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In Kadoma (Zimbabwe) gold is extracted from ore based on a simple technology using mercury. Women are exposed whilst living in an exposed area, or even more working directly with mercury. Breast fed infants are exposed via mercury contaminated milk and the general environmental mercury exposure. The aim of the study was to measure infants and mothers levels of mercury in urine and hair, as well as in breast milk. In 2006, an environmental epidemiological field study with 120 mother - child pairs was conducted. A non exposed control group (n = 42) was compared with a medium exposed group (n = 51) and a high exposed group (occupational exposure, n = 27). Urine and hair samples from mother and infants plus breast milk samples were analyzed for total mercury. 120 breast milk samples were analyzed, median (maximum) concentrations [μg Hg/l] were (i) control group < 0.50 (1.55), (ii) medium exposed group 1.10 (10.48), (iii) high exposed group 1.20 (24.80) (p < 0,001). Urine and hair results were distributed similarly for infants and mothers, with higher levels according to the exposure subgroup. All specimen results correlated very well with another, indicating there is a pathway between breast milk and infant's level of mercury. The daily uptake of mercury via breast milk was calculated. The reference dose of 0.3°[μg Hg/kg BW/d] was used to compare the burden of the infants. No infant from the control group, but 17.6% of the medium and 18.5% of the high exposed group were above the reference dose. Mercury in breast milk is generally higher in artisanal and small scale gold mining areas. Breast fed infants were burdened with toxic mercury via breast milk and via the general environment, both are important public health issues., Competing Interests: Declaration of competing interest There are no competing financial interests., (Copyright © 2020 Elsevier Inc. All rights reserved.)

Objectives: Gold miners use mercury to extract gold from ore adding liquid mercury to the milled gold-containing ore. This results in a mercury-gold compound, called amalgam. Miners smelt this amalgam to obtain gold, vaporizing it and finally inhaling the toxic mercury fumes. The objective was to merge and analyze data from different projects, to identify typical signs and symptoms of chronic inorganic mercury exposure., Material and Methods: Miners and community members from various artisanal small-scale gold mining areas had been examined (Philippines, Mongolia, Tanzania, Zimbabwe, Indonesia). Data of several health assessments were pooled. Urine, blood and hair samples were analyzed for mercury (N = 1252). Questionnaires, standardized medical examinations and neuropsychological tests were used. Participants were grouped into: Controls (N = 209), living in an exposed area (N = 408), working with mercury as panners (N = 181), working with mercury as amalgam burners (N = 454). Chi 2 test, linear trend test, Mann-Whitney test, Kruskal-Wallis test, correlation coefficient, Spearman's rho, and analysis of variance tests were used. An algorithm was used to define participants with chronic mercury intoxication., Results: Mean mercury concentrations in all exposed subgroups were elevated and above threshold limits, with amalgam burners showing highest levels. Typical symptoms of chronic metallic mercury intoxication were tremor, ataxia, coordination problems, excessive salivation and metallic taste. Participants from the exposed groups showed poorer results in different neuropsychological tests in comparison to the control group. Fifty-four percent of the high-exposed group (amalgam burners) were diagnosed as being mercury-intoxicated, compared to 0% within the control group (Chi 2 p < 0.001)., Conclusions: Chronic mercury intoxication, with tremor, ataxia and other neurological symptoms together with a raised body burden of mercury was clinically diagnosed in exposed people in artisanal small-scale mining areas. The mercury exposure needs to be urgently reduced. Health care systems need to be prepared for this emerging problem of chronic mercury intoxication among exposed people. Int J Occup Med Environ Health 2017;30(2):249-269., (This work is available in Open Access model and licensed under a CC BY-NC 3.0 PL license.)

Background: Artisanal small-scale gold mining (ASGM) is a poverty-driven activity practiced in over 70 countries worldwide. Zimbabwe is amongst the top ten countries using large quantities of mercury to extract gold from ore. This analysis was performed to check data availability and derive a preliminary estimate of disability-adjusted life years (DALYs) due to mercury use in ASGM in Zimbabwe., Methods: Cases of chronic mercury intoxication were identified following an algorithm using mercury-related health effects and mercury in human specimens. The sample prevalence amongst miners and controls (surveyed by the United Nations Industrial Development Organization in 2004 and the University of Munich in 2006) was determined and extrapolated to the entire population of Zimbabwe. Further epidemiological and demographic data were taken from the literature and missing data modeled with DisMod II to quantify DALYs using the methods from the Global Burden of Disease (GBD) 2004 update published by the World Health Organization (WHO). While there was no disability weight (DW) available indicating the relative disease severity of chronic mercury intoxication, the DW of a comparable disease was assigned by following the criteria 1) chronic condition, 2) triggered by a substance, and 3) causing similar health symptoms., Results: Miners showed a sample prevalence of 72% while controls showed no cases of chronic mercury intoxication. Data availability is very limited why it was necessary to model data and make assumptions about the number of exposed population, the definition of chronic mercury intoxication, DW, and epidemiology. If these assumptions hold, the extrapolation would result in around 95,400 DALYs in Zimbabwe's total population in 2004., Conclusions: This analysis provides a preliminary quantification of the mercury-related health burden from ASGM based on the limited data available. If the determined assumptions hold, chronic mercury intoxication is likely to have been one of the top 20 hazards for population health in Zimbabwe in 2004 when comparing with more than 130 categories of diseases and injuries quantified in the WHO's GBD 2004 update. Improving data quality would allow more accurate estimates. However, the results highlight the need to reduce a burden which could be entirely avoided.

Background: Elemental mercury (Hg0) is widely used in small-scale gold mining. Persons working or living in mining areas have high urinary concentrations of Hg (U-Hg). Differences in genes encoding potential Hg-transporters may affect uptake and elimination of Hg., Objective: We aimed to identify single nucleotide polymorphisms (SNPs) in Hg-transporter genes that modify U-Hg., Methods: Men and women (1,017) from Indonesia, the Philippines, Tanzania, and Zimbabwe were classified either as controls (no Hg exposure from gold mining) or as having low (living in a gold-mining area) or high exposure (working as gold miners). U-Hg was analyzed by cold-vapor atomic absorption spectrometry. Eighteen SNPs in eight Hg-transporter genes were analyzed., Results: U-Hg concentrations were higher among ABCC2/MRP2 rs1885301 A-allele carriers than among GG homozygotes in all populations, though differences were not statistically significant in most cases. MRP2 SNPs showed particularly strong associations with U-Hg in the subgroup with highest exposure (miners in Zimbabwe), whereas rs1885301 A-allele carriers had higher U-Hg than GG homozygotes [geometric mean (GM): 36.4 µg/g creatinine vs. 21.9; p = 0.027], rs2273697 GG homozygotes had higher U-Hg than A-allele carriers (GM: 37.4 vs. 16.7; p = 0.001), and rs717620 A-allele carriers had higher U-Hg than GG homozygotes (GM: 83 vs. 28; p = 0.084). The SLC7A5/LAT1 rs33916661 GG genotype was associated with higher U-Hg in all populations (statistically significant for all Tanzanians combined). SNPs in SLC22A6/OAT1 (rs4149170) and SLC22A8/OAT3 (rs4149182) were associated with U-Hg mainly in the Tanzanian study groups., Conclusions: SNPs in putative Hg-transporter genes may influence U-Hg concentrations.

Mercury is still used in developing countries to extract gold from the ore in small-scale gold mining areas. This is a major health hazard for people living in mining areas. The concentration of mercury in urine was analysed in different mining areas in Zimbabwe, Indonesia and Tanzania. First the urine samples were analysed by CV-AAS (cold vapour atomic absorption spectrometry) during the field projects with a mobile mercury analyser (Lumex(®) or Seefelder(®)) and secondly, in a laboratory with a stationary CV-AAS mercury analyser (PerkinElmer(®)). Caused by the different systems (reduction agent either SnCl(2) (Lumex(®) or Seefelder(®))) or NaBH(4) (PerkinElmer(®)), with the mobile analysers only the inorganic mercury was obtained and with the stationary system the total mercury concentration was measured. The aims of the study were whether the results obtained in field with the mobile equipments can be compared with the stationary reference method in the laboratory and allow the application of these mobile analysers in screening studies on concerned populations to select those, who are exposed to critical mercury levels. Overall, the concentrations obtained with the two mobile systems were approximately 25% lower than determined with the stationary system. Nevertheless, both mobile systems seem to be very useful for screening of volunteers in field. Moreover, regional staff may be trained on such analysers to perform screening tests by themselves., (Copyright © 2011 Elsevier GmbH. All rights reserved.)

Background: Many poor in developing countries have turned to artisanal small-scale gold mining (ASGM) in an attempt to improve their situation. However, the mercury used to extract gold from ore is discharged in vaporized form into the environment, where it poses a hazard for human health., Methods: As part of an environmental epidemiological study in Mongolia-to evaluate the burden of environmental mercury contamination-urine, blood and hair samples were collected from residents of areas with or without mercury contamination. A total of 200 blood, urine and hair samples were analyzed for mercury and divided into three subgroups according to mercury content: (1) occupational exposure (high/medium); (2) environmental exposure (low); and (3) no exposure. Internal mercury distributions of the subgroups were compared using the Kruskal-Wallis and Mann-Whitney U-test. The Chi-square test and likelihood ratio proportion were used to compare the findings with threshold limits., Results: The highest values and greatest differences were seen in the urine samples (p<0.001, Kruskal-Wallis). The occupational group showing the highest exposure with a median mercury level of 4.36μg/l (control group: 0.10μg/l, p<0.001), 7.18μg/g creatinine and 12 results above the threshold limit HBM I (Human Biomonitoring I). Even participants from the low-exposure subgroup showed elevated mercury levels (median 2.88μg/l urine and 2.98μg/g creatinine, p<0.001), with 10 individuals above the HBM I threshold limits., Discussion: The body burden resulting from the use of mercury in artisanal gold mining is high not only in the miners themselves, an increased mercury hazard was also found for inhabitants of mining areas who were not actively involved in mining. Public health support measures are urgently needed to alleviate the situation., (Copyright © 2010 Elsevier B.V. All rights reserved.)

Breast-feeding can be a source of mercury exposure for infants. The main concern up to now is methyl-mercury exposure of women at child-bearing age. Certain fish species have high levels of methyl-mercury leading to consumer's advisory guidelines in regard of fish consumption to protect infants from mercury exposure passing through breast milk. Little is known about the transfer of inorganic mercury passing through breast milk to infants. Epidemiological studies showed negative health effects of inorganic mercury in gold mining areas. Small-scale gold miners use mercury to extract the gold from the ore. Environmental and health assessments of gold mining areas in Indonesia, Tanzania and Zimbabwe showed a high exposure with inorganic mercury in these gold mining areas, and a negative health impact of the exposure to the miners and the communities. This paper reports about the analysis and the results of 46 breast milk samples collected from mercury-exposed mothers. The median level of 1.87mug/l is fairly high compared to other results from literature. Some breast milk samples showed very high levels of mercury (up to 149mug/l). Fourteen of the 46 breast milk samples exceed 4mug/l which is considered to be a "high" level. US EPA recommends a "Reference Dose" of 0.3mug inorganic mercury/kg body weight/day [United States Environmental Protection Agency, 1997. Volume V: Health Effects of Mercury and Mercury Compounds. Study Report EPA-452/R-97-007: US EPA]. Twenty-two of the 46 children from these gold mining areas had a higher calculated total mercury uptake. The highest calculated daily mercury uptake of 127mug exceeds by far the recommended maximum uptake of inorganic mercury. Further systematic research of mercury in breast milk from small-scale gold mining areas is needed to increase the knowledge about the bio-transfer of mercury from mercury vapour-exposed mothers passing through breast milk to the breast-fed infant.

In many developing countries, mercury is used to extract gold from ore in small-scale mining areas. Exposure through mercury in these small-scale mining communities is a serious health hazard, especially to the children living and working there. Many children begin working with immediate contact to mercury from the very early age of seven. In Indonesia and Zimbabwe, 166 children were clinically examined for mercury. The mercury concentration in the blood, urine, and hair was analyzed. Compared to the control groups, the exposed children showed typical symptoms of mercury intoxication, such as ataxia. The children working with mercury had high levels of this substance in the various biomonitors. The exposure derives mainly from the liquid mercury used to bind gold, forming an amalgam. The amalgam is heated and the smelting amalgam releases mercury vapor plus the wanted gold. Mercury vapor in contrast to liquid mercury is highly toxic. This elemental, vaporized mercury is the main form of exposure. Since in over 50 countries children live in small-scale gold mining areas and are exposed in a similar way to mercury, immediate action is needed to reduce this severe chemical health hazard for children. Child labor with hazardous substances such as mercury must be stopped.

Dental amalgam, which has been used for over 150 years in dental practice, consists of about 50% metallic mercury. Studies on animal and humans show that mercury is continuously released from dental amalgam and absorbed by several body tissues. It is widely accepted that the main source of mercury vapor is dental amalgam and it contributes substantially to mercury load in human body tissues. There is still a controversy about the consequences of this additional mercury exposure from amalgam to human health. Many studies were performed to evaluate possible adverse effects. In this comment, these studies were analyzed with regard to their methodical quality by considering the newest findings on mercury toxicity and metabolism. In sum, a number of studies are methodically flawed drawing inaccurate conclusions as to the safety of dental amalgam.

Recent studies have shown that at a higher mercury (Hg) burden, the molar ratio of selenium (Se) and Hg in tissues tends to approximate 1:1 by the formation of biologically largely inert adducts. From the toxicological standpoint, this trapping of free Hg is welcome. However, this binding of Se to Hg reduces the portion of Se in tissues, which is available for the formation of essential selenoenzymes like glutathione peroxidase, type I deiodase, and so forth and could result in a relative deficiency of Se. Therefore, we tried to determine the concentration of non-Hg-associated Se in several human tissues. As there is no proved trace method for the speciation of non-Hg-bound and Hg-bound Se in tissues, the total concentrations of Hg and Se were determined and the portion of non-Hg-associated Se was calculated by the difference of the molar concentrations of Se and Hg. For this investigation, the following tissues were obtained by autopsy from 133 adults: kidney cortex, thyroid gland, liver, spleen, cerebrum cortex, and pituitary gland. In no case was an occupational Hg burden known. The results confirm the assumption of a 1:1 association of Hg and Se in human tissues. The mean concentration of non-Hg-bound Se was calculated to 576 microg/kg in the kidney cortex, 363 microg/kg in the thyroid gland, 308 microg/kg in the liver, 205 microg/kg in the spleen, 111 microg/kg in the cerebrum cortex, and 545 microg/kg in the pituitary gland. In none of the cases under investigation in any tissue was the molar Se/Hg ratio below 1. This means that a total deficiency of non-Hg-bound Se could not be seen in this normal population, even at a higher Hg burden. Nevertheless, at a suboptimal Se supply like in Germany, any reduction of the part of Se, which is available for the formation of essential seleno-enzymes, should be avoided. Therefore, any additional Hg burden such as from dental amalgam should to be considered critically. The different distribution of Hg and Se in the body confirms that there is a controlled hierarchy in the Se supply of different organs, which tries to prevent a Se deficiency in organs with essential seleno-enzymes like the thyroid gland even under an suboptimal Se supply.

The mercury concentration in 70 breast milk samples (Hg-M) from 46 mothers, collected within the first 7 days after delivery, was determined by cold vapour atomic absorption spectrometry. For comparison, 9 formula milk samples (reconstituted with Hg-free water) were investigated. The Hg-M in the human milk samples ranged from < 0.2 to 6.86 micrograms/L (median 0.37), in the formula milk samples from 0.4 to 2.5 micrograms/L (median 0.76). The Hg-M in the breast milk samples correlates positively with the number of maternal teeth with dental amalgam. The mean Hg-M of amalgam-free mothers was < 0.2 microgram/L, while milk from mothers with 1-4 amalgam fillings contained 0.57 microgram/L, with 5-7 fillings 0.50 microgram/L and with more than 7 fillings 2.11 micrograms/L. Hg-M correlated negatively to the day after delivery. Frequency of fish consumption tends to influence Hg-M positively, while the age of the mother shows no significant correlation. In the first 2 to 3 days after delivery some colostrum samples with Hg-M higher than in formula milk were found. Later on, the Hg-concentration in the breast milk was equal or even lower to that in formula milk. The higher Hg burden of infants' tissues from mothers with dental amalgam, as reported previously, must be explained (1) by a prenatal transfer of Hg from the mother's fillings through the placenta to the fetus, followed by a redistribution of this Hg in the body of the newborn, and (2) an additional burden via breast milk. Nevertheless, the comparison of Hg-M in breast and formula milk, the relatively moderate Hg burden in both kinds of milk, and the multiple manifest advantages of breast feeding speak against any limitation of nursing, even for mothers with a large number of dental amalgam fillings.

Alzheimer's disease (AD) is a common neurodegenerative disorder that leads to dementia and death. In addition to several genetic parameters, various environmental factors may influence the risk of getting AD. In order to test whether blood levels of the heavy metal mercury are increased in AD, we measured blood mercury concentrations in AD patients (n = 33), and compared them to age-matched control patients with major depression (MD) (n = 45), as well as to an additional control group of patients with various non-psychiatric disorders (n = 65). Blood mercury levels were more than two-fold higher in AD patients as compared to both control groups (p = 0.0005, and p = 0.0000, respectively). In early onset AD patients (n = 13), blood mercury levels were almost three-fold higher as compared to controls (p = 0.0002, and p = 0.0000, respectively). These increases were unrelated to the patients' dental status. Linear regression analysis of blood mercury concentrations and CSF levels of amyloid beta-peptide (A beta) revealed a significant correlation of these measures in AD patients (n = 15, r = 0.7440, p = 0.0015, Pearson type of correlation). These results demonstrate elevated blood levels of mercury in AD, and they suggest that this increase of mercury levels is associated with high CSF levels of A beta, whereas tau levels were unrelated. Possible explanations of increased blood mercury levels in AD include yet unidentified environmental sources or release from brain tissue with the advance in neuronal death.

The total mercury (Hg) and selenium (Se) concentrations were determined in kidney cortex samples of 195 deceased, non-occupationally burdened individuals. Mercury was determined by means of Cold-vapour Atomic Absorption Spectrometry (CV-AAS) and selenium by Graphite-Furnace Atomic Absorption Spectrometry (GF-AAS). The molar Se/Hg ratio is high (up to (a) 300) in cases with relatively low mercury concentrations [Hg]. The ratio decreases with increasing [Hg]. At [Hg] of 700-1000 ng/g it reaches unity, where it remains constant even at larger [Hg]. Since in vitro mercury and selenium form relatively stable adducts, our results suggest the formation of a 1:1 Hg-Se compound that may explain mercury detoxification by selenium. This effect also results in the trapping of available selenium by mercury, too. Decreasing the reserve of free (i.e. not Hg-bound) selenium. The effect of this decrease of free selenium is under further investigation.

Unlabelled: The total mercury concentrations in the liver (Hg-L), the kidney cortex (Hg-K) and the cerebral cortex (Hg-C) of 108 children aged 1 day-5 years, and the Hg-K and Hg-L of 46 fetuses were determined. As far as possible, the mothers were interviewed and their dental status was recorded. The results were compared to mercury concentrations in the tissues of adults from the same geographical area. The Hg-K (n = 38) and Hg-L (n = 40) of fetuses and Hg-K (n = 35) and Hg-C (n = 35) of older infants (11-50 weeks of life) correlated significantly with the number of dental amalgam fillings of the mother. The toxicological relevance of the unexpected high Hg-K of older infants from mothers with higher numbers of dental amalgam fillings is discussed., Conclusion: Future discussion on the pros and cons of dental amalgam should not be limited to adults or children with their own amalgam fillings, but also include fetal exposure. The unrestricted application of amalgam for dental restorations in women before and during the child-bearing age should be reconsidered.

In the former GDR it was almost impossible to perform studies on environmental pollution. Therefore, a short time after the opening of the German interior border the authors started an investigation on the heavy metal burden of humans in the former District of Leipzig (Saxonia). In 1990/91 tissues from 57 deceased were collected from this region. The concentrations of cadmium were determined in specimens from the liver and renal cortex, of mercury in liver, renal cortex and grey matter of the cerebrum and of lead in samples of the pelvic bone and the cortical part of the femur. After sample pretreatment, the heavy metal concentrations were determined by GF-AAS or CV-AAS. The results were compared with studies recently performed by the authors in the region of Munich (southern Bavaria, FRG) and with values from the literature. It was found that the burden with cadmium was similar in both regions, whereas on the average, the bone lead concentrations in Leipzig were 10 times (!) higher than in Munich. Considering dental amalgam as main factor for the burdening with inorganic mercury, the mercury concentrations in the liver and the renal cortex were of the same order of magnitude in both regions. In contrast to this, significantly higher mercury concentrations were found in the brain samples from Leipzig than from Munich. Possible negative health effects of these elevated lead and mercury burden in the Leipzig area are discussed.