Mercury in human hair and relation to fish consumption in Bangladesh

A high-throughput, straightforward procedure for biomonitoring organomercury species in human hair

Mercury is a pervasive and concerning pollutant due to its toxicity, mobility, and tendency to biomagnify in aquatic and terrestrial ecosystems. Speciation analysis is crucial to assess exposure and risks associated with mercury, as different mercury species exhibit varying properties and toxicities. This study aimed at developing a selective detection method for organic mercury species in a non-invasive biomonitoring matrix like human hair. The method is based on frontal chromatography (FC) in combination with inductively coupled plasma mass spectrometry (ICP-MS), using a low pressure, homemade, anion exchange column inserted in a standard ICP-MS introduction system, without requiring high-performance liquid chromatography (HPLC) hyphenation. In addition to the extreme simplification and cost reduction of the chromatographic equipment, the proposed protocol involves a fast, streamlined and fully integrated sample preparation process (in contrast to existing methods): the optimized procedure features a 15-min ultrasonic assisted extraction procedure and 5 min analysis time. Consequently, up to 100 samples could be analyzed daily, making the method highly productive and suitable for large-scale screening programs in public and environmental health. Moreover, the optimized procedure enables a limit of detection (LOD) of 5.5 μg/kg for a 10 mg hair microsample. All these features undeniably demonstrate a significant advancement in routine biomonitoring practices. To provide additional evidence, the method was applied to forty-nine human hair samples from individuals with varying dietary habits successfully finding a clear correlation between methylmercury levels (ranging from 0.02 to 3.2 mg/kg) in hair and fish consumption, in line with previous literature data.

Blood lead, cadmium and hair mercury concentrations and association with soil, dust and occupational factors in e-waste recycling workers in Bangladesh

BACKGROUND

Electronic waste (e-waste) recycling activities release toxic metals, which pose substantial hazard to the environment and human health. We evaluated metal concentrations in biological and environmental samples, and examined the associations between biological lead (Pb), cadmium (Cd), and mercury (Hg) with soil and dust metals, and other possible determinants, among populations exposed and non-exposed to e-waste in Bangladesh.

METHODS

A total of 199 e-waste workers and 104 non-exposed individuals were recruited. We measured blood Pb (BPb) and Cd (BCd) concentrations and total Hg (THg) from hair samples. Data were collected on occupational, and behavioral factors. We fitted an elastic net regression (ENET) to model the relationship between a set of influencing factors and metals as outcome variables while controlling for potential covariates.

RESULTS

The median concentrations of BPb (11.89 μg/dL) and BCd (1.04 μg/L) among exposed workers were higher than those of non-exposed workers (BPb: 3.63 μg/dL and BCd: 0.83 μg/L respectively). A 100 ppm increment in soil Pb level was associated with an increase in ln-Pb (transformed) in blood (β = 0.002; 95% CI = 0.00, 0.02). Similarly, ln-BCd level increased (β = 0.02; 95% CI = 0.001, 0.07) with every ppm increase in dust Cd level. The number of years worked in e-waste activities was associated with elevated ln-BPb (β = 0.01; 95% CI = 0.01, 0.02) and ln-BCd levels (β = 0.003; 95% CI = 0.00, 0.05). Smoking significantly contributed to elevated levels of ln-BCd (β = 0.46; 95% CI = 0.43, 0.73). An increment of 100 kg of e-waste handling per week led to an increase in ln-BPb levels (β = 0.002; 95% CI = 0.00, 0.01), while respondents knowledge about adverse impact on e-waste reduced the ln-BPb level (β = -0.14; 95% CI = -0.31, -0.03). Fish consumption frequency had a positive association with THg in hair.

CONCLUSIONS

Our data show the need for workplace controls to reduce exposure to Pb and Cd with a broader view of exposure source taken.

High variability of mercury content in the hair of Russia Northwest population: the role of the environment and social factors

PURPOSE

The purpose of this work is to study mercury levels in the hair of different social and demographic groups of the population of the Vologda region in Northwest Russia. This region is selected due to a heterogeneous distribution of rivers and lakes-a resource base for fishing.

METHODS

The mercury content was determined in the hair from the root with a length of about 2 cm. The concentration of total mercury in human hair was determined by the atomic absorption method without preliminary sample preparation using an RA-915M mercury analyzer and a PYRO-915 + pyrolysis unit.

RESULTS

The average level of mercury in the human hair was 0.445 μg/g (median 0.220 μg/g). The concentration of mercury in the hair of people older than 44 years (0.875 μg/g) was three times higher than in the hair of children under 18 years of age (0.270 μg/g). People who eat fish less than once per month had a hair mercury concentration of 0.172 μg/g, for 1-2 times a month 0.409 μg/g, once a week 0.555 μg/g, and several times a week 0.995 μg/g. The concentration of mercury in the hair of smokers (0.514 μg/g) was higher than in the hair of non-smokers (0.426 μg/g).

CONCLUSION

Significantly higher concentrations of mercury were observed in the hair of participants from the western part of the region, where reservoirs are the main commercial sources of fish products. The data showed that the main source of people's mercury intake was fish.

Characterization of the mercury-binding proteins in tuna and salmon sashimi: Implications for health risk of mercury in food

Fish consumption is one of the major ways through which humans receive exposure to mercury (Hg). The existing forms of Hg in food, particularly Hg bound to proteins, may affect the absorption of Hg by humans and subsequently its potentially toxic effects. However, the knowledge regarding Hg-binding proteins in edible fish muscle is scarce. In the present study, salmon and tuna fish muscles, collected from seven different regions and countries, were analyzed using metallomics- and proteomics-based techniques. The concentration of Hg in sashimi samples ranged from 4.4 to 317.4 ng/g. Size exclusion chromatography (SEC) coupled with inductively coupled plasma mass spectrometer (ICP-MS) showed that beta-actin was a novel Hg-binding protein from the fish muscles, and this protein could also bind bismuth (Bi), silver (Ag), and copper (Cu). Hg bound to beta-actin accounted for approximately 30.2-37.6% of the total Hg in the tuna muscles and was significantly correlated to total Hg in the fish muscles (r = 0.98, p < 0.01) and in the fraction of soluble proteins (r = 0.94, p < 0.01). These findings suggest that proteins act as the main Hg accumulation sites in edible fish; thus, increasing human exposure to Hg following gastrointestinal digestion.

Total mercury and methylmercury in rice: Exposure and health implications in Bangladesh

Rice methylmercury (MeHg) contamination has attracted global attention, especially in countries where rice is considered a staple food. The daily rice intake rate in Bangladesh ranks first in the world; however, no attention has been paid to rice MeHg contamination in Bangladesh. Total Hg (THg) and MeHg concentrations of commercial rice (n = 172) from Bangladesh were first analyzed to accurately evaluate both rice MeHg and inorganic Hg (IHg) exposure in different age-gender groups of Bangladeshis. The corresponding adverse health impacts and associated economic loss were also assessed. The results showed that THg concentration in all samples ranged from 0.42 to 14.4 ng/g, with an average of 2.48 ± 1.41 ng/g, while the MeHg concentration ranged from 0.026 to 7.47 ng/g, with an average of 0.83 ± 0.60 ng/g. The highest average MeHg and IHg were both recorded in rice from Chittagong. The highest mean MeHg and IHg exposures were observed in 2-5 years-old group and were 16.2% of the reference dose (RfD) of 0.1 μg/kg/day for MeHg and 7.09% of the provisional tolerable weekly intake (PTWI) of 0.571 μg/kg/day for IHg. Surprisingly, MeHg exposure of the 2-5 year-old children could be up to 93.7% of the RfD at a high percentile (P99.9). The total intelligence quotient reduction caused by rice MeHg exposure could be 54700 points, and the associated economic loss is approximately 42.5 million USD. To avoid high rice MeHg exposure, it was suggested that diet structure be improved. More attention should be paid to residents with long-term rice MeHg exposure, especially children in the 2-5 year-old group.

The Relationship between Mercury Exposure Indices and Dietary Intake of Fish and Shellfish in Women of Childbearing Age

Women of childbearing age who are susceptible to mercury exposure were studied to understand the relation between mercury intake through fish and shellfish consumption and mercury exposure indices from blood, hair, and urine samples. A total of 711 women of childbearing age from coastal areas with a high concentration of mercury exposure in Korea were studied. Data were collected on demographic characteristics, dietary intake of fish and shellfish using the simple Food Frequency Questionnaire. Mercury concentration was estimated from the collected samples of blood, hair, and urine. The geometric mean of blood methyl mercury concentration of mercury exposure through seafood was 3.06 μg/L for the low tertile, 3.12 μg/L for the middle tertile, and 3.60 μg/L for the high tertile, indicating a clear tendency of blood methyl mercury to increase as the mercury exposure by fish and shellfish intake ascended. For total blood mercury and hair mercury, the middle and high tertiles had higher values than the low. Mercury exposure through fish and shellfish intake is a main factor for an increase of blood methyl mercury concentration in women of childbearing age. More attention needs to be paid to mercury exposure through seafood intake, considering the serious effect mercury concentration has on women of childbearing age.

Mercury Detection in Benthic and Pelagic Fish Collected from Western Sicily (Southern Italy)

Simple Summary

In highly polluted water, fish can accumulate Hg at concentrations that cause risk to human health. This has occurred in Sicily (Southern Italy), where there is activity from the petrochemical pole. In this paper, we present concentrations of mercury in 14 fish species collected from western Sicilian coasts in 2013. A significant difference was found between fish species examined but not between pelagic and benthic fish. Four out of 130 analyzed samples showed mercury concentrations over the European limits.

Abstract

In highly polluted water, fish can accumulate mercury up to a concentration of 10 mgKg⁻¹. This has occurred on the eastern coasts of Sicily (Southern Italy), probably due to the intense industrial activity of this area. However, little is known about Hg accumulation in fish of the western Sicilian coasts. In this work, we examined the Hg accumulation of 108 fish samples belonging to 14 species collected from western Sicilian coasts using a direct mercury analyzer. The samples showed a mean mercury concentration of 0.165 ± 0.22 mg kg⁻¹ with a maximum in Lepidopus caudatus (1.72 mgKg⁻¹), exceeding the limits provided by EC Reg. 1881/2006. The lowest Hg levels were found in Sparus aurata samples (0.001 mgKg⁻¹). A significant difference was found between the fish species examined (p < 0.05). The comparison between benthic and pelagic species did not show statistical differences (p < 0.05). Fish food constitutes the main route of Hg uptake for humans. Only four of the 130 samples examined reached a mercury concentration over the European limits. The comparative analysis of Hg pollution for benthic and pelagic species did not confirm a different trend in metal contamination.

More surprises in the global greenhouse: Human health impacts from recent toxic marine aerosol formations, due to centennial alterations of world-wide coastal food webs

Reductions of zooplankton biomasses and grazing pressures were observed during overfishing-induced trophic cascades and concurrent oil spills at global scales. Recent phytoplankton increments followed, once Fe-, P-, and N-nutrient limitations of commensal diazotrophs and dinoflagellates were also eliminated by respective human desertification, deforestation, and eutrophication during climate changes. Si-limitation of diatoms instead ensued during these last anthropogenic perturbations of agricultural effluents and sewage loadings. Consequently, ~15% of total world-wide annual asthma trigger responses, i.e. amounting to ~45 million adjacent humans during 2004, resulted from brevetoxin and palytoxin poisons in aerosol forms of western boundary current origins. They were denoted by greater global harmful algal bloom [HAB] abundances and breathing attacks among sea-side children during prior decadal surveys of asthma prevalence, compiled here in ten paired shelf ecosystems of western and eutrophied boundary currents. Since 1965, such inferred onshore fluxes of aerosolized DOC poisons of HABs may have served as additional wind-borne organic carriers of toxic marine MeHg, phthalate, and DDT/DDE vectors, traced by radio-iodine isotopes to potentially elicit carcinomas. During these exchanges, as much as 40% of mercury poisonings may instead have been effected by inhalation of collateral HAB-carried marine neurotoxic aerosols of MeHg, not just from eating marine fish. Health impacts in some areas were additional asthma and pneumonia episodes, as well as endocrine disruptions among the same adjacent humans, with known large local rates of thyroid cancers, physician-diagnosed pulmonary problems, and ubiquitous high indices of mercury in hair, pesticides in breast milk, and phthalates in urine.

Mercury contamination in deposited dust and its bioaccumulation patterns throughout Pakistan

Mercury (Hg) contamination of environment is a major threat to human health in developing countries like Pakistan. Human populations, particularly children, are continuously exposed to Hg contamination via dust particles due to the arid and semi-arid climate. However, a country wide Hg contamination data for dust particles is lacking for Pakistan and hence, human populations potentially at risk is largely unknown. We provide the first baseline data for total mercury (THg) contamination into dust particles and its bioaccumulation trends, using scalp human hair samples as biomarker, at 22 sites across five altitudinal zones of Pakistan. The human health risk of THg exposure via dust particles as well as the proportion of human population that are potentially at risk from Hg contamination were calculated. Our results indicated higher concentration of THg in dust particles and its bioaccumulation in the lower Indus-plain agricultural and industrial areas than the other areas of Pakistan. The highest THg contamination of dust particles (3000ppb) and its bioaccumulation (2480ppb) were observed for the Lahore district, while the highest proportion (>40%) of human population was identified to be potentially at risk from Hg contamination from these areas. In general, children were at higher risk of Hg exposure via dust particles than adults. Regression analysis identified the anthropogenic activities, such as industrial and hospital discharges, as the major source of Hg contamination of dust particles. Our results inform environmental management for Hg control and remediation as well as the disease mitigation on potential hotspots.

Hair mercury concentrations in residents of Sundarban and Calcutta, India

Few studies on hair mercury have been conducted in India despite the fact that India is the world's third largest producer of coal and coal is India's primary energy source. No studies have been conducted in the Indian state of West Bengal which has a coastline with the Bay of Bengal. This study examined the concentration of mercury in hair in two diverse populations in West Bengal, India: Sundarban, a mangrove wetland where fishing is a common occupation, and Calcutta, a megacity and India's oldest functioning port. Individuals from whom scalp hair was collected (N=100) were asked a series of questions on occupation, education, age, smoking and alcohol consumption, and fish consumption. SAS was utilized to generate descriptive statistics including frequency and univariate analyses and to perform regression analyses to determine significant predictors of hair mercury in this population. The mean hair mercury increased across the first three age categories (<21, 21-30, 31-45) and decreased in the fourth category (>45). Hair mercury concentration was significantly higher among residents of Sundarban compared to Calcutta (p=0.0005). In multivariable analysis, location (Sundarban vs. Calcutta) and age were significant predictors of hair mercury concentration (p=0.0120 and p=0.0161, respectively). Average hair mercury concentrations in this study were not particularly elevated. Smoking and alcohol consumption were predictors of hair mercury concentration. The hair mercury in Sundarban residents compared to Calcutta residents may be elevated due to greater consumption of fish and type of fish consumed.

Hair Mercury Levels Detection in Fishermen from Sicily (Italy) by ICP-MS Method after Microwave-Assisted Digestion

A number of ninety-six hair samples from Sicilian fishermen were examined for total mercury detection by an Inductively Coupled Plasma Mass Spectrometry (ICP-MS) method. The mercury levels obtained were compared with mercury levels of 96 hair samples from a control group, in order to assess potential exposure to heavy metals of Sicilian fishermen due to fish consumption and closeness to industrial activities. Furthermore, the mercury levels obtained from hair samples were sorted by sampling area in order to verify the possible risks linked to the different locations. The overall mean concentration in the hair of the population of fishermen was 6.45 ± 7.03 μg g⁻¹, with a highest value in a fisherman of Sciacca (16.48 μg g⁻¹). Hair mercury concentration in fishermen group was significantly higher than in control group (p < 0.01). There was no significant difference in hair total mercury concentrations between sampling areas (p > 0.05). The results of this study indicate a greater risk of exposure to mercury in Sicilian fishermen, in comparison to the control population, due to the high consumption of fish and the close relationship with sources of exposure (ports, dumps, etc.).

Impact of tannery effluents on the aquatic environment of the Buriganga River in Dhaka, Bangladesh

This study presents an overview of the existence and effects of six heavy metals, chromium (Cr), lead (Pb), cadmium (Cd), mercury (Hg), manganese (Mn), and aluminum (Al), in tannery effluents released to the Buriganga River in Dhaka, Bangladesh. The pollutants were found in three different sources, such as effluents from tanneries, contaminated river water and three species of fish—climbing perch ( Anabas testudineus), spotted snakehead ( Channa punctata), and Black tilapia ( Oreochromis mossambicus) caught from the river. Tannery effluents, water, and fish samples were collected from three different factories, five sample stations, and three different harvesting points, respectively. Effluents from all three factories contained significant amounts of heavy metals, especially Cr (374.19 ppm in average), whereas lesser amounts were found in the tissues of the three fish species studied. The trends in tissue elemental concentrations of fish were Cr > Pb > Al > Hg > Mn > Cd. In most cases (Cr, Cd, Mn, and Al), heavy metal concentrations were found to be greater in climbing perch than in Black tilapia and spotted snakehead. Although the river water contained high concentrations of harmful heavy metals, the fish species under study had concentrations well below the permissible Food and Agriculture Organization/World Health Organization levels for those metals and seemed to be safe for human consumption.

Hair mercury and urinary cadmium levels in Belgian children and their mothers within the framework of the COPHES/DEMOCOPHES projects

A harmonized human biomonitoring pilot study was set up within the frame of the European projects DEMOCOPHES and COPHES. In 17 European countries, biomarkers of some environmental pollutants, including urinary cadmium and hair mercury, were measured in children and their mothers in order to obtain European-wide comparison values on these chemicals. The Belgian participant population consisted in 129 school children (6-11 years) and their mothers (≤ 45 years) living in urban or rural areas of Belgium. The geometric mean levels for mercury in hair were 0.383 μg/g and 0.204 μg/g for respectively mothers and children. Cadmium in mother's and children's urine was detected at a geometric mean concentration of respectively 0.21 and 0.04 μg/l. For both biomarkers, levels measured in the mothers and their child were correlated. While the urinary cadmium levels increased with age, no trend was found for hair mercury content, except the fact that mothers hold higher levels than children. The hair mercury content increased significantly with the number of dental amalgam fillings, explaining partially the higher levels in the mothers by their higher presence rate of these amalgams compared to children. Fish or seafood consumption was the other main parameter determining the mercury levels in hair. No relationship was found between smoking status and cadmium or mercury levels, but the studied population included very few smokers. Urinary cadmium levels were higher in both mothers and children living in urban areas, while for mercury this difference was only significant for children. Our small population showed urinary cadmium and hair mercury levels lower than the health based guidelines suggested by the WHO or the JECFA (Joint FAO/WHO Expert Committee on Food Additives). Only 1% had cadmium level slightly higher than the German HBM-I value (1 μg/l for adults), and 9% exceeded the 1 μg mercury/g hair suggested by the US EPA.

Accumulation of total mercury and methylmercury in rice plants collected from different mining areas in China

A total of 155 rice plants were collected from ten mining areas in three provinces of China (Hunan, Guizhou and Guangdong), where most of mercury (Hg) mining takes place in China. During the harvest season, whole rice plants were sampled and divided into root, stalk & leaf, husk and seed (brown rice), together with soil from root zone. Although the degree of Hg contamination varied significantly among different mining areas, rice seed showed the highest ability for methylmercury (MeHg) accumulation. Both concentrations of total mercury (THg) and MeHg in rice plants were significantly correlated with Hg levels in soil, indicating soil is still an important source for both inorganic mercury (IHg) and MeHg in rice plants. The obvious discrepancy between the distribution patterns of THg and MeHg reflected different pathways of IHg and MeHg accumulation. Water soluble Hg may play more important role in MeHg accumulation in rice plants.

Mercury in scalp hair near the Mid-Atlantic Ridge (MAR) in relation to high fish consumption

The aim of this study was to evaluate the potential risk of mercury contamination near the Mid-Atlantic Ridge relating total mercury (THg) concentrations in the human scalp hair (n = 110) and high fish consumption levels. THg was quantified in human scalp hair, and volunteers were questioned about age, gender, and smoking habits being subsequently grouped in categories based on the individual average intake of fish meals per week. THg concentrations ([THg]) in hair samples ranged from 0.05 to 2.24 μg g(-1), and significant differences were found according to age (p < 0.05) and also among volunteers presenting different fish consumption rates (p < 0.001) being the highest [THg] observed on the adult population and also on volunteers that indicated consuming five or more meals of fish per week. Results indicate a pattern of increased mercury accumulation with increasing fish consumption. Despite mercury availability and a potential mercury intake of up to seven times, the WHO provisional tolerable weekly intake of mercury value, in consequence of high fish consumption, mercury concentrations in scalp hair are comparatively low regarding recommended levels by WHO.

Mercury concentration in the breast milk of Iranian women

Human milk is usually the only source of food for infants during the first 4 to 5 months of their life. In this research, 80 human milk samples were collected from mothers in Tehran, Noushahr and the countryside of Tabriz, Iran, who were not occupationally exposed to mercury. The mean concentration of mercury in breast milk obtained from mothers in the countryside of Tabriz, Noushahr and Tehran was 0.86, 0.15 and 0.12 μg/L, respectively. There was a significant difference in mercury concentration in human breast milk between that from the countryside of Tabriz with that from Tehran and Noushahr. Only 3.7% of infant samples (three infants) had mercury concentration higher than normal versus the WHO recommended limit (0.5 μg g(-1)). The fish consumption of these mothers in Tehran and Noushahr was a factor that significantly affected the mercury concentration in their breast milk. Also, their age affected the mercury levels in breast milk (p = 0.04).

Freshwater fish-consumption relations with total hair mercury and selenium among women in eastern China

Wild fish from Qiandao Hu, a reservoir in the Zhejiang Province in eastern China, have increased mercury (Hg) concentrations exceeding the World Health Organization's (WHO) recommended guidelines. Due to the importance of freshwater biota in the local cuisine, dietary exposure to increased neurotoxic Hg is a concern in this region. An environmental hair-marker study was undertaken coincident with a cross-sectional epidemiologic study with 50 women age 17-46 years living in a Qiandao Hu fishing village. Diet, occupation, and other possible sources of Hg were recorded by way of questionnaires. Total mercury (THg) and selenium (Se) concentrations were measured in human hair samples and in important market fish species. Fish THg and Se concentrations were increased, with some fish concentrations >200 ng/g THg and 500 ng/g Se (wet weight [ww]). However, the average hair THg was low at 0.76 ± 0.51 μg/g dry weight, lower than the WHO's no observable-adverse effect level (50 μg/g), whereas the average hair Se was 1.0 μg/g. Hair THg concentration was positively associated with the average mass of fish consumed weekly, indicating that fish consumption is the main contributor to hair THg in this geographic area. The age-related hair THg trend was not linear but instead demonstrated a rapid increase in THg before age 25 years, followed by consistent concentrations in all ages after age 25 years. There was a positive correlation (p < 0.001) between molar Se and Hg in the hair samples, suggesting a possible antagonistic relation. This is the first study examining the relation between dietary Hg exposure and hair THg in an eastern China community where freshwater fish, as opposed to marine fish, dominates the cuisine.

Mercury contamination in human hair and some marine species from Sfax coasts of Tunisia: levels and risk assessment

The aim of this study was to measure the mercury (Hg) contents of three marine fish and common seafood species (Diplodus annularis, Sarpa salpa and Sepia officinalis) at two sampling sites in the gulf of Gabes, i.e. Sidi Mansour (polluted site) and Kerkennah (control site). These species are frequently consumed by the population living at the Sfax coasts of Tunisia, particularly by the families of fisherman. Additionally, the hair mercury levels of 55 volunteers (28 women, 27 men) were analysed and the daily total mercury intake through the fish and seafood diet was estimated. The key findings were: (1) the mercury contents of the examined fish and seafood species frequently exceeded the regulatory guideline value of 0.5 mg/kg, (2) no site-specific differences in hair mercury contents were found, (3) fish and seafood consumption is probably the major contributor of mercury exposure in this population, (4) the daily mercury intake through frequent consumption of D. annularis exceeds the US EPA reference dose. Further studies are necessary to evaluate the health risks associated with such high mercury exposure levels in order to allow optimal counseling and therapy of the concerned population and to avoid future impairment of human health, particularly children's health.

Determinants of exposure to mercury in hair from inhabitants of the largest mercury mine in the world

Mercury exposure of the local population was assessed in two areas of the Almadén mercury mining district, Spain, which has been the world's largest producer of this element. Two groups, who are exposed to different sources of mercury, from a point source in Almadén and a diffuse source hundreds of kilometres away in the same region, were studied. Total mercury (THg) in human hair ranged from 0.20 to 9.35 mg kg(-1) and the mean value was 2.64 mg kg(-1). About 87% of subjects had THg levels in excess of the EPA reference dose (RfD=1.0 mg kg(-1)), while a high percentage (68%) of them live in Almadén. There was a clear increase in hair Hg with reported fish consumption and the highest mean hair mercury level was 4 times the RfD in a group who had reported the highest consumption of fish. For the whole group, there was a significant effect of age, gender and fish consumption in relation to Hg concentration in the hair. Nevertheless, when both groups were tested separately by means of a multivariate regression model, there was significant exposure in those living near the mine area. Several factors such as age, gender and fish consumption remained statistically significant and were associated with THg. The main conclusion is that people living close to the hot spot are more impacted by mercury than people living further away. The intake of Hg through consumption of fish is an important parameter for Hg exposure; however, in the case of people living close to the hot spot, their levels are related to the highly Hg-impacted living environment.

Mercury human exposure through fish consumption in a reservoir contaminated by a chlor-alkali plant: Babeni reservoir (Romania)

PURPOSE

Chlor-alkali plants are one of the most important point sources of mercury to aquatic environment. The problem of Hg contamination has been studied in a region, Rm Valcea (Romania), impacted by the wastewater discharge of a chlor-alkali plant. The purpose of the present study is to evaluate the current status of mercury pollution in the Babeni reservoir (Olt River) and the exposure of local population via fish consumption to mercury originating from the chlor-alkali plant.

METHODS

Sediments were collected from Valcea, Govora and Babeni reservoirs. Grain size distribution, organic content and total mercury (THg) concentrations were analysed in sediments. Fish were purchased from local anglers, and the scalp hair was collected from volunteers. THg in sediment, fish and hair samples was determined using an atomic absorption spectrophotometer for Hg determination. Monomethylmercury (MMHg) was analysed in the muscle and liver tissues by species-specific isotope dilution and capillary gas chromatography hyphenated to inductively coupled plasma mass spectrometer.

RESULTS

High mercury concentrations were found in the sediments and in fish from Babeni reservoir, with a median of 2.1 mg/kg (IQR = 3.2) in sediments and a mean value of 1.8 +/- 0.8 mg/kg_ww in fish muscle. MMHg concentrations in fish were well above the WHO guidelines for fish consumption. Local population consuming fish from the Babeni reservoir had THg concentrations in hair significantly higher than those consuming fish from upstream reservoirs and/or from the shops and reached a median value of 2.5 mg/kg (IQR = 3.6).

CONCLUSIONS

The remnant pollution in the fish of this reservoir, and probably many other lakes and reservoirs receiving Hg polluted wastewater, represents a considerable health risk for the local fish consumers.

Survey of total mercury and methylmercury levels in edible fish from the Adriatic Sea

Total mercury and methylmercury concentrations were measured in the muscle tissue of different fish species from the Adriatic Sea to ascertain whether the concentrations exceeded the maximum level fixed by the European Commission. Large species-dependent variability was observed. The highest total mercury mean concentrations were in benthic (0.20-0.76 microg g(-1) wet wt) and demersal fish (0.22-0.73 microg g(-1) wet wt), while pelagic species showed the lowest levels (0.09-0.23 microg g(-1) wet wt). In 15% of frost fish, in 42% of skate and in 30% of angler fish samples total mercury concentrations exceeded the maximum level fixed by the European Commission (Hg = 1 microg g(-1) wet wt); for the species for which the maximum level was set to 0.5 microg g(-1) wet wt, concentrations exceeding the prescribed legal limit were observed in 6.4% of bokkem, in 6.6% of pandora, in 20% of megrin, in 12.5% of four-spotted megrim, in 16% of striped mullet, in 5.0% of forkbeard and in 5.3% of picarel samples. In all the different species, mercury was present almost completely in the methylated form, with mean percentages between 70 and 100%. Weekly intake was estimated and compared with the provisional tolerable weekly intake recommended by the FAO/WHO Expert Committee on Food Additives. A high exposure was associated with the consumption of only skates, frost fish and angler fish, thought the consumption of the other species, such as, megrim, four spotted megrim, red fish striped mullet and forkbeard, resulted in a weekly intake slightly below the established provisional tolerable weekly intake.

Modification of a reaction vessel for the determination of total mercury in hair by cold vapor atomic absorption spectrometry

A classical cold vapor atomic absorption spectrometric (CVAAS) method for the determination of total mercury in blood has been previously adapted for application to samples of human hair. The reaction vessel specified in the original adaptation was, however, large and difficult to use with small hair samples. In the present study, the reaction vessel has been modified and reduced in size and the protocols have been optimized in order to provide an analytical method that is more efficient, less time-consuming, and gives lower blank values than the original adaptation. The optimized method was validated by multiple, independent, replicated assays of certified reference hair samples, and the mean recovery obtained (98.7%) indicated an efficient performance of the digestion and detection processes. The method was applied to the assay of 144 hair samples derived from populations that had or had not been exposed to mercury from environmental sources. The results from all of the samples analyzed were consistent with those published previously for similar samples.

Human health effects of methylmercury exposure

Mercury (Hg), and the organometallic compounds formed from it, are among the most toxic of substances to the global environment. Mercury is environmentally ubiquitous, and both wildlife and humans are exposed to the toxic effects of its environmental residues, primarily elemental mercury (Hg0), divalent mercury (Hg2+) and methylmercury (MeHg). Humans are exposed to different forms of Hg, and potential health risks have been reported from such exposures; examples of Hg exposure include mercury vapor from dental amalgams, occupational exposures and exposures during artisan and small-scale gold mining operations. Despite the significance of those foregoing Hg exposures, of particular concern is human and wildlife exposure to MeHg, a potent neurotoxicant. Once incorporated into the body, MeHg easily penetrates the blood-brain barrier and causes damage to the central nervous system, particularly in fetuses. It bioaacumulates and biomagnifies in the aquatic food chain; consequently, fish and seafood consumption is the major pathway by which humans are exposed to MeHg. MeHg is the focus of this review. It adversely affects humans and is currently the subject of intense public health interest and worldwide concern. In this review, I summarize the sources and cycling of global mercury in the environment, pathways of exposure, toxicity and exposure evaluation, toxicokinetics, the common biomarkers to evaluate exposure and effects in populations, and finally review the nutritional risks and benefits from fish consumption.

Mercúrio total em cabelo de crianças de uma população costeira, Cananéia, São Paulo, Brasil

Os níveis de mercúrio (Hg) total em cabelos estão diretamente relacionados à alimentação, particularmente ao consumo de peixes por populações costeiras com grande representação caiçara. No presente estudo foram avaliados os níveis de mercúrio total em cabelos de crianças com idade entre 4 e 12 anos, pertencente a três escolas públicas da cidade de Cananéia, São Paulo, Brasil. Os resultados obtidos (mediana e intervalo) para mercúrio total foram de: 0,04mg.kg-1 (0,01-0,77mg.kg-1), 0,39mg.kg-1 (< 0,01-3,33mg.kg-1) e 0,39mg.kg-1 (< 0,01-2,81mg.kg-1) considerando as escolas ES1, ES2 e ES3, respectivamente. Em geral, os valores encontrados estiveram bem abaixo do valor preconizado pela Organização Mundial da Saúde para uma população adulta não exposta ao mercúrio (2,0mg.kg-1). Os baixos valores observados e a inexistência de valores de referência para mercúrio total em cabelos de crianças brasileiras possibilitam a consideração desses valores como possível referência nacional em cabelos de populações costeiras, uma vez que foram obtidos em região de baixo impacto ambiental.

Human and crab exposure to mercury in the Caribbean coastal shoreline of Colombia: impact from an abandoned chlor-alkali plant

Human hair samples from male and female people aged 6-85 years, as well as muscle of crabs (Callinectes sapidus and Callinectes bocourti) were collected from different fishing places along the Caribbean coastal shoreline of Colombia and analyzed for total mercury (T-Hg) in order to establish the impact of mercury-polluted sediments in Cartagena bay on the ecosystem. Hair T-Hg in inhabitants varied between 0.1 and 21.8 microg/g, with average and median of 1.52 microg/g and 1.1 microg/g, respectively. Differences between sampling locations were significant (P<0.01) and median values decreased in the order: Caño del Oro (1.5 microg/g)<Bocachica (1.4 microg/g) (both located in Cartagena Bay)<Coveñas (1.2 microg/g)<Lomarena (0.7 microg/g)=Tasajera (0.7 microg/g). A similar trend was observed for T-Hg in muscle of crabs, however, along Cartagena bay, T-Hg distribution in these organisms varied widely, with highest values detected in samples collected in front of the extinct chlor-alkali plant. Although the T-Hg median for these people is equal to the threshold risk level recommended by U.S. EPA, this study highlights the fact that contaminated sediments are still driving the distribution of mercury through the food chain, allowing its accumulation in fishermen whose diet includes marine products as sources of protein.

Antioxidant and biotransformation responses in Liza aurata under environmental mercury exposure - relationship with mercury accumulation and implications for public health

This study was carried out in the Laranjo basin (Ria de Aveiro, Portugal), an area impacted by mercury discharges. Liza aurata oxidative stress and biotransformation responses were assessed in the liver and related to total mercury (Hgt) concentrations. A seasonal fish survey revealed a sporadic increase in total glutathione (GSHt) and elevated muscle Hgt levels, although Hg levels did not exceed the EU regulatory limit. As a complement study, fish were caged for three days both close to the bottom and on the water surface at three locations, and displayed higher Hgt levels accompanied by increased GSHt content and catalase activity as well as EROD activity inhibition. The bottom group displayed higher hepatic Hgt and GSHt contents compared with the surface group. Globally, both wild and caged fish revealed that the liver accumulates higher Hgt concentrations than muscle and, thus, better reflects environmental contamination levels. The absence of peroxidative damage in the liver can be attributed to effective detoxification and antioxidant defense.

Hair mercury levels in an urban population from southern Italy: fish consumption as a determinant of exposure

Mercury levels in hair of a general population, 237 adults aged between 35-45, in Naples, Italy, were assessed. The subjects were asked to fill in a questionnaire about age, gender, body weight, height, body mass index (BMI), fish consumption, number, surface and area of dental amalgam fillings. Total mercury (THg) concentrations in human hair ranged from 0.221 to 3.402 microg/g and the mean value for the subjects under study was 0.638 microg/g. Study participants were divided into three groups in accordance with fish consumption and dental amalgam: ANF (amalgam and no fish); NAF (no amalgam but with fish) and AAF (amalgam and fish). Significant differences in THg were found in the three groups (p<0.05). A multiple linear regression analysis showed a weak but significant correlation of THg content in hair with respect to gender and age, but almost no association was found between THg and dental fillings. Conversely, a strong correlation was obtained between THg and fish consumption regardless of the group evaluated. Finally, mercury levels in hair exceeded the levels corresponding to the EPA reference dose (RfD) of 0.1 microg Hg/kg body weight per day (1 microg Hg/g hair) in 6% of the population (4% men and 2% women). However, the THg limits in our subjects were not exceeded according to the WHO guidelines, which use a benchmark dose of 0.23 microg Hg/kg bw/day (14 microg Hg/g maternal hair).

Human exposure to methylmercury through rice intake in mercury mining areas, Guizhou province, China

The toxicity of methylmercury (Me-Hg) has caused widespread public human concern as a result of several widely publicized disasters. Me-Hg is highly toxic, and the nervous system is its principal target tissue for humans. Although the general population is primarily exposed to Me-Hg through contaminated fish and marine mammals, in Hg mining areas a long history of mining activities can produce serious Hg pollution to the local environment In a study of 98 persons from the Wanshan Hg mining area, hair Me-Hg levels indicated Me-Hg exposure. Rice, the staple food of the local inhabitants also showed high total Hg (T-Hg) and Me-Hg levels. The geometric mean concentration of T-Hg and mean concentration of Me-Hg in rice samples collected from 3 villages in Wanshan Hg mining area were 36.2 (ranging from 4.9 to 214.7), and 8.5 (ranging from 1.9 to 27.6) microg/kg, respectively, which were significantly elevated compared to the rice samples collected from a reference area, where the mean T-Hg and Me-Hg concentrations were 7.0 (3.2-15.1) and 2.5 (0.8-4.3) microg/kg, respectively. Pork meat, vegetable, and drinking water samples collected in Wanshan Hg mining area contained highly elevated T-Hg, but very low levels of Me-Hg. The relationships between the estimated rice Me-Hg intake and hair Me-Hg levels (r = 0.65, p < 0.001) confirmed rice with high Me-Hg levels indeed was the main route of Me-Hg exposure for the local residents in the Wanshan Hg mining area. From our study, we can conclude that the main human exposure to Me-Hg via food consumption is not restricted to fish, but in some cases in mining areas of China to frequent rice meals.

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 microg g(-1) of weight wet (mean, 0.68 microg g(-1)) and between 0.09 and 1.62 microg g(-1) (mean, 0.51 microg 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 microg/kg of body weight; Mediterranean horse mackerel, 5.86 to 13.55 microg/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.

Cadmium and mercury in cephalopod molluscs: Estimated weekly intake

Cadmium and mercury concentrations were measured in the flesh and hepatopancreas of different species of cephalopod molluscs (European squid, common octopus, curled octopus, horned octopus, pink cuttlefish, common cuttlefish) in order to establish whether the concentrations exceeded the maximum levels fixed by the European Commission. In hepatopancreas, the levels of cadmium were substantially higher than those in flesh (flesh 0.11-0.87 microg g(-1) wet weight, hepatopancreas 2.16-9.39 microg g(-1) wet weight), whilst the levels of mercury (flesh 0.13-0.55 microg g(-1) wet weight, hepatopancreas 0.23-0.79 microg g(-1)) were approximately double those in flesh. Concentrations exceeding the maximum permitted limit of cadmium were found in 39.8 and 41.0% of common octopus and pink cuttlefish flesh, respectively. For mercury, concentrations above the limit were found only in octopuses, and precisely in 36.8, 50.0 and 20.0% of flesh samples of common, curled and horned octopus, respectively. In the hepatopancreas, concentrations of cadmium and mercury were above the proposed limits in all the samples examined. The estimated weekly intake of between 0.09 and 0.49 microg kg(-1) body weight for cadmium and between 0.05 and 0.24 microg kg(-1) body weight for mercury made only a small contribution to the provisional tolerable weekly intake (cadmium 1.3-7.0%, mercury 1.0-4.8%) set by the WHO.

Mercury contamination in human hair and fish from Cambodia: levels, specific accumulation and risk assessment

Mercury (Hg) concentrations in human hair and fish samples from Phnom Penh, Kien Svay, Tomnup Rolork and Batrong, Cambodia, collected in November 1999 and December 2000 were determined to understand the status of contamination, and age- and sex-dependent accumulation in humans and to assess the intake of mercury via fish consumption. Mercury concentrations in human hair ranged from 0.54 to 190mug/g dry wt. About 3% of the samples contained Hg levels exceeding the no observed adverse effects level (NOAEL) of WHO (50mug/g) and the levels in some hair samples of women also exceeded the NOAEL (10mug/g) associated with fetus neurotoxicity. A weak but significant positive correlation was observed between age and Hg levels in hair of residents. Mercury concentrations in muscle of marine and freshwater fish from Cambodia ranged from <0.01 to 0.96mug/g wet wt. Mercury intake rates were estimated on the basis of the Hg content in fish and daily fish consumption. Three samples of marine fish including sharp-tooth snapper and obtuse barracuda, and one sample of sharp-tooth snapper exceeded the guidelines by US EPA and by Joint FAO/WHO Expert Committee on Food Additives (JECFA), respectively, which indicates that some fish specimens examined (9% and 3% for US EPA and JECFA guidelines, respectively) were hazardous for consumption at the ingestion rate of Cambodian people (32.6g/day). It is suggested that fish is probably the main source of Hg for Cambodian people. However, extremely high Hg concentrations were observed in some individuals and could not be explained by Hg intake from fish consumption, indicating some other contamination sources of Hg in Cambodia.

Human exposure to mercury in San Jorge river basin, Colombia (South America)

During May-September 1999 human hair samples were collected from the village of Caimito, a fishing community of the state of Sucre (Colombia), in the San Jorge River basin area, and analyzed for total mercury (t-Hg) by cold vapor atomic absorption spectroscopy. T-Hg was measured in both male and female people aged 15-65 years, whose diet mainly consists of fish collected in nearby marshes. Average hair t-Hg concentration in people from Caimito was 4.91 +/- 0.55 microg/g (n = 94), similar to the value previously detected in fishermen living in the gold mining area, 50 km east. Males had similar t-Hg concentrations (4.31 +/- 0.42 microg/g; n = 56) to females (5.78 +/- 1.21 microg/g; n = 38) and there was no difference in t-Hg levels between groups of different age. Mercury content in hair was weakly but significantly associated (R = 0.20, P = 0.05) with fish consumption.

The impact of pollution from a mercury processing plant in KwaZulu-Natal, South Africa, on the health of fish-eating communities in the area: an environmental health risk assessment

The objective of this study was to determine the human health risk associated with fish consumption in a contaminated area downstream from a mercury processing plant in KwaZulu-Natal, South Africa. The study population consisted of fish consumers living in close proximity to the u'Mgeni River and the Inanda Dam downstream from the plant. A control group was selected from the area upstream from the mercury plant as far as the Nagle Dam. Total daily mercury consumption per kilogram body weight per day was calculated for each person included in the study. These data were compared with the tolerable daily intake standard published by the World Health Organization, as well as to the United States Environmental Protection Agency's reference dose. Human hair samples obtained from the study population and a control group were analysed for mercury content. The results of the risk estimation indicated that the study population is at risk. Human hair samples, however, indicated that dangerous levels of mercury had not yet been consumed. Humans in this study area could be subject to an excessive health risk from mercury as a result of their fish consumption. Fish mercury levels in the contaminated area should be monitored closely.

Factors influencing the total mercury and methyl mercury in the hair of the fishermen of Kuwait

Total and methyl mercury (MeHg) levels in the hair of fishermen are described anticipating that they represent the critical group for dietary exposure. One-hundred human hair samples were collected from fishermen (Egyptians: age range 25-60), living in Doha Fishing Village, Kuwait. Thirty-five additional samples were taken from a control group working in a local construction company (age range 26-35). Overall mean concentrations in the hair of the population of fishermen are 4.181+/-3.220 and 4.025+/-3.130 microg g(-1) for total and MeHg, respectively. The equivalent values for the control are 2.617+/-1.404 and 2.556+/-1.391 microg g(-1) for total and MeHg, respectively. MeHg concentrations are strongly correlated to those of total Hg ( [Formula: see text], [Formula: see text] ) and MeHg concentrations in human hair are unrelated to age and duration of residence in Kuwait but show a positive correlation with the quantity of fish consumed. Levels of Hg in hair also show a tendency to increase in those who prefer to eat the entire fish, including the heads. In general, the concentrations of total and MeHg in fishermens' hair are twice the WHO 'normal' level (2.0 microg g(-1)) but are still less than the WHO threshold level (10.0 microg g(-1)). The results also show that grey hair contains undetectable amounts of Hg and therefore does not reflect individual exposure to this contaminant.

Determination of reference ranges for elements in human scalp hair

Expected values, reference ranges, or reference limits are necessary to enable clinicians to apply analytical chemical data in the delivery of health care. Determination of references ranges is not straightforward in terms of either selecting a reference population or performing statistical analysis. In light of logistical, scientific, and economic obstacles, it is understandable that clinical laboratories often combine approaches in developing health associated reference values. A laboratory may choose to: 1. Validate either reference ranges of other laboratories or published data from clinical research or both, through comparison of patients test data. 2. Base the laboratory's reference values on statistical analysis of results from specimens assayed by the clinical reference laboratory itself. 3. Adopt standards or recommendations of regulatory agencies and governmental bodies. 4. Initiate population studies to validate transferred reference ranges or to determine them anew. Effects of external contamination and anecdotal information from clinicians may be considered. The clinical utility of hair analysis is well accepted for some elements. For others, it remains in the realm of clinical investigation. This article elucidates an approach for establishment of reference ranges for elements in human scalp hair. Observed levels of analytes from hair specimens from both our laboratory's total patient population and from a physician-defined healthy American population have been evaluated. Examination of levels of elements often associated with toxicity serves to exemplify the process of determining reference ranges in hair. In addition the approach serves as a model for setting reference ranges for analytes in a variety of matrices.

Mercury speciation and accumulation in Bangladesh freshwater and anadromous fish

Total mercury concentration in the muscle of 417 fish of 12 common freshwater and four anadromous species from Bangladesh were low, varying from 2 to 430 ng/g fresh wt. Depending on Hg speciation, three types of accumulation mechanisms were defined. Type I covers the majority of species and describes a pattern widely accepted as 'normal', with increasing levels of organic (methyl) mercury with length (age), combined to a low and constant inorganic level. This accumulation pattern leads to a relative increase of the organic mercury fraction with age, eventually reaching 90-100% of organic mercury in full grown specimens. Type II is found in both planktivorous genera only and showed increasing levels of inorganic mercury combined to low and constant organic mercury levels, leading to a relative decrease in organic mercury fraction with age. This unexpected pattern was only reported in cases of some marine species where it seemed to be linked to demethylation mechanisms or regional influences on Hg levels. A third intermediate accumulation pattern with increasing concentrations of both the organic and the inorganic Hg fraction with age was found in one bottom dwelling species only. The implications of these observations for the accumulation mechanisms of mercury in fish are discussed.