Anthropogenic short-lived halogens increase human exposure to mercury contamination due to enhanced mercury oxidation over continents.

Mercury (Hg) is a contaminant of global concern, and an accurate understanding of its atmospheric fate is needed to assess its risks to humans and ecosystem health. Atmospheric oxidation of Hg is key to the deposition of this toxic metal to the Earth's surface. Short-lived halogens (SLHs) can provide halogen radicals to directly oxidize Hg and perturb the budget of other Hg oxidants (e.g., OH and O3). In addition to known ocean emissions of halogens, recent observational evidence has revealed abundant anthropogenic emissions of SLHs over continental areas. However, the impacts of anthropogenic SLHs emissions on the atmospheric fate of Hg and human exposure to Hg contamination remain unknown. Here, we show that the inclusion of anthropogenic SLHs substantially increased local Hg oxidation and, consequently, deposition in/near Hg continental source regions by up to 20%, thereby decreasing Hg export from source regions to clean environments. Our modeling results indicated that the inclusion of anthropogenic SLHs can lead to higher Hg exposure in/near Hg source regions than estimated in previous assessments, e.g., with increases of 8.7% and 7.5% in China and India, respectively, consequently leading to higher Hg-related human health risks. These results highlight the urgent need for policymakers to reduce local Hg and SLHs emissions. We conclude that the substantial impacts of anthropogenic SLHs emissions should be included in model assessments of the Hg budget and associated health risks at local and global scales.

A Novel Approach to Assessing the Joint Effects of Mercury and Fish Consumption on Neurodevelopment in the New Bedford Cohort.

Understanding health risks from methylmercury (MeHg) exposure is complicated by its link to fish consumption which may confound or modify toxicities. One solution is to include fish intake and a biomarker of MeHg exposure in the same model, but resulting estimates do not reflect the independent impact of accumulated MeHg or fish exposures. In fish-eating populations, this can be addressed by separating MeHg exposure into fish intake and average Hg content of the consumed fish. We assessed the joint association of prenatal MeHg exposure (maternal hair Hg) and fish intake (among fish-eating mothers) with neurodevelopment in 361 eight-year-olds from the New Bedford Cohort (born 1993-1998). Neurodevelopmental assessments used standardized tests of IQ, language, memory, and attention. Covariate-adjusted regression assessed the association of maternal fish consumption, stratified by tertiles of estimated average fish Hg, with neurodevelopment. Associations between maternal fish intake and child outcomes were generally beneficial for those in the lowest average fish Hg tertile, but detrimental in the highest average fish Hg tertile where, for example, each serving of fish was associated with 1.3 fewer correct responses (95% CI: -2.2, -0.4) on the Boston Naming test. Standard analyses showed no outcome associations with hair Hg or fish intake.

Should ebselen be considered for the treatment of mercury intoxication? A minireview.

Mercury is a ubiquitous environmental contaminant and can be found in inorganic (Hg0, Hg+ and Hg2+) and organic forms (chiefly CH3Hg+ or MeHg+). The main route of human, mammals and bird exposure occurs via predatory fish ingestion. Occupational exposure to Hg0 (and Hg2+) can also occur; furthermore, in gold mining areas the exposure to inorganic Hg can also be high. The toxicity of electrophilic forms of Hg (E+Hg) is mediated by disruption of thiol (-SH)- or selenol (-SeH)-containing proteins. The therapeutic approaches to treat methylmercury (MeHg+), Hg0 and Hg2+ are limited. Here we discuss the potential use of ebselen as a potential therapeutic agent to lower the body burden of Hg in man. Ebselen is a safe drug for humans and has been tested in clinical trials (for instance, brain ischemia, noise-induce hearing loss, diabetes complications, bipolar disorders) at doses varying from 400 to 3600 mg per day. Two clinical trials with ebselen in moderate and severe COVID are also approved. Ebselen can be metabolized to an intermediate with -SeH (selenol) functional group, which has a greater affinity to electrophilic Hg (E+Hg) forms than the available thiol-containing therapeutic agents. Accordingly, as observed in vitro and rodent models in vivo, Ebselen exhibited protective effects against MeHg+, indicating its potential as a therapeutic agent to treat MeHg+ overexposure. The combined use of ebselen with thiol-containing molecules (e.g. N-acetylcysteine and enaramide)) is also commented, because they can have synergistic protective effects against MeHg+.

Factors influencing mercury exposure in Arctic-breeding shorebirds.

Mercury (Hg) pollution remains a concern to Arctic ecosystems, due to long-range transport from southern industrial regions and melting permafrost and glaciers. The objective of this study was to identify intrinsic, extrinsic, and temporal factors influencing Hg concentrations in Arctic-breeding shorebirds and highlight regions and species at greatest risk of Hg exposure. We analyzed 1094 blood and 1384 feather samples from 12 shorebird species breeding at nine sites across the North American Arctic during 2012 and 2013. Blood Hg concentrations, which reflect Hg exposure in the local area in individual shorebirds: 1) ranged from 0.01-3.52 µg/g ww, with an overall mean of 0.30 ± 0.27 µg/g ww; 2) were influenced by species and study site, but not sampling year, with birds sampled near Utqiagvik, AK, having the highest concentrations; and 3) were influenced by foraging habitat at some sites. Feather Hg concentrations, which reflected Hg exposure from the wintering grounds: 1) ranged from 0.07-12.14 µg/g fw in individuals, with an overall mean of 1.14 ± 1.18 µg/g fw; and 2) were influenced by species and year. Most Arctic-breeding shorebirds had blood and feather Hg concentrations at levels where no adverse effects of exposure were predicted, though some individuals sampled near Utqiagvik had Hg levels that would be considered of concern. Overall, these data increase our understanding of how Hg is distributed in the various shorebird breeding areas of the Arctic, what factors predispose Arctic-breeding shorebirds to Hg exposure, and lay the foundation for future monitoring efforts.

Oral and inhalation bioaccessibility of mercury in contaminated soils and potential health risk to the kidneys and neurodevelopment of children in Taiwan.

Health risk assessments of exposure to mercury (Hg) from soils via ingestion and inhalation are indispensable for Taiwanese people living in the vicinity of Hg-contaminated sites. In this study, anthropogenic soils were collected from various polluted sources in Taiwan. In vitro oral and inhalation bioaccessible fractions of Hg were analyzed to avoid from overestimating the exposure risk. Discrepancies in oral and inhalation bioaccessible levels of Hg in soils were found using different in vitro assays with different pH levels and chemical compositions. The freshly contaminated soil (soil S7) polluted by chlor-alkali production activity sampled before the site was remediated had the highest total Hg concentration of 1346 mg/kg, with the highest oral bioaccessibility of 26.2% as analyzed by SW-846 Method 1340 and inhalation bioaccessibility of 30.5% as analyzed by modified Gamble's solution. The lesser extent of aging of Hg in soil S7 increased the Hg availability for humans, which was also found based on results of a sequential extraction procedure. Results of the hazard quotient showed that soil ingestion was the main pathway causing non-carcinogenic risks for children and adults. Children were also exposed to higher risks than were adults due to higher frequencies of hand-to-mouth behaviors and lower body weights. Furthermore, hazard index results adjusted for oral and inhalation bioaccessible Hg were lower than those obtained based on the total Hg content; however, an unacceptable value of the non-carcinogenic risk (> 1) for children living near soil S7 was still observed. This study suggests that children living near sites polluted for a short period of time may suffer potential renal effects regardless of the bioaccessibility. Our findings provide suggestions for decision makers on setting new strategies for managing risks of Hg-contaminated soils in Taiwan.

Pre and postnatal exposure to mercury and sexual development in 9-year-old children in Spain: The role of brain-derived neurotrophic factor.

Early exposure to mercury has been related to endocrine disruption. Steroid hormones play a crucial role in neural cell migration, differentiation, etc., as well as protecting against several neurotoxic compounds. We investigate the relation between mercury exposure and children's sexual development, and we evaluate the possible influence of different brain-derived neurotrophic factor (BDNF) polymorphisms on this association. Our study sample comprised 412 9-year-old children participating in the INMA cohort (2004-2015). Mercury concentrations were measured at birth (cord blood) and at 4 and 9 years of age (hair). Sexual development was assessed by levels of sex steroid hormones (estradiol and testosterone) in saliva and the Tanner stages of sex development at 9 years (categorized as 1: prepuberty and >1: pubertal onset). Covariates and confounders were collected through questionnaires during pregnancy and childhood. Polymorphisms in the BDNF gene were genotyped in cord blood DNA. Multivariate linear regression analyses were performed between mercury levels and children's sexual development by sex. Effect modification by genetic polymorphisms and fish intake was assessed. We found marginally significant inverse associations between postnatal exposure to mercury (at 9 years) and testosterone levels (ß[95%CI] = -0.16[-0.33,0.001], and -0.20[-0.42,0.03], for boys and girls, respectively). Additionally, we found that prenatal mercury was negatively associated with Tanner stage >1 in boys. Finally, we found significant genetic interactions for some single nucleotide polymorphisms in the BDNF gene. In conclusion, pre and postnatal exposure to mercury seems to affect children's sexual development and BDNF may play a role in this association, but further research would be needed.

Long-term monitoring of mercury in young German adults: Time trend analyses from the German Environmental Specimen Bank, 1995-2018.

As highlighted in the Minamata Convention, Mercury (Hg) in its various forms poses a substantial risk to human health and the environment. The health relevance of Hg is also recognized by the European Human Biomonitoring Initiative (HBM4EU), which classifies Hg as a priority substance, since considerable knowledge and data gaps on Hg exposure levels and their changes over time still exist in Europe. The German Environmental Specimen Bank (German ESB) provides valuable policy relevant data and long-term trends of substance exposure on a national level for international comparison and evaluation. In this study we analysed data of the German ESB on Hg exposure of young adults aged 20 to 29 including data on urinary Hg levels from 1995 to 2018 and whole blood Hg levels from 2001 to 2010. Results show a clear decrease in both, about 86% in urine total daily Hg excretion from 1995 (0.76 µg/L) to 2018 (0.11 µg/L) (n = 10,069) and about 57% in blood concentrations of Hg from 2001 (1.76 µg/L) to 2010 (0.77 µg/L) (n = 4085). Over the investigated timeframe only a few values exceeded the toxicologically derived health based guidance value HBM I for blood and urine, with these exceedances decreasing over time in line with the general trend. The factors mostly influencing Hg excretion identified in this study are dental amalgam as well as fish and seafood consumption. Besides other factors (e.g. age and sex), also airborne Hg exposure appears to be a low but evident influencing factor in Germany. Although a considerable decrease in internal Hg exposure is recognized in the last decades, the current low-level exposure may cause adverse health effects especially to vulnerable groups such as pregnant women and children. To further elucidate and evaluate current exposure sources and to reduce human exposure to Hg, continuous environmental and human biomonitoring is needed.

Associations of maternal food safety-related risk perceptions and protective behaviors with daily mercury intake and internal doses of Taiwanese women and their preschool children.

Mercury (Hg) is a well-known toxicant that can affect children's neurodevelopment. This study attempted to evaluate the internal dose of Hg in hair and fingernails and external Hg exposure from dietary consumption in 283 pairs of mothers and their children aged under 6 years in Taiwan. Mean Hg levels in hair and fingernail samples were 1.07 ± 0.67 and 0.42 ± 0.34 µg/g for mothers, and 1.11 ± 1.22 and 0.36 ± 0.26 µg/g for children, respectively. Our results showed that 42% of mothers and 41% of children had hair Hg levels exceeding the US Environmental Protection Agency recommended value of 1 µg/g. Hg exposure in children was greater than that of their mothers. Estimated daily intake (EDI) levels of Hg among preschool children were 3.3-times higher than those of their mothers. A sensitivity analysis indicated that fish consumption was the main potential factor of Hg exposure among both mothers and their children. External Hg exposure using estimated daily dietary ingestion by mothers was a surrogate for internal hair Hg concentrations. However, poor correlations were found between EDI Hg levels and hair Hg levels among children aged 4-6 years. Exposure sources from food and other media, such as soil and dust, need to be considered to arrive at more-valid risk assessments for younger children's exposure to Hg. Children of mothers who did not have food safety-related risk perceptions or protective behaviors had significantly higher hair Hg concentrations compared to children whose mothers had risk perceptions and protective behaviors. Hg exposure of women of childbearing age and preschool children in Taiwan is still an area of great concern. Providing food safety information and risk-benefits of fish consumption for mothers may avoid harm to the developing nervous systems of their children.

Bioaccumulation and effects of selenium from surface coal mining in an aquatic songbird.

Open-pit mining operations are hailed for safe working conditions for miners as well as economically and logistically favourable outcomes for mining companies. However, ecological impacts of these operations may persist for decades. Expansions of open-pit coal mining in British Columbia of Western Canada are planned. Governmental regulation of background contaminants leached from these mines into nearby water systems were established to mitigate environmental impacts associated with these operations. We analyzed water, periphyton, invertebrate, and American dipper (Cinclus mexicanus) blood, egg, and feather samples for selenium and mercury exposure related to mining operations in the Elk Valley. We also quantified effects associated with exposure on clutch size and hatching success. Selenium concentrations in water, periphyton, and invertebrates were significantly higher downstream of mines compared to reference sites within and outside of the Elk River watershed. Selenium concentrations in water from exposed sites exceeded current regulatory levels established to protect wildlife by up to 20 times. Mercury concentrations were below toxic levels for birds in all media and did not factor into determination of selenium exposure or effects. Egg selenium concentrations were on average 0.9 times the regulatory threshold. Our stable isotope analyses showed that diets of nesting females included a negligible proportion of higher order consumers. We did not detect a significant effect of selenium on the rate of hatching success or clutch size of dippers nesting in exposed sites. We conclude that at the time of the investigation, selenium exposure was not impairing hatching of American dippers at the sampled locations.

Association between mercury exposure and thyroid hormones levels: A meta-analysis.

BACKGROUND: The relationship between mercury (Hg) exposure and thyroid hormones (THs) levels in the general population has been inconclusive. We conducted a random effects model meta-analysis to identify the association between Hg exposure and THs levels in the general population. METHODS: This meta-analysis were performed based on the PECO questions (P = general population; E =1ug/L Hg in blood and urine; C =1ug/L incremental increase on; and O = variation of THs levels). We searched four electronic databases including PubMed, Web of Science, Embase, and Cochrane Library for studies published on or before 20th July 2020. Prospective and cross-sectional studies that evaluated the association between Hg exposure and the levels of thyroid stimulating hormone (TSH), triiodothyronine (T3), thyroxine (T4), free triiodothyronine (FT3), and free thyroxine (FT4) were included. We also assessed aggregate risks for the reliability of the included studies. RESULTS: Initially, we retrieved 4889 articles. 18 studies met our inclusion criteria after screening and 13 articles were eligible to be included in the meta-analysis. The meta-analysis results suggest that blood Hg may be significantly associated with THs levels. The presence of Hg in blood may significantly increase the levels of TSH (ß=0.55; 95%CI: 0.20,0.90; p < 0.001) and FT4 (ß=0.47; 95%CI: 0.11,0.82; p < 0.001), with the opposite association in T4 (ß=-0.02; 95%CI: 0.02, -0.01; p < 0.001). For the subgroup analysis, blood Hg was positively correlated with TSH levels in children and adolescents (ß=0.62; 95%CI: 0.09, 1.15; p < 0.001) and FT4 levels in pregnant women (ß=1.00; 95%CI: 0.99, 1.00; p < 0.001) respectively. CONCLUSIONS: This meta-analysis indicates that exposure to Hg in blood could significantly corrrelate with the levels of TSH, T4, and FT4 in the general population. Therefore, it is crucial to control the use of Hg and strengthen protection of the thyroid.

Monthly variations in mercury exposure of school children and adults in an industrial area of southwestern China.

Recent studies have shown that rice consumption can be the major pathway for human methylmercury (MeHg) exposure in inland China. However, few studies have considered the susceptible population of school children's exposure through rice ingestion. In this study, monthly variations in total Hg (THg)/MeHg concentrations in rice, fish, hair, and urine samples were studied to evaluate the Hg (both THg and MeHg) exposure in Guiyang, a typical industrial area with high anthropogenic emission of Hg. A total of 17 primary school (school A) students, 29 middle school (school B) students, and 46 guardians participated in this study for one year. Hair THg, hair MeHg, and urine THg concentrations ranged from 355-413 ng g-1, 213-236 ng g-1, and 469-518 ng g-1 Creatinine (ng·g-1 Cr), respectively, and no significant differences were observed between different genders and age groups. Hair and urine Hg concentrations showed slightly higher values in the cold season (October to February) than the hot season (March to September), but without significant difference. High monthly variability of individual hair and urine Hg concentrations suggested that long-term study could effectively decrease the uncertainty. The school students showed significantly higher urine THg concentrations than adults due to children's unique physiological structure and behaviors. Probable daily intake (PDI) of MeHg via rice and fish ingestion averaged at 0.0091, 0.0090, and 0.0079 µg kg-1 d-1 for school A students, school B students, and their guardians, respectively, which means that 86%, 84%, and 87% of the PDI were originated from rice ingestion, respectively. Therefore, more attention should be paid to children as a susceptible population. The results indicated low risk of Hg exposure via rice and fish consumption for urban residents in a Chinese industrial city.

A Study on Hair Mercury Levels of University Students.

Total mercury (THg) and methylmercury (MeHg) concentrations were measured in hair of 98 Chinese university students to study their levels of Hg exposure and influencing factors. The results showed that Hg exposure for university students was at a low level with concentrations lower than the USEPA recommended reference level (1 µg/g) across all hair samples. The percentage of MeHg to THg (%MeHg) in hair was about 50%, lower than the previously reported value of 70-100%, probably associated with the low %MeHg in the diet of university students. Fish and rice consumption were not a primary factor affecting hair Hg levels of university students, while smoking could be one main pathway of Hg exposure. In addition, the similarly dietary structure in the studied university narrowed the difference of Hg exposure levels among students.

Maternal inorganic mercury exposure and renal effects in the Wanshan mercury mining area, southwest China.

This study evaluated the relationship between urine mercury (UHg) concentrations and renal function (serum creatinine (SCr) and blood urea nitrogen (BUN)) in delivery women in the Wanshan mercury (Hg) mining area. Leishan County was selected as the control area. 165 and 65 maternal samples were collected from the Wanshan and Leishan area, respectively. The geometric means of UHg concentrations were 1.09 and 0.29 µg/L in Wanshan and Leishan subjects, respectively. Significant differences (p < 0.01) of UHg were observed between the two populations, indicating the potential risks of inorganic Hg exposure in the Wanshan population. The median (interquartile range) values of SCr were 69.1 (12.5) µmol/L and 46.0 (11.0) µmol/L for the Wanshan and Leishan populations, respectively, indicating significant differences (p < 0.01) between the two groups. However, no significant differences among BUN values for the two groups were observed. A significant positive correlation (r = 0.385, p < 0.001) was observed between UHg concentration and SCr in the study population. The odds ratio (OR) value of UHg in Wanshan area was 9.29 times higher than that in Leishan area (95% confidence interval (CI): 3.58-24.1). The OR value of SCr decrease in patients with low UHg was 0.32 times higher than that in patients with high UHg (95% CI: 0.19-0.55). The OR value of SCr decrease in the population with fish consumption was 0.71 times higher than that of the population without fish consumption (95% CI: 0.58-0.88). In conclusion, maternal IHg exposure caused impaired renal function and fish consumption may play a role in preventing Hg-induced nephrotoxicity.

Estimated exposure to mercury from fish consumption among women anglers of childbearing age in the Great Lakes region.

Women of childbearing age (WCBA) are advised by state, tribal, and federal agencies to limit their consumption of certain fish, in part, because of concerns about the ingestion of methylmercury and its impact on the development of fetuses. We studied the fish-eating habits of WCBA who had a fishing license and lived near the Great Lakes, where mercury in locally-caught fish is a concern, as these women were likely at greater risk of elevated mercury exposure than the general population. We used a web-based diary method to gather fish consumption data from WCBA anglers over a 4-month period in the summer of 2014. We estimated mercury intake based on reported mercury content of species consumed, frequency of consumption, and meal portion size, and calculated percent exceeding the USEPA reference dose (RfD). Based on these calculations, we estimated that study participants (n = 1395) ingested 0.031 ±â€¯0.002 (95% CI) ug/kg/d of methylmercury (arithmetic mean). We also found that 3.4% of study participants exceeded the RfD when we averaged estimated intake over the 4-month study period. While most (82%) of the fish meals WCBA anglers ate were purchased fish meals generally low in mercury, study participants ingested a disproportionate amount of mercury from locally-caught fish meals (18% of meals contributed 37% of mercury intake). We estimated 11% of WCBA anglers who did not follow state and federal guidelines in effect at the time of our study exceeded the mercury RfD, whereas fewer than 1% of WCBA anglers who followed the guidelines exceeded the RfD. These findings highlight the importance of encouraging WCBA to follow guidelines from agencies for locally-caught fish, in combination with guidelines for purchased fish.

[Analysis of electrocardiogram and blood related indicators in workers occupationally exposed to mercury in Jiangsu Province from 2016 to 2018].

Objective: To investigate the health status of occupational mercury workers and reveal the effects of mercury exposure on the cardiovascular system. Methods: In June 2019, a total of 2651 mercury workers participated in the occupational health examination between 2016-2018 from a thermometer manufacturing plant and a fluorescent lamp manufacturing plant were included in this study. Then, they were divided into a high-level mercury exposure group (425 workers whose urine mercury concentration >35 µg/g creatinine) and a low-mercury mercury exposure group (2226 workers whose urinary mercury concentration <35 µg/g creatinine) . Mercury concentration in the workplace was also detected. Finally, the results of electrocardiogram (ECG) , blood routine, blood biochemistry and other physical examinations were analyzed. The measurement data of age and exposure years were analyzed by test. Urinary mercury and blood parameters were analyzed by Mann-Whitney nonparametric test. Chi-square test was used for the analyses of gender, ECG abnormality rate and other categorical data. Results: The 8-hour weighted average allowable concentration (CTWA) of mercury in the workplace of high-exposure group was 0.002 2-0.152 mg/m(3). The abnormal rate of ECG in the high-exposed group (29.6%) was higher than that in the low-exposure group (10.1%) in 2018 (P<0.01) . Compared with the low-exposure group, the WBC of the high-exposure group from 2016 to 2018 was increased, with statistically significance (P<0.05) ; the RBC of the high-exposure group in 2016 and 2017 was decreased, with statistically significance (P<0.01) ; the total bilirubin concentration in the high-exposure group was decreased from 2016 to 2018, with statistically significance (P<0.05) . Conclusion: Long-term exposure to high concentration of mercury in the workplace may influence cardiovascular system. Therefore, engineering protection and individual protection should be implemented well.

Environmentally relevant concentrations of mercury exposure alter thyroid hormone levels and gene expression in the hypothalamic-pituitary-thyroid axis of zebrafish larvae.

Mercury (Hg) is one of the most toxic heavy metals that can cause severe damage to fish. Studies have demonstrated that Hg has a specific affinity for the endocrine system, but little is known about the effects of Hg on thyroid endocrine system in fish. In this study, zebrafish embryos were exposed to environmentally relevant concentrations of 1, 4, and 16 µg/L Hg2+ (added as HgCl2) from 2 h post-fertilization (hpf) to 168 hpf. Thyroid hormone (TH) levels and mRNA expression levels of genes involved in the hypothalamus-pituitary-thyroid (HPT) axis were determined. The results showed that exposure to 16 µg/L Hg2+ increased the whole-body thyroxine (T4) and triiodothyronine (T3) levels. The transcription levels of corticotrophin releasing hormone (crh) and thyroid stimulating hormone (tshß) were up-regulated by Hg2+ exposure. Analysis of the mRNA levels of genes related to thyroid development (hhex, nkx2.1, and pax8) and THs synthesis (nis and tg) revealed that exposure to higher Hg2+ concentrations markedly up-regulated hhex, nkx2.1, nis, and tg expression, while had no significant effect on the transcripts of pax8. For the transcription of two types of deiodinases (deio1 and deio2), deio1 showed no significant changes in all the treatments, whereas deio2 was significantly up-regulated in the 16 µg/L Hg2+ group. In addition, Hg2+ exposure up-regulated thyroid hormone receptor ß (trß) mRNA level, while the transcription of trα was not changed. Overall, our study indicated that environmentally relevant concentrations of Hg2+ exposure could alter TH levels and the transcription of related HPT-axis genes, disturbing the normal processes of TH metabolism.

Exposure to mercury in susceptible population groups living in the former mercury mining town of Idrija, Slovenia.

500 years of mercury (Hg) mining in the town of Idrija has caused severe pollution in Idrija and its surroundings. Following the closure of the mine in 1995, the environment remains contaminated with Hg. Sources of elemental-, inorganic- and methyl Hg exposure were identified, potential environmental level of exposure to Hg was evaluated and actual internal exposure to Hg was assessed in selected susceptible population groups comprising school-age children and pregnant women living in Idrija and in control groups from rural and urban environments. The study of pregnant women (n=31) was conducted between 2003 and 2008, and the study of school-age children (n=176) in 2008. Potential interaction of Hg with selenium (Se) in plasma was assessed in both study populations, while in pregnant women antioxidative enzyme activity (glutathione peroxidase, superoxide dismutase and catalase) in erythrocytes of maternal and cord blood was also assessed. Actual exposure to Hg as indicated by levels of Hg in children's blood (geometric mean (GM) 0.92µg/L), mother's blood (GM 1.86µg/L), children's urine (GM 1.08µg/g crea.), mother's urine (GM 2.51µg/L), children's hair (GM 241ng/g) and mother's hair (GM 251ng/g) was higher in the two study groups from Idrija than in the control groups from rural areas, but was still at the level of a "normal" population and reflects mainly exposure to elemental Hg (Hg°) from dental amalgam and, to a certain extent atmospheric Hg°. Furthermore, the internal doses of Hg received during pregnancy did not decrease the bioavailability of Se. Based on observation in children, the increase in Se protein expression is suggested to be a consequence of moderately elevated exposure to Hg°. The observed changes in activity of antioxidative enzymes, as biomarkers of oxidative stress, appear to be mainly associated with pregnancy per se and not with an increased exposure to Hg. In view of the continuing increased potential for Hg exposure and the low number of pregnant women studied, the results warrant a further longitudinal study of a larger group of pregnant women residing in the area of the former mercury mine.

Characterization and risk of exposure to elements from artisanal gold mining operations in the Bolivian Andes.

Artisanal and small-scale gold mining (ASGM) offers low-skilled workers an opportunity to elevate themselves out of poverty. However, this industry operates with little to no pollution controls and the cost to the environment and human health can be large. The objectives of this study were to measure levels of arsenic (As), manganese (Mn), cobalt (Co), lead (Pb), and mercury (Hg) in the environment and characterize health risks to miners and residents in an area with active ASGM operations. An exposure assessment was conducted at two different mining sites and a nearby village in the Bolivian Anders. The resulting measurements were then used to quantify cancerous and noncancerous health risks to children and adults working at and living near ASGM areas. Soil concentrations of As were well above background levels and showed great variations between the village and mining area. Mercury vapor levels at the two mining sites were approximately 30 times larger than the EPA reference concentration. The risk of developing non-cancerous health effects were primarily due to exposure to As and Hg. The probability of individuals developing cancer was considerably increased with adult miners having a probability of 1.3 out of 100. Cancer potential was driven by exposure to As, with de minimus cancer risk from all other elements. Based on the environmental characterization of elements in soils and Hg vapors, the risk of developing cancerous and non-cancerous health outcomes were above a level of concern based on EPA risk assessment guidance. Personal protective equipment was not worn by workers and Hg amalgam is commonly heated in workers' homes. Better education of the risks of ASGM is needed as well as simple controls to reduce exposure.

Reduced egfr, elevated urine protein and low level of personal protective equipment compliance among artisanal small scale gold miners at Bibiani-Ghana: a cross-sectional study.

BACKGROUND: Mercury is a toxic metal with its effects on human health ranging from acute to chronic in a very short time of exposure. Artisanal and small-scale gold mining (ASGM) is the main source of direct human exposure to mercury. AIM: To access the effect of mercury exposure on the renal function and level of personal protective equipment (PPE) compliance among small-scale gold miners in Bibiani District of the Western Region of Ghana METHOD: 110 consenting male gold miners were purposively recruited for this study. A structured questionnaire was used to collect socio-demographic information from the participants. Work place assessment and interviews were conducted. Urine samples were analysed for protein; blood was analysed for mercury and creatinine. Estimated glomerular filtration rate (eGFR) was calculated using the chronic kidney disease-epidemiology collaboration (CKD-EPI) equation. RESULTS: Of the 110 participants, 61(55.5%) exceeded the occupational exposure threshold (blood mercury <5µg/L). Urine protein (41.72±68.34, P<0.0001), serum creatinine (2.24±1.19, P<0.0001) and blood mercury (18.37±10.47, P<0.0001) were significantly elevated among the exposed group compared to the non-exposed group. However, the exposed group had a significantly reduced eGFR (P<0.0001). There was a significant correlation (r=0.7338, p<0.0001) between blood mercury concentration and urine protein concentration. An increase in blood mercury correlated negatively (r = -0.8233, P<0.0001) with eGFR among the exposed group. High urine protein (P< 0.0001) and high serum creatinine (P< 0.0001) were significantly associated with increased mercury exposure. Increased mercury exposure was significantly associated with burning of amalgam (P=0.0196), sucking of excess mercury (P=0.0336), longer work duration (P=0.0314) and low educational background (P=0.0473). CONCLUSION: Small scale miners at the Bibiani work site are exposed to excess mercury. Proteinuria and reduced eGFR is common in mine workers exposed to excess mercury. We found poor PPE compliance among the study population.

Altered urinary porphyrins and mercury exposure as biomarkers for autism severity in Egyptian children with autism spectrum disorder.

Autism spectrum disorder (ASD) is a complex neurodevelopmental disorder that affects social, communication, and behavioral development. Recent evidence supported but also questioned the hypothetical role of compounds containing mercury (Hg) as contributors to the development of ASD. Specific alterations in the urinary excretion of porphyrin-containing ring catabolites have been associated with exposure to Hg in ASD patients. In the present study, the level of urinary porphyrins, as biomarkers of Hg toxicity in children with ASD, was evaluated, and its correlation with severity of the autistic behavior further explored. A total of 100 children was enrolled in the present study. They were classified into three groups: children with ASD (40), healthy controls (40), and healthy siblings of the ASD children (20). Children with ASD were diagnosed using DSM-IV-TR, ADI-R, and CARS tests. Urinary porphyrins were evaluated within the three groups using high-performance liquid chromatography (HPLC), after plasma evaluation of mercury (Hg) and lead (Pb) in the same groups. Results showed that children with ASD had significantly higher levels of Hg, Pb, and the porphyrins pentacarboxyporphyrin, coproporphyrin, precoproporphyrin, uroporphyrins, and hexacarboxyporphyrin compared to healthy controls and healthy siblings of the ASD children. However, there was no significant statistical difference in the level of heptacarboxyporphyrin among the three groups, while a significant positive correlation between the levels of coproporphyrin and precoproporphyrin and autism severity was observed. Mothers of ASD children showed a higher percentage of dental amalgam restorations compared to the mothers of healthy controls suggesting that high Hg levels in children with ASD may relate to the increased exposure to Hg from maternal dental amalgam during pregnancy and lactation. The results showed that the ASD children in the present study had increased blood Hg and Pb levels compared with healthy control children indicating that disordered porphyrin metabolism might interfere with the pathology associated with the autistic neurologic phenotype. The present study indicates that coproporphyrin and precoproporhyrin may be utilized as possible biomarkers for heavy metal exposure and autism severity in children with ASD.