Mercury Levels in Women and Children from Interior Villages in Suriname, South America

Global mercury concentrations in biota: their use as a basis for a global biomonitoring framework

An important provision of the Minamata Convention on Mercury is to monitor and evaluate the effectiveness of the adopted measures and its implementation. Here, we describe for the first time currently available biotic mercury (Hg) data on a global scale to improve the understanding of global efforts to reduce the impact of Hg pollution on people and the environment. Data from the peer-reviewed literature were compiled in the Global Biotic Mercury Synthesis (GBMS) database (>550,000 data points). These data provide a foundation for establishing a biomonitoring framework needed to track Hg concentrations in biota globally. We describe Hg exposure in the taxa identified by the Minamata Convention: fish, sea turtles, birds, and marine mammals. Based on the GBMS database, Hg concentrations are presented at relevant geographic scales for continents and oceanic basins. We identify some effective regional templates for monitoring methylmercury (MeHg) availability in the environment, but overall illustrate that there is a general lack of regional biomonitoring initiatives around the world, especially in Africa, Australia, Indo-Pacific, Middle East, and South Atlantic and Pacific Oceans. Temporal trend data for Hg in biota are generally limited. Ecologically sensitive sites (where biota have above average MeHg tissue concentrations) have been identified throughout the world. Efforts to model and quantify ecosystem sensitivity locally, regionally, and globally could help establish effective and efficient biomonitoring programs. We present a framework for a global Hg biomonitoring network that includes a three-step continental and oceanic approach to integrate existing biomonitoring efforts and prioritize filling regional data gaps linked with key Hg sources. We describe a standardized approach that builds on an evidence-based evaluation to assess the Minamata Convention's progress to reduce the impact of global Hg pollution on people and the environment.

Possible Risk Factors and Their Potential Associations with Combined Heavy Metal Exposures in Pregnant Women in the Republic of Suriname

Background

The exposure of pregnant women to multiple environmental pollutants may be more disadvantageous to birth outcomes when compared to single-compound contaminations.

Objective

This study investigated the mixed exposures to mercury, manganese, or lead in 380 pregnant Surinamese women. The factors that might be associated with the heavy metal exposures and the relative risk of the potential factors to cause the mixed exposures were explored. The influencing factors of exposures to mixed contaminants assessed were living in Suriname's rural regions, several parts of which are contaminated with heavy metals emitted from artisanal and small-scale gold mining and agricultural activities; the consumption of potentially contaminated foods; advanced maternal age; as well as a relatively low formal educational level and monthly household income.

Methods

Descriptive statistics were used to calculate frequency distributions and χ2-contingency analyses to calculate associations and relative risks (RR) with 95% confidence intervals (CI).

Findings

Blood levels of two or three of the heavy metals above public health limits were observed in 36% of the women. These women were more often residing in the rural regions, primarily consumed potentially contaminated food items, were 35 years or older, were lower educated, and more often had a lower household income. However, only living in the rural regions (RR = 1.48; 95% CI 1.23-1.77) and a low household income (RR = 1.38; 95% CI 1.15-1.66) significantly increased the risk of exposure exceeding levels of concern to two or three of the heavy metals (by 48% and 38%, respectively).

Conclusion

More comprehensive pharmacological, ecological, and epidemiological studies about exposures to mixed heavy metal contaminations in pregnant women are warranted.

Contrasting mercury contamination scenarios and site susceptibilities confound fish mercury burdens in Suriname, South America

In Suriname, mercury (Hg) use has recently increased because of gold mining, which has put fish-reliant communities (e.g., Indigenous and Tribal) at risk of enhanced Hg exposure through the riverine fish these communities consume. To quantify how the magnitude of these risks change according to location and time, we measured total mercury (HgT) in fish at sites downstream and upstream of an artisanal and small-scale gold mining (ASGM) operation in 2004-2005 and in 2017-2018. We tested whether fish HgT burdens over dynamic ranges were increased. Surprisingly, our findings did not support broadly increased fish Hg burden over time or that proximity to ASGM was diagnostic to fish HgT-burden. Subsequently, we elected to test the HgT stable isotope ratios on a set of freshly collected 2020 fish to determine whether differences in Hg source and delivery pathways might cofound results. We found that remote unmined sites were more susceptible to gaseous elemental Hg deposition pathways, leading to enhanced risk of contamination, whereas ASGM proximate sites were not. These results highlight that elemental mercury releases from ASGM practices may have significant impact on fish-reliant communities that are far removed from ASGM point source contamination.

Prenatal Exposure to Mercury, Manganese, and Lead and Adverse Birth Outcomes in Suriname: A Population-Based Birth Cohort Study

Globally, adverse birth outcomes are increasingly linked to prenatal exposure to environmental contaminants, such as mercury, manganese, and lead. This study aims to assess an association between prenatal exposure to mercury, manganese, and lead and the occurrence of adverse birth outcomes in 380 pregnant women in Suriname. The numbers of stillbirths, preterm births, low birth weights, and low Apgar scores were determined, as well as blood levels of mercury, manganese, lead, and relevant covariates. Descriptive statistics were calculated using frequency distributions. The associations between mercury, manganese, and lead blood levels, on the one hand, and adverse birth outcomes, on the other hand, were explored using contingency tables, tested with the χ²-test (Fisher's exact test), and expressed with a p value. Multivariate logistic regression models were computed to explore independent associations and expressed as (adjusted) odds ratios (aOR) with 95% confidence intervals (CI). The findings of this study indicate no statistically significant relationship between blood mercury, manganese, or lead levels and stillbirth, preterm birth, low birth weight, and low Apgar score. However, the covariate diabetes mellitus (aOR 5.58, 95% CI (1.38-22.53)) was independently associated with preterm birth and the covariate hypertension (aOR 2.72, 95% CI (1.081-6.86)) with low birth weight. Nevertheless, the observed high proportions of pregnant women with blood levels of mercury, manganese, and lead above the reference levels values of public health concern warrants environmental health research on risk factors for adverse birth outcomes to develop public health policy interventions to protect pregnant Surinamese women and their newborns from potential long-term effects.

Exposure Assessment of methyl mercury from consumption of fish and seafood in Peninsular Malaysia

The concentration of meHg in freshwater fish and seafood was investigated, as well as the consumption patterns of fish and seafood by different demographic groups (age, ethnicity, gender). A potential alarm for human health hazards was also assessed, and the results were compared to the provisional tolerable weekly intakes (PTWIs) and the hazard quotient parameter (HQ). The results showed that meHg levels of 67 species ranged from 0.013 to 0.252 mg/kg of wet weight (WW) with significant differences between different fish and seafood groups (χ2KW = 49.09; p < 0.001). Median concentrations of meHg in fish and seafood groups in descending orders are as follows: demersal fish (0.1006 mg/kg WW) > pelagic fish (0.0686 mg/kg WW) > freshwater fish 0.045 mg/kg WW) > cephalopods (0.0405 mg/kg WW) crustaceans (0.0356 mg/kg WW). The results revealed that older population (> 40 years old) consumed significantly (p = 0.000) more fish compared to younger generations and the elderly consumed the highest amounts of fish (104.0 ± 113.0 g/day). The adolescents (10-17 years old) consumed more than double of amount for both cephalopod and crustacean compared to the older populations (p < 0.05). Malay ethnic (96.1 ± 99.6 g/day) consumed significantly (p = 0.000) higher amounts of fish and seafood compared to other ethnicities, similar to male subjects (95.2 ± 102 g/day; p = 0.026) when compared to the female (86 ± 96.3 g/day). The estimated weekly intake (EWI) values showed results below 1.6 µg/kg BW/week, the tolerable levels recommended by the Joint FAO/WHO Expert Committee on Food Additives (JECFA) for all different demographic factors except for higher consumers at 75th percentile and above. Consumption of marine fish contributed to a higher value of PTWI to all different demographic groups (the estimated weekly intake (EWI) range: 0.2988-0.6893 µg/kg BW/week) but for the adolescents, where from the consumption of crustaceans (0.3488 µg/kg BW/week or 21.8% of PTWI) and cephalopods (0.504 µg/kg BW/week or 31.5% of PTWI). The results from this study also revealed the HQ value for overall consumption of fish and seafood by the adolescents and elderly exceeded one. This was contributed from the consumption of demersal fish and cephalopods, thus indicating the nonacceptable level of noncarcinogenic adverse health effects.

Associations between hair levels of trace elements and the risk of preterm birth among pregnant Wwomen: A prospective nested case-control study in Beijing Birth Cohort (BBC), China

Trace elements have various physiochemical functions in humans and are associated with the occurrence of preterm birth (PB). However, their mixed effects on PB risk have rarely been studied. We aimed to investigate the associations between hair levels of trace elements and PB risk among pregnant women. A nested case-control study with a prospective cohort was conducted in Beijing City, China. We included 82 women who had a PB [total PB (tPB)] as cases [including 40 with a spontaneous PB (SPB)] and 415 who had a term delivery as controls. Hair levels of the concerned trace elements were measured including endocrine disrupting metal(loid)s [EDMs; lead, mercury (Hg), arsenic, and cadmium] and nutritional trace metal(loid)s [NTMs; zinc (Zn), iron (Fe), copper, and selenium]. Logistic regression analysis was performed to estimate the odds ratios (ORs) for PB. Bayesian kernel machine regression (BKMR) was used to assess the associations between mixed exposure to the trace elements and PB risk. Significantly lower maternal hair concentrations of Zn and Fe were observed in the SPB cases than in the controls, whereas no differences for the other trace elements. Single-element modeling results suggested second-quartile Hg maternal hair concentrations, third-quartile Zn concentrations, and fourth-quartile Fe concentrations were associated with a reduced risk of tPB with adjusted ORs of 0.43 [95% confidence interval (CI): 0.21-0.87], 0.38 (95% CI: 0.18-0.82), and 0.48 (95% CI: 0.24-0.98), respectively, compared to first-quartile values. Similar results were obtained for SPB. According to the BKMR models, hair NTMs were significantly, monotonously, and inversely associated with the risk of SPB, after controlling for covariates and levels of the four EDMs. Fe and Zn contributed the most strongly to the association. We concluded that maternal higher levels of NTMs, especially Fe and Zn, may reduce the risk of PB.

Validity, reliability, and transcultural adaptations of the Bayley Scales of Infant and Toddler Development (BSID-III-NL) for children in Suriname

BACKGROUND

A valid and reliable measure of infant neurodevelopment is needed in Suriname, South America. The Bayley Scales of Infant and Toddler Development, 3rd edition (BSID-III), was created for evaluation of United States infants and toddlers and subsequently validated for use in Dutch speaking infants of the Netherlands (BSID-III-NL). Given that Suriname was a previous Dutch colony and Dutch remains the national language of Suriname, this study sought to evaluate the psychometric properties of the BSID-III-NL in Suriname.

AIMS

Given that the cultural context differs between Suriname, the United States, and the Netherlands, the aims of this study were to determine if any cultural adaptations of the BSID-III-NL were needed for Surinamese infants and to evaluate its psychometric properties.

METHODS

Two hundred and ninety-nine infants between the ages of 10 to 26 months were assessed in three geographic regions of Suriname between May 2018 and July 2019. Minor adaptations to the BSID-III-NL imagery were made based on the input of Surinamese pediatricians and neuropsychologists who were also involved in the administration of the BSID-III-NL in Suriname. Raw scores were collected for the cognitive, communicative, and motor subscales of the BSID-III-NL. Factor structure was evaluated with exploratory factor analysis and cluster analysis, and reliability of internal consistency was assessed using Cronbach's alpha coefficient for each subscale.

RESULTS

Content validity was endorsed by pediatricians and neuropsychologists in Suriname who participated in the administration of the BSID-III-NL. Construct validity was demonstrated through agreement of items from cluster analysis where at least 81.56% of all variability was explained by clustering with correct or incorrect responses and mean raw scores in subscales increased with age group. Cronbach's alpha coefficient was above 0.77 for all subscales.

CONCLUSIONS

This internationally validated developmental measure was found to be valid and reliable in assessing neurodevelopment of infants in Suriname.

Association of Mercury Exposure and Maternal Sociodemographics on Birth Outcomes of Indigenous and Tribal Women in Suriname

Information regarding adverse birth outcomes (ABO) of Indigenous and Tribal women living in the remote tropical rainforest of Suriname, where mercury (Hg) use is abundant in artisanal gold mining, is not available. In the context of a health system analysis, we examined the association between Hg exposure, maternal sociodemographics on the ABO of Indigenous and Tribal women living in Suriname’s interior and its capital, Paramaribo. ABO were determined in pregnant women enrolled from December 2016 to July 2019 in the Caribbean Consortium for Environmental and Occupational Health prospective environmental epidemiologic cohort study. Associations were explored using Pearson’s χ²-test and the Mann–Whitney U-test. Among 351 singleton participants, 32% were Indigenous, residing mainly in the interior (86.8%), and 23.1% had ABO. Indigenous participants had higher rates of ABO (29.8% vs. 19.8%) and preterm birth (PTB) (21.2% vs. 12.4%), higher Hg levels, delivered at a younger age, were less educated, and had lower household income compared to Tribal participants. Multivariate logistic regression models revealed that Indigenous participants had higher odds of ABO (OR = 3.60; 95% CI 1.70–7.63) and PTB (OR = 3.43; 95% CI 1.48–7.96) compared with Tribal participants, independent of Hg exposure and age at delivery. These results highlight the importance of effective risk reduction measures in support of Indigenous mothers, families, and communities.

Exposure to total and methylmercury among pregnant women in Suriname: sources and public health implications

Previous research has found that women and children living in rural, interior communities in Suriname have high concentrations of mercury in hair. Freshwater fish from these areas also have high concentrations of mercury. Artisanal and small-scale gold mining operations in parts of the country use elemental mercury to extract gold from soils and sediments. Total mercury and methylmercury concentrations have been determined in hair and blood from pregnant women across the country. Pregnant women from interior communities have significantly higher concentrations of both total and methylmercury in hair (median total mercury in hair 3.64 µg/g) compared with pregnant women from two urban coastal cities, Paramaribo (0.63 µg/g) and Nickerie (0.74 µg/g). Total and methylmercury concentrations in blood and hair are highly correlated (r = 0.986, r = 0.974) with methylmercury making up 86% of the total in blood and 97% of the total in hair. Most women in the interior regions rely heavily on local fish as part of their regular diet, and many live outsides of areas with active ASGM operations. This study demonstrates that diet and fish consumption largely govern mercury exposures in pregnant women in Suriname.

Caribbean Consortium for Research in Environmental and Occupational Health (CCREOH) Cohort Study: influences of complex environmental exposures on maternal and child health in Suriname

PURPOSE

The Caribbean Consortium for Research in Environmental and Occupational Health prospective environmental epidemiologic cohort study addresses the impact of chemical and non-chemical environmental exposures on mother/child dyads in Suriname. The study determines associations between levels of environmental elements and toxicants in pregnant women, and birth outcomes and neurodevelopment in their children.

PARTICIPANTS

Pregnant women (N=1143) were enrolled from December 2016 to July 2019 from three regions of Suriname: Paramaribo (N=738), Nickerie (N=204) and the tropical rainforest interior (N=201). Infants (N=992) were enrolled at birth. Follow-up will take place until children are 48 months old.

FINDINGS TO DATE

Biospecimens and questionnaire data on physiological and psychosocial health in pregnant women have been analysed. 39.1% had hair mercury (Hg) levels exceeding values considered safe by international standards. Median hair Hg concentrations in women from Paramaribo (N=522) were 0.64 µg/g hair (IQRs 0.36-1.09; range 0.00-7.12), from Nickerie (N=176) 0.73 µg/g (IQR 0.45-1.05; range 0.00-5.79) and the interior (N=178) 3.48 µg/g (IQR 1.92-7.39; range 0.38-18.20). 96.1% of women ate fish, respective consumption of the three most consumed carnivorous species, Hoplias aimara, Serrasalmus rhombeus and Cichla ocellaris, known to have high Hg levels, was 44.4%, 19.3% and 26.3%, respectively, and was greater among the interior subcohort. 89% frequently consumed the vegetable tannia, samples of which showed presence of worldwide banned pesticides. 24.9% of pregnant women had Edinburgh Depression Scale scores indicative of probable depression.

FUTURE PLANS

Fish consumption advisories are in development, especially relevant to interior women for whom fish consumption is likely to be the primary source of Hg exposure. Effects of potentially beneficial neuroprotective factors in fish that may counter neurotoxic effects of Hg are being examined. A pesticide literacy assessment in pregnant women is in progress. Neurodevelopmental assessments and telomere length measurements of the children to evaluate long-term effects of prenatal exposures to toxicant mixtures are ongoing.

Evaluation of the Effect of Gold Mining on the Water Quality in Monterrey, Bolívar (Colombia)

Gold mining uses chemicals that are discharged into rivers without any control when there are no good mining practices, generating environmental and public health problems, especially for downstream inhabitants who use the water for consumption, as is the case in Monterrey township, where the Boque River water is consumed. In this study, we evaluate Boque River water quality analyzing some physicochemical parameters such as pH, heavy metals, Hg, and cyanide; bioassays (Lactuca sativa, Hydra attenuata, and Daphnia magna), mutagenicity (Ames test), and microbiological assays. The results show that some physicochemical parameters exceed permitted concentrations (Hg, Cd, and cyanide). D. magna showed sensitivity and L. sativa showed inhibition and excessive growth in the analyzed water. Mutagenic values were obtained for all of the sample stations. The presence of bacteria and somatic coliphages in the water show a health risk to inhabitants. In conclusion, the presence of Cd, Hg, and cyanide in the waters for domestic consumption was evidenced in concentrations that can affect the environment and the health of the Monterrey inhabitants. The mutagenic index indicates the possibility of mutations in the population that consumes this type of water. Bioassays stand out as an alert system when concentrations of chemical contaminants cannot be analytically detected.

Influence of Prenatal Exposure to Mercury, Perceived Stress, and Depression on Birth Outcomes in Suriname: Results from the MeKiTamara Study

Prenatal exposure to mercury, stress, and depression may have adverse effects on birth outcomes. Little is known on the influence of chemical and non-chemical stressors on birth outcomes in the country of Suriname. We assessed the influence of prenatal exposure to mercury, perceived stress, and depression on adverse birth outcomes in 1143 pregnant Surinamese women who participated in the Caribbean Consortium for Research in Environmental and Occupational Health-MeKiTamara prospective cohort study. Associations between mercury (≥1.1 μg/g hair, USEPA action level/top versus bottom quartile), probable depression (Edinburgh Depression Scale ≥12), high perceived stress (Cohen's Perceived Stress Scale ≥20), and adverse birth outcomes (low birthweight (<2500 g), preterm birth (<37 completed weeks of gestation), and low Apgar score (<7 at 5 min)) were assessed using bivariate and multivariate logistic regressions. Prevalence of elevated mercury levels, high perceived stress, and probable depression were 37.5%, 27.2%, and 22.4%, respectively. Mercury exposure was significantly associated with preterm birth in the overall study cohort (OR 2.47; 95% CI 1.05-5.83) and perceived stress with a low Apgar score (OR 9.73; 95% CI 2.03-46.70). Depression was not associated with any birth outcomes. These findings can inform policy- and practice-oriented solutions to improve maternal and child health in Suriname.

Prenatal Mercury Exposure in Pregnant Women from Suriname's Interior and Its Effects on Birth Outcomes

Prenatal mercury (Hg) exposure was determined in a sub-cohort of the Caribbean Consortium for Environmental and Occupational Health’s environmental epidemiologic prospective cohort study of pregnant women living in Suriname’s interior. The associations between Hg exposure, low birth weight (LBW, <2500 g) and preterm birth (PTB, <37 weeks) were explored. Correlation analysis, Fisher’s exact test and logistic regression analyses were conducted to evaluate the associations between maternal hair Hg levels and birth weight, LBW and PTB, and between potential confounders, LBW and PTB, respectively. Among 204 singleton births were 198 live births, five stillbirths and one miscarriage. The mean participant age was 26 years; 15.7% of participants had PTBs and 8.1% delivered a child with a LBW. The median hair Hg level was 3.48 μg/g hair. Low hair Hg exposure, based on lowest tertile < 2.34 μg/g, was associated with LBW (OR = 7.2; 95% CI 1.5–35.6; p = 0.015); this association was independent of maternal age, ethnic background, household income and village location, and no correlation was found between hair Hg and PTB. Young maternal age was associated with PTB (RR = 5.09, 95% CI: 1.92–13.85; p = 0.0004) while maternal age was not associated with hair Hg or LBW. The impact of prenatal Hg exposure on pediatric neurodevelopment is currently being evaluated in the infant sub-cohort.

Mercury Exposure Among Artisanal and Small-Scale Gold Miners in Four Regions in Uganda

BACKGROUND

Artisanal and small-scale gold mining is a human health concern, especially in low-income countries like Uganda due to the use of mercury (Hg) in the mining process.

OBJECTIVE

The aim of the present study was to assess Hg exposure among artisanal and small-scale gold miners in Uganda through biologic monitoring parameters and Hg-related clinical manifestations.

METHODS

A cross-sectional study was conducted from June to July 2018 among 183 miners from Ibanda (Western region), Mubende (Central region), Amudat (Karamoja region) and Busia (Eastern region) in Uganda. An interviewer-administered questionnaire and health assessment were used to collect socio-demographic, exposure and self-reported Hg poisoning symptoms. In addition, 41 urine, 41 blood and 26 environment samples were assessed. Descriptive statistics, Kruskal-Wallis test and Wilcoxon signed-rank test for comparison of Hg levels in urine and blood among miners were performed while logistic regression was used to assess associations between exposure and Hg poisoning-related symptoms.

RESULTS

The miners ranged from 15 to 65 years old and were primarily male (72.6%). The majority (73.3%) had worked directly with Hg for an average duration of 5.3 years. Symptoms associated with working directly with Hg included chest pain (odds ratio (OR)=9.0, confidence interval (CI)=3.3 to 24.6), numbness (OR=8.5, CI=2.1 to 34.4), back pain (OR=6.2, CI= 2.2 to 17.5), fatigue and stress (OR=5.4, 2.0 to CI=14.9), headache (OR=4.7, CI=1.9 to 11.3), dizziness (OR=3.8, CI=1.5 to 9.7) joint pain (OR=3.2, CI=1.3 to 8.3) and respiratory problems (3.2, 1.0 to 10.1). Statistically significant differences in Hg levels with p-values less than 0.05 were observed across district, gender and type of work. Mubende had the highest blood and urine levels (136 μg/l and 105.5 μg/l) in comparison with Busia (60 μg/l and 70.6 μg/l) and Ibanda (43 μg/l and 58 μg/l). Females (84.7 μg/l), panners (109 μg/l) and those with knowledge of occupational health and safety measures (95.6 μg/l) reported higher levels of Hg in urine. The average levels of Hg in water and soil samples were 23.79 μg/l and 0.21 μg/l, respectively.

CONCLUSIONS

Variation in Hg levels were attributed to varied duration of exposure across geographical sites. There was considerable exposure to Hg as indicated by both clinical manifestations and biologic parameters among miners in Uganda with Hg in urine exceeding the recommended thresholds.

PARTICIPANT CONSENT

Obtained.

ETHICS APPROVAL

Ethical approval was obtained from the Makerere University School of Health Science Institutional Review Board (reference number SHSREC REF 2018-2019) and Uganda National Council for Science and Technology (reference number SS 4577).

COMPETING INTERESTS

The authors declare no competing financial interests.

Mercury exposure assessment in indigenous communities from Tarapaca village, Cotuhe and Putumayo Rivers, Colombian Amazon

Mercury (Hg) is a complex and multifaceted global pollutant. Artisanal and small-scale gold mining activities are largely responsible for Hg contamination in developing countries, in many cases impacting areas of high biodiversity such as the Amazon. The aim of the study was to establish Hg exposure in indigenous citizens from the Tarapaca village, Cotuhe and Putumayo Rivers, at the Colombian Amazon. Total Hg (T-Hg) concentrations were measured employing a DMA-80 Hg analyzer. For that purpose, 190 hair samples were taken from volunteers living in different communities of Tarapaca. The overall mean T-Hg level for all samples was 10.6 ± 0.4 μg/g, with values ranging from 0.61 to 31.1 μg/g. The mean T-Hg level decreased in the order Puerto Huila > Puerto Ticuna > Ventura > Nueva Union > Buenos Aires > Santa Lucia > Puerto Nuevo > Caña Brava > Pupuña. Based on recommendations from the United States Environmental Protection Agency (US EPA), 99.5% of the samples exceeded the maximum level of 1.0 μg/g. Hg content in human hair was significantly associated with fish consumption (ρ = 0.253; p < 0.001). According to the health survey, at least 24.7% of the volunteers manifested some signs and symptoms of Hg poisoning. In short, these data support the extensive Hg exposure in the environment of the Colombian Amazon, a process that could be impacting the quality of life of its vulnerable indigenous groups. Immediate actions must be taken by competent authorities to protect these communities from Hg poisoning.