Selenium Health Benefit Values: Updated Criteria for Mercury Risk Assessments

Toxic and essential elements determination in edible tissues of different elasmobranch species from Southeastern Brazil and potential human health risks

Brazil is the largest consumer of shark meat, which is sold by fishmongers under the umbrella term cação. The population consumes this meat due to its low cost and lack of fish bones. In this work, morphometric measurements and metal/metalloid concentration (75As, 202Hg, and 82Se) were assessed in the muscle tissue of species from Dasyatis spp., as well as Rhizoprionodon porosus and Zapteryx brevirostris, obtained from Farol de São Tomé beach in Southeastern Brazil. A principal component analysis (PCA) was conducted to evaluate the separation of species based on morphometric variables and elemental concentrations. Additionally, human health risk assessment indices-estimated daily intake (EDI), target hazard quotient (THQ), target cancer risk (TCR), and selenium health benefit values (HBVSe)-were calculated to estimate the risks associated with the consumption of elasmobranch meat in the region. The PCA revealed distinct clustering patterns by species. The human health risk assessment indices indicated potential risks associated with the consumption of the analyzed species. For Dasyatis spp., the EDI of As, THQ of inorganic As (iAs), and TCR exceeded their respective thresholds. For R. porosus, the EDI of As, THQ of iAs and Se, and TCR exceeded the established thresholds. For Z. brevirostris, the EDI of As and Hg, THQ of iAs and MeHg, TCR, and HBVSe exceeded the thresholds. These results suggest a potential risk to public health associated with the consumption of elasmobranch meat from the analyzed species, especially Z. brevirostris.

Selenium Differentially Influences Methylmercury Retention across Mayfly Life Stages

Though high mercury and selenium concentrations are individually toxic to organisms, there is a hypothesized antagonistic relationship. This potential mercury-selenium interaction is under-studied in aquatic macroinvertebrates, particularly in relation to complex life histories. We examined the proposed effect of selenium on methylmercury accumulation between four life stages for a parthenogenetic mayfly (Neocloeon triangulifer). We exposed diatoms to elevated methylmercury concentrations and fed them to mayflies exposed to elevated aqueous selenomethionine. We found some support for the mercury-selenium antagonism hypothesis, but it was context-specific. Selenium reduced methylmercury accumulation in high but not low methylmercury environments. Though terrestrial adult life stages had higher mercury concentrations compared to aquatic larval life stages, cumulative life history transfer factor (LHTF; ratio of methylmercury in adult imago to late instar larvae) differed by treatment. LHTF was constant for all aqueous selenium exposure levels at high dietary methylmercury (selenium impacts on methylmercury uptake and loss) but increased with aqueous selenium exposures at low dietary methylmercury (selenium impacts on methylmercury uptake only), suggesting a synergistic enhancement of MeHg transfer between life stages with increased aqueous Se exposure levels. These results suggest that animals eating adult aquatic insects are exposed to higher concentrations of methylmercury than those feeding on larval insects across selenium and methylmercury levels, but interference of selenium on methylmercury accumulation is only present at high methylmercury environments.

Metal(oid) bioaccumulation, SeHg balance, and human health risk assessment in anchovy (Engraulis encrasicolus) from the southern Black Sea

The European anchovy (Engraulis encrasicolus) is the widely caught fish species in Türkiye, both in terms of catch volume and widespread consumption. It holds significant economic and cultural value, particularly in the Black Sea region, where it is a staple in local diets. This study aimed to assess toxic element contamination in anchovies and evaluate potential human health risks. Metal(oid) levels were analyzed in samples collected monthly over a one-year period from the southeastern Black Sea. Although concentrations varied monthly, they remained below national and international safety limits. Seasonal variations in the concentration of 15 metal(oid)s were statistically insignificant. Health risk assessments, including estimated weekly intake (EWI), target hazard quotients (THQ), and hazard index (HI), revealed no adverse effects from regular consumption. The study also noted low mercury (Hg) levels, with a selenium (Se) to mercury molar ratio above 1 during all seasons, suggesting that selenium may mitigate the toxic effects of mercury. Thus, consuming anchovies presents a favorable risk/benefit balance for health. Carcinogenic risk index (CRI) values for arsenic (As), lead (Pb), and chromium (Cr) were within acceptable thresholds. These results demonstrate that anchovies from the region are safe to eat and pose no significant health risk. Importantly, this is the first study to investigate monthly and seasonal variations in metal levels in European anchovies from the Black Sea. The findings contribute valuable data for public health assessments and support the need for continued monitoring to address environmental changes and maintain seafood safety.

Combined effect of mercury and ammonia toxicity and its mitigation through selenium nanoparticles in fish

An experiment was conducted to mitigate mercury and ammonia toxicity (Hg + NH₃) in Oreochromis niloticus (GIFT strain) using selenium nanoparticles (Se-NPs). The Se-NPs were synthesized using green methods, employing fish waste as the substrate. Experimental diets were prepared by supplementing Se-NPs at 0, 0.3, and 0.6 mg kg⁻¹. The oxidative stress enzymes, including catalase (CAT) and glutathione peroxidase (GPx), in the liver and kidney tissues were significantly reduced by Se-NPs at 0.3 and 0.6 mg kg⁻¹ under Hg + NH₃ stress compared to the control and stressor in 20 and 40 day periods. Additionally, superoxide dismutase (SOD) activity in the kidney at 20 days and in the liver at 40 days was significantly reduced by supplementation of Se-NPs under similar conditions. The activity of acetylcholine esterase (AChE), was significantly inhibited by Hg + NH₃ toxicity. Whereas, AChE activity was enhanced by Se-NPs supplementation at 0.3 and 0.6 mg kg⁻¹ during 20 and 40 day intervals. The gene expression of HSP70, iNOS, CYP450, Caspase-3a, and TNFα in liver tissue, and MYST in muscle tissue was upregulated by Hg+NH₃ toxicity. However, this upregulation was significantly downregulated by supplementation of Se-NPs at 0.3 and 0.6 mg kg⁻¹ under Hg + NH₃ stress. Moreover, immunoglobulin (Ig) and growth hormone (GH) levels were noticeably upregulated with Se-NPs compared to the control and Hg+NH₃ stress. The activities of alanine aminotransferase (ALT), aspartate aminotransferase (AST), lactate dehydrogenase (LDH), and malate dehydrogenase (MDH) in liver and gill tissues, were significantly elevated by Hg+NH₃ toxicity, were reduced by Se-NPs diet. Conversely, digestive enzyme activities, including protease, amylase, and lipase, were significantly enhanced by Se-NPs under stress conditions. Dietary supplementation with Se-NPs at 0.3 and 0.6 mg kg⁻¹ improved growth performance parameters such as final weight gain percentage, feed conversion ratio, protein conversion ratio, specific growth rate, daily growth index, and relative feed intake compared to the control and other groups. DNA damage, assessed in terms of tail DNA percentage, was significantly reduced with Se-NPs supplementation. Additionally, mercury detoxification was significantly enhanced with Se-NPs-supplemented diets. In conclusion, this study demonstrates that dietary Se-NPs effectively alleviate the adverse effects of mercury and ammonia toxicity by modulating antioxidant status, enhancing immunomodulation, and mitigating stress biomarker impacts through changes in gene expression in fish.

The content and associated health risk assessment of toxic elements, micro-, and macrominerals in common carp, Wels catfish, and silver carp from the Danube River in Serbia

Three fish species (common carp, Wels catfish, and silver carp) were collected from three locations along the Danube River in Serbia, and fish meat was analyzed for the content of toxic elements, micro- and macrominerals. Silver carp had the highest lead (Pb), arsenic (As), and cadmium (Cd) content, while Wels catfish had the highest level of mercury (Hg). Moreover, metal pollution index (MPI) ranged from 0.1096 to 0.275 and among the fish, the silver carp had the highest MPI (from 0.21 to 0.28), indicating that it could be reliable bioindicator of river pollution. Maximum determined levels of As (0.1968 mg/kg of w.w.), Hg (0.175 mg/kg of w.w.), and Pb (0.0315 mg/kg of w.w.) did not exceed values prescribed by the European Commission Regulation, Codex Alimentarius Commission, Food and Agriculture Organization (FAO), and national regulations, but Cd in silver carp was at levels higher than prescribed (0.0808 mg/kg of w.w.). Furthermore, our study's results showed that the target hazard quotient (THQ) of each analyzed element and hazard index (HI) were < 1, indicating that consumers would not be exposed to adverse health effects after consuming these fish species from the Danube River. Regarding target cancer risk (TR), for Pb this was below 10-6, which was regarded as negligible, while TRs for As and Cr were between 10-4 and 10-6, which was regarded as acceptable. Moreover, since the studied fish had low values of health risk indexes, it could be concluded that fish meat did not pose a significant risk to human health.

A preliminary assessment of mercury, methylmercury and other potentially toxic elements in largemouth bass (Micropterus salmoides) from the Almadén mining district

The food chain of the Valdezogues River system is at considerable risk due to the presence of mercury in the environment and to intense bioaccumulation and biomagnification processes in some fish species, particularly in piscivorous. Moreover, the presence of mercury in fish is a reliable indicator of the presence of its most toxic form, methylmercury. Of interest is that selenium, when present together with mercury in food, represents a significant decrease in the risks related to the ingestion of methylmercury. This study presents the concentrations of total mercury, methylmercury, selenium, and other elements in Micropterus salmoides from a transect of the Valdeazogues River. This water course cuts across the Almadén mining district, which has been the most important producer of this element for over 2000 years. Results highlight the highest total- and methylmercury concentrations ranging between 0.47 and 7.61 mg kg-1 ww for total mercury, and with methylmercury representing between 79.7 and 92.1% of total mercury. These are the highest concentrations in the element ever found in this species. Seven sampling sites were examined along a 34 km long transect of the river, starting at an open pit lake corresponding to a decommissioned Hg mine (El Entredicho open pit, isolated from the river course), with the rest of the sites located downstream. Concentrations of mercury are the highest in this open pit lake and decrease steadily downstream. Concentrations of selenium are also high to very high, ranging between < 2.5 and 11.4 mg kg-1 ww. The Se/Hg molar ratio, as well as the HBVSe index, show values indicating low risk, except for specimens of low size/age from the most highly Hg contaminated site considered in this study. The rest of the potentially toxic elements (Se, As, Pb, Zn, Sb and Cu) show no concerning values even though the area is heavily populated with decommissioned polymetallic mines.

Regional variations and drivers of essential and non-essential elements in Steller sea lion pups from the Aleutian Islands, Alaska

Exposure and resulting tissue concentrations of various elements from natural and anthropogenic sources are influenced by multiple factors, such as geographic location, age, diet, and metabolic rate, that can influence wildlife health. Essential and non-essential elements were assessed in lanugo and whole blood collected in 2019 from 102 Steller sea lion (Eumetopias jubatus) pups from two rookeries from the western and central Aleutian Islands: Agattu (WAI, n = 54) and Ulak Islands (CAI, n = 48). Rookery, sex, dorsal standard length, and trophic ecology (ẟ15N, ẟ13C values) effects on element concentration were evaluated. Significant differences in element concentrations of lanugo were exhibited across rookeries (p < 0.05), except for zinc (Zn). For example, higher mercury (Hg) and selenium (Se) concentrations were observed in WAI than CAI, while other elements were lower in WAI. Whole blood showed higher sulfur (S) and Se concentrations in CAI compared to WAI, while WAI had elevated strontium (Sr) and Hg concentrations relative to CAI. Trophic ecology significantly influenced most element concentrations, possibly due to regional variations in adult female feeding and food web dynamics. Interactions between elements were found in lanugo across both rookeries, with varying strengths. Whole blood displayed less pronounced yet consistent associations, with variable intensities. Essential elements sodium (Na), potassium (K), and calcium (Ca) formed a distinct group whose interaction is crucial for nervous system function and muscle contraction. Another group comprised zinc (Zn), iron (Fe), manganese (Mn), magnesium (Mg), phosphorous (P), S, and Se, which are known for indirectly interacting with enzyme function and metabolic pathways. Hg and Se formed a distinct group probably due to their known chemical interactions and physiological protective interactions.

Evaluation of Health Risks Attributed to Toxic Trace Elements and Selenium in Farmed Mediterranean Mussels from Türkiye and Bulgaria

Farmed mussels accumulate contaminants from their production environment rather than releasing them into water. This study reveals potential health risks associated with selenium, cadmium, mercury, and lead resulting from the consumption of mussels (Mytilus galloprovincialis) cultured along the coasts of Türkiye and Bulgaria. The concentrations of Se and toxic trace metals were measured by inductively coupled plasma mass spectrometry (ICP-MS). The detection limits (LOD) were 0.100, 0.015, 0.025, and 0.180 µg/kg for Se, Cd, Hg, and Pb, respectively. The mean Se concentrations were between 1.305 and 1.957 µg/g, and toxic metals were below the maximum limits. Due to Turkish and Bulgarian consumers' limited mollusk consumption, mussels could only provide a maximum of 7.35% of the daily Se need. THQ and TTHQ of Se, Cd, and methyl-Hg were below 1, indicating that farmed mussels were safe for consumption. Percent PTWI values were calculated only for Cd and MeHg, as the PTWI value for Pb was discarded by the authorities and not determined for Se. Accordingly, weekly mussel consumption did not pose any risks. The margin of exposure approach was used to evaluate Pb intake. MOE-SBP and MOE-NE were significantly higher than 10, designating no significant health risks. Long-term consumption of mussels also does not pose a carcinogenic risk regarding the TR index calculated between 10-5 and 10-6 for Pb. Positive HBVSe (10.13-37.27) indicated that Se in mussels overcame Hg-related potential health concerns. Consequently, mussels grown in Türkiye and Bulgaria did not pose a risk for human consumption, based on current risk analysis methods.

Se and Hg in processed fish-derived products and their fish raw materials: Occurrence, Se:Hg molar ratio, HBVSe index, bioaccessibility and Caco-2 cells toxicity

Processing conditions applied during food production could affect food component contents and bioaccessibility. Here, possible changes in Hg and Se total and species contents and bioaccessibility have been tracked in each stage of the production chain of processed fish-derived products. Therefore, Se:Hg molar ratio and Selenium Health Benefit Value (HBVSe) were calculated for final products and raw materials, resulting favorable in all cases, suggesting the safety of surimi-based products regarding mercury. Speciation studies revealed the presence of SeMeSeCys and SeMet in all samples. Thus, the integrity of the selenium species seems to be maintained. Moreover, in vitro gastrointestinal digestion model evidenced that Se bioaccessibility ranged between 20-39 % for all samples, while in case of Hg was between 8-37 %. Additionaly, SeMeSeCys and SeMet were also identified in the gastrointestinal extracts. Finally, no cytotoxicity was observed after exposure of Caco-2 cells to the gastrointestinal extracts.

Assessment of dietary Selenium and its role in Mercury fate in cultured fish rainbow trout with two sustainable aquafeeds

This study enhances the current limited understanding of the interaction between mercury (Hg) and selenium (Se) species in fish. Rainbow trout (Oncorhynchus mykiss), a model aquaculture fish, was exposed to Hg and Se species through controlled dietary conditions. Over a 6-month feeding trial, the impact of dietary Se on Hg bioaccumulation in fish, including flesh, brain, and liver, was tracked. Twelve dietary conditions were tested, including plant-based diets (0.25 µgSe g-1) and tuna byproduct diets (0.25 µgHg g-1, 8.0 µgSe g-1) enriched with methylmercury and/or Se as selenite or selenomethionine. The tuna byproduct diet resulted in lower Hg levels than the plant-based diets, with muscle Hg content below the European Commission's safe threshold. This study highlights the significant impact of specific Se compounds in the diet, particularly from tuna-based aquafeed, on Hg bioaccumulation. These promising results provide a strong recommendation for future use of fisheries byproducts in sustainable aquafeeds.

Single-cell ICP-MS for evaluating the Se-protective effect against MeHg+-induced neurotoxicity in human neuroblastoma cell line (SH-SY5Y)

The protective effect of selenium (Se) against Hg-induced neurotoxicity has been widely investigated; however, the mechanisms behind this interaction have not been fully elucidated yet. In the current work, the role of Se against MeHg+-induced cytotoxicity in the human neuroblastoma cell line (SH-SY5Y) is reported for the first time by tracking Hg uptake and accumulation at the single-cell level by inductively coupled plasma-mass spectrometry in single-cell mode (SC-ICP-MS). The influence of different Se species (SeMet, SeMeSeCys, citrate-SeNPs, and chitosan-SeNPs) on MeHg+ cytotoxicity was evaluated by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assays. SeMet and SeMeSeCys exhibited protective effects against MeHg+-induced cell death, particularly at high MeHg+ concentrations (LC50). In addition, chitosan-SeNPs showed greater protection compared to citrate-SeNPs when co-exposed with MeHg+. Interestingly, SC-ICP-MS unveiled the heterogeneous distribution of Hg uptake by SH-SY5Y cells. Co-exposure of SeMet and SeMeSeCys with MeHg+ led to a reduction of the amount of Hg accumulated per individual cell, which decreased the maximum level of Hg per cell by half (from 60 fg Hg cell-1 to 30 fg Hg cell-1) when SeMet was present, along with a decrease in the percentage of cells that accumulated the highest quantity of MeHg+. All these data corroborate the protective role of Se against Hg toxicity at the cellular level.

Potentially toxic trace elements in the muscle of coastal South American fish: Implications for human consumption and health risk assessment

Micropogonias furnieri and Urophycis brasiliensis are two coastal demersal fish species distributed in the southwestern Atlantic Ocean. Considering that many coastal areas in the southwestern Atlantic Ocean suffer from anthropogenic pressure, the aim of this study was to assess the level of potentially toxic trace elements (Ag, Al, As, Cd, Co, Cr, Cu, Fe, Hg, Mn, Mo, Ni, Pb, Se, Sr, V and Zn) in the muscle of coastal species, and evaluated the human health risk related to the consumption of muscle. Mercury, inorganic As (Asi), V, and Se showed a higher contribution to the total THQ. Considering two possible scenarios, Asi represents 1 % or 5 % of the total As, the total THQ was <1 for general population and of some health concerns for fishermen population (Total THQ > 1; 5 % Asi). Consequently these results show the importance of quantifying As species in muscle to generate more reliable risk estimates for human health.

P. Oliveira MB, Prieto MA. Health benefits of bluefin tuna consumption: (Thunnus thynnus) as a case study

Consumers are increasingly interested in food products with high nutritional value and health benefits. For instance, fish consumption is linked with diverse positive health benefits and the prevention of certain widespread disorders, such as obesity, metabolic syndrome, or cardiovascular diseases. These benefits have been attributed to its excellent nutritional value (large amounts of high-quality fatty acids, proteins, vitamins, and minerals) and bioactive compounds, while being relatively low-caloric. Atlantic bluefin tuna (Thunnus tynnus) is one of the most consumed species worldwide, motivated by its good nutritional and organoleptic characteristics. Recently, some organizations have proposed limitations on its consumption due to the presence of contaminants, mainly heavy metals such as mercury. However, several studies have reported that most specimens hold lower levels of contaminants than the established limits and that their richness in selenium effectively limits the contaminants' bioaccessibility in the human body. Considering this situation, this study aims to provide baseline data about the nutritional composition and the latest evidence regarding the beneficial effects of Atlantic bluefin tuna consumption. A review of the risk-benefit ratio was also conducted to evaluate the safety of its consumption, considering the current suggested limitations to this species' consumption.

Mercury bioaccumulation and its relationship with trophic biomarkers in a Mediterranean elasmobranch mesopredator

Human activity has led to increased concentrations of mercury (Hg) in the world's oceans. Mercury can bioaccumulate and biomagnify in animal tissues via trophic transfer, thus, becoming most pronounced in larger and older predators. Here, we measured Hg concentrations and their relationship with stable isotopes-based proxies of trophic level (δ13C and δ15N values) in multiple tissues of Mustelus spp. from the Mediterranean Sea. We found higher Hg concentrations in muscle than in liver and fin tissues. The relationship between Hg concentrations and δ15N values in muscle suggested repeated foraging for low trophic level and Hg-poor prey, and biomagnification of Hg at higher trophic levels. Seasonal variations in δ13C values could indicate shifts in primary production sources and/or in local prey availability. The HBVSe index suggested no risk to human health, however the safe meal limit recommendations are 4.5 and 2.2 portions per month for adults and children, respectively.

Biomonitoring of mercury and selenium in commercially important shellfish: Distribution pattern, health benefit assessment and consumption advisories

This study aims to explore the concentrations of Se and Hg in shellfish along the Gulf of Mannar (GoM) coast (Southeast India) and to estimate related risks and risk-based consumption limits for children, pregnant women, and adults. Se concentrations in shrimp, crab, and cephalopods ranged from 0.256 to 0.275 mg kg-1, 0.182 to 0.553 mg kg-1, and 0.176 to 0.255 mg kg-1, respectively, whereas Hg concentrations differed from 0.009 to 0.014 mg kg-1, 0.022 to 0.042 mg kg-1 and 0.011 to 0.024 mg kg-1, respectively. Se and Hg content in bamboo shark (C. griseum) was 0.242 mg kg-1 and 0.082 mg kg-1, respectively. The lowest and highest Se concentrations were found in C. indicus (0.176 mg kg-1) and C. natator (0.553 mg kg-1), while Hg was found high in C. griseum (0.082 mg kg-1) and low in P. vannamei (0.009 mg kg-1). Se shellfishes were found in the following order: crabs > shrimp > shark > cephalopods, while that of Hg were shark > crabs > cephalopods > shrimp. Se in shellfish was negatively correlated with trophic level (TL) and size (length and weight), whereas Hg was positively correlated with TL and size. Hg concentrations in shellfish were below the maximum residual limits (MRL) of 0.5 mg kg-1 for crustaceans and cephalopods set by FSSAI, 0.5 mg kg-1 for crustaceans and 1.0 mg kg-1 for cephalopods and sharks prescribed by the European Commission (EC/1881/2006). Se risk-benefit analysis, the AI (actual intake):RDI (recommended daily intake) ratio was > 100%, and the AI:UL (upper limit) ratio was < 100%, indicating that all shellfish have sufficient level of Se to meet daily requirements without exceeding the upper limit (UL). The target hazard quotient (THQ < 1) and hazard index (HI < 1) imply that the consumption of shellfish has no non-carcinogenic health impacts for all age groups. However, despite variations among the examined shellfish, it was consistently observed that they all exhibited a Se:Hg molar ratio > 1. This finding implies that the consumption of shellfish is generally safe in terms of Hg content. The health benefit indexes, Se-HBV and HBVse, consistently showed high positive values across all shellfish, further supporting the protective influence of Se against Hg toxicity and reinforcing the overall safety of shellfish consumption. Enhancing comprehension of food safety analysis, it is crucial to recognize that the elevated Se:Hg ratio in shellfish may be attributed to regular selenoprotein synthesis and the mitigation of Hg toxicity by substituting Se bound to Hg.

Dietary selenium and mercury intakes from fish consumption during pregnancy: Seychelles Child Development Study Nutrition Cohort 2

Some health agencies have issued precautionary principle fish advisories to pregnant women based on the presence of methylmercury (MeHg) in fish that could possibly be harmful to the developing fetus. Fish, however, is a rich source of selenium (Se) and other nutrients essential for normal brain development. Selenium is also thought to have a key role in alleviating MeHg toxicity. We estimated the dietary Se and MeHg intakes and dietary Se:Hg molar ratios from the fish consumed in a high fish-eating pregnant cohort where no adverse associations of fish consumption and outcomes has been reported. We used dietary data collected as part of the Seychelles Child Development Study Nutrition Cohort 2 (n = 1419). In this cohort 98% of participants consumed fish, with an average intake of 106.2 g per day. Daily Se intakes from fish consumption were 61.6 µg/ d, within the range recommended during pregnancy. The mean dietary Se:Hg molar ratios was 6. These findings demonstrate that fish consumption exposes pregnant Seychellois women to Se in excess of MeHg. Based on these findings, fish consumption, especially fish with Se:Hg ratios above 1, may help pregnant women achieve optimum dietary Se intakes, which may protect against MeHg toxicity.

Selenium and mercury concentration, Se/Hg molar ratio and risk-benefit assessment of marine fish consumption: Human health risks and protective role of Se against Hg toxicity

This study aimed to explore the concentrations of Se and Hg in marine fish along the Gulf of Mannar (southeast coast of India) and to assess related risks and risk-based consumption limits for children, pregnant women, and adults. Se concentrations in pelagic and benthic fish ranged from 0.278 to 0.470 mg/kg and 0.203 to 0.294 mg/kg, respectively, whereas Hg concentrations ranged from 0.028 to 0.106 mg/kg and 0.026 to 0.097 mg/kg, respectively. Se and Hg contents in demersal fish (Nemipterus japonicus) were 0.282 and 0.039 mg/kg, respectively. The lowest and highest Hg concentrations in pelagic fish were found in Scomberomorus commersoni and Euthynnus affinis whereas the lowest and highest Se concentrations in benthic fish were found in Scarus ghobban and Siganus javus. Se concentrations in marine fishes were found in the following order: pelagic > demersal > benthic whereas Hg concentrations were found in the following order: pelagic > benthic > demersal. The presence of Se in fish was positively correlated with trophic level (TL) and size whereas that of Hg was weakly correlated with TL and habitat and negatively correlated with size. Se risk-benefit analysis, the AI/RDI (actual intake/recommended daily intake) ratio was > 100 % and the AI/UL (upper limit) ratio was < 100 %, indicating that all fish have sufficient levels of Se to meet daily requirements without exceeding the UL. Hg level was below the maximum residual limit (MRL) of 0.5 mg/kg for most fish but it was 1 mg/kg in E. affinis and Lethrinus lentjan. The target hazard quotient (THQ < 1) and hazard index (HI < 1) imply that the consumption of fish poses no noncarcinogenic health risks. However, all examined fish had a mean Se/Hg molar ratio > 1, indicating that human intake of fishwas rather safe relative to Hg content. Health benefit indexes (Se-HBV and HBVse) with high positive values in all fish supported the protective effect of Se against Hg toxicity, suggesting the overall safety of fish consumption. The high Se/Hg ratio in fish could be attributed to the replacement of Se bound to Hg, thereby suppressing Hg toxicity and maintaining normal selenoprotein synthesis. This insight is useful for a better understanding of food safety analysis.

Maternal seafood consumption is associated with improved selenium status: Implications for child health

Selenium (Se) is required for synthesis of selenocysteine (Sec), an amino acid expressed in the active sites of Se-dependent enzymes (selenoenzymes), including forms with essential functions in fetal development, brain activities, thyroid hormone metabolism, calcium regulation, and to prevent or reverse oxidative damage. Homeostatic mechanisms normally ensure the brain is preferentially supplied with Se to maintain selenoenzymes, but high methylmercury (CH3Hg) exposures irreversibly inhibit their activities and impair Sec synthesis. Due to Hg's high affinity for sulfur, CH3Hg initially binds with the cysteine (Cys) moieties of thiomolecules which are selenoenzyme substrates. These CH3Hg-Cys adducts enter selenoenzyme active sites and transfer CH3Hg to Sec, thus irreversibly inhibiting their activities. High CH3Hg exposures are uniquely able to induce a conditioned Se-deficiency that impairs synthesis of brain selenoenzymes. Since the fetal brain lacks Se reserves, it is far more vulnerable to CH3Hg exposures than adult brains. This prompted concerns that maternal exposures to CH3Hg present in seafood might impair child neurodevelopment. However, typical varieties of ocean fish contain far more Se than CH3Hg. Therefore, eating them should augment Se-status and thus prevent Hg-dependent loss of fetal selenoenzyme activities. To assess this hypothesis, umbilical cord blood and placental tissue samples were collected following delivery of a cohort of 100 babies born on Oahu, Hawaii. Dietary food frequency surveys of the mother's last month of pregnancy identified groups with no (0 g/wk), low (0-12 g/wk), or high (12 + g/wk) levels of ocean fish consumption. Maternal seafood consumption increased Hg contents in fetal tissues and resulted in ∼34% of cord blood samples exceeding the EPA Hg reference level of 5.8 ppb (0.029 µM). However, Se concentrations in these tissues were orders of magnitude higher and ocean fish consumption caused cord blood Se to increase ∼9.4 times faster than Hg. Therefore, this study supports the hypothesis that maternal consumption of typical varieties of ocean fish provides substantial amounts of Se that protect against Hg-dependent losses in Se bioavailability. Recognizing the pivotal nature of the Hg:Se relationship provides a consilient perspective of seafood benefits vs. risks and clarifies the reasons for the contrasting findings of certain early studies.

Total mercury and selenium levels in commercial shrimp along the Pacific coast of Mexico

The present study analyzed the content of total mercury (THg) and selenium (Se) in the muscle of shrimp collected from local markets in the 11 Pacific coastal states of Mexico. Methylmercury (MeHg) concentration, Se:Hg ratio, health benefits value from selenium consumption (HBVSe) and the permissible weekly consumption were estimated to assess the health risk to consumers. All THg and Se concentrations were below the maximum permissible limits. All hazard quotient (HQ) values were <1, however in Hermosillo, Culiacán and Guadalajara, the Se:Hg ratio and HBVSe were <1 and negative, due to the low concentrations of Se. As a general conclusion, there is no risk nor benefit from the consumption of shrimp from the Pacific coast of Mexico due to its Hg and Se content.

Selenium Health Benefit Values and Hg and Se speciation studies for elucidating the quality and safety of highly consumed fish species and fish-derived products

Nowadays, there has been an increase in the consumption of fish-derived products that constitute alternative ways of introducing fish into the diet, such as fish roe and products made from fish (crab sticks andsurimi-derived products). However, there is no data available considering selenium and mercury total contents along with speciation studies in these kinds of samples, which are mandatory for a proper safety and quality assessment. In this study,Selenium Health Benefit Values (HBVSe) in fish and fish-derived products were evaluated, resulting inpositivein all cases. Selenium speciation studies performed by HPLC-ICP-MS and confirmed by HPLC-ESI-MS/MS revealed that SeMet and SeMeSeCys are present in fish and fish-derived products. Finally, Hg speciation studiesshow that the percentage of Hg2+ increases in fishes lower in the food chain as well as in fish-derived products.

Approaches to risk-benefit assessment of seafood consumption: lessons learned from an evidence scan

Qualitative and quantitative risk-benefit assessments (RBA) can be used to support public health decisions in food safety. We conducted an evidence scan to understand the state of the science regarding RBA in seafood to help inform seafood dietary advice in the United States. We collected published RBA studies assessing seafood consumption, designed inclusion and exclusion criteria to screen these studies, and conducted systematic data extraction for the relevant studies published since 2019. Our findings indicate the selection of health risks and benefits does not generally follow a systematic approach. Uncertainty and variability in RBAs is often not addressed, and quantitative RBAs making use of a single health metric generally have not been leveraged to directly support published regulatory decisions or dietary guidance. To elevate the role of RBA in supporting regulatory decision-making, risk assessors and risk managers must work together to set expectations and goals. We identified the need for a prioritization phase (e.g., multicriteria decision analysis model) to determine the risks and benefits of greatest public health impact to inform the RBA design. This prioritization would consider not only the degree of public health impact of each risk and benefit, but also the potential for risks and benefits to converge on common health outcomes and their importance to subpopulations. Including a prioritization could improve the utility of the RBAs to better inform risk management decisions and advance public health. Our work serves to guide the United States Food and Drug Administration's approaches to RBA in foods.

Hg and Se in Muscle and Liver of Blue Shark (Prionace glauca) from the Entrance of the Gulf of California: An Insight to the Potential Risk to Human Health

The blue shark (Prionace glauca) is the most commonly caught species of Elasmobranchii at the entrance to the Gulf of California. Although fins are the primary target commodity, the entire organism is consumed. This study examined the concentration of Hg and Se in muscle and liver to understand the antagonistic process that occurs between these two elements within the organism. Twenty-two individuals were captured at the Gulf of California inlet between September 2019 and March 2021. Hg was measured by cold vapor atomic absorption, and Se by atomic absorption spectrophotometry in a graphite furnace. All individuals studied showed higher concentrations (µg g-1 wet weight) of Hg (0.69) and Se (2.49) in liver than in muscle (Hg 0.63 and Se 0.08). Although the mean Hg values were below the maximum allowable limits (Hg 1.0 µg g-1 wet weight), the molar ratio (< 1.0) and the negative health benefit value of selenium (HBVSe) in muscle show that additional caution should be taken when consuming this species. We recommend a more thorough study of the antagonistic interaction between Hg and Se to accurately assess the health risk for consumers of blue shark.

Mercury and selenium in three fish species from a dam 20 months after a mine-tailing spill in the SE Gulf of California ecoregion, Mexico

During January 2013, a mining spill occurred in the Santa Maria mining region, releasing around 300,000 m3 of tailings on Los Remedios river, which was transported through the San Lorenzo river and finally to El Comedero (EC) dam. Twenty months later, we examined the concentrations of Hg and Se in the muscle, liver, gills, and guts of three fish species (Cyprinus carpio, Oreochromis aureus, Micropterus salmoides) captured in the EC dam to assess the performance of the cleaning operations. A high Se concentration in the liver of all species (carp, 1.2 ± 0.4; tilapia, 3.9 ± 2.1; bass, 3.5 ± 1.1 µg g-1 ww) was consistently observed, while this behavior was only found in the blue tilapia for Hg (0.15 ± 0.11 µg g-1 ww). Tilapia (benthic-detritivorous) exhibited the highest Se concentrations compared to the carp (omnivore) and the largemouth bass (piscivore). In contrast, the largemouth bass had the highest Hg levels in the muscle compared with the other fishes. Such differences could be related to the different metabolism and feeding habits among species. Compared to a tilapia study carried out three months after the mine spill during a mortality event, a decrease was evident in the liver for Se and Hg by 7.2 and 4.7 times, respectively. This reveals that cleaning operations were more efficient for Se and less for Hg, and that a prolonged period was required for the partial recovery of the element levels in fish from sites impacted by mining. Considering the Mexican consumption scenarios for each fish species, it could be concluded that there will be no non-cancer risk by exposure to Hg or Se.

Synchrotron speciation of umbilical cord mercury and selenium after environmental exposure in Niigata

The insidious and deadly nature of mercury's organometallic compounds is informed by two large scale poisonings due to industrial mercury pollution that occurred decades ago in Minamata and Niigata, Japan. The present study examined chemical speciation for both mercury and selenium in a historic umbilical cord sample from a child born to a mother who lived near the Agano River in Niigata. The mother had experienced mercury exposure leading to more than 50 ppm mercury measured in her hair and was symptomatic 9 years prior to the birth. We sought to determine the mercury and selenium speciation in the child's cord using Hg Lα1 and Se Kα1 high-energy resolution fluorescence detected X-ray absorption spectroscopy, the chemical speciation of mercury was found to be predominantly organometallic and coordinated to a thiolate. The selenium was found to be primarily in an organic form and at levels higher than those of mercury, with no evidence of mercury-selenium chemical species. Our results are consistent with mercury exposure at Niigata being due to exposure to organometallic mercury species.

Potential role of selenium in modifying the effect of maternal methylmercury exposure on child neurodevelopment - A review

Selenium (Se) is an essential trace element for normal neurodevelopment. It is incorporated into multiple selenoenzymes which have roles in the brain and neurological function, the synthesis of thyroid hormones, the antioxidant defense system, DNA synthesis, and reproduction. Fish is a source of both Se and neurotoxic methylmercury (MeHg). Selenium is known to ameliorate the effects of MeHg in experimental animals, but studies in children exposed to both Se and MeHg through prenatal fish consumption have been inconclusive. Research on Se's implications for pregnancy and child neurodevelopment is limited. The aims of this review are to summarize the literature on the biological roles of Se during pregnancy and the potential role in mitigating the effects of MeHg exposure from fish consumption on human health. This review has shown that Se concentrations among pregnant women globally appear insufficient, with the majority of pregnant women reporting Se concentrations below 70 µg/L during pregnancy. The role of Se in child development and its interactions with MeHg in children are inconclusive. Further investigation of the interaction between Se and MeHg in relation to child neurodevelopment in high fish-eating populations is required to fully elucidate effects.

Determination of Hg and Se in swordfish (Xiphias gladius) from Mediterranean Sea: Implications for nutritional recommendations during pregnancy and childhood

Swordfish (Xiphias gladius) are important marine predators facing potential mercury (Hg) contamination. This study analyzed Hg levels in swordfish muscle tissue from two Mediterranean Sea stocks. Italian specimens showed significantly higher Hg concentrations (1.4 ± 0.8 mg kg-1 ww) than Spanish ones (0.8 ± 0.5 mg kg-1 ww), with many samples exceeding EU's safety limit (1 mg kg-1 ww). Selenium (Se) content and Se:Hg ratios were examined, along with the maximum safe fish meals per month for vulnerable consumers. These results highlight the urgent need for monitoring and mitigation strategies to reduce health risks, especially for susceptible populations.

Synchrotron X-ray methods in the study of mercury neurotoxicology

In situ methods are valuable in all fields of research. In toxicology, the importance of dose is well known, elevating the need for in situ techniques to measure levels of toxicants and their byproducts in precise anatomically identifiable locations. More recently, additional emphasis has been placed on the value of techniques which can detect chemical form or speciation, which is equally important in the toxicology of a chemical compound. Many important but conventional methods risk losing valuable information due to extractions, digestions, or the general reliance on mobile phases. Few analytical tools possess the power and diversity of X-ray methods as in-situ methods. Here we present an overview, intended for toxicologists and pathologists, of a variety of synchrotron X-ray methods for determining in situ chemical form and distribution of heavier elements. The versatility and range of these synchrotron techniques, which are both established and emerging, is demonstrated in the context of the study of neurotoxicology of mercury, a global pollutant with the ability to harm both human health and the environment.

Selenium-rich food potentially useful to control mercury levels among Afro-Colombians: Towards an intercultural intervention

INTRODUCTION

Diet-based interventions may be a culturally acceptable option to decrease mercury levels and thus prevent the adverse effects of this metal on population health. Selenium is an element present in Colombian geology that can act as a chelator, decreasing mercury concentrations in the human body.

OBJECTIVE

To identify potentially useful selenium-rich foods to control the effects of mercury exposure among Afro-Colombians.

MATERIALS AND METHODS

A cross-sectional study was carried out with 320 individuals from five municipalities of Chocó. They were asked about the frequency of consumption of selenium-rich foods, and their association with mercury concentrations in hair was estimated with multiple robust regression.

RESULTS

Guava, whole wheat flour, strawberries, cow liver, spinach and yeast extract were the foods with higher consumption. Walnuts, whole wheat flour, and yeast extract were identified in multiple robust regression as foods to consider in future interventions.

CONCLUSION

It is proposed that the banana juice, the pineapple colada, the borojó (Borojoa patinoi) sorbet, the cucas, and the enyucado are basic elements for a culturally acceptable intervention.

Relationship of mercury and selenium in ocean fish frequently consumed in the Seychelles: A comparison to levels in ocean fish consumed in the US

We characterized mercury and selenium in the fish consumed in the Seychelles Islands to determine if their levels are similar to fish consumed in the US. A secondary aim was to examine whether fish weight and species predict mercury and selenium in fish consumed in the Seychelles. We measured total mercury (THg) and selenium (Se) content of 10 samples from each of the 19 most frequently consumed fish species in Seychelles and for each calculated the Se:Hg molar ratios and the Selenium Health Benefit Value Index (HBV Se). Linear regression models examined associations with weight and species. Average MeHg levels in fish ranged from less than 0.01 ppm (streamlined spinefoot) to 0.7 ppm (bludger trevally) with an overall mean of 0.21 ± 0.23 ppm. Average Se levels ranged from 0.34 ppm (blue-barred parrot fish) to 0.93 ppm (blue-lined large-eye bream) with a mean of 0.54 ± 0.23 ppm. All fish species had a mean Se:Hg molar ratio > 1 and positive mean HBV Se index values. Weight was strongly predictive of MeHg and Se:Hg molar ratio, both across and within most species, but was less predictive of Se and HBV Se. Our study demonstrated that fish consumed in Seychelles have mercury and selenium content similar to that of fish consumed in the US. Fish in both countries have favorable positive values for Se:Hg molar ratios and HBV Se indexes. Because mercury and selenium concentrations in fish are similar to those in the US but fish consumption is substantially higher in Seychelles, the Seychellois make an ideal population in which to determine if there are adverse effects of prenatal, postnatal, and lifetime low dose MeHg exposure from fish consumption.

Geographic differences in exposures to metals and essential elements in pregnant women living in Suriname

BACKGROUND

In Suriname, 20% of pregnancies end in adverse birth outcomes. While prenatal exposure to metals may lead to adverse health outcomes, exposure assessments in Suriname are scant. Environmental contamination from mercury (Hg) used in artisanal goldmining in the Amazonian Interior, and the uncontrolled use of pesticides in suburban regions are of particular concern.

OBJECTIVE

This study assessed geographic differences in exposures to metals and essential elements in pregnant Surinamese women.

METHODS

This study is a subset (n = 400) of the Caribbean Consortium for Research in Environmental and Occupational Health (CCREOH) cohort study. Sector-field inductively-coupled plasma mass spectrometry was used to determine concentrations of lead (Pb), Hg, selenium (Se), cadmium (Cd), manganese (Mn) and tin (Sn) in whole blood of the pregnant women. High vs. low exposures to Pb and Hg were determined and were based respectively on CDC (3.5 ug/dL) and USEPA (3.5 ug/L) action levels. Differences in geographic exposures were tested with the Mann-Whitney U-test, and differences between blood elemental concentrations and action levels for Pb and Hg with the Wilcoxon signed rank test. The association between demographics and high exposures of Pb and Hg was examined with multivariate logistic regression models.

RESULTS

The median concentrations of Pb, Hg and Se (5.08 μg/dL, 7.87 μg/L, and 228.26 μg/L respectively) in Interior women, were higher than the Urban and Suburban regions (p < 0.001), and higher than internationally accepted action levels (p < 0.001). The median concentrations of Mn and Sn found in Suburban women (17.55 and 0.97 ug/L respectively) were higher than Urban and Interior regions (p < 0.02).

SIGNIFICANCE

Pregnant women living in Suriname's Amazonian Interior are exposed to Hg and Pb at levels of public health concern. Urgently needed is a comprehensive source characterization assessment and the development, implementation and monitoring of environmental health policies, specifically addressing the chemicals of concern.

IMPACT

In a subset of participants enrolled in the CCREOH environmental epidemiology cohort study elevated levels of Hg and Pb were identified. This is the first comprehensive exposure assessment in the Surinamese population. Health concerns include adverse birth- and neurodevelopmental outcomes. Geographic differences require a tailored approach to health intervention and comprehensive source characterization. Future research should ascertain the role of Se as a potential protective factor. Environmental policy development, implementation and monitoring is pivotal to mitigate exposures to these neurotoxicants.

Metal and metalloid bioaccumulation in dried red seaweed Hypnea musciformis and health risk assessment for consumers

This study measured 22 metal and metalloid concentrations in Hypnea musciformis from the Bakkhali River estuary and Saint Martin's Island, Bangladesh and determined their potential impact on consumption. Student t-tests showed a significant variation in metal concentrations between the two sampling sites (p < 0.05). Mean concentrations of Co (2.49 ± 0.05 mg/kg), Fe (793.29 ± 11.76 mg/kg), Mn (368.72 ± 4.87 mg/kg), Pb (3.82 ± 0.02 mg/kg), V (11.23 ± 0.20 mg/kg) and Zn (16.60 ± 0.28 mg/kg) were higher in samples collected from the Bakkhali River estuary compared to Saint Martin's Island, while mean concentrations of Ca (484.18 ± 4.68 mg/kg), Cd (2.44 ± 0.03 mg/kg), Mg (2112.70 ± 17.80 mg/kg), Mo (1.57 ± 0.06 mg/kg), Sr (2377.57 ± 29.98 mg/kg), and Ti (258.27 ± 4.62 mg/kg) were higher in samples collected from Saint Martin's Island. Eight heavy metals (Pb, Cd, Zn, Cu, Ni, Mn, Cr, Fe) were used to assess potential health risks for adults, but no potential health risk was detected (HQ value>1). This study reveals positive Se-HBV for H. musciformis collected from both sampling sites, indicating no potential risks involved with Hg toxicity.

Mercury and selenium in oysters Saccostrea palmula and Crassostrea corteziensis from coastal lagoons of the southeastern Gulf of California: molar ratio and risk assessment on human health

Total mercury (Hg) and selenium (Se) contents were determined in oysters Saccostrea palmula and Crassostrea corteziensis soft tissues from four coastal lagoons of the southeastern Gulf of California. The annual Hg mean concentrations for S. palmula (0.09 ± 0.04 µg g- 1, wet weight) and C. corteziensis (0.08 ± 0.04 µg g- 1) were similar (p ˃ 0.05) among the lagoons and did not exceed the limit established by the Norma Oficial Mexicana and World Health Organization (< 1.0 µg g- 1 Hg). On the other hand, the annual mean concentrations of Se for S. palmula (3.34 ± 0.96 µg g- 1) and C. corteziensis (2.79 ± 0.89 µg g- 1) were higher (p < 0.05) in El Colorado lagoon. The Se/Hg molar ratios were above 1; the positive selenium health benefit value index suggested that Se load in oysters could reduce the Hg potential toxic effect. The hazard quotient for Hg in both species was below 1. Therefore, the consumption of oysters does not represent a risk due to Hg ingestion.

Relationship between trace element concentrations and body length in dolphinfish (Coryphaena hippurus) in the northwest Atlantic Ocean

Dolphinfish (Coryphaena hippurus) is a popular seafood choice worldwide, however, except for mercury (Hg) and selenium (Se), little is known about the concentration of other trace elements in dolphinfish muscle tissue, especially in the northwest Atlantic Ocean. This study investigated the relationship between body length (61 to 94 cm fork length) and trace element [silver (Ag), arsenic (As), cadmium (Cd), chromium (Cr), cobalt (Co), copper (Cu), iron (Fe), Hg, manganese (Mn), nickel (Ni), lead (Pb), Se, and zinc (Zn)] concentrations in muscle tissue of dolphinfish caught off Long Island, New York (n = 16). There was a positive relationship with body length for As and Hg, a negative relationship with body length for Cu and Zn, and no relationship with body length for Cd, Fe, Mn, Pb, and Se. A negative relationship between the Se:Hg molar ratio and body length and Se:Hg molar ratio and Hg concentration was observed. Dolphinfish were low in Hg with only 18.9% (n = 3) of individuals exceeding the U.S. EPA human health criterion of 0.3 µg/g wet weight, making this species a suitable seafood choice to reduce dietary intake of Hg at the investigated body length. All fish had a Se:Hg molar ratio > 1:1 indicating that Se may have a protective effect against Hg toxicity. The selenium health benefit value (HBVSe) for all individuals was > 1, indicating there may be health benefits from consuming dolphinfish.

High accumulation of metals and metalloids in the liver of the blue tilapia (Oreochromis aureus) during a massive mortality event induced by a mine tailing spill

In this study, the concentration of six metal(loid)s was examined in the fish Oreochromis aureus collected from El Comedero dam during a massive mortality event induced by a mine tailing spill. A major spill (~ 300,000 m³) of waste was released into the San Lorenzo River System following a rupture in the tailing dam of a mining plant in NW Mexico; consequently, the discharged material flowed into El Comedero dam. The accumulation of metal(oid)s in the tissues of O. aureus showed higher levels in the liver than in the guts and muscle. Concentrations in the liver were high (As, 1.1-1063; Cd, 8.9-392; Cu, 372-59,129; Hg, 0.46-19.79; Se, 8.7-748; and Zn, 116-820 μg g^-1), revealing that these fish were exposed to high concentrations of these elements. The mortality of fish could have resulted from the combined effect of the six analyzed metal(loid)s, as well as other residues present in mine tailings.

Fate of selenium in a Se-enriched region of North China: Translocation, bioaccumulation, source, and health benefits

There are limited studies on the translocation and bioaccumulation of selenium (Se) in weak alkaline cultivated Se-enriched soil, and the sources and speciation of Se in wheat grains remain unclear. In this study, we measured the Se levels in soils, roots, stems, and wheat grains from Se-enriched cultivated land in Ci County, China, which has a high incidence of esophageal cancer. The Se levels in the roots were higher than those in the soils, indicating that wheat plants bioaccumulated high concentrations of Se from the soil (enrichment coefficient [EC] range from the soil to the root: 0.94-3.29). Redundancy analysis indicated that the bioaccumulated factor, translocation coefficient, and EC were mainly controlled by phosphorus, pH, and Fe₂O₃ (contribution rates: 37.5%, 19.5%, and 15.9%, respectively). Linear regression analysis revealed that the sources of Se in grains were mainly from the water-soluble fraction (R² = 0.55, at p < 0.05), the weakly acidic fraction (R² = 0.84, at p < 0.05), the reducible fraction (R² = 0.84, at p < 0.05), and the oxidizable fraction (R² = 0.70, at p < 0.05), as well as from atmospheric deposition (R² = 0.37, at p < 0.01). There is a significant correlation between the Se from atmospheric deposition and the oxidizable fraction (R² = 0.62, at p < 0.01) and the residual fraction (R² = 0.33, at p < 0.01). The contribution of Se input flux from atmospheric deposition was 5.50 g/hm² for one year. Furthermore, the average content of organic Se in wheat grains was 58.93%. The Se concentrations found in wheat grains were considered beneficial for human health based on a comparison with the Chinese Society of Nutrition standard and worldwide levels. The results of this study will increase the overall knowledge on the theme, which could help prevent and control the harmful effects of undesirable concentrations of Se on human health.

Total mercury, methylmercury, and selenium concentrations in blue marlin Makaira nigricans from a long-term dataset in the western north Atlantic

Mercury in seafood is a neurotoxicant that threatens human health. Dynamic rates of mercury emission, re-emission, and atmospheric deposition warrant studies into mercury concentrations in fish because many are consumed by humans and can serve as sentinels of mercury levels in the environment. We modeled trends in total mercury content in an apex marine fish predator, Atlantic blue marlin Makaira nigricans, whose muscle tissues were opportunistically sampled from North Carolina (USA) sportfishing tournaments over a discontinuous time period: between 1975 and 77 and 1998-2021 (n = 148). The model-estimated influence of marlin weight on total mercury concentration was constant across years (shared slope) allowing for comparisons of weight-corrected mercury concentrations among years. Weight-corrected total mercury concentrations revealed an inter-decadal decline of approximately 45 % between the 1970s and late 1990s and then variable but relatively stable concentrations through 2021. The mean (SD) wet weight concentration of total mercury was 9.47 (4.11) from 1975 to 77 and 4.17 (2.61) from 2020 to 2021. Methylmercury and selenium were measured on a subset of fish to address questions related to human health and consumption. Methylmercury levels (mean = 0.72 μg/g) were much lower than total mercury (mean = 4.69 μg/g) indicating that total mercury is not a good proxy for methylmercury in Atlantic blue marlin. Selenium, examined as a Se:Hg molar ratio and as a selenium health benefit value (HBV_Se), showed high protective value against mercury toxicity. Long-term trends in the concentration of mercury in blue marlin should continue to be monitored to determine whether policies to mitigate anthropogenic contributions to global mercury are achieving their intended goals and to provide information to inform safe human consumption.

Total Mercury and Selenium in wild Shrimp from Coastal Lagoons of Northwest Mexico: Human Health risk Assessment

This study analyzed total mercury (THg), and selenium (Se) in edible tissues of white shrimp (Litopenaeus vannamei), blue shrimp (L. stylirostris) and brown shrimp (F. californiensis), from three states of the Northwest of Mexico in September and October 2017. Concentrations of THg and Se in the muscle were between 0.026 and 0.829 and 0.126-1.741 µg/g dry weight (dw), respectively. Significant differences were observed among Hg concentration of Sonora and Nayarit and among Se concentration of Sinaloa and Nayarit. In addition, the health risk assessment (HQ) in the three species of shrimp was between 0.550 and 0.607. All Se:Hg molar ratios were > 1 and positive HBV_Se values that showed that shrimp from Northwest of Mexico does not represent a risk to human health.

Element concentrations of cultured fish in the Black Sea: selenium-mercury balance and the risk assessments for consumer health

Fish are a powerful model for risk-benefit analyses to explore the impact of elements on human health among all accessible species. The sea bream (Sparus aurata), sea bass (Dicentrarchus labrax), turbot (Scophthalmus maximus), and weights of > 1 kg large rainbow trout registered as "Turkish Salmon," (Oncorhynchus mykiss) are four economically important cultured species in the Black Sea In this research, it is aimed (1) to determine the value of the elements, (2) to determine total Hg and Se concentrations, Se/Hg molar ratios, and the HBVSe index, and (3) to calculate the consumer's possible health risk in the edible tissues of cultivated four economically important Black Sea fish species. Fish and diet samples from all species were obtained in 2020 from aquaculture locations in the Black Sea (Sinop, Samsun, and Trabzon cites of Turkey). At the end of the study, the elements in all edible tissues and all the parameters analyzed [Se/Hg, estimated daily intake (EDI), target hazard quotient (THQ), maximum allowable consumption rate (CR_lim and CR_mm)] in cultured fish tissues were below permissible values. Additionally, when compared with the data of the World Health Organization and The National Academy of Sciences, it determined that consuming cultured fish in the Black Sea adequately meets the daily elemental requirement.

Metals in Ten Commercial Demersal Fish from the East China Sea: Contribution to Aquatic Products Nutrition and Toxic Risk Assessment

Metal accumulation in the marine environment can increase the metal content of fish living in it. For this reason, it is essential to evaluate the nutrition from fish consumption and assess metal toxicity risk. Ten species of demersal fish, which are part of the daily diet of coastal residents, were sampled using trammel net in the East China Sea. Levels of the microelements, the constant elements, and the toxic elements of muscle tissue were analyzed. Spiny red gurnard had the highest concentrations of calcium, copper, and iron, whereas pufferfish and threadfin porgy were good sources of zinc and magnesium. The levels of lead, cadmium, and inorganic arsenic in all samples were below the limit values according to Chinese national standards. Although some concerns were raised about the concentration of mercury (Hg) in threadfin porgy, silver croaker, and fivespot flounder, molar ratios (selenium, Se:Hg) and the Se health benefit values (HBV_Se) indicated that they were safe for human consumption. Additionally, the estimated weekly intake and % weekly contribution of 10 fish species with different elements were provided, giving a reference for the people's healthy consumption.

Quantitative risk-benefit assessment of Portuguese fish and other seafood species consumption scenarios

Portugal has high fish/seafood consumption, which may have both risks and benefits. This study aims to quantify the net health impact of hypothetical scenarios of fish/seafood consumption in the Portuguese population using a risk-benefit assessment methodology. Consumption data from the National Food, Nutrition and Physical Activity Survey 2015-2016 (n 5811) were used to estimate the mean exposure to methylmercury and EPA + DHA in the current and the alternative scenarios considered. Alternative scenarios (alt) were modelled using probabilistic approaches to reflect substitutions from the current consumption in the type of fish/seafood (alt1: excluding predatory fishes; alt2: including only methylmercury low-level fishes) or in the frequency of weekly fish/seafood consumption (alt3 to alt6: 1, 3, 5 or 7 times a week, replacing fish/seafood meals with meat or others). The overall health impact of these scenarios was quantified using disability-adjusted life years (DALY). In the Portuguese population, about 11 450 DALY could be prevented each year if the fish/seafood consumption increased to a daily basis. However, such a scenario would result in 1398 extra DALY considering the consumption by pregnant women and the respective risk on fetal neurodevelopment. Our findings support a recommendation to increase fish/seafood consumption up to 7 times/week. However, for pregnant women and children, special considerations must be proposed to avoid potential risks on fetal neurodevelopment due to methylmercury exposure.

Determination of heavy metals from Aloe vera by- product in golden mullet (Liza aurata); A consumer health risk assessment

Heavy metals have become subject of concern in the recent years because of its potency to cause cardiovascular diseases and other toxic health effects. Therefore, this research was assumed to investigate the level of toxicity in terms of heavy metals accumulation in the fish samples and its benefits and risk for human consumers health and also evaluate the partial replacement of plant sources by canarian Aloe vera diets as a pure product or like a by-product on toxicological effects on the golden mullet (Liza aurata) fillet and whole body. In this study risks arising from fish metal content has been measured using various parameters as Estimated Daily Intake (EDI), Maximum Safe Consumption (MSC_A), Target Hazard quotient (THQ), Hazard Index (HI) Carcinogenic risk of As (As- CR), the Value Selenium Health Benefit (Se HBV) and also the Nutritional Values has been evaluated. The results showed that all heavy metal levels in the fish tissue and diets were below the confirmed safe limits for consumption. In case of diets, it is obvious that with the exception of As, Hg, and Se, the presence of heavy or essential metals in both whole fish and raw fillet in golden grey mullet given experimental diets revealed that the whole fish had the highest concentration. Thus, it can be concluded that Aloe vera product and byproduct were in safety limits for fish and also for humans through food chain. Various risk and benefit assessment measures established by national and international authorities concluded that Liza aurata use was mostly safe.

Trace element bioaccumulation in edible red seaweeds (Rhodophyta): A risk assessment for consumers

As a precursor to risk assessment and risk management through consuming contaminated seafood, food safety needs to be quantified and assured. Seaweed is an increasing dietary component, especially in developing countries, but there are few studies assessing uptake rates of contaminants from this route. As such, the present study determined likely human uptake due to the trace elemental (Fe, Mn, Ni, Cu, Zn, Se, Hg, and As) concentrations in the edible red seaweeds (Rhodophyta) Gelidium pusillum and Hypnea musciformis, growing in the industrialised Cox's Bazar coastal area of Bangladesh. Metal and metalloid concentrations in G. pusillum were in the order (mg/kg): Fe (797 ± 67) > Mn (69 ± 4) > Ni (12 ± 5) > Zn (9 ± 4) > Cu (9 ± 4) >Se (0.1 ± 0.1) > Hg (0.1 ± 0.01), and in H. musciformis: Fe (668 ± 58) > Mn (28 ± 5) > Ni (14 ± 2) > Zn (11 ± 5) > Cu (6 ± 4) >Se (0.2 ± 0.03) > Hg (0.04 ± 0.01). Despite the industrial activities in the area, and based on 10 g. day-1 seaweed consumption, it is concluded that these concentrations pose no risk to human health as part of a normal diet according to the targeted hazard quotient and hazard index (THQ and HI) (values < 1). In addition, and as a novel aspect for seaweeds, Selenium Health Benefit Values (Se-HBV) were determined and found to have positive values. Seaweed can be used as an absorber of inorganic metals for removing contamination in coastal waters. The results are a precursor to further research regarding the efficiency and rate at which seaweeds can sequester metal contamination in water. In addition, management techniques need to be developed thereby to control the contaminant inputs.

The role of tropical small-scale fisheries in trace element delivery for a Small Island Developing State community, the Seychelles

The concentrations of 13 trace elements were determined in 1032 muscles of 54 small-scale fisheries species collected from the Seychelles waters between 2013 and 2019. Overall, profiles were dominated by zinc (Zn) > arsenic (As) > iron (Fe) > copper (Cu) > selenium (Se), with the spiny lobsters, spanner crab and octopus exhibiting the highest levels of As, Cu and Zn while fish had higher Fe concentrations. Both taxonomy-dependent processes and ecological factors explained the interspecific differences of trace element profiles observed. A benefit-risk assessment revealed that crustaceans and cephalopods were good sources of Cu and Zn. One portion of any fish could provide 30-100 % of daily Se needs, and one portion of demersal and pelagic teleost fish could bring 5-20 % of Cu, Fe and Zn needs, especially for young adult and adult women. Finally, our analysis showed that there was very low health risks associated with small-scale fisheries consumption for the Seychelles population.

Mercury and selenium bioaccumulation in wild commercial fish in the coastal East China Sea: Selenium benefits versus mercury risks

This study investigated the contents of total mercury (THg), methylmercury (MeHg) and selenium (Se) in 22 fish species and 10 invertebrate species from the coastal East China Sea. The THg and MeHg contents were significantly higher in benthic fishes. Both Hg and Se biomagnified in the food webs, with evidences of associations during trophic transfer. In addition, Se:Hg molar ratio and Se health benefit value (HBV_Se) were used as novel criteria for Hg exposure risk assessments, showing that Se presented in molar excess of Hg in all samples, which would negate the risks of Hg toxicity. HBV_Se provided more informative results than Se:Hg molar ratio, pointing to possibly lower health risks for some fishes containing high levels of Hg and Se. Although the HBV_Se results challenge the traditional Hg health risk assessment, its future application still requires worldwide comprehensive investigations.

Risk and Benefit Analysis of Fish Consumption in NW Mexico: Mercury, Selenium, and Fatty Acids

To balance the risks and benefits of fish consumption, selenium, fatty acids (DHA + EPA), and mercury in fishery products were determined. Analyzed products were canned tuna, frozen tuna (Thunnus albacares), smoked striped marlin (Tetrapturus audax), fresh Pacific sierra (Scomberomorus sierra), fresh dolphinfish (Coryphaena hippurus), fresh tilapia (Gerres cinereus), and fresh bullseye puffer (Sphoeroides annulatus). Mercury (μg g^-1 wet weight) ranged from 0.01 (dolphinfish) to 0.23 (bullseye puffer); Se ranged from 0.12 to 0.25. EPA + DHA ranged from 1.16 to 10.72 mg g^-1. Intake of EPA + DHA was comparable or above the recommended daily intake; Hg intake was below the reference dose but Se intake was below than recommended values for the different population groups. Considering the HBV_Se, fishery products had positive values; i.e., they are healthy food items. According to the interaction of Hg and Se and the rate of fishery product consumption, the risk for consumers is below one percent.

Molecular Fates of Organometallic Mercury in Human Brain

Mercury is ubiquitous in the environment, with rising levels due to pollution and climate change being a current global concern. Many mercury compounds are notorious for their toxicity, with the potential of organometallic mercury compounds for devastating effects on the structures and functions of the central nervous system being of particular concern. Chronic exposure of human populations to low levels of methylmercury compounds occurs through consumption of fish and other seafood, although the health consequences, if any, from this exposure remain controversial. We have used high energy resolution fluorescence detected X-ray absorption spectroscopy to determine the speciation of mercury and selenium in human brain tissue. We show that the molecular fate of mercury differs dramatically between individuals who suffered acute organometallic mercury exposure (poisoning) and individuals with chronic low-level exposure from a diet rich in marine fish. For long-term low-level methylmercury exposure from fish consumption, mercury speciation in brain tissue shows methylmercury coordinated to an aliphatic thiolate, resembling the coordination environment observed in marine fish. In marked contrast, for short-term high-level exposure, we observe the presence of biologically less available mercuric selenide deposits, confirmed by X-ray fluorescence imaging, as well as mercury(II)-bis-thiolate complexes, which may be signatures of severe poisoning in humans. These differences between low-level and high-level exposures challenge the relevance of studies involving acute exposure as a proxy for low-level chronic exposure.

Antioxidant Activities and Selenogene Transcription in the European Sea Bass (Dicentrarchus labrax) Liver Depend, in a Non-linear Manner, on the Se/Hg Molar Ratio of the Feeds

Feeding 3.9 and 6.7 mg Hg/kg (Se/Hg molar ratios of 0.8 and 0.4, respectively) for 14 days negatively affected Dicentrarchus labrax growth and total DNTB- and thioredoxin-reductase (TrxR) activities and the transcription of four redox genes (txn1, gpx1, txnrd3, and txnrd2) in the liver, but a diet with 0.5 mg Hg/kg (Se/Hg molar ratio 6.6) slightly increased both reductase activities and the transcription of txn1, gpx1, and txnrd2. Feeding 6.7 mg Hg/kg for 53 days downregulated the genes of the thioredoxin system (txn1, txnrd3, and txnrd2) but upregulated gpx1, confirming the previously proposed complementarity among the antioxidant systems. Substitution of 20% of the feed by thawed white fish (hake) slightly counteracted the negative effects of Hg. The effects were not statistically significant and were dependent, in a non-linear manner, on the Se/Hg molar ratio of the feed but not on its Hg concentration. These results stress the need to consider the Se/Hg molar ratio of the feed/food when evaluating the toxicity of Hg.

Health Hazard Assessment Due to Slimming Medicinal Plant Intake

According to the World Health Organization (WHO), about 80% of people rely on medicinal plants for their primary health needs. Traditional medicine's principal benefits are their vast population knowledge, low severe adverse effects rate, low cost, and the lack of a medical prescription to use them. While obesity has become a global health issue, an increase in finding cheap and fast ways to lose weight escalates medicinal herbs' use for this purpose, both in dietary supplements or in teas. At the same time that Brazil aims to expand traditional medicine, reports regarding toxicology and poisoning put natural products' safety in check. Plants can accumulate heavy metals and metalloids leading to health risks; however, there is a lack of information on that matter, possibly due to a lack of international standardization regarding elemental contamination - this study aimed to determine metal and metalloid concentrations in slimming medicinal plants and their respective teas and evaluate their safety consumption. Metal and metalloid content were determined by inductively coupled plasma optical emission spectrometry (ICP OES). All plants and teas were within the set limits for tolerable upper intake level (UL), provisional tolerable daily maximum intake (PTDMI), and provisional tolerable weekly intake (PTWI). The hazard quotient index (HQ) was above 1 for almost all plants, and the Hibiscus sabdariffa tea regarding aluminum content. The arsenic level was above the Brazilian Pharmacopeia limit in natura plants demonstrating risk in their consumption. Some herbs also presented detection for elements with no safety limits set, such as lead, cadmium, and arsenic, which could mark as a red flag for consumption once their security intake is not precise yet.