Polar Front) to assess spatial mercury variability in Antarctic krill. There was clear geographic differentiation in mercury concentrations, with specimens from the South Orkney Islands having total mercury concentrations 5 to 7 times higher than Antarctic krill from South Georgia and the Antarctic Polar Front. Mercury did not appear to accumulate with life-stage since juveniles had higher concentrations of total mercury (0.071 μg g−1 from South Orkney Islands; 0.014 μg g−1 from South Georgia) than adults (0.054 μg g−1 in females and 0.048 μg g−1 in males from South Orkney Islands; 0.006 μg g−1 in females and 0.007 μg g−1 in males from South Georgia). Results suggest that females may use egg laying as a mechanism to excrete mercury, with eggs having higher concentrations than the corresponding somatic tissue. Organic mercury makes up a minor percentage of total mercury (15–37%) with the percentage being greater in adults than in juveniles. When compared to euphausiids from other parts of the world, the concentration of mercury in Antarctic krill is within the same range, or higher, highlighting the global distribution of this contaminant. Given the high potential for biomagnification of mercury through food webs, concentrations in Antarctic krill may have deleterious effects on long-lived Antarctic krill predators.

Levels of Mercury in Fish-Eating Children, With and Without Amalgam Restoration.

Background:Mercury is a naturally occurring metal that exists in three forms: elemental (metallic), inorganic, and organic mercury. Amalgam, which is an alloy of inorganic mercury, is used as a restorative material in dentistry. Organic mercury gets ingested in the body mainly by the consumption of seafood. Mercury is also stated to cause various adverse health effects such as gastrointestinal disturbances, dermatitis, muscle weakness, and neurological disorders. In recent years, the use of amalgam has become a controversy stating the various adverse effects of mercury. Hence, the study was conducted to determine and compare the variation in levels of organic and inorganic mercury in fish-eating children before and after placement of amalgam restoration.Materials and Methods:Seventy-five subjects, 42 males (56%) and 35 females (44%) of age group ranging 7–13 years, living in South Canara district of Karnataka, India, were selected as a part of the study. Hair and urine samples were collected for estimation of organic and inorganic levels of mercury, respectively. Informed consent was collected from all the participating subjects.Results:On comparison between organic and inorganic mercury levels during the study period, the concentration of organic mercury in hair samples was greater irrespective of amalgam restorations present (1.172 and 0.085, respectively; P < 0.001).Conclusion:Thus inorganic levels of mercury do not seem to pose a threat as much as the organic levels observed in hair, which remain fairly constant for a longer period of time. Hence in a coastal region where this study was undertaken and fish being a staple food, the risk could probably be attributed to more of an organic toxicity than an inorganic one. Thus amalgam is relatively safe to be practiced and the controversy against it should be reevaluated.

Accumulation properties of inorganic mercury and organic mercury in the red-crowned crane Grus japonensis in east Hokkaido, Japan

The red-crowned (Japanese) crane Grus japonensis is native to east Hokkaido, Japan, in contrast to the East Asia mainland. Previously, we reported that red-crowned cranes in Hokkaido were highly contaminated with mercury in the 1990s and that the contamination rapidly decreased to a moderate level in the 2000s. In the present study, we determined levels of organic mercury (O–Hg) in the liver and kidney of cranes in east Hokkaido in comparison with levels of total mercury (T–Hg). T–Hg levels in the kidneys were higher than those in the livers in adults but not in subadults and juveniles; however, the reverse was the case for O–Hg even for adults. The ratio of O–Hg to T–Hg in both the liver and kidney decreased as T–Hg increased in the three developmental stages. While the ratios of O–Hg to T–Hg in the liver and kidney of adults were significantly lower than those of juveniles, the ratios were similar for adults and juveniles in a lower range of T–Hg. The ratio of selenium (Se) to T–Hg decreased as T–Hg increased in both the liver and kidney, irrespective of stages. Mercury burdens in feathers were about 59% and 67% of the total body burdens for juveniles and adults, respectively. Furthermore, ratios of carbon and nitrogen stable isotopes to T–Hg varied greatly, with no relation to mercury level in the liver. The results suggest slow accumulation of inorganic mercury in the kidney of red-crowned cranes in east Hokkaido, Japan.

Demographic, behavioral, dietary, and socioeconomic characteristics related to persistent organic pollutants and mercury levels in pregnant women in Japan

Persistent organic pollutants and mercury are known environmental chemicals that have been found to be ubiquitous in not only the environment but also in humans, including women of reproductive age. The purpose of this study was to evaluate the association between personal lifestyle characteristics and environmental chemical levels during the perinatal period in the general Japanese population. This study targeted 322 pregnant women enrolled in the Hokkaido Study on Environment and Children’s Health. Each participant completed a self-administered questionnaire and a food-frequency questionnaire to obtain relevant information on parental demographic, behavioral, dietary, and socioeconomic characteristics. In total, 58 non-dioxin-like polychlorinated biphenyls, 17 dibenzo-p-dioxins and -dibenzofuran, and 12 dioxin-like polychlorinated biphenyls congeners, perfluorooctane sulfonate, perfluorooctanoic acid, and mercury were measured in maternal samples taken during the perinatal period. Linear regression models were constructed against potential related factors for each chemical concentration. Most concentrations of environmental chemicals were correlated with the presence of other environmental chemicals, especially in the case of non-dioxin-like polychlorinated biphenyls and, polychlorinated dibenzo-p-dioxins and -dibezofurans and dioxin-like polychlorinated biphenyls which had similar exposure sources and persistence in the body. Maternal smoking and alcohol habits, fish and beef intake and household income were significantly associated with concentrations of environmental chemicals. These results suggest that different lifestyle patterns relate to varying exposure to environmental chemicals.

Inorganic and Organic Mercury Levels in the United States National Health and Nutrition Examination Survey (NHANES) 2005-2010

Aims: Mercury is an environmental hazard. Therefore, we studied recent trends in the blood level of organic and inorganic mercury in the United States (US). Methodology: We analyzed newly available data on blood inorganic mercury levels in NHANES 2005-2010. Organic mercury level was calculated by subtracting inorganic mercury level from the total mercury level. As complex sampling was used in NHANES, appropriate weights were used to adjust for oversampling of minorities and sampling from the same location. Results: There were 8364, 8161 and 8727 participants in NHANES 2005-6, 2007-8 and 2009-10 respectively. Inorganic mercury levels (geometric mean [95% confidence intervals]) were 0.31 [0.30-0.32], 0.30 [0.30-0.31], 0.28 [0.27-0.28] µg/L and organic mercury levels were 0.24 [0.190.30], 0.19 [0.14-0.25], 0.27 [0.22-0.33] µg/L in 2005-6, in 2007-8, in 2009-10, respectively. Inorganic mercury levels showed a significant decreasing trend ( P<.05). Organic mercury levels were significantly lower in participants aged <20 compared to those ≥20 years. The adjusted proportion (mean±SE) of participants with a total mercury level ≥5.8µg/L was 3.0±0.2%, 3.5±0.6%,

High Consumption of Farmed Salmon Does Not Disrupt the Steady State of Persistent Organic Pollutants (POP) in Human Plasma and Adipose Tissue

The aims of this study were to (1) determine any changes in the levels of persistent organic pollutants (POP) and mercury (Hg) in human plasma and adipose tissue and (2) examine associations between plasma levels of pollutants and dietary fat intake. Outpatients with different metabolic disorders (n = 42) consumed 380 g of farmed Atlantic salmon fillets or 60 g of salmon oil per week in two study periods of 15 wk each, and were compared with a control group (n = 14). Concentrations of POP and Hg were measured in salmon fillets, salmon oil capsules, plasma and abdominal fat biopsies from patients before and after intervention. Mean concentrations of hexachlorobenzene (HCB), p,p′-DDE, sum of indicator polychlorinated biphenyls (PCB) (id-PCB), and sum polybrominated diphenyl ethers (PBDE) in abdominal fat at intervention start were 21, 191, 267, and 4.2 ng/g lipid weight. After 15 or 30 wk of salmon consumption no significant changes in concentrations of POP and Hg in samples of human plasma and abdominal fat were observed, indicating that steady-state levels of these pollutants were not markedly affected. The lack of significant changes may partly be attributed to a limited number of samples, large interindividual variation in POP levels, and a large age span (20–70 yr). After adjusting for age, significant associations were found between different plasma long-chain fatty acid concentrations, including n-3 and n-6 fatty acids and oleic acid, and some of the POP. The results indicate that the latter have different food products as their main sources of human exposure.

Evidence of elevated mercury levels in carnivorous and omnivorous fishes downstream from an Amazon reservoir

Hydroelectric reservoirs can stratify, producing favorable conditions for mercury methylation in the hypolimnion. The methylmercury (MeHg) can be exported downstream, increasing its bioavailability below the dam. Our objective was to assess the mercury levels in plankton, suspended particulate matter (SPM) and fish collected upstream (UP) and downstream (DW) from the Reservatorio de Samuel dam, an Amazonian reservoir that stratifies during half of the year. Mercury concentrations in both SPM and plankton were similar between the two sites, which could indicate there are no conditions favoring methylation at the moment of sampling (absence of stratification). Almost all mercury found in the muscle of fishes was in organic form, and differences of mercury levels between sites were dependent on the fishes trophic level. Herbivores showed similar mean organic mercury levels (UP = 117 μg g−1; DW = 120 μg g−1; n = 12), whereas omnivores (UP = 142 μg g−1; DW = 534 μg g−1; n = 27) and carnivores (UP = 545 μg g−1; DW = 1,366 μg g−1; n = 69) showed significantly higher values below the dam. The absence of a reservoir effect in herbivores is expected, since they feed on grassy vegetation, near the riverbanks, which is not much influenced by mercury in aquatic systems. On the other hand, the higher mercury levels below the dam observed for omnivores and carnivores suggest a possible influence of the reservoir since they feed on items that could be contaminated by MeHg exported from upstream. The results highlight the necessity of assessing areas downstream of reservoirs.

Relationship of methyl mercury accumulation with lipid and weight in two river cat fish species, Wallagoo attu and Mystus aor, from West Bengal, India

This study focuses on mercury (Hg) bioaccumulation in Indian cat fish, Wallagoo attu and Mystus aor, from different rivers. Methyl mercury (MeHg) concentrations were determined in muscle tissue of two different parts, ventral and dorsal part, of each species and the levels of organic mercury were co-related with lipid content of each part. The MeHg concentrations increased in a linear fashion with both weight and age for these river species. The average concentration of MeHg was found to be 0.93 ± 0.60 and 1.26 ± 0.62 μg Hg g(-1) (expressed in wet weight basis) for ventral and dorsal parts, respectively in W. attu and this was above the 0.25 μg Hg g(-1) of wet weight, the limit set by the Prevention of Food Adulteration Act for the maximum level for consumption of fish exposed to mercury pollution. In M. Aor the concentration of MeHg was not above the standard limit but threatening, it was 0.22 ± 0.07 and 0.23 ± 0.08 μg Hg g(-1) (expressed in wet weight basis) in dorsal and ventral parts, respectively.

Total mercury, methylmercury and ethylmercury in marine fish and marine fishery products sold in Seoul, Korea

In 2009, a survey of 177 samples of fish and fishery products from the markets in Seoul was carried out to investigate total mercury and organic mercury (methylmercury) concentrations and to establish a correlation, if any, between total and organic mercury levels. Concentrations of total and organic mercury in canned tuna ranged 0.001–2.581 and 0.003–1.307 mg/kg, respectively; those for fish, such as cod or salmon, ranged 0.012–2.529 and 0.021–0.507 mg/kg, respectively. Ethylmercury was not detected. More than 50% of total mercury in the samples existed as organic mercury. The correlation coefficients (r 2) between total mercury and methylmercury concentrations of fish and fishery products found to have methylmercury were 0.844 and 0.976, respectively, which was statistically significant. There was a higher correlation in fishery products than in fish. Although there was no product in which mercury exceeded the standard set by the Food Code in 2008, with the exception of marlin steak, a processed food, which contained 1.307 mg/kg methylmercury. None exceeded the provisional tolerable weekly intake (PTWI) for mercury. Collectively, the results indicate that fish or fishery products marketed in Seoul, with the exception of marlin, have low levels of total or organic mercury and, thus, intake of these products is not a risk to public health.

Methyl mercury exposure from fish consumption in vulnerable racial/ethnic populations: Probabilistic SHEDS-Dietary model analyses using 1999–2006 NHANES and 1990–2002 TDS data

NHANES subjects self-identified as “Asian, Pacific Islander, Native American, or multiracial” (A/P/N/M) have higher levels of blood organic mercury than other racial/ethnic groups; however, the reasons for this have been unclear. This research uses exposure modeling to determine the reasons for elevated blood methylmercury (MeHg) levels, and also extends previous analyses of observed NHANES blood levels. The probabilistic SHEDS-Dietary model was applied, using MeHg fish residue data from FDA's Total Diet Study (1990–2002) combined with NHANES/WWEIA (1999–2006) fish consumption data, to generate exposure estimates by race/ethnicity, age group, and fish type. Statistical analyses of blood methylmercury levels in the (6 times larger) 1999–2006 NHANES data were compared against previous published results for 1999–2002 data.The A/P/N/M group has higher fish intake, modeled MeHg exposures, and blood levels than the general population and other racial/ethnic groups. Tuna, other saltwater fish, and other freshwater fish are key food types driving dietary MeHg exposure. The 1–<3years-old A/P/N/M group has the highest mean dietary MeHg intake per body weight (0.06μg/kg/day; ~2.3 times higher than the rest of the population). Fish intake and modeled exposure predictions correlate well with NHANES blood biomarker levels. This study, using the SHEDS-Dietary model with national data, reinforces and expands upon previous observations that dietary exposure via fish consumption is an important route for methylmercury intake by the general population, and especially for racial/ethnic groups with higher fish consumption. These probabilistic dietary modeling approaches could be applied for local populations (e.g., tribes) and other chemicals and foods, if data are available.

Methyl mercury in fish—a case study on various samples collected from Ganges river at West Bengal

This study investigated the presence of total mercury (Hg) and organic mercury levels in the muscle of 19 common fresh water fish species captured from river Ganges, West Bengal, India. The total mercury level found in our study may not cause any toxic effect, but the methyl mercury (MeHg) level in some freshwater fish species was surprisingly very high and toxically unacceptable. The results of mercury analysis in various specimens indicated that some fish muscles tended to accumulate high levels of Hg, and approximately 50-84% of Hg was organic mercury. A strong positive correlation between mercury levels in muscle with food habit and fish length (age) was found. Wallago attu possessed the highest amount of organic mercury in their muscle tissues, and it was 0.93 ± 0.61 μg Hg/g of wet weight. Whereas in small-sized fishes Eutropiichthys murius, Puntius sarana, Cirrhinus mrigala, Mystus vittatus or Mystus gulio, and Tilapia mossambicus, it was below the detection limit. Contamination in Catla catla (0.32 ± 0.11), Anguilla bengalensis bengalensis (0.26 ± 0.07 μg Hg/g), Chitala chitala (0.25 ± 0.18), Rita rita (0.34 ± 0.14), and Ompok pabda (0.26 ± 0.04) was also above the 0.25 μg Hg/g of wet weight, the limit set by the PFA for the maximum level for consumption of fish exposed to MeHg. Though in Labeo rohita (0.12 ± 0.03), Mastacembelus armatus (0.17 ± 0.02), Pangasius pangasius (0.12 ± 0.16), Bagarius bagarius (0.12 ± 0.01), and Clupisoma garua (0.1 ± 0.01), concentration was below the recommended level, in Lates calcarifer (0.23 ± 0.0) and Mystus aor (0.23 ± 0.1), it was threatening. Interestingly, a low concentration of Hg was found in post-monsoon samples.

Organic and total mercury levels in bigeye tuna, Thunnus obesus, harvested by Taiwanese fishing vessels in the Atlantic and Indian Oceans

Muscle samples of 121 and 110 bigeye tuna (Thunnus obesus) caught by Taiwanese long-line fishing vessels in the Atlantic and Indian Oceans, respectively, were used to analyze total mercury (THg) and organic mercury (OHg) content. The overall THg and OHg concentrations were 0.786 ± 0.386 (0.214–3.133) and 0.595 ± 0.238 (0.143–2.222) mg kg−1 wet weight, respectively, similar to the results of previous studies. Our findings, however, reflected the highest THg and OHg concentrations for the species in each ocean among the published data. Mean THg and OHg concentrations in Atlantic tuna were significantly (p < 0.05) higher than those in Indian tuna. Two of 121 samples of tuna from the Atlantic Ocean, but no samples from the Indian Ocean, had levels of OHg above 2 mg kg−1 wet weight set by the Department of Health Taiwan, and 13 of 121 samples of tuna from the Atlantic Ocean and three of 110 samples from the Indian Ocean had levels of OHg above 1 mg kg−1 wet weight set by US FDA and WHO. Accordingly, for adult Taiwanese men and women with average body weight of 65 and 55 kg, respectively, the maximum allowable weekly intake of bigeye tuna is suggested to be 170 and 145 g, respectively.

Levels of organic and inorganic mercury in human blood predicted from measurements of total mercury

The toxicologically relevant mercury species inorganic and organic Hg in blood are frequently determined by separate measurements of total Hg and of inorganic Hg, with their difference indicating organic Hg. It is shown that the different partition of inorganic and organic Hg between erythrocytes and plasma (e/p ratio) can be used to calculate the concentrations of either Hg species in either blood constituent from measurement of total Hg only. This was tested on the blood of different groups of volunteers. The calculated concentrations of inorganic and organic Hg in cells and plasma were then compared by linear regression with their previously measured counterparts. An accurate prediction has been found for individual levels of inorganic Hg in plasma and organic Hg in cells. These calculated levels were little affected by variations of the e/p ratios. The coincidence between calculated and measured levels of inorganic Hg in cells and organic Hg in plasma was more sensitive to alterations of the e/p ratios. In conclusion, the relevant concentrations of inorganic Hg in plasma and organic Hg in cells can reliably be calculated from measurements of total Hg and from assumed e/p ratios. This means a sizeable reduction of analytical work, and also provides specific information in cases of low-level co-exposure to both Hg species. Besides the possibility to introduce automated analyses of total Hg in mercury speciation in blood, the proposed calculation scheme has the potential to easily enlarge the data base in epidemiological and toxicological surveys of mercury exposure.

Thimerosal distribution and metabolism in neonatal mice: comparison with methyl mercury

Thimerosal, which releases the ethyl mercury radical as the active species, has been used as a preservative in many currently marketed vaccines throughout the world. Because of concerns that its toxicity could be similar to that of methyl mercury, it is no longer incorporated in many vaccines in the United States. There are reasons to believe, however, that the disposition and toxicity of ethyl mercury compounds, including thimerosal, may differ substantially from those of the methyl form. The current study sought to compare, in neonatal mice, the tissue concentrations, disposition and metabolism of thimerosal with that of methyl mercury. ICR mice were given single intramuscular injections of thimerosal or methyl mercury (1.4 mg Hg kg(-1)) on postnatal day 10 (PND 10). Tissue samples were collected daily on PND 11-14. Most analysed tissues demonstrated different patterns of tissue distribution and a different rate of mercury decomposition. The mean organic mercury in the brain and kidneys was significantly lower in mice treated with thimerosal than in the methyl mercury-treated group. In the brain, thimerosal-exposed mice showed a steady decrease of organic mercury levels following the initial peak, whereas in the methyl mercury-exposed mice, concentrations peaked on day 2 after exposure. In the kidneys, thimerosal-exposed mice retained significantly higher inorganic mercury levels than methyl mercury-treated mice. In the liver both organic and inorganic mercury concentrations were significantly higher in thimerosal-exposed mice than in the methyl mercury group. Ethyl mercury was incorporated into growing hair in a similar manner to methyl mercury. The data showing significant kinetic differences in tissue distribution and metabolism of mercury species challenge the assumption that ethyl mercury is toxicologically identical to methyl mercury.

Mercury Levels in Mothers

Vol. 112, No. 17 PerspectivesOpen AccessMercury Levels in Mothers Katherine M. Shea Katherine M. Shea Search for more papers by this author Published:1 December 2004https://doi.org/10.1289/ehp.112-a978aAboutSectionsPDF ToolsDownload CitationsTrack Citations ShareShare onFacebookTwitterLinked InReddit I read with great interest the excellent article by Mahaffey et al. (2004), which further describes the characteristics of the 1,709 women from the National Health and Nutrition Examination Survey (NHANES) 1999–2000 who were sampled for total and organic mercury levels in blood. It adds valuable detail to the initial report published last year (Schober et al. 2003). I would appreciate clarification on one important point: in the “Discussion,” the authors cited a new analysis which indicates that the cord blood:maternal blood ratio is not 1:1 as assumed by the National Research Council (NRC) in 2000 (Committee on the Toxicological Effects of Methylmercury 2000), but rather 1.7:1. Using the same benchmark dose lower limit and uncertainty factor used by the NRC, Mahaffey et al. (2004) calculated that blood total mercury levels > 3.5 μg/L in mothers could be associated with increased risk to the developing fetal nervous system. I am very interested in the details of this analysis and particularly in understanding why the uncertainty factor applied by the NRC to account in part for toxicokinetic variability does not compensate for uncertainty related to the cord blood:maternal blood mercury ratio. This is a critical concept because it has a dramatic impact on how many women may carry mercury levels in excess of what is believed to be safe for a fetus.ReferencesCommittee on the Toxicological Effects of Methylmercury, Board on Environmental Studies and Toxicology, Commission on Life Sciences, National Research Council 2000. Toxicological Effects of Methylmercury. Washington, DC:National Academy Press. Available: http://www.nap.edu/books/0309071402/html/ [accessed 28 October 2004]. Google ScholarMahaffey KR, Clickner RP, Bodurow CC. 2004. Blood organic mercury and dietary mercury intake: National Health and Nutrition Examination Survey, 1999 and 2000. Environ Health Perspect 112:562-57015064162. Link, Google ScholarSchober SE, Sinks TH, Jones RL, Bolger PM, McDowell M, Osterloh Jet al.. 2003. Blood mercury levels in U.S. children and women of childbearing age, 1999–2000. JAMA 289:1667-167412672735. Crossref, Medline, Google ScholarFiguresReferencesRelatedDetails Vol. 112, No. 17 December 2004Metrics About Article Metrics Publication History Originally published1 December 2004Published in print1 December 2004 Financial disclosuresPDF download License information EHP is an open-access journal published with support from the National Institute of Environmental Health Sciences, National Institutes of Health. All content is public domain unless otherwise noted. Note to readers with disabilities EHP strives to ensure that all journal content is accessible to all readers. However, some figures and Supplemental Material published in EHP articles may not conform to 508 standards due to the complexity of the information being presented. If you need assistance accessing journal content, please contact [email protected]. Our staff will work with you to assess and meet your accessibility needs within 3 working days.

Organic mercury levels among the Yanomama of the Brazilian Amazon Basin.

The Catrimani River basin in northern Brazil is the home of the Yanomama and has been the site of renegade gold mining since 1980. Gold-mining operations release inorganic mercury (Hg) into the environment where it is organified and biomagnified in aquatic ecosystems. Ingestion of mercury-contaminated fish poses a potential hazard to fish-eating populations such as the Yanomama. We surveyed Hg levels in Yanomama villagers living near mined and unmined rivers in 1994 and 1995, and analyzed Hg levels in piranha caught by villagers. In 1994, 90 Yanomama Indians from 5 villages and in 1995, 62 Yanomama Indians from 3 villages participated in the studies. Four villages surveyed in 1994 were located directly on the Catrimani River, approximately 140-160 km downstream from past gold-mining activities. The other village surveyed in 1994 was situated on the unmined Ajaraní River. In 1995, 2 of the Catrimani River villages were revisited, and a third Yanomama village, on the unmined Pacu River, was surveyed. Blood organic mercury levels among all villagers surveyed ranged from 0 to 62.6 microg L(-1) (mean levels in each village between 21.2 microg L(-1) and 43.1 microg L(-1)). Mercury levels in piranha from the mined Catrimani River ranged from 235 to 1084 parts per billion (ppb). Nine of 13 piranhas, measuring 30 cm or longer had total mercury levels which exceeded mercury consumption limits (500 ppb) set by both the World Health Organization and the Brazilian Ministry of Health. Unexpectedly, high mercury levels were also observed in fish and villagers along the unmined Ajaraní and Pacu Rivers suggesting that indirect sources may contribute to environmental mercury contamination in the Amazon basin.

Biological approaches for disposing and reusing chemical wastewater

A serial study on the integrated disposal and utilization of chemical industrial wastewater containing high levels of organic compounds, mercury, nutrients and chlorides was carried out with biological approaches in Hangu region, Tianjin city, China. Results indicated that the quality of wastewater could be improved by a biological stabilization pond system under appropriate load of organic matter and well operation. The effluent from this stabilization pond could not be used for irrigation due to high salinity, but it may be used for fish culture. Because of high levels of mercury, the fish living in this effluent could not be used as food for both humans and breeding sables ( Martes zibellina L.) whereas it could be served as a part of diet for growing sables. Results demonstrated that this chemical wastewater could be controlled and reused through ecological techniques combined with environmental engineering approaches. This system could improve environmental quality and enhance economic.