The hair-organ relationship in mercury concentration in contemporary Japanese

Mercury in the brain (tumor tissues) and in markers (hair and blood) of exposure in Western Amazonia patients

BACKGROUND

Central nervous system tumors (CNSTs) represent the second most frequent form of malignant tumors in childhood and the second leading cause of death associated with neurological diseases, affecting individuals of all age groups. In adults, CNSTs are the sixth most common cause of death in patients with malignant tumors. Additionally, the brain is the most sensitive and studied organ for mercury (Hg) toxicity.

METHOD

We studied total Hg (THg) in tissue samples (of benign and malignant CNSTs) and explored its associations with THg in exposure markers (hair and blood) from 65 patients (40 females and 25 males) who underwent surgical treatment.

RESULTS

No statistically significant differences were found in THg concentrations in brain tumors or in blood and hair from these patients (classified as malignant/benign or glioma/non-glioma); also, there were no statistically significant differences between males and females. However, statistically significant correlations were found between THg in CNSTs and in hair (r_s = 0.4967; p = 0.0001) and in blood (r_s = 0.4702; p = 0.0058); but no significant correlations were found between THg in hair and blood (r_s = 0.1229; p = 0.5332). In the Western Amazon, with endemic exposure to fish-methylmercury, these urban patients were low to moderate fish consumers; THg concentrations in blood (median: 0.645 µg.L^-1; range: 8.01-21.02 µg.L^-1; n = 56) and hair (median: 0.686 µg.g-¹; range: 0.01-10.02 µg.g^-1; n = 65) were relatively low, whereas THg levels in brain tumors (median: 8.194 ng.g^-1; range: <0.10-69.16 ng.g^-1; n = 65) were within range of published studies in brain autopsies. Additionally, no statistically significant correlations (p = 0.4828) were observed between frequency of fish consumption and THg in the brain.

CONCLUSION

Although no significant THg concentrations in the type of brain tumors (benign versus malignant) were found, the significantly positive correlation between markers of THg exposure (hair and blood) and THg in the brain tissues indicates its usefulness as a marker/proxy for brain-THg load. These findings confirm the value of using hair and blood as constructs of THg in the brain of exposed populations.

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.

Concentration of mercury species in hair, blood and urine of individuals occupationally exposed to gaseous elemental mercury in Asturias (Spain) and its comparison with individuals from a control group formed by close relatives

Between November 19th, 2012 and December 3rd, 2012, 50 workers were intoxicated with gaseous Hg in San Juan de Nieva (Asturias, Spain) during the maintenance of a heat exchanger of a zinc manufacturer. We have quantified the concentration of methylmercury (MeHg), ethylmercury (EtHg) and Hg(II) in blood, hair and urine samples of those individuals taken three years after the accident. Blood, hair and urine of their closest relatives were also analyzed to assess whether the mercury burden present in the intoxicated individuals was due to the occupational exposure or to environmental or lifestyle-related factors. The determination of the mercury species in the samples was carried out applying multiple spiking Isotope Dilution GC-ICP-MS. This procedure corrects for possible interconversion reactions between the Hg species during the sample preparation procedure. Linear correlations were observed for both groups when plotting MeHg in blood vs MeHg in hair, and MeHg in hair vs Hg (II) in urine. The concentrations of Hg species in the intoxicated individuals were not significantly different from those obtained in the control group except for MeHg in blood. Significantly higher levels of MeHg in blood were obtained in some of the intoxicated individuals who had not consumed fish or seafood since the accident. A different correlation between MeHg in hair and MeHg in blood was obtained for these individuals compared to the control group who showed a hair-to-blood ratio consistent with the reported value for people exposed to Hg via fish consumption. Our results suggest that ingested MeHg followed the same pathway of deposition in hair in exposed and non-exposed individuals. However, the exposed individuals with high MeHg levels in blood showed a significantly different extent of MeHg deposition in hair compared to the control group.

Effects of a Closed Space Environment on Gene Expression in Hair Follicles of Astronauts in the International Space Station

Adaptation to the space environment can sometimes pose physiological problems to International Space Station (ISS) astronauts after their return to earth. Therefore, it is important to develop healthcare technologies for astronauts. In this study, we examined the feasibility of using hair follicles, a readily obtained sample, to assess gene expression changes in response to spaceflight adaptation. In order to investigate the gene expression changes in human hair follicles during spaceflight, hair follicles of 10 astronauts were analyzed by microarray and real time qPCR analyses. We found that spaceflight alters human hair follicle gene expression. The degree of changes in gene expression was found to vary among individuals. In some astronauts, genes related to hair growth such as FGF18, ANGPTL7 and COMP were upregulated during flight, suggesting that spaceflight inhibits cell proliferation in hair follicles.

Mercury in marine fish, mammals, seabirds, and human hair in the coastal zone of the southern Baltic

Mercury (Hg), aside from having high toxicity, is characterized by its ability to biomagnify in the marine trophic chain. This is an important problem especially in estuaries, or in the coastal zone, particularly near the mouths of large rivers. This study was conducted in the years 2001-2011, in the coastal zone of the Baltic Sea near to the mouth of the River Vistula, which is the second biggest river discharging into the Baltic. Mercury concentration was measured in the tissues and organs of cod, flounder, herring, seals (living in the wild and in captivity), great black-backed gulls, and African penguins from Gdańsk Zoo, and also in human hair. Penguins and seals at the seal sanctuary in Hel were fed only herring. In marine birds and mammals and in the pelagic herring, the highest Hg concentration was observed in the kidney and in the liver, while in cod and flounder (located on a higher trophic level) the muscles were the most contaminated with mercury. In gray seals living in the seal sanctuary, Hg concentration in all analyzed tissues and organs except the kidneys was lower in comparison with seals living in the wild. The comparatively small share of fish in the diet of local Polish people and their preference towards the consumption of herring contributed to low concentration of Hg in their hair. The protective mechanisms related to detoxification and elimination of mercury were shown to be more effective in the seals than in the penguins, despite the former consuming around 10 times more food per day.

High iron accumulation in hair and nail of people living in iron affected areas of Assam, India

Human populace of Assam, India repeatedly exposed to high concentration of iron in groundwater results in adverse health effects like hemochromatosis, liver cirrhosis and siderosis. In the present study, human hair and nail analysis were carried out to establish a possible relationship between iron toxicity and its deposition among the residents. Nail and hair iron concentrations ranged from 28.2 to 1046μgg(-1) (n=114) and 26.5-838 (n=108)μgg(-1) levels, respectively, among all the study participants. The iron content of the groundwater (421-5340μgL(-1)) (n=64) used for drinking purposes was positively correlated with both nail (r=0.788, p<0.0001) and hair (r=0.709, p<0.0001) iron concentrations. Age- and sex-matched controls corresponding to each group were selected from population residing in other parts of the country where groundwater does not have excess iron. All the study groups included population drinking iron-contaminated water above the WHO/BIS limit (>300µgL(-1)) for 5 years (Group 1), for more than 5-10 years (Group 2) and for more than 10 years (Group 3). Results suggested that the participants consuming groundwater exceeding the WHO limit of iron had significantly more iron accumulation than those using groundwater containing ≤300μgL(-1) iron (p<0.01). There was statistically higher concentration of iron in the nail samples than the hair samples in all the study groups (p<0.01). There was a positive correlation in iron concentration and the residence time of the participants (p<0.01). Iron levels in the male participants were significantly higher than the female participants in the present study (p<0.01). The current findings are sufficiently compelling to warrant more extensive study of iron exposure through drinking water and adverse effects to the human in the areas where iron concentration is high.

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.

Mercury content of hair in different populations relative to fish consumption

Hair has been used in many studies as a bioindicator of mercury exposure for human populations. At the time of hair formation, mercury from the blood capillaries penetrates into the hair follicles. As hair grows approximately 1 cm each month, mercury exposure over time is recapitulated in hair strands. Mercury levels in hair closest to the scalp reflect the most recent exposure, while those farthest from the scalp are representative of previous blood concentrations. Sequential analyses of hair mercury have been useful for identifying seasonal variations over time in hair mercury content, which may be the result of seasonal differences in bioavailability of fish and differential consumption of piscivorous and herbivorous fish species. Knowledge of the relation between fish-eating practices and hair mercury levels is particularly important for adequate mitigation strategies. Methyl mercury is well absorbed, and because the biological half-life is long, the body burden in humans may reach high levels. People who frequently eat contaminated seafood can acquire mercury concentrations that are potentially dangerous to the fetus in pregnant women. The dose-response relationships have been extensively studied, and the safe levels of exposure have tended to decline. Individual methyl mercury exposure is usually determined by analysis of mercury in blood and hair. The objective of the present review was to examine variations in hair mercury levels from different populations with respect to fish-eating practices.

Comparison of trace element accumulation in Baikal seals (Pusa sibirica), Caspian seals (Pusa caspica) and northern fur seals (Callorhinus ursinus)

Concentrations of 18 trace elements (V, Cr, Mn, Co, Cu, Zn, Se, Rb, Sr, Zr, Mo, Ag, Cd, Sb, Cs, Hg, Tl and Pb) were determined in liver, kidney, muscle and hair of Baikal seals, Caspian seals and northern fur seals. All the three species showed the highest concentrations of Hg, V, Mn, Se and Ag in liver, Cd, Co and Tl in kidney, and Cs in muscle among the soft tissues examined. The highest burdens of Zn, Rb and Cs were observed in muscle, Mo and Ag in liver, and Sb and Pb in hair in all the three species. Concentrations of non-essential elements, Rb, Cd, Cs and Hg, showed significant positive correlations among liver, kidney and muscle, whereas correlation coefficients for essential elements, Mn, Co, Cu, Zn and Se, between the three tissues were generally low for all the species, suggesting that homeostasis controls the concentrations of essential elements but not the non-essential elements in the tissues of these animals. Significant age-dependent increase was found in the concentrations of V, Se and Ag in liver and Hg in liver and kidney of all the three species. Hair concentrations showed significant positive correlations with Zn levels in liver and kidney and Hg in muscle for Caspian seals, Hg in liver and kidney for Baikal seals, and Pb in liver for northern fur seals. Furthermore, regression analysis using the data in the present study and in the literature showed significant positive correlations between Hg levels in hair, and liver, kidney and muscle for various species of pinnipeds. These results indicate the possibility of using hair samples for monitoring these trace elements in pinnipeds.

Total Mercury Levels in Human Autopsy Materials from a Nonexposed Polish Population

Mercury is considered to be one of the most harmful metals. Studies of the so-called normal mercury content in human internal organs, blood, and urine can be useful for assessment of the level of environmental exposure and also for legal and medical expert opinions. The examination encompassed 75 autopsies of inhabitants of southern Poland (50 male and 25 female) investigated at the Institute of Forensic Research in Kraków, Poland, between the end of 1998 and the beginning of 2001. Samples of internal organs were homogenized and digested with nitric and sulfuric acids. Determination of total mercury was performed by the use of cold vapor atomic absorption spectrometry. The following results (range and mean, in ng/g wet weight) were obtained: brain (n = 49) 0-14.2, 2.3 +/- 1.9; liver (n = 69) 2.6-55.0, 15.5 +/- 9.5; kidney (n = 63) 3.2-170, 35.9 +/- 31.7; heart (n = 4) 1.2-2.8, 2.2 +/- 0.75; spleen (n = 17) 2.4-9.6, 4.0 +/- 1.8; lung (n = 22) 1.8-9.1, 3.3 +/- 1.8; stomach (n = 48) 0-4.5, 2.0 +/- 1.0; small intestine (n = 32) 0-14.2, 2.8 +/- 2.7; large intestine (n = 13) 0 - 23.9, 5.2 +/- 7.2; blood (n = 35) 0 6.5, 1.6 +/- 1.2; urine (n = 14) 0 2.6, below detection limit. The above mentioned levels of mercury are similar to those reported by other Polish authors, but are lower than those determined in normal Korean and Japanese organs.

Determination of methylmercury in human hair by ethylation followed by headspace solid-phase microextraction-gas chromatography-cold-vapour atomic fluorescence spectrometry

An analytical procedure for the determination of methylmercury in human hair after acid digestion using aqueous ethylation, headspace solid-phase microextraction sampling and final gas chromatography-cold-vapour atomic fluorescence spectrometry detection is described. Acid digestion, extraction procedure and chromatographic conditions were optimised. An optimal linear range using standard mercury solutions was found and concentration detection limits for the mercury species, MeHg and Hg2+, were about 50 and 80 ng/g, respectively, for 100 mg of human hair. The reproducibility of the developed analytical procedure assessed for hair samples with incurred MeHg was better than 18% (n=5). A certified reference material from the National Institute of Environmental Studies (Japan) was used for validation. Analysis of human hair collected from urban inhabitants was performed and the mean value of methylmercury content in hair samples was 0.764 +/- 0.732 microg/g for the population tested. The developed analytical method is simple, fast and a suitable procedure for the monitoring and screening of human exposure to methylmercury.

Organic mercury compounds: human exposure and its relevance to public health

Humans may be exposed to organic forms of mercury by either inhalation, oral, or dermal routes, and the effects of such exposure depend upon both the type of mercury to which exposed and the magnitude of the exposure. In general, the effects of exposure to organic mercury are primarily neurologic, while a host of other organ systems may also be involved, including gastrointestinal, respiratory, hepatic, immune, dermal, and renal. While the primary source of exposure to organic mercury for most populations is the consumption of methylmercury-contaminated fish and shellfish, there are a number of other organomercurials to which humans might be exposed. The antibacterial and antifungal properties of organomercurials have resulted in their long use as topical disinfectants (thimerosal and merbromin) and preservatives in medical preparations (thimerosal) and grain products (both methyl and ethyl mercurials). Phenylmercury has been used in the past in paints, and dialkyl mercurials are still used in some industrial processes and in the calibration of certain analytical laboratory equipment. The effects of exposure to different organic mercurials by different routes of exposure are summarized in this article.

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.

Total mercury in human renal cortex, liver, cerebellum and hair

The aim of this study was: (a) to estimate the concentration of total mercury in the renal cortex, liver, cerebellum and hair of 46 persons who died suddenly in the Gdańsk region, northern Poland, between the ages of 17 and 90; and (b) to assess whether a correlation occurs between mercury content in the investigated biological media. The mean concentrations of mercury in the human hair, renal cortex, liver and cerebellum were: 378 +/- 315.4 ng/g; 68.6 +/- 92.3 ng/g; 29.9 +/- 22 ng/g and 5.3 +/- 6.9 ng/g respectively. Positive correlations were found between mercury levels in: cerebellum and liver (r = 0.873), cerebellum and hair (r = 0.853), cerebellum and renal cortex (r = 0.578), hair and liver (r = 0.771), hair and renal cortex (r = 0.478) liver and renal cortex (r = 0.66). The geometric mean levels of mercury in the renal cortex, liver, cerebellum and hair in the residents of the Gdańsk region are 15-19 times lower than in the population of Tokyo and its environs [Suzuki T, Hongo T, Yoshinaga J et al. The hair-organ relationship in mercury concentration in contemporary Japanese. Arch Environ Health 1993;44:361-365].

Uncertainty analysis methods for comparing predictive models and biomarkers: A case study of dietary methyl mercury exposure

Biologically based markers (biomarkers) are currently used to provide information on exposure, health effects, and individual susceptibility to chemical and radiological wastes. However, the development and validation of biomarkers are expensive and time consuming. To determine whether biomarker development and use offer potential improvements to risk models based on predictive relationships or assumed values, we explore the use of uncertainty analysis applied to exposure models for dietary methyl mercury intake. We compare exposure estimates based on self-reported fish intake and measured fish mercury concentrations with biomarker-based exposure estimates (i.e., hair or blood mercury concentrations) using a published data set covering 1 month of exposure. Such a comparison of exposure model predictions allowed estimation of bias and random error associated with each exposure model. From these analyses, both bias and random error were found to be important components of uncertainty regarding biomarker-based exposure estimates, while the diary-based exposure estimate was susceptible to bias. Application of the proposed methods to a simple case study demonstrates their utility in estimating the contribution of population variability and measurement error in specific applications of biomarkers to environmental exposure and risk assessment. Such analyses can guide risk analysts and managers in the appropriate validation, use, and interpretation of exposure biomarker information.

Preparation of hair for measurement of elements by inductively coupled plasma-mass spectrometry (ICP-MS)

The preparation of hair for the determination of elements is a critical component of the analysis procedure. Open-beaker, closed-vessel microwave, and flowthrough microwave digestion are methods that have been used for sample preparation and are discussed. A new digestion method for use with inductively coupled plasma-mass spectrometry (ICP-MS) has been developed. The method uses 0.2 g of hair and 3 mL of concentrated nitric acid in an atmospheric pressure-low-temperature microwave digestion (APLTMD) system. This preparation method is useful in handling a large numbers of samples per day and may be adapted to hair sample weights ranging from 0.08 to 0.3 g. After digestion, samples are analyzed by ICP-MS to determine the concentration of Li, Be, B, Na, Mg, Al, P, S, K, Ca, Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Zn, Ge, As, Se, Rb, Sr, Zr, Mo, Pd, Ag, Cd, Sn, Sb, I, Cs, Ba, Pt, Au, Hg, Tl, Pb, Bi, Th, and U. Benefits of the APLTMD include reduced contamination and sample handling, and increased precision, reliability, and sample throughput.

Methylmercury in fish from Owyhee Reservoir in southeast Oregon: scientific uncertainty and fish advisories

Data collected during 1987-1994 showed elevated levels of mercury (Hg) in fish tissue from the Owyhee Reservoir in southeastern Oregon. Sixty-five percent of the samples analyzed had total Hg levels exceeding the US Environmental Protection Agency's (EPA) health screening value of 0.6 mg/kg. Eighteen out of 89 (20%) fish tissue samples also had total Hg levels greater than the US Food and Drug Administration's (FDA) mercury action level of 1.0 mg/kg. The overall mean Hg content for all fish collected from the reservoir was 0.75 mg/kg wet weight (wet wt.). Fish muscle taken from largemouth bass (Micropterus salmoides), smallmouth bass (Micropterus dolomieu) and channel catfish (Ictalurus punctatus) had the highest mean Hg levels of 0.92, 0.87 and 0.82 mg/kg, respectively. In contrast, rainbow trout (Salmo gairdneri) had the lowest mean Hg content of 0.37 mg/kg. Increases in total Hg concentrations were found to be positively correlated with size for rainbow trout and yellow perch. A weak but significant correlation was also observed between total mercury content and age for smallmouth bass. Based on these data, in 1994 the Oregon Health Division (OHD) issued a fish consumption advisory for the Owyhee Reservoir using a conservative risk-based approach. The process of defining and communicating these consumption limits is the subject of this paper.

Mercury in hair for a child population from Tarragona Province, Spain

Mercury concentrations were determined in scalp hair of 233 school children aged 6-16 years. The study was carried out in three communities (Flix, Tarragona and Tortosa) from Tarragona Province (Southern Catalonia, Spain). The influence of the variables place of residence, age, sex, fish and seafood consumption, number of dental amalgam fillings, hair color, parents' occupation, and smoking habits of the household members was also examined. The geometric mean mercury concentration in hair was 0.77 microgram/g. The place of residence, sex, and the frequency in consuming fish and seafood were the variables that significantly affected hair mercury concentrations. Girls had more mercury in their hair than boys, whereas hair mercury levels were significantly correlated with the frequency in the fish and seafood consumption, with the levels being more elevated when the fish and seafood consumption was also higher. Hair mercury concentrations were also affected by the place of residence, with school children of Flix showing lower mercury concentrations than those found in children from Tarragona and Tortosa. The remaining variables had no influence on hair mercury levels.