Elevated Mercury Levels Research Articles

Emerging Problems with Mercury in Cambodia

Background: Development of Cambodia is proceeding quickly with deforestation and hydroelectric dams potentially exacerbating mercury contamination from gold mines. Furthermore, mercury in consumer goods also threatens to compromise the health of Cambodians. Objectives: It is important to provide essential information on sources and pathways of mercury so that Cambodians can avoid exposure to elevated levels of mercury and to support informed decision making about management of consumer goods and the environment. Methods: We review current data available from our projects and the literature, compare the effects of similar development elsewhere, and discuss relevant methods to mitigate damage. Discussion: The mercury used by artisanal miners to extract gold contaminates thou- sands of miners. The extent of the toxic zone from gold mines is not clear due to the com- pounding effect of deforestation that is likely a larger source of mercury than the gold mines. Downstream from the gold mines, the levels of mercury in human hair in the Srepok River Basin are three to five times higher than that recommended by USEPA (1 μg g -1 ) and the level found associated with attention deficit hyperactivity disorder in the United States. In the same area, mercury in hair is at similar levels as has been correlated with suppressed male fertility in Hong Kong. Fishes in the Srepok River already show levels of mercury that exceed USEPA human consumption guidelines by 4-11 times. This problem could become worse with the completion of new hydroelectric dams, which typically in- creases levels of mercury in fish by fivefold. Unregulated Chinese traditional medicines sold in pharmacies exceed international guidelines by up to 30,000 times. Children's toys contain up to 2% mercury. Finally, there is widespread use of skin whitening creams with mercury that exceeds ASEAN guidelines by up to 35,000 times. Conclusion: Further field mercury monitoring of water, fish, and people is needed in Cambodia as the potential for toxicity is significant. Anticipated health problems are subtle and require professional analysis to detect. Those most at risk are women of child- bearing age and children. Assessment of mercury contamination must include several sources of mercury.

Elevated Blood Mercury Levels in Adult Avid Seafood Consumers

Background: Mercury (Hg) is a known neurotoxicant but risk at low levels of exposure is uncertain, particularly among the adult population. The most common source of exposure is in the form of meth...

Compact fluorescent lighting in Wisconsin: elevated atmospheric emission and landfill deposition post-EISA implementation

The majority of states in the USA, including Wisconsin, have been affected by elevated air, soil and waterborne mercury levels. Health risks associated with mercury increase from the consumption of larger fish species, such as Walleye or Pike, which bio-accumulate mercury in muscle tissue. Federal legislation with the 2011 Mercury and Air Toxics Standards and the Wisconsin legislation on mercury, 2009 Wisconsin Act 44, continue to aim at lowering allowable levels of mercury emissions. Meanwhile, mercury-containing compact fluorescent lights (CFL) sales continue to grow as businesses and consumers move away from energy intensive incandescent light bulbs. An exchange in pollution media is occurring as airborne mercury emissions from coal-burning power plants, the largest anthropogenic source of mercury, are being reduced by lower energy demand and standards, while more universal solid waste containing mercury is generated each time a CFL is disposed. The treatment of CFLs as a 'universal waste' by the Environmental Protection Agency (EPA) led to the banning of non-household fluorescent bulbs from most municipal solid waste. Although the EPA encourages recycling of bulbs, industry currently recycles fluorescent lamps and CFLs at a rate of only 29%. Monitoring programs at the federal and state level have had only marginal success with industrial and business CFL recycling. The consumer recycling rate is even lower at only 2%. A projected increase in residential CFL use in Wisconsin owing to the ramifications of the Energy Independence and Security Act of 2007 will lead to elevated atmospheric mercury and landfill deposition in Wisconsin.

Mercury in pheasant (Phasianus colchicus) organs in Podravina, Croatia

Since 1995 the concentrations of total mercury were analyzed in the pheasant organs (liver, kidney, brain and muscle) that live freely in an area that was exposed to elevated levels of mercury as a result of industrial activity (mercury contaminated natural gas production and processing which began in 1980). The range of the median mercury concentration values (wet weight) in pheasant organs in Podravina, Croatia were 0.0004–0.024, 0.0001–0.034, 0.0002–0.016 and 0.0001–0.025 μg/g for liver, kidney, brain, and muscle, respectively. Results of these studies confirms that in the study area in the observed period there was no significant mercury contamination which can be linked to anthropogenic activities (hydrocarbon production)‥ On the contrary, systematic measurements demonstrate a small but constant (barely noticeable) decline in mercury concentrations in pheasant's organs. Primarily, this is the result of the significant improvement in the technological process which involves the removal of mercury from the natural gas that was designed and implemented in 1993. However, due to the need for reliable control of mercury contaminated natural gas production and the importance for better understanding of long-term exposure to low levels of mercury, and assessment of their possible harmful effects on the environment, human and animal health, research will be continued.

Mercury Toxicity in Wildland Firefighters

Recent studies have shown that significant levels of mercury are being released into the atmosphere by wildland fires throughout the United States. Eagle populations in the western United States are experiencing mercury toxicity in areas where many of these massive fires are occurring. We hypothesized that wildland firefighters exposed to smoke and other contaminates from these extensive fires would also reflect elevated blood levels of mercury. Wildland firefighters in the western United States were studied during the summers of 2007, 2008, and 2009. Pre- and post-fire season blood samples were tested for mercury in a cohort of firefighters and control subjects. Over the course of 3 summers, 66 firefighters were studied (41 had pre- and postseason blood draws). In 2008 and 2009 a control group was added with a total of 39 subjects (24 had pre- and postseason blood draws). Detectable blood levels of mercury were found in 6 firefighters, and 1 elevated level was found over the course of the study period. Six control subjects had detectable mercury levels, and no elevated levels were found. This study did not show statistically significant elevated blood levels of mercury in our cohort of wildland firefighters. However, as forest fires continue to ignite, we recommend continued investigation to ensure the health and safety of firefighting crews.

The Influence of Fish Length on Tissue Mercury Dynamics: Implications for Natural Resource Management and Human Health Risk

Consumption of fish has well-known human health benefits, though some fish may contain elevated levels of mercury (Hg) that are especially harmful to developing children. Fish length is most often the basis for establishing fishery harvest regulations that determine which fish will ultimately be consumed by humans. It is, therefore, essential to quantify the relationship between fish length and Hg accumulation in regard to harvest regulations for effective fishery and public health policy. We examined this relationship for three sportfish from six lakes across North Carolina, USA. Bluegill (Lepomis macrochirus) had the lowest Hg levels and only the very largest fish in the most contaminated site exceeded the US Environmental Protection Agency (USEPA) Hg screening level. Black crappie (Pomoxis nigromaculatus) had an intermediate level of Hg and larger individuals exceeded the USEPA screening level; however, they tended not to exceed this level before reaching the harvest length limit. Largemouth bass (Micropterus salmoides) exceeded the USEPA screening level at sizes below the fishery length limit in two lakes, leaving only higher risk fish for anglers to harvest and consume. Removing the effects of fish age and trophic position, we found strong positive correlations between Hg and fish length for largemouth bass and black crappie. We suggest public health officials and wildlife managers collaborate to structure fishery regulations and length-based fish consumption advisories that protect consumers from Hg exposure and communicate the relative risk of fish consumption.

Human Placenta and Markers of Heavy Metals Exposure

In their review, Esteban-Vasallo et al. (2012) discussed the use of human placenta to evaluate biomarkers of exposure to heavy metals. They correctly concluded that the use of placental tissue specimens to assess heavy metal exposure is actually underused. Surprisingly, they did not mention the well-documented relationship between mercury released from mercury-containing dental amalgam fillings and mercury disposition in placental tissues (Clarkson and Magos 2006; Gundacker and Hengstschlager 2012; Richardson et al. 2011). Studies have suggested an association between mercury levels in placental tissues and the observed mercury dental amalgams in women (Ask et al. 2002; Palkovicova et al. 2008; Richardson et al. 2011). Elevated placental mercury levels have been reported in dental workers who, throughout pregnancy, were exposed to mercury vapor (Hg0) released during preparation of mercury amalgam in dental offices (Guzzi and Pigatto 2007; Wannag and Skjaerasen 1975). As noted by Drasch et al. (1994), the mother-to-fetus transfer of mercury Hg0 from amalgams has been reported in human autopsy samples, and elevated levels of total mercury have been observed in the brain, liver, and kidney of human fetuses; these levels have been linked to the number of maternal amalgam-restored surfaces. Transplacental exposure to heavy metals may affect child growth and cause neurodevelopmental delays. Thus, further efforts should be made to measure and quantify maternal exposure to heavy metals in placenta to estimate environmental prenatal exposure.

834: Seafood in pregnancy and mercury levels in umbilical cord blood

levels in umbilical cord blood Reni Soon, Timothy Dye, Nicholas Ralston, Marla Berry, Lynnae Sauvage University of Hawaii, Obstetrics & Gynecology, Honolulu, HI, University of North Dakota, Energy & Environmental Research Center, Grand Forks, ND, University of Hawaii, Cell & Molecular Biology, Honolulu, HI OBJECTIVE: The purpose of this study was to examine the influence of maternal fish consumption during pregnancy on umbilical cord mercury (Hg) concentrations in a multiethnic cohort of US women. STUDY DESIGN: This was a secondary analysis of a prospective cohort pilot study examining antenatal fish consumption and neonatal outcomes in Hawaii. The first 100 women who met eligibility criteria and consented were enrolled. After delivery umbilical cord blood was collected and women completed a dietary survey of their last month of pregnancy. RESULTS: 86% of women reported eating fish during the previous month, with 9% eating more than the recommended limit of 12 oz per week. 75% of Filipina ate fish, which was significantly less than nonFilipina (p .05). Women of most ethnicities consumed similar quantities of fish, with the exception of Japanese women, who consumed significantly less fish than non-Japanese, and Pacific Islander women, who consumed significantly more. Fish consumption varied significantly by income status, with 30% of poor women averaging more than 12 oz per week. Fish consumption did not vary by women’s age, or education. 44% of all women had 5 g Hg/L or more. Filipina were significantly less likely to have elevated Hg levels when compared with non-Filipina ( .05). Mercury levels did not vary by other demographic characteristics. Women who reported eating more than 12 oz of fish per week were significantly more likely to have 5 g Hg/L or more, but mean Hg levels were not significantly higher (6.1 3.3 v 5.0 3.7). The odds ratio for elevated Hg, however, was significant among fish-consumers compared with non-consumers (5.7; 95% confidence interval: 1.2, 27.1). CONCLUSION: Despite variation by ethnicity and income status in fish consumption during pregnancy, there exists a strong correlation between fish consumption and mercury levels. Almost half of the women in this study had elevated mercury levels. This project was supported by grants NCRR U54RR026136 and NIMHD U54MD007584 from the National Institutes of Health.

Estimation of mercury emissions from forest fires, lakes, regional and local sources using measurements in Milwaukee and an inverse method

Abstract. Gaseous elemental mercury is a global pollutant that can lead to serious health concerns via deposition to the biosphere and bio-accumulation in the food chain. Hourly measurements between June 2004 and May 2005 in an urban site (Milwaukee, WI) show elevated levels of mercury in the atmosphere with numerous short-lived peaks as well as longer-lived episodes. The measurements are analyzed with an inverse model to obtain information about mercury emissions. The model is based on high resolution meteorological simulations (WRF), hourly back-trajectories (WRF-FLEXPART) and a chemical transport model (CAMx). The hybrid formulation combining back-trajectories and Eulerian simulations is used to identify potential source regions as well as the impacts of forest fires and lake surface emissions. Uncertainty bounds are estimated using a bootstrap method on the inversions. Comparison with the US Environmental Protection Agency's National Emission Inventory (NEI) and Toxic Release Inventory (TRI) shows that emissions from coal-fired power plants are properly characterized, but emissions from local urban sources, waste incineration and metal processing could be significantly under-estimated. Emissions from the lake surface and from forest fires were found to have significant impacts on mercury levels in Milwaukee, and to be underestimated by a factor of two or more.

Integrating mercury science and policy in the marine context: Challenges and opportunities

Mercury is a global pollutant and presents policy challenges at local, regional, and global scales. Mercury poses risks to the health of people, fish, and wildlife exposed to elevated levels of mercury, most commonly from the consumption of methylmercury in marine and estuarine fish. The patchwork of current mercury abatement efforts limits the effectiveness of national and multi-national policies. This paper provides an overview of the major policy challenges and opportunities related to mercury in coastal and marine environments, and highlights science and policy linkages of the past several decades. The U.S. policy examples explored here point to the need for a full life cycle approach to mercury policy with a focus on source reduction and increased attention to: (1) the transboundary movement of mercury in air, water, and biota; (2) the coordination of policy efforts across multiple environmental media; (3) the cross-cutting issues related to pollutant interactions, mitigation of legacy sources, and adaptation to elevated mercury via improved communication efforts; and (4) the integration of recent research on human and ecological health effects into benefits analyses for regulatory purposes. Stronger science and policy integration will benefit national and international efforts to prevent, control, and minimize exposure to methylmercury.

Elevated mercury levels in biota along an agricultural land use gradient in the Oldman River basin, Alberta

This study examines relationships between anthropogenic influence and mercury concentrations in biota along an elevational river gradient with intensifying agricultural and urban land use in the Oldman River basin, Alberta, Canada. We use nitrogen stable isotope signatures (δ15N) indicative of anthropogenic sources of N to indicate the extent of land use influence on the river ecosystem. δ15N values in biota increased by 4.2‰ along the river gradient, consistent with increasing nitrogen sources from sewage and manure. Mercury concentrations in longnose dace ( Rhinichthys cataractae ), suckers ( Catostomus catostomus , Catostomus commersonii ), and net-spinning caddisfly larvae, the most abundant macroinvertebrates, all increased downstream; dace ranged from 0.023 ppm total mercury below the Oldman reservoir to 0.10 ppm total mercury downstream of Lethbridge. Dace consumed mostly insect larvae, and no increase in trophic position (as estimated by δ15N) was observed along the gradient. Fish directly exposed to agricultural and urban effluents had significantly lower mercury levels, or showed no difference, relative to reference sites, which suggests that these effluents play no significant role in elevating mercury levels in river food webs.

Environmental contamination and risk assessment of mercury from a historic mercury mine located in southwestern China

A field survey of mercury pollution in environmental media and human hair samples obtained from residents living in the area surrounding the Chatian mercury mine (CMM) of southwestern China was conducted to evaluate the health risks of mercury to local residents. The results showed that mine waste, and tailings in particular, contained high levels of mercury and that the maximum mercury concentration was 88.50 μg g(-1). Elevated mercury levels were also found in local surface water, paddy soil, and paddy grain, which may cause severe health problems. The mercury concentration of hair samples from the inhabitants of the CMM exceeded 1.0 μg g(-1), which is the limit recommended by the US EPA. Mercury concentrations in paddy soil were positively correlated with mercury concentrations in paddy roots, stalks, and paddy grains, which suggested that paddy soil was the major source of mercury in paddy plant tissue. The average daily dose (ADD) of mercury for local adults and preschool children via oral exposure reached 0.241 and 0.624 μg kg(-1) body weight per day, respectively, which is approaching or exceeds the provisional tolerable daily intake. Among the three oral exposure routes, the greatest contributor to the ADD of mercury was the ingestion of rice grain. Open-stacked mine tailings have resulted in heavy mercury contamination in the surrounding soil, and the depth of appreciable soil mercury concentrations exceeded 100 cm.

The effect of a continuous mercury stress on mercury reducing community of some characterized bacterial strains

Active resistance to the mercuric ion is widely distributed in environmental microbes and results from the action of mercuric reductase. Five mercury resistant bacteria:Escherichia coli Z1, Escherichia coli Z3, Pseudomonas putida Z2, Serratia marcescensZ4 and Xanthomonas sp. Z5 were isolated and identified from sludge sample. The presence of mercury resistance determinants was screened by PCR using merA-specific primers. Based on the analysis of merA amplicons, high similarity was recorded between the merA region of the strains P. putida Z2 and Xanthomonas sp. Z5 with those of Tn5053; while the merA of E. coli Z1 was analogous to those of Tn21. In case of the bacterial strains E. coli Z3 and S. marcescens Z4 a great matching was obtained between their merA and those of Tn5036. The effect of mercury stress upon the structure of mercury reducing biofilm at the species level and the type of mercury resistance determinants was studied in a continuous bioreactor. Community analysis suggested that the bacterial strain E. coli Z3 containing Tn5036-like determinant is the well adapted strain that tolerated elevated levels of mercury whereas the other strains showed a less fitness under these extreme conditions. Key words: Mercury resistant bacteria, mercuric reductase gene, PCR-RFLP, mercury stress.

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.

A case of multiple sclerosis improvement following removal of heavy metal intoxication

Multiple sclerosis (MS) is a chronic progressive disease of the central nervous system (CNS) provoking disability and neurological symptoms. The exact causes of SM are unknown, even if it is characterized by focal inflammatory lesions in CNS accompanied by autoimmune reaction against myelin. Indeed, many drugs able to modulate the immune response of patients have been used to treat MS. More recently, toxic metals have been proposed as possible causes of neurodegenerative diseases. The objective of this study is to investigate in vivo the impact of heavy metal intoxication in MS progression. We studied the case of a patient affected by MS, who has been unsuccessfully treated for some years with current therapies. We examined his levels of toxic heavy metals in the urine, following intravenous "challenge" with the chelating agent calcium disodium ethylene diamine tetraacetic acid (EDTA).The patient displayed elevated levels of aluminium, lead and mercury in the urine. Indeed, he was subjected to treatment with EDTA twice a month. Under treatment, the patient revealed in time improved symptoms suggestive of MS remission. The clinical data correlated with the reduction of heavy metal levels in the urine to normal range values. Our case report suggests that levels of toxic metals can be tested in patients affected by neurodegenerative diseases as MS.

Mercury Levels in Sediments and Mangrove Oysters, Crassostrea rizophorae, from the North Coast of Villa Clara, Cuba

Total mercury levels were quantified in sediments and oyster tissues (Crassostrea rizophorae) from the Sagua la Grande River estuary and offshore mangrove keys 19km downstream of a chlor-alkali plant (CAP) in Villa Clara, Cuba. Relatively elevated total mercury levels were found in sediments from the estuary itself, ranging from 0.507 to 1.81μgg(-1) dry weight. However, levels were lower in sediments from the keys farther from the estuary. Oyster mercury levels were always acceptable for human consumption, although levels significantly correlated in sediments and oysters across sampling sites (p<0.05), which suggests that mercury from the CAP is impacting coastal water quality conditions.

Duration and extent of elevated mercury levels in downstream fish following reservoir creation

Duration and extent of elevated mercury levels in downstream fish following reservoir creation

Resetting our priorities in environmental health: An example from the south–north partnership in Lake Chapala, Mexico

Lake Chapala is a major source of water for crop irrigation and subsistence fishing for a population of 300,000 people in central Mexico. Economic activities have created increasing pollution and pressure on the whole watershed resources. Previous reports of mercury concentrations detected in fish caught in Lake Chapala have raised concerns about health risks to local families who rely on fish for both their livelihood and traditional diet. Our own data has indicated that 27% of women of childbearing age have elevated hair mercury levels, and multivariable analysis indicated that frequent consumption of carp ( i.e., once a week or more) was associated with significantly higher hair mercury concentrations. In this paper we describe a range of environmental health research projects. Our main priorities are to build the necessary capacities to identify sources of water pollution, enhance early detection of environmental hazardous exposures, and deliver feasible health protection measures targeting children and pregnant women. Our projects are led by the Children's Environmental Health Specialty Unit nested in the University of Guadalajara, in collaboration with the Department of Environmental Health of Harvard School of Public Health and Department of Pediatrics of the New York School of Medicine. Our partnership focuses on translation of knowledge, building capacity, advocacy and accountability. Communication will be enhanced among women's advocacy coalitions and the Ministries of Environment and Health. We see this initiative as an important pilot program with potential to be strengthened and replicated regionally and internationally.

Erratum: "A Biomonitoring Study of Lead, Cadmium, and Mercury in the Blood of New York City Adults".

[This corrects the article DOI: 10.1289/ehp.10056.].

Serum heavy metal and antioxidant element levels of children with recurrent wheezing

Study Objectives The aim of the study is to investigate the levels of toxic heavy metals related with environmental pollution and trace elements involved in antioxidant system in children suffering from recurrent wheezing. Study Design One hundred children with recurrent wheezing (at least three recurrences) between the ages from 1 to 6 years took part in the study, and also 116 age- and sex- matched healthy children were involved in the study as a control group. Venous blood samples were collected and serum mercury, lead, aluminium, zinc, selenium, and copper levels were studied using ICP-MS. Results Serum lead (0.76 ± 0.15 vs. 0.27 ± 0.01, p:0.001) and mercury levels (1.31 ± 0.15 vs 0.71 ± 0.05, p < 0.001) were higher in wheezy group than those acquired from the control group. Serum zinc (69.4 ± 1.65 vs. 78.9 ± 2.78, p:0.005) and selenium (115.6 ± 1.87 vs. 125.4 ± 2.94, p:0.008) levels were lower in wheezy group than those acquired from the control group. Serum zinc levels were found to be correlated with number of ARTIs (r p:−0.332, p:0.001) and the number of wheezy attacks (r p:−0.776, p < 0.001) during the previous year in the wheezy group. Conclusion Elevated levels of serum lead and mercury and low levels of zinc and selenium may suggest some disturbances in the antioxidant system in children with recurrent wheezing. This means that children with recurrent wheezing are much more susceptible to environmental pollutants and respiratory tract infections than healthy children and this heavy metal-antioxidant relationship may play a role as a contributing factor in the pathogenesis of recurrent wheezing in children.