Mercury Exposure Assessment Research Articles

Assessment of chronic mercury exposure within the U.S. population, National Health and Nutrition Examination Survey, 1999–2006

The purpose of this study was to assess chronic mercury exposure within the US population. Time trends were analyzed for blood inorganic mercury (I-Hg) levels in 6,174 women, ages 18-49, in the NHANES, 1999-2006 data sets. Multivariate logistic regression distinguished a significant, direct correlation within the US population between I-Hg detection and years since the start of the survey (OR = 1.49, P < 0.001). Within this population, I-Hg detection rose sharply from 2% in 1999-2000 to 30% in 2005-2006. In addition, the population averaged mean I-Hg concentration rose significantly over that same period from 0.33 to 0.39 μ/L (Anova, P < 0.001). In a separate analysis, multivariate logistic regression indicated that I-Hg detection was significantly associated with age (OR = 1.02, P < 0.001). Furthermore, multivariate logistic regression revealed significant associations of both I-Hg detection and mean concentration with biomarkers for the main targets of mercury deposition and effect: the liver, immune system, and pituitary. This study provides compelling evidence that I-Hg deposition within the human body is a cumulative process, increasing with age and in the population over time, since 1999, as a result of chronic mercury exposure. Furthermore, our results indicate that I-Hg deposition is associated with the significant biological markers for main targets of exposure, deposition, and effect. Accumulation of focal I-Hg deposits within the human body due to chronic mercury exposure provides a mechanism which suggests a time dependent rise in the population risks for associated disease.

An Exposure Assessment of Methyl Mercury via Fish Consumption for the Japanese Population

The objective of this article was to propose an exposure assessment model to describe the relationship between fish consumption and body methyl mercury (MeHg) levels in the Japanese population. Individual MeHg intake was estimated by the summation of species-specific fish consumption multiplied by species-specific fish MeHg levels. The distribution of fish consumed by individuals and the MeHg level in each fish species were assigned based on published data from Japanese government institutions. The probability of MeHg intake for a population was accomplished through a Monte Carlo simulation by the random sampling of fish consumption and species-specific MeHg levels. Internal body MeHg levels in blood and hair were estimated using a one-compartment model. Overall, the mean value of MeHg intake for the Japanese population was estimated to be 6.76 microg/day or 0.14 microg/kg body weight per day (bw/day), while the mean value for the hair mercury level was 2.02 microg/g. Compared with the survey data that tabulated hair mercury levels in a cross-section of the Japanese population, the simulation results matched the hair mercury survey data very well for women, but somewhat underestimated for men and all of the population. This exposure assessment model is a useful attempt at further risk assessment with respect to a risk-benefit analysis.

Mercury exposure in a high fish eating Bolivian Amazonian population with intense small-scale gold-mining activities

Methylmercury exposure in Amazonian communities through fish consumption has been widely documented in Brazil. There is still a lack of data in other Amazonian countries, which is why we conducted this study in the Bolivian Amazon basin. Simple random sampling was used from a small village located in the lower Beni River, where there is intense gold mining and high fish consumption. All participants were interviewed and hair samples were taken to measure total mercury concentrations. The hair mercury geometric mean in the general population was 3.02 μg/g (CI: 2.69–3.37; range: 0.42–15.65). Age and gender were not directly associated with mercury levels. Fish consumption showed a positive relation and so did occupation, especially small-scale gold mining. Hair mercury levels were lower than those found in Brazilian studies, but still higher than in non-exposed populations. It is necessary to assess mercury exposure in the Amazonian regions where data is still lacking, using a standardized indicator.

Human exposure to mercury in the vicinity of chlor-alkali plant

The main objectives of our study were to estimate the impact of a mercury cell chlor-alkali (MCCA) complex in Rosignano Solvay (Tuscany, Italy) on the local environment and to assess mercury exposure of inhabitants living near the plant. Measurement campaigns of atmospheric Hg near the MCCA plant showed that the impact of the emitted Hg from the industry on the terrestrial environment is restricted to a close surrounding area. Total gaseous mercury concentrations in ambient air of inhabited area around the MCCA plant were in the range of 8.0-8.7 ng/m3 in summer and 2.8-4.2 ng/m3 in winter. Peaks of up to 100 ng/m3 were observed at particular meteorological conditions. Background levels of 2 ng/m3 were reached within a radius of 3 km from the plant. Reactive gaseous mercury emissions from the plant constituted around 4.2% of total gaseous mercury and total particulate mercury emission constituted around 1.0% of total gaseous mercury emitted. Analysis of local vegetables and soil samples showed relatively low concentrations of total mercury (30.1-2919 microgHg/kg DW in the soil; <0.05-111 microgHg/kg DW in vegetables) and methylmercury (0.02-3.88 microgHg/kg DW in the soil; 0.03-1.18 microgHg/kg DW in vegetables). Locally caught marine fish and fresh marine fish from the local market had concentrations of total Hg from 0.049 to 2.48 microgHg/g FW, of which 37-100% were in the form of methylmercury. 19% of analysed fish exceeded 1.0 microgHg/g FW level, which is a limit set by the European Union law on Hg concentrations in edible marine species for tuna, swordfish and shark, while 39% of analysed fish exceeded the limit of 0.5 microgHg/g FW set for all other edible marine species. Risk assessment performed by calculating ratio of probable daily intake (PDI) and provisional tolerable daily intake (PTDI) for mercury species for various exposure pathways showed no risks to human health for elemental and inorganic mercury, except for some individuals with higher number of amalgam fillings, while PDI/PTDI ratio for methylmercury and total mercury exceeded the toxicologically tolerable value due to the potential consumption of contaminated marine fish.

Assessment of Hg contamination and exposure to miners and schoolchildren at a small-scale gold mining and recovery operation in Thailand

Gold extracted by Hg-amalgamation process, which can cause both health and environmental problems, is widespread in South East Asia including Myanmar, Laos, Cambodia, and Thailand. Small-scale gold mining operations have been carried out since the year 2000 in Phanom Pha District, Phichit Province, Thailand. Since no data is available for evaluating Hg exposure, an investigation of mercury (Hg) contamination and exposure assessment was carried out at this mine site. Environmental monitoring illustrated the total Hg in water was as high as 4 μg/l while Hg in sediment ranged between 102 to 325 μg/kg dry weight. Both Hg deposition from the air (1.28 μg/100 cm2/day) and concentration in surface soil (20,960 μg/kg dry weight) were elevated in the area of amalgamation. The potential of Hg exposure to miners as well as to schoolchildren was assessed. The concentrations of Hg in urine of 79 miners who were directly (group I) or indirectly (group II) involved in the gold recovery operation were 32.02 and 20.04 μg/g creatinine, respectively, which did not exceed regulatory limits (35 μg/g creatinine). Hair Hg levels in both groups (group I and group II) also were not significantly higher than the non-exposed group. In terms of risk factors, gender and nature of food preparation and consumption were the two significant variables influencing the concentration of Hg in urine of miners (P < 0.05). A hazard quotient (HQ) was estimated based on the inorganic Hg exposure of individual miners. The HQ values of group I were in a range 16 to 218 times higher than the safety level set as 1. By comparison the group II HQ index was very low (0.03–0.39). The miners in group I who worked and ate food from this area experienced potentially high exposure to Hg associated with the mining process. In a second Hg exposure assessment, a group of 59 schoolchildren who attended an elementary school near the gold mine site was evaluated for Hg exposure. A slightly higher Hg urine concentration was detected in group I and group II (involved and not involved in gold recovery) at average levels of 15.82 and 9.95 μg/g creatinine, respectively. The average Hg values for both groups were below the established levels indicating no risk from Hg intake. Average Hg hair level in all schoolchildren (0.93 μg/g) was not significantly higher than reference group. There were two variables (gender and personal hygiene) which affected the concentration of Hg in urine of schoolchildren (P < 0.05). The result (HQ) also suggested that schoolchildren were not at risk (< 1). Schoolchildren involved in gold mining activities showed some indirect exposure to Hg from the adults working in mining area.

Community-directed risk assessment of mercury exposure from gold mining in Suriname

The overarching objective of this project was to support the indigenous people in Kwakoegron, Suriname, in self-diagnosis of public and environmental health problems. The specific objectives, defined by the people of Kwakoegron were: (1) to determine for themselves if they are at risk of exposure to mercury (Hg) contamination, (2) to measure the extent of the Hg contamination problem, and (3) to initiate an intervention plan. Field work was conducted from June 2005 to April 2006. Community members were trained to collect hair samples for analysis using methods designed to maximize sample quality and consistency and minimize cross-contamination. Each hair sample, of approximately 20 mg, was weighed, added to the sample boat, and analyzed immediately without preservation or storage. Technicians educated in analytical chemistry and trained in the operation of the portable Lumex Zeeman Hg analyzer measured the total Hg (THg) for each hair sample. Confidential meetings were held with each person sampled and any questions were answered. Afterwards, a community meeting was held to reflect on the process, outcome, and future needs. Hair samples from 16 of the 22 participants had Hg levels of 2.2-20.2 microg/g THg, exceeding normal THg levels for hair (2 microg/g THg). During the confidential, individual meetings and the followup community meeting, information was shared regarding the Hg levels found, what the numbers meant scientifically, what the potential health effects could be, and how exposure levels might be brought down. At the conclusion of the followup meeting, the Kwakoegron community proposed an intervention plan that had three principle parts: (1) routine analysis of Hg exposure to monitor trends and track the effects of exposure-reduction efforts; (2) routine health assessments to determine the effects of Hg exposure, particularly in children less than 5 years of age; and (3) fish advisories based on fish biology and trophic level or on the specific measurement of Hg levels in various fish species from various locations and different times throughout the year. This project showed that a democratic approach to science does not automatically compromise the orderly search for answers. Specifically, our experience in Kwakoegron suggests that the collaborative relationship that emerges by empowering an indigenous community to initiate its own research projects, and address the needs it identifies, can contribute positively to the risk assessment process. This project showed that when Kwakoegron was acknowledged as an equal partner, the risk assessment process led to an open exchange of information and an intervention plan that was both pragmatic and acceptable in the context of the community's unique social and cultural needs.

Risk Assessment of Mercury Exposure in Population of Irkutsk Region, Russia

Risk Assessment of Mercury Exposure in Population of Irkutsk Region, Russia

Assessment of mercury exposure and potential effects on common loons (Gavia immer) in Québec

Assessment of mercury exposure and potential effects on common loons (Gavia immer) in Québec

Health and environmental assessment of mercury exposure in a gold mining community in Western Mindanao, Philippines

The small-scale gold mining activities using mercury began in the late 1980s in Sibutad, Western Mindanao. It is located very near the Murcielagos Bay with tailing ponds directly discharging into bodies of water. This cross-sectional study aimed to determine the health and environmental effects of gold mining activities on the community. Residents were randomly selected and classified into two groups, namely, the directly exposed and indirectly exposed populations using a set inclusion criteria. Complete medical and laboratory examinations were performed. Environmental and biologic samples were collected for total mercury and methylmercury determinations. The results showed that the directly exposed group had significantly higher mean blood total mercury and methylmercury levels in comparison with the indirectly exposed population. Although there were no significant differences between hair total mercury and methylmercury levels, there was a trend for higher levels of these biomarkers among the directly exposed residents as compared with the unexposed group. The absence of statistically significant differences may be attributable to the small sample size. Ambient air quality monitoring for mercury exceeded the allowable levels. However, levels of mercury in drinking water and sediments were within allowable limits. Frequency of gastrointestinal complaints was significantly associated with elevated hair methylmercury levels ( p=0.02). Also, there appears to be a trend towards higher blood total mercury levels and frequency of gastrointestinal complaints ( p=0.09). An interesting finding in this study was the increasing incidence of elevated diastolic blood pressure with elevated hair total mercury levels ( p=0.07). Mercury storage at home is a risk factor.

Relationship between Total Mercury Concentration and Fish Size in Two Pelagic Fish Species: Implications for Consumer Health

Total mercury concentrations were determined in different size classes of two pelagic fish species of great commercial importance, horse mackerel (Trachurus trachurus) and Mediterranean horse mackerel (Trachurus mediterraneus), to evaluate the relationship between total mercury concentration and fish size and to determine whether any differences might affect the quantitative assessment of mercury exposure for consumers. Mercury concentrations in horse mackerel and in Mediterranean horse mackerel were between 0.16 and 2.41 μg g−1 of weight wet (mean, 0.68 μg g−1) and between 0.09 and 1.62 μg g−1 (mean, 0.51 μg g−1), respectively. The regression curves revealed a significant relationship between mercury concentration and fish size (length and weight) for both species. Concentrations exceeding the proposed limit for human consumption were observed in 33.3% of the samples of both species and were associated with larger specimens. The consumption of the larger specimens could lead to an increase in mercury exposure for consumers. Estimated weekly intakes, calculated on the basis of concentrations relative to each size class, revealed a high exposure associated with the consumption of fish larger than 30 cm (horse mackerel, 11.63 to 20.16 μg/kg of body weight; Mediterranean horse mackerel, 5.86 to 13.55 μg/kg of body weight). An understanding of the factors leading to an increase in mercury exposure can help consumers make informed decisions about eating fish.

Assessing Mercury Exposure and Effects to American Dippers in Headwater Streams near Mining Sites

To evaluate mercury (Hg) exposure and possible adverse effects of Hg on American dipper (Cinclus mexicanus) reproduction, we collected eggs and nestling feathers and the larval/nymph form of three Orders of aquatic macroinvertebrates (Ephemeroptera, Plecoptera and Trichoptera = EPT) important in their diet from three major headwater tributaries of the upper Willamette River, Oregon in 2002. The Coast Fork Willamette River is contaminated with Hg due to historical cinnabar (HgS) mining at the Black Butte Mine; the Row River is affected by past gold-mining operations located within the Bohemia Mining District, where Hg was used in the amalgamation process to recover gold; and the Middle Fork Willamette River is the reference area with no known mining. Methyl mercury (MeHg) concentrations (geometric mean) in composite EPT larvae (111.9 ng/g dry weight [dw] or 19.8 ng/g wet weight [ww]), dipper eggs (38.5 ng/g ww) and nestling feathers (1158 ng/g ww) collected from the Coast Fork Willamette were significantly higher than MeHg concentrations in EPT and dipper samples from other streams. Total mercury (THg) concentrations in surface sediments along the same Hg-impacted streams were investigated by others in 1999 (Row River tributaries) and 2002 (Coast Fork). The reported sediment THg concentrations paralleled our biological findings. Dipper breeding territories at higher elevations had fewer second clutches; however, dipper reproductive success along all streams (including the lower elevation and most Hg-contaminated Coast Fork), was judged excellent compared to other studies reviewed. Furthermore, MeHg concentrations in EPT samples from this study were well below dietary concentrations in other aquatic bird species, such as loons and ducks, reported to cause Hg-related reproductive problems. Our data suggest that either dipper feathers or EPT composites used to project MeHg concentrations in dipper feathers (with biomagnification factor of 10-20x) may be used, but with caution, to screen headwater streams for potential Hg-related effects on dippers. When actual feather concentrations or projected feather concentrations are equal to or lower than concentrations reported for the Coast Fork, dippers are expected to reproduce well (assuming adequate prey and suitable nest sites). When Hg concentrations are substantially higher, more detailed investigations may be required. Birds feeding almost exclusively on fish (e.g., osprey [Pandion haliaetus]) and usually found further downstream from the headwaters would not be adequately represented by dippers given the higher MeHg concentrations in fish resulting from biomagnification, compared to lower trophic level invertebrates.

AN ASSESSMENT OF MERCURY EXPOSURE AMONG YOUNG CHILDREN LIVING IN NYC

ISEE-555 Introduction: Mercury exposure in young children may occur from a variety of sources containing mercury in different forms (elemental mercury, inorganic mercury salts, and organic mercury compounds). This presentation describes the methods and preliminary results of a study designed to examine dietary (organic mercury), medicinal (inorganic or elemental mercury), or traditional (elemental mercury) exposure among children living in New York City (NYC) by collecting questionnaire data and measuring mercury in biological samples. The study is focusing on communities where mercury exposure from various sources is suspected. Methods: A cross-sectional study design is utilized. Blood and/or urine samples are collected from children (<10 years of age) seen in community-based health clinics in neighborhoods where mercury may currently or historically have been used in residential settings. Standardized questionnaires are administered to parents of participating children. Individual blood and urine mercury concentrations are directly reported to the parent(s) or guardian(s) of the child, and to the child’s health care provider. Excess urine samples, routinely provided for other diagnostic purposes, are collected anonymously at the clinic to assess the potential for participation bias to influence the study results. A door-to-door pilot study to assess mercury exposure in children living in neighborhoods with Botanicas (stores selling items used for religious purposes, e.g., mercury) is also conducted. Urine samples (only) and questionnaire data are collected in the door-to-door study. Study blood and urine mercury levels are compared to levels found in previous studies and national assessments (background). Results: We compare the background levels of mercury to the mercury levels of children in all three study populations. Using the sampling results, we also assess whether mercury concentrations for the children can be predicted by parent-reported mercury exposures; are consistent with values reported for other pediatric populations; and are associated with demographic or environmental factors. Comparison of the anonymous residual urine sample results to those obtained with parental consent and interview allows an assessment of selection bias, potentially introduced through the consent process. Discussion: The data obtained by this study will be used to determine if mercury exposure above background is occurring in the study population. If so, then guidance on ways to reduce future exposure will be provided to parents and guardians. Community outreach and programs for monitoring childhood exposure to mercury will be developed depending upon study findings.

Practical assessment of mercury exposure, contamination and clean-up

Practical assessment of mercury exposure, contamination and clean-up

Assessment of Mercury Exposure and Malaria in a Brazilian Amazon Riverine Community

Small-scale gold mining in the Brazilian Amazon occurs in areas with high rates of malaria transmission. Amazonian populations can be exposed to mercury through direct contact with the mining process and/or through fish consumption. Because of data from experimental studies, we examined the potential for mercury to affect host response to malaria. A cross-sectional survey was done in Jacareacanga, a riverine community in Para state, in a region of intense alluvial gold mining. A sample of 205 persons was selected by cluster sampling from the total population of approximately 2000. A brief medical history and exam were conducted, malaria slides were obtained, and hair samples were taken to measure mercury levels. The average hair mercury level was 8.6 μg/g, ranging from 0.3 to 83.2 μg/g. The most important predictors of elevated mercury levels were high fish consumption and low income. Although there was no prevalent malaria, the odds of reporting a past malaria infection was four times higher for those also reporting a history of working with mercury.

P1H215 - Health risk assessment of mercury exposure in dental surgery in the Czech Republic

P1H215 - Health risk assessment of mercury exposure in dental surgery in the Czech Republic

Probabilistic assessment of regional mercury exposure

Probabilistic assessment of regional mercury exposure

A Monte Carlo assessment of mercury exposure and risks from dental amalgam

Abstract Dental amalgam is approximately 50% mercury (Hg) by weight, and persons bearing amalgam fillings are exposed to this element, primarily as Hg vapor. For Canadians with amalgam‐filled teeth, it was estimated, based on two independent models, that Hg exposure from amalgam averaged: 0.045 to 0.082 μg/kg bw/day in toddlers (aged 3 to 4 years); 0.044 to 0.069 μg/kg bw/day in children (aged 5 to 11 years); 0.034 to 0.044 μg/kg bw/day in teens (aged 12 to 19 years); 0.050 to 0.055 μg/kg bw/day in adults (aged 20 to 59 years); and 0.031 to 0.041 μg/kg bw/day in seniors (aged 60+ years). Amalgam was estimated to contribute, on average, 50% of total Hg exposure from all sources (amalgam, air, water, food, soil) in adults, and 32 to 42% for other age groups. Numerous studies have consistently reported effects on the central nervous system (CNS) in persons occupationally exposed to Hg vapor. Most such studies have failed to detect a threshold for the CNS effects measured. A tolerable daily intake (TDI) of 0....

Exposure analysis of the inhabitants living in the neighbourhood of a mercury-contaminated industrial site

The inhabitants living in the neighbourhood of a deserted mercury-contaminated industrial site are subjected to an age-group differentiated mercury exposure assessment based on a scenario-linked calculation. Analytical input data for the calculation procedure are provided for from soil, air and plants in a large number. The most sensitive group are small children being mainly exposed by soil ingestion which makes up nearly 80% of the ADI, followed by inhalation of mercury contaminated indoor air. On the other hand, inhalation of indoor air has a predominant impact on youth and adults.

Mercury Exposure from Exterior Latex Paint

Abstract In the United States, mercury has been routinely used as a biocide to preserve exterior latex paint. Although the concentration of mercury in exterior latex paints can be up to 1500 mg/L, mercury exposure from these paints has never been studied. We performed this investigation to determine the extent of mercury exposure from the outdoor application of exterior latex paints. To assess mercury exposure we compared air and urinary mercury concentrations of 13 professional male painters with those of 29 men having other occupations (nonpainters). The painters used two brands of exterior latex paint that contained mercury. The median concentration for the four paint samples obtained was 570 mg/L. The median air mercury concentration was higher for painters (1.0 μg/m3; range, nondetectable [ND], 4 μg/m3) than for nonpainters (ND; range, ND, 3 μg/m3); p = 0.0004. The median urinary mercury concentration was nearly twice as high for painters (9.7 μg/L; range, 5.9–20.4 μg/L) than for nonpainters (5.0 μg/L; range, 2.6–11.6 μg/L); p = 0.0001 (normal range < 20 μg/L). Among painters, urinary mercury concentrations increased with the percentage of time spent applying exterior paint (Pearson r = 0.6). These data suggest increased mercury exposure among professional painters who use mercury-containing exterior latex paint outdoors.

Biological monitoring of environmental and occupational exposure to mercury

Biological monitoring was used to assess mercury exposure from occupational and environmental sources in a group of chloralkali workers (n = 89) and in a control group (n = 75). In the control group, the median value for blood mercury (B-Hg) was 15 nmol/l, that for serum mercury (S-Hg) was 4 nmol/l and that for urinary mercury (U-Hg) was 1.1 nmol/mmol creatinine. Corresponding levels in the chloralkali group were 55 nmol/l, 45 nmol/l and 14.3 nmol/mmol creatinine, respectively. In the control group, there were statistically significant relationships between fish consumption and both B-Hg and S-Hg values (P less than 0.001), whereas U-Hg correlated best with the individual amalgam burden (P less than 0.01). In the chloralkali group, the mercury levels in blood and urine were significantly related to the type of work (P less than 0.001) but not to the length of employment, to fish consumption or to the quantity of dental amalgam fillings. In both groups there were poor correlations between smoking or alcohol intake and the mercury levels in blood and urine. The results strongly suggest that fish is an important source of methylmercury exposure and that amalgam fillings are probably the most important source of inorganic mercury exposure among occupationally unexposed individuals. In the chloralkali group, mercury exposure from fish and amalgam was overshadowed by occupational exposure to inorganic mercury.