Assessment of human health risk associated with methylmercury in the imported fish marketed in the Caribbean

Analysis of Mercury in Aquifers in Gold Mining Areas in the Ecuadorian Amazon and Its Associated Risk for Human Health

Gold mining activity is a source of supply in many areas of the world, and especially in developing countries, it is practiced illegally and by applying unsafe techniques. Particularly in Ecuador, artisanal and small-scale gold mining (ASGM) is widespread, and it is based on the use of toxic substances, such as mercury (Hg), in gold recovery. Hg is a heavy metal that is water-insoluble, which, once mobilized, poses a threat to both the environment and human health. This study analyzes Hg concentrations in the six provinces of Napo, Sucumbíos, Orellana, Pastaza, Morona Santiago, and Zamora Chinchipe of the Ecuadorian Amazon region to conduct a human health risk assessment. Significant differences in Hg levels were found between provinces, but concentrations were below MPL imposed by Ecuadorian regulations everywhere. Nevertheless, a worrisome picture emerges, especially with regard to the most vulnerable receptors represented by the child population. There are multiple factors of incidence that may affect the possible future development of the phenomenon, and with reference to the social, economic, and environmental context of the region, it can be concluded that it may be appropriate to plan further investigation to arrive at a more comprehensive assessment. The results of this study can be used by decision makers to plan further investigation and to implement monitoring networks, risk mitigation strategies, and groundwater protection measures.

Assessment of Hg pollution in stream waters and human health risk in areas impacted by mining activities in the Ecuadorian Amazon

Illegal gold mining activities have contributed to the release and mobilization of Hg and environmental degradation in many parts of the world. This study aims to determine the concentration of Hg in five provinces of the Amazon Region of Ecuador, in addition to assessing the risk to human health of exposed populations, applying deterministic and probabilistic methods. For this purpose, 147 water samples were collected in rivers and streams crossing and/or located near mining areas. As a result, 100% of the samples analyzed exceeded the maximum permissible limit (MPL) according to the water quality criteria for the preservation of aquatic life of the Ecuadorian regulations, while 7% of the samples exceeded the MPL for drinking water. On the other hand, considering the European Environmental Quality Standard (EQS) for surface water bodies, in our study, 100% of the samples exceed the maximum permissible limit (0.07 µg/L), and with respect to the Canadian water quality guidelines, 35% of the samples exceed the permissible limit (0.001 mg/l) for drinking water, and 100% of the samples exceed the limit for life in water bodies (0.0001 mg/l). The risk assessment revealed that the probability of developing adverse health effects from exposure to Hg is below the recommended limits according to the probabilistic assessment; this is in relation to the criterion of residential and recreational use of water resources. However, it was identified that the child population doubles the acceptable systemic risk level according to the results of the deterministic assessment in the residential scenario. This information can be used by decision-makers to implement strategies to reduce Hg contamination and exposure of the population in Ecuadorian Amazonian rivers.

Determination of methylmercury and inorganic mercury in human hair samples of individuals from Colombian gold mining regions by double spiking isotope dilution and GC-ICP-MS

With the aim to distinguish between routes of exposition to mercury (Hg) in artisanal and small-scale gold mining (ASGM) communities and to distinguish between Hg contamination sources, Hg species composition should be performed in human biomarkers. In this work, Hg species-specific determination were determined in human hair samples (N = 96), mostly non-directly occupied in ASGM tasks, from the six most relevant gold mining Colombian regions. Therefore, MeHg, Hg(II) and THg concentrations were simultaneously determined by double spiking species-specific isotope dilution mass spectrometry (IDMS) and GC-ICP-MS. Only 16.67% of participants were involved at some point in AGSM works and fish consumption ranged from 3 to 7 times/week, which is between medium and high intake levels. The median concentration of THg obtained from all samples is higher than the reference dose weekly acceptable of MeHg intake established by the EPA (1 ppm), whereas a 25% were more than 4 times higher than the WHO level (2.2 μg Hg g^-1). Median THg value of individuals consuming fish 5-7 times per week was significantly higher (p < 0.05) than those of the other consuming groups (12.5 μg Hg g^-1). Most of the samples presented a % of MeHg relative to THg higher than 80%. The average % of Hg(II)/THg was 11% and only 10 individuals presented a Hg(II) content over 30%. No significant differences (p > 0.05) were found when the amount of Hg(II) was compared between people involved in AGSM task and people not involved. Interestingly, significant differences among the evaluated groups where found when the percentage of the Hg(II)/THg ratio of these groups were compared. In fact, people involved in AGSM tasks showed 1.7 times higher Hg(II)/THg vs. inhabitants uninvolved. This suggest that Hg(II) determination by IDMS-GC-ICP-MS could be a good proxy for evaluating Hg(II) adsorption by direct exposure to mercury vapors onto hair.

Nine decades of data on environmental chemical pollutant exposure in dogs: a bibliometric analysis

In recent decades, a global concern associated with environmental chemical contamination has emerged as an important risk factor for the development of human diseases. Risk assessment methods based on animal approaches have shown to be very useful as early warning systems. However, questions, knowledge gaps, and limitations still need to be addressed in animals close to humans, such as dogs. The objective of this study was to analyze citation patterns, impact of publications, and most relevant authors, countries, institutional affiliations, and lines of research on environmental chemical contaminants and their relationship with dogs, in terms of exposure and biological effects. For this, a bibliometric analysis was carried out. Results revealed an increase in scientific production on this subject during the last 90 years in journals such as Health Physics, Science of the Total Environment, and Plos One, highlighting authors such as Muggenburg, Sonne, Boecker, and Dietz. The USA, Brazil, Germany, and the UK and universities such as California, Colorado State, and Purdue were the most relevant countries and institutional affiliations in scientific production and collaboration in relation to this topic. There is a growing interest in the development of lines of research related to heavy metals (mercury and lead mainly) and persistent organic compounds (PCBs, PBDEs, pesticides) using dogs as sentinels, as well as new sources of interest related to zoonosis and One Health. Finally, issues related to pollutants, sentinel lymph nodes, and epidemiology appear as new areas of research. These results highlight interesting current challenges and future research perspectives on dogs as sentinels for environmental chemical contamination.

Possible health risk assessment for heavy metal concentrations in water, sediment, and fish species and Turkmen pregnant women's biomonitoring in Miankaleh Peninsula, Iran

This study investigated the human biomonitoring of heavy metals in the water, sediments, and tissues of mostly consumed fish species using Turkmen pregnant women's biomarkers in winter 2019, at the Miankaleh Peninsula, north of Iran. Metal concentrations were measured in various fish organs as well as pregnant women's blood, hair, and nail as biological indicators. For this purpose, a total of 20 water and sediment, 14 fish, and 16 human samples were collected. Inductively coupled plasma mass spectrometry (ICP-MS) was used to evaluate the concentration of Cr, Co, Cu, As, Hg, and Pb. Results showed metals with the highest concentrations as Cu and Cr in water (93.35 and 80.91 µg/l, respectively), Hg and Pb in sediment (7.40 µg/g for both), Cu and Pb in the liver (27.00 and 18.9 µg/g for C. carpio; 1414 and 31.7 µg/g for L. auratus), muscle (10.00 and 18.80 for C. carpio; 37.20 and 8.27 µg/g for L. auratus), and skin (26.40 and 9.90 for C. carpio; 10.80 and 11.74 µg/g for L. auratus). In addition, Cu, in pregnant women samples, had the highest values at 2.53 mg/l, 8.87, 36.46, and 29.04 µg/g for blood, hair, fingernail, and toenail, respectively. However, Co showed the lowest concentration in all studied samples. Fish liver and fingernail of pregnant women did reveal the highest heavy metal accumulation, whereas fish muscle and blood of pregnant women had the lowest accumulated heavy metals. The concentration of Hg in water, sediment, fish muscle, and women's blood and hair exceeded the limits suggested by various organizations. Therefore, this study highlighted that heavy metal concentration, in particular Hg, in water, sediments, and fish is a serious risk to the health of local inhabitants who rely on fisheries products and recommended that necessary information should be provided to warn Turkmen pregnant women in consumption of Hg-contaminated fish in this area.

Migration of mercury in the food chains of the Beloosipovo biocenosis (part 1)

Introduction. Mercury and its compounds are among the most dangerous toxic substances, which makes mercury pollution one of the most urgent environmental issues. The present research objective was to study the accumulation of mercury and its impact on the terrestrial ecosystems in the area of the Beloosipovo mercury deposit (Kemerovo Region, West Siberia, Russia). Study objects and methods. The study used standard methods to test soil, herbs, herpetobiont insects, and small mammals. The sampling was conducted at 13 points in the cardinal directions at 0.5, 1.5, and 3 km from the pollution source. The method of atomic absorption was employed to measure the concentration of mercury in the samples prepared by the wet mineralization method. Results and discussion. The main components of terrestrial ecosystems revealed no excessive concentration of mercury in the soil. However, the water samples from the Belaya Osipova river demonstrated an excess in the maximum permissible concentration of mercury from 5 to 20% (0.00056–0.00074 mg/L). Further up the food chains, the concentration of mercury in organisms decreased by 1–2 orders of magnitude, depending on the sampling point. The study also revealed Siberian trout lily (Erythronium sibiricum (Fisch. et C. A. Mey) Kryl.), which is protected at the federal and regional levels, as well as several nemoral tertiary relics. Conclusion. The decreasing concentration of mercury in the food chains means the ecosystem is under no severe negative impact.

Potentially Toxic Elements (PTEs) in the Fillet of Narrow-Barred Spanish Mackerel (Scomberomorus commerson): a Global Systematic Review, Meta-analysis and Risk Assessment

The contamination of seafood like narrow-barred Spanish mackerel (Scomberomorus commerson) fillets by potentially toxic elements (PTEs) has converted to worldwide health concerns. In this regard, the related citations regarding the concentration of PTEs in fillets of narrow-barred Spanish mackerel were collected through some of the international databases such as Scopus, Cochrane, PubMed, and Scientific Information Database (SID) up to 10 March 2020. The concentration of PTEs in fillets of narrow-barred Spanish mackerel fish was meta-analyzed and the health risk (non-carcinogenic risk) was estimated by the total target hazard quotient (TTHQ). The meta-analysis of data indicated that the rank order of PTEs in fillet of narrow-barred Spanish mackerel was Fe (10,853.29 μg/kg-ww) > Zn (4007.00 μg/kg-ww) > Cu (1005.66 μg/kg-ww) > total Cr (544.14 μg/kg-ww) > Mn (515.93 μg/kg-ww) > Ni (409.90 μg/kg-ww) > Pb (180.99 μg/kg-ww) > As (93.11 μg/kg-ww) > methyl Hg (66.60 μg/kg-ww) > Cd (66.03 μg/kg-ww). The rank order of health risk assessment based on the country by the aid of TTHQ for adult consumers was Malaysia (0.22251) > Philippines (0.21912) > Egypt (0.08684) > Taiwan (0.07430) > Bahrain (0.04893) > Iran (0.03528) > China (0.00620) > Pakistan (0.00316) > Yemen (0.00157) > India (0.00073). In addition, the rank order of health risk assessment based on the country by the aid of TTHQ for child consumers was Malaysia (1.03838) > Philippines (1.02257) > Egypt (0.40523) > Taiwan (0.34674) > Bahrain (0.22832) > Iran (0.16466) > China (0.02892) > Pakistan (0.01474) > Yemen (0.00731) > India (0.00340). Therefore, the children in Malaysia and the Philippines were at considerable non-carcinogenic risk. Hence, approaching the recommended control plans in order to decrease the non-carcinogenic risk associated with the ingestion of PTEs via the consumption of narrow-barred Spanish mackerel fish fillets is crucial.

The consumption of shark meat in the Amazon region and its implications for human health and the marine ecosystem

Here, we evaluated the levels of As, Hg, Pb, and Cd in shark meat sold along the Amazon Coast of Brazil and used nitrogen stable isotope values to determine trophic position and to assess element biomagnification. From market samples, a total of 13 species were identified via molecular analysis, including those listed as endangered and vulnerable by the IUCN Red List. Arsenic was present in significantly higher concentrations than all other elements, followed by Hg, with the highest mean concentrations recorded in M. higmani (As: 19.46 ± 8.79 μg/g ww) and C. acronotus (Hg: 1.12 ± 0.68 μg/g ww). Lead and Cd were recorded at much lower levels in all species. The EWI of individual elements were above PTWI for all species when considering Hg, seven species for inorganic arsenic (iAs), and one species for Pb. The weekly consumption of 10 species should be reduced to less than 416.39 g, which is equivalent to the daily estimated fish consumption rate in the region. The mean (±SD) δ¹⁵N values of species ranged from 10.7 ± 0.51‰ in M. higmani to 14.2 ± 0.59‰ in C. porosus, indicating feeding over >1 trophic level. Arsenic was negatively correlated with δ¹⁵N values, while Hg was positively correlated indicating biodilution and biomagnification, respectively. Our results indicate that the sale and consumption of shark meat will expose consumers to potentially harmful levels of iAs and Hg, as well as contributing to the population decline of species including those that are currently categorized as threatened.

Occupational human exposure to mercury in artisanal small-scale gold mining communities of Colombia

With the aim of protecting human life and the environment, the Minamata Convention seeks to reduce and monitor mercury (Hg) concentrations in the environment. Artisanal and Small-scale Gold Mining (ASGM) has been identified as the most important anthropogenic source of Hg at a global scale and an important route of human exposure to Hg. In this context, this study assessed total Hg (THg) in blood, urine and hair, and methylmercury (MeHg) in human hair samples from 238 participants with occupational exposure to Hg in the most relevant ASGM communities of Colombia. Mercury concentrations in different biological matrices were related to several variables of interest such as age, gender, body mass index, fish consumption, exposure time, and specific occupational activities, such as amalgamation and amalgam burning. The median values of THg in blood (3.70 µg/L), urine (4.00 µg/L) and hair (1.37 mg/kg), and hair MeHg (1.47 mg/kg) for all participants were below permissible concentrations set by WHO. However, about 40% of the miners showed Hg concentrations in blood, urine and/or hair above the WHO thresholds. In all the biological matrices studied, miners burning amalgams showed significantly higher concentrations than miners who did not burn amalgams, with values 7-, 7-, and 8-fold higher in blood, urine and hair, respectively. A multiple linear regression model revealed that burning amalgam and fish consumption were significant predictors of Hg exposure in miners. Miners from Guainía had the highest concentrations in urine and hair, most likely due to the high manipulation and burning of amalgam, and a high fish consumption. In contrast, miners from Caldas showed the lowest Hg concentrations in all the biomarkers because they do not manipulate or burn amalgam, as well as reporting the lowest fish consumption. Our study also highlighted that gold miners exposure to Hg depends on their work practices. Therefore, the implementation of a health education programme on gold mining strategies is required, especially in Guaina, Vaupés, Córdoba, and Antioquia departments.

Dietary exposure assessment of methylmercury and polyunsaturated fatty acids in saltwater fish and processed foods among Taiwanese women of child-bearing age and children: A novel core food-matching approach

Saltwater fish is rich in health-promoting polyunsaturated fatty acids such as eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA). Excessive fish intake may also cause health hazards due to methylmercury (MeHg). A novel dose estimation method was proposed in this study to improve the quality of food matching by considering the usage ratio of cooking and processing methods in sampling design. In total, 39 table-ready samples were specified according to 2-3 common cooking methods, and MeHg and total mercury (THg) were analyzed. The results showed that mercury was detected in 20 samples (LOD = 0.01 μg/g). High MeHg samples included fried-Spanish mackerel (1.23 μg/g), non-cooked shredded swordfish (0.325 μg/g), pan-fried Spanish mackerel (0.248 μg/g), and non-cooked shredded salmon (0.208 μg/g). Consumption data (n = 166,911) were obtained from 24-h recalls in the 2005-2008 Nutrition and Health Surveys in Taiwan (NAHSIT). The average whole-group estimated daily intake (EDI_WG) was 0.018 (7.9% tolerable daily intake, TDI) for women of child-bearing age and 0.031 μg/day per kg body weight (13.6% TDI) for children. However, 95th percentile values (P95) of 90.4% TDI and 185% TDI were estimated for the two consumer-only populations, which have raised public health concerns. The ratio of % TDI to % daily reference intake (% DRI) was used as a risk-benefit (R/B) indicator. The top 4 R/B foods were: tuna sashimi (0.089 and 0.14), non-cooked shredded swordfish (0.033 and 0.052), fried-Spanish mackerel (0.027 and 0.043) and deep-fried fish balls (0.022 and 0.035) in the two perspective populations.

Total mercury in commercial fishes and estimation of Brazilian dietary exposure to methylmercury

BACKGROUND

Mercury, in particular its most toxic form methylmercury, poses a risk to public health. Dietary methylmercury exposure is mainly by fish, and it can vary with fish contamination and by dietary habits of the population. This study aimed to quantify total mercury levels in different fish from Brazil and to estimate Brazilian exposure to methylmercury by fish consumption.

METHODS

Total mercury occurrence was investigated in 18 different fish species by atomic absorption spectrometry with thermal decomposition and gold amalgamation. Dietary exposure to methylmercury was estimated by a deterministic method for different groups considering consumption by sex, different Brazilian geographical regions and habitat (rural or urban).

RESULTS

Carnivorous fish showed higher levels of mercury (0.01 to 0.93 mg/kg) compared to non-strictly carnivorous fish (<0.01 to 0.30 mg/kg). Farmed fishes showed significantly lower levels compared to wild fish. Mean Brazilian fish consumption achieves FAO/WHO health recommendation of about two portions of fish per week. However, there is a large difference between fish consumption at urban and rural homes and among Brazilian geographic regions. These differences in consumption impacted estimated methylmercury intake that was higher in the Northern (1.85 μg/kg bw week) and in the Northeastern (0.72 μg/kg bw week) regions and also by rural population (1.08 μg/kg bw week). These values were compared with the toxicological reference dose for neurotoxicity of 1.6 μg/kg bw week.

CONCLUSION

Even though total levels of mercury in fish were lower than Brazilian and international legislations, in the Northern Brazilian region methylmercury intake overpassed the toxicological reference dose for neurotoxicity and in rural areas it achieved 68% of this reference dose.

Total mercury, methylmercury, and selenium in aquatic products from coastal cities of China: Distribution characteristics and risk assessment

This study analyzed total mercury (THg), methylmercury (MeHg) and selenium (Se) in 114 aquatic product samples (representing 39 species) from eight coastal cities of China. The THg and MeHg levels in different parts of the same sample species were in the order of muscle ≥ skin/shell > roe, whereas Se levels were much higher in roe. Concentrations of THg, MeHg, and Se in the muscles were between 2.27-154, 0.36-135, and 57.8-1.20 × 10³ ng g^-1 wet weight (ww), respectively. Although significant differences in analyte concentrations were not observed among cities, they existed among three species; marine fish, freshwater fish, and shellfish. Shellfish had generally lower Hg content (mean: 20.2 ng g^-1 ww THg, 6.71 ng g^-1 ww MeHg, and 30.9% MeHg/THg ratio); however it had higher Se content (528 ng g^-1 ww) than the other types of fish (mean: 33.3 ng g^-1 ww THg, 28.2 ng g^-1 ww MeHg, and 79.2% MeHg/THg ratio, 257 ng g^-1 ww Se). In addition to species, the individual growth and HgSe interaction influenced Hg distribution. Evident correlations were observed between several individual body features and Hg content, and between Se and THg concentrations (p < 0.05). The greater correlation coefficient between two elements for fish indicated stronger HgSe antagonism through HgSe compound formation in fish. Relatively low THg daily intakes (mean 0.013-0.080 μg kg^-1 day^-1) and MeHg daily intakes (0.006-0.065 μg kg^-1 day^-1) along with Se:Hg molar ratios >1 and positive HBV_Se values suggest that aquatic products from these sites will not pose immediate health problems to consumers. Fish was the dominating contributor for MeHg intake whereas shellfish was the dominating contributor for Se intake. To safeguard against mercury exposure, residents in these areas can appropriately increase shellfish intake (especially bivalves), rather than exclusively consuming marine fish.

Multi-pathway human exposure risk assessment using Bayesian modeling at the historically largest mercury mining district

The largest mercury (Hg) mining district in the world is located in Almadén (Spain), with well-known environmental impacts in the surrounding ecosystem. However, the impact of mercury on the health of the inhabitants of this area has not been documented accordingly. This study aims to carry out a probabilistic human health risk assessment using Bayesian modeling to estimate the non-carcinogenic risk related to Hg through multiple exposure pathways. Samples of vegetables, wild mushrooms, fish, soil, water, and air were analyzed, and adult residents were randomly surveyed to adjust the risk models to the specific population data. On the one hand, the results for the non-carcinogenic risk based on Hazard Quotient (HQ) showed unacceptable risk levels through ingestion of Hg-contaminated vegetables and fish, with HQ values 20 and 3 times higher, respectively, than the safe exposure threshold of 1 for the 97.5th percentile. On the other hand, ingestion of mushrooms, dermal contact with soil, ingestion of water, dermal contact with water and inhalation of air, were below the safety limit for the 97.5th percentile, and did not represent a risk to the health of residents. In addition, the probabilistic approach was compared with the conservative deterministic approach, and similar results were obtained. This is the first study conducted in Almadén, which clearly reveals the high levels of human health risk to which the population is exposed due to the legacy of two millennia of Hg mining.

Transfer and bioaccumulation of mercury from soil in cowpea in gold mining sites

In this study, we evaluated the phytoremediation ability of three different genotypes of cowpea (Vigna unguiculata L. Walp) grown on mercury-contaminated soils from gold mining areas. In particular we compared a native genotype with two commercial lines L-019 and L-042. The plants were cultivated in soils amended at different concentrations of Hg (i.e. 0.2, 1, 2, 5 and 8 mg kg^-1). After three months exposure, we determined plant growth, seed production, and Hg accumulation in different plant tissues (root, leaf, seed and stem). Indices of soil-plant metal transfer such as translocation, bioconcentration and bioaccumulation factors were calculated. Results showed that the native variety presented the highest seed production (3.8 g), however the highest plant biomass (7.9 g) was observed in line L-019, both on Hg-contaminated soil of 1 mg kg^-1. The different plant tissues differed in terms of Hg concentration (root > leaf > stem). In the highest treated soil, the line L-042 accumulates higher Hg in both roots and leaves, while line L-019 accumulates more metal in stems. In line L-019, Hg concentrations in the fruit showed significant differences being higher in the valves than in the seeds. The transfer factors were generally lower than 1 and indicates the low accumulation of Hg by cowpeas. The estimated daily Hg intake through cowpea consumption showed values far below the threshold of 0.57 μg kg^-1 dw day^-1 recommended by the World Health Organization. Our results show cowpea V. unguiculata as a good protein-rich food substitute of Hg-contaminated fish for populations living near gold mining sites.

Methylmercury in Predatory and Non-predatory Fish Species Marketed in the Amazon Triple Frontier

This study assessed if the concentrations of methylmercury (MeHg) in predatory and non-predatory fish caught in the Upper Solimões River are safe for human consumption, according to the reference values established by the Joint FAO/WHO Expert Committee on Food Additives (JECFA). MeHg concentrations were evaluated in muscle of 5 predatory and 4 non-predatory fish species by gas chromatography with electron capture detector (GC-ECD). MeHg concentrations in predatory (0.09 mg kg^-1) and non-predatory (0.04 mg kg^-1) fish were under the safe upper limit for human consumption. The general average concentration of MeHg in these fish were 0.05 mg kg^-1. The Estimated Weekly Intake of MeHg was higher than the provisional tolerable weekly intake in both predatory and non-predatory fish, especially for women. Due to the high rates of fish consumption in the Amazon, the risk assessment based only on the concentration of MeHg in fish may not be accurate.

Mercury in fish marketed in the Amazon Triple Frontier and Health Risk Assessment

Fish has great socioeconomic, cultural, and nutritional importance for Amazonian populations. Despite all health benefits, fish can accumulate great amounts of mercury (Hg). The entry of Hg in aquatic trophic chains is an issue of concern to animal and human health. Higher risks of human exposure are strongly related to fish consumption. Upper Solimões population has one of the highest fish consumption rates of the Amazon. This study aimed to access the concentration of total Hg (THg) in muscle, liver, and gills of 17 species of fishes marketed in the Upper Solimões Region and Health Risk Assessment. Higher concentrations were observed in Carnivores/Piscivores. The highest THg concentration was found in liver of Cichla ocellaris (4.549 μg/g) and the lowest in gills of Hoplosternum littorale (0.002 μg/g). Most species had higher THg concentrations in muscle>liver>gills, in the Ebb period, and liver>muscle>gills, in the Flood period. Hoplias malabaricus, Pseudoplatystoma fasciatum, Plagioscion squamosissimus, Ageneiosus inermis, and C. ocellaris presented average THg concentrations above the safe limit stablished by WHO. THg levels in C. ocellaris, H. malabaricus, P. squamosissimus, P. fasciatum, and Semaprochilodus insignis were higher than those found in fish of heavily impacted areas. Signs of bioaccumulation and biomagnifications of Hg can already be observed in this region. The Western Amazon Region urgently needs government actions to inhibit Hg release in aquatic ecosystems and to advise this population on the safe amount of fish to be eaten according to species and period of the year.

Human Health Risk Assessment of Trace Metals in the Commonly Consumed Fish Species in Nakuru Town, Kenya

The present study was conducted to determine daily intake of cadmium (Cd), copper (Cu), and lead (Pb) and to assess noncarcinogenic human health risk caused by these trace metals in the commonly consumed fish species (Oreochromis niloticus, Rastrineobola argentea, Lates niloticus, and Protopterus aethiopicus) in Nakuru town, Kenya. Trace metal determination in the composite samples of the commonly consumed fish species was done using flame atomic absorption spectrophotometer. Cd, Cu, and Pb content in the muscle tissues of the commonly consumed fish species ranged from 0.11 ± 0.045 to 1.11 ± 0.931 mg kg^-1 for Cd, 0.48 ± 0.013 to 3.00 ± 0.009 mg kg^-1 for Cu, and 3.42 ± 0.045 to 12.78 ± 0.108 mg kg^-1 for Pb. Cu concentrations were within Food and Agriculture Organization (FAO) recommended limits for this trace metal in fish. In contrast, Cd and Pb had values above their respective permissible limits in fish. The assessment of human exposure to trace metals indicated that exposure doses of Cd and Cu were safe for fish consumers. Conversely, target hazard quotient (THQ) values of Pb suggested possible health risks for consumers of the commonly consumed fish species in Nakuru town, Kenya.

Human health risk of methylmercury from fish consumption at the largest floodplain in Colombia

Colombia is one of the countries with the highest emissions of mercury (Hg) to the environment, due to its use in gold mining. This study evaluated the human health risk from exposure to Hg through fish consumption in 11 municipalities located in the Mojana region, northern Colombia. The study participants (n = 839) were categorized into three population groups: children (CHD), women of childbearing age (WCHA) and the rest of population (RP). Total Hg (THg) and methylmercury (MeHg) concentrations were evaluated in the top ten most consumed fish species (n = 292). Median concentrations (range: 0.22-0.58 μg/g ww) of the five carnivorous fish species exceeded the reference limit established by FAO/WHO (0.2 μg/g ww) for vulnerable populations. For 6 of the 10 studied fish species, the estimated weekly intake (EWI) in children was above the provisional tolerable weekly intake (PTWI, 1.6 μg/kg bw/week) of MeHg established by JECFA. EWI values for WCHA were above PTWI in 4 fish species, whereas in general, for RP group values were below PTWI (3.2 μg/kg bw/week). Our assessment of potential risks to MeHg exposure indicated that most of the consumed fish could generate negative effects in vulnerable groups, because according to ingestion rate, MeHg permissible is, in some cases, up to 4 times higher than reference limits. Consumption advisories should be a guidance to avoid risk, gain nutritional benefits, and sustain fish populations. Because its high MeHg levels as well as high ingestion, it is recommended that inhabitants of this region should stop eating certain kinds of fish and the whole fish as a single meal. To reduce its harmful intake, we have proposed a didactic strategy based on marbles that control the portion of fish they are eating.

Health Risks Associated with Heavy Metals in Imported Fish in a Coastal City in Colombia

Colombia is a fish exporter and consumer country because of its geographical location. Since 2012, imported fish have become a more economical option than domestic species due to free trade agreements. Concentrations of Pb, Cd, and Zn were evaluated in three imported and highly commercialized fish species in a city on the Caribbean coast of Colombia: Prochilodus lineatus, Prochilodus reticulatus, and Pangasianodon hypophthalmus, plus one brand of canned tuna and one brand of sardines. The canned species showed the highest values for Pb, Cd, and Zn; canned tuna (oil-packed) contained 0.189 ± 0.047 mg/kg Pb and 238.93 ± 76.43 mg/kg Zn, while canned sardines contained 0.111 ± 0.099 mg/kg Cd, suggesting a relationship between the canning process and the metal concentrations. The estimated daily intake (EDI) and hazard quotient (HQ) suggested that there is no risk for consumer health in the short term, but the presence of these heavy metals certainly should be a concern in the long term because of the bioaccumulation phenomenon due to the high intake of these fish species in this coastal and tourist community. It is recommended that continuous monitoring of heavy metal concentrations take place to protect communities in a local and global context.

Exposure to Mercury in Workers and the Population Surrounding Gold Mining Areas in the Mojana Region, Colombia

In Colombia, the inhabitants of the Mojana region have historically been subjected to high levels of environmental and occupational exposure to mercury; however, there are few robust data on the magnitude of this exposure and associated factors. This study aimed to describe the levels of mercury in the workers and inhabitants in this region, and to identify the main sociodemographic and occupational factors that are associated with this exposure. A cross-sectional study was conducted, in which mercury levels were determined in biological samples (blood, urine, hair) from 1119 people in the Mojana region. A questionnaire was also administered, which was adapted from the Global Mercury Assessment. Linear regression models were adjusted for the natural logarithm of mercury levels in blood, urine, and hair, using the factors that were explored as independent variables. The study reports high mercury levels in 35.0% of blood samples (95% CI 31.9⁻38.1%), 28.8% (95% CI 24.9⁻32.8%) of urine samples, and 56.3% (95% CI 53.1⁻59.5%) of hair samples. The reported source of water for consumption was associated with high levels of mercury (p-value < 0.05). We provide evidence of high levels of mercury exposure for the population in the Mojana region.