Global methylmercury exposure from seafood consumption and risk of developmental neurotoxicity: a systematic review

Mercury, natural fertility and outcomes of assisted reproduction: A systematic review

The primary route of mercury exposure for the general population is through consumption of contaminated seafood. There is a biological basis for an adverse effect of mercury exposure on human fertility. The goal of this review was to evaluate the existing literature on the association between mercury and pregnancy, among men and women attempting to conceive with and without assisted reproductive technology (ART). Systematic searches were performed in PubMed, EMBASE, Scopus and Web of Science for papers published up to March 2023 with no early date restriction, only including studies with a biomarker measurement of mercury exposure. We identified 11 studies examining mercury and natural fertility and 12 studies examining mercury and outcomes of assisted reproduction (implantation or clinical pregnancy). The accumulated evidence provides some support for a null association between bodily mercury concentrations and natural fertility among women, however, a large proportion of studies did not report adjusted estimates or were extremely imprecise. The majority of studies of natural fertility were also cross-sectional in nature. There was no evidence for an inverse or null association between mercury and natural fertility among men, or mercury and ART outcomes among men or women. In spite of biological plausibility, the existing evidence includes studies that are imprecise and often conflicting and does not allow us to make definitive conclusions on the associations of mercury exposure with successful pregnancy. Additional, larger studies are warranted, especially among individuals with high concentrations of mercury exposure as these individuals may be underrepresented in the current literature.

Hair Mercury Levels in Pregnant Women: Fish Consumption as a Determinant of Exposure

The consumption of fish in food may contain mercury, a harmful element and dangerous chemical detrimental to human health. The purpose of this study was to determine the mercury level in the hair of pregnant women with different fish intakes in their diets. The concentration of total mercury in hair was determined using an atomic absorption spectrometer. In this study, 98 pregnant women were invited to participate (aged from 18 to 48 years). The mean content of mercury in the hair of pregnant women in Northwestern Russia was 0.428 mg/kg (ranging from 0.018 to 3.1 mg/kg). As a result, 22% of women had mercury values above 0.58 mg/kg, which is considered dangerous for the fetus. The hair mercury concentration in a village area was higher than that in a city area (i.e., 0.548 mg/kg and 0.326 mg/kg). Moreover, the maximum level of mercury was noted for a group of pregnant women who consumed more than 5 kg/month of fish and fish products. Furthermore, the consumption of freshwater fish in the diet leads to a higher mercury content in the hair of pregnant women than the consumption of marine fish.

Early exposure to mercury and cardiovascular function of seven-year old children in Guadeloupe (French West Indies)

BACKGROUND

The cardiotoxicity of prenatal exposure to mercury has been suggested in populations having regular contaminated seafood intake, though replications in the literature are inconsistent.

METHODS

The Timoun Mother-Child Cohort Study was set up in Guadeloupe, an island in the Caribbean Sea where seafood consumption is regular. At seven years of age, 592 children underwent a medical examination, including cardiac function assessment. Blood pressure (BP) was taken using an automated blood pressure monitor, heart rate variability (HRV, 9 parameters) and electrocardiogram (ECG) characteristics (QT, T-wave parameters) were measured using Holter cardiac monitoring during the examination. Total mercury concentrations were measured in cord blood at birth (median = 6.6 μg/L, N = 399) and in the children's blood at age 7 (median = 1.7 μg/L, N = 310). Adjusted linear and non-linear modelling was used to study the association of each cardiac parameter with prenatal and childhood exposures. Sensitivity analyses included co-exposures to lead and cadmium, adjustment for maternal seafood consumption, selenium and polyunsaturated fatty acids (n3-PUFAs), and for sporting activity.

RESULTS

Higher prenatal mercury was associated with higher systolic BP at 7 years of age (βlog2 = 1.02; 95% Confidence Interval (CI) = 0.10, 1.19). In boys, intermediate prenatal exposure was associated with reduced overall HRV and parasympathetic activity, and longer QT was observed with increasing prenatal mercury (βlog2 = 4.02; CI = 0.48, 7.56). In girls, HRV tended to increase linearly with prenatal exposure, and no association was observed with QT-wave related parameters. Mercury exposure at 7 years was associated with decreased BP in girls (βlog2 = -1.13; CI = -2.22, -0.004 for diastolic BP). In boys, the low/high-frequency (LF/HF) ratio increased for intermediate levels of exposure.

CONCLUSION

Our study suggests sex-specific and non-monotonic modifications in some cardiac health parameters following prenatal exposure to mercury in pre-pubertal children from an insular fish-consuming population.

Deforestation as an Anthropogenic Driver of Mercury Pollution

Deforestation reduces the capacity of the terrestrial biosphere to take up toxic pollutant mercury (Hg) and enhances the release of secondary Hg from soils. The consequences of deforestation for Hg cycling are not currently considered by anthropogenic emission inventories or specifically addressed under the global Minamata Convention on Mercury. Using global Hg modeling constrained by field observations, we estimate that net Hg fluxes to the atmosphere due to deforestation are 217 Mg year-1 (95% confidence interval (CI): 134-1650 Mg year-1) for 2015, approximately 10% of global primary anthropogenic emissions. If deforestation of the Amazon rainforest continues at business-as-usual rates, net Hg emissions from the region will increase by 153 Mg year-1 by 2050 (CI: 97-418 Mg year-1), enhancing the transport and subsequent deposition of Hg to aquatic ecosystems. Substantial Hg emissions reductions are found for two potential cases of land use policies: conservation of the Amazon rainforest (92 Mg year-1, 95% CI: 59-234 Mg year-1) and global reforestation (98 Mg year-1, 95% CI: 64-449 Mg year-1). We conclude that deforestation-related emissions should be incorporated as an anthropogenic source in Hg inventories and that land use policy could be leveraged to address global Hg pollution.

Risk assessment of some toxic metals in canned fish products retailed in Mansoura, Egypt

Background

Canned fish products are widely consumed in Egypt, particularly for protein-rich meals that are quick to prepare and low in calories. Canned fish products are contaminated with toxic metals from the fish itself or from canning materials during processing.

Aim

To determine the residual levels of cadmium (Cd), lead (Pb), arsenic (As), mercury (Hg), aluminum (Al), and Tin (Sn) in some canned fish products obtained from retail shops in Mansoura, Egypt. Furthermore, noncarcinogenic health risks evaluation for the Egyptian population due to hazardous metal oral intake.

Methods

One hundred canned fish products (20 each of herring, mackerel, salmon, sardine, and tuna) were collected from May to September 2023, and canned fish products were obtained from Mansoura city markets in Egypt. Samples were digested in a solution composed of 60% nitric acid and 40% perchloric acid, and then an atomic absorption spectrophotometer was used for the detection of selected toxic metals.

Results

It was found that the residual level of hazardous metals exceeded the acceptability level established in the European Union for Pb, Cd, and Hg by 20%, 10%, and 10%, 15%, 5%, and 20%, 35%, 30%, and 45%, 25%, 25%, and 40%, in examined herring, mackerel, sardine, and tuna, respectively. In contrast, all salmon samples were accepted for Pb and Hg, and only 5% were not accepted due to a higher Cd level than the maximum permissible limit. The average estimated daily intake of (EDI) is below the tolerable daily intakes (TDIs) for all metals. Comparatively, the EDI of Hg was 0.265 µg/kg body weight (B.W) exceeded TDIs 0.228 µg/kg B.W. The hazard index for canned tuna and sardines is more than one.

Conclusion

Canned fish products are contaminated with a variety of toxic metals, especially sardine and tuna. Therefore, it is advised to decrease the consumption rate of such fish products.

Increase of blood mercury level with shark meat consumption: A repeated-measures study before and after Chuseok, Korean holiday

Sharks are known to contain high levels of mercury in their meat. However, few studies have directly assessed the changes in mercury concentration in the human body according to shark meat intake. One hundred and ninety-seven participants that traditionally consume shark meat during the Chuseok holiday were recruited from two areas of Gyeongsangbuk-do, South Korea to examine their blood mercury level before and after the holiday season. Blood mercury levels were measured before and after the holiday season. Characteristics such as the consumption of shark meat, intake amount, and the effect on mercury concentration were assessed during the survey. Univariable and multivariable analysis (Linear Mixed Model) were done for assessing the association between shark meat consumption of holiday season and blood mercury level. Among the total participants, 83 consumed shark meat during holiday. In the univariable analysis, a significant increase in blood mercury levels before and after Chuseok was observed only for the group that consumed shark meat during holiday. The multivariable analysis (adjusted for identified confounders that affect both exposure and outcome considering repeated measurements) showed that consuming shark meat was significantly associated with increased blood mercury levels by 3.56 μg/L (95% confidence interval [CI], 2.64-4.67 μg/L). In the model considering the amount consumed as two group, the level of increase was 2.61 μg/L (95% CI, 1.63-3.58 μg/L) for those consuming <100 g, and 6.20 μg/L (95% CI, 4.77-7.62 μg/L) for those consuming ≥100 g compared to group without consuming shark meat. Considering amount consumed as continuous value, 0.02 μg/L (95% CI, 0.01-0.02 μg/L) of blood mercury increase was significantly associated with consuming 1 g. Consumption of shark meat significantly elevated blood mercury levels, exceeding commonly suggested reference concentrations in less than 2 weeks. These findings suggest the need for public health warnings and regulations regarding shark meat consumption.

Assessing comparability and uncertainty of analytical methods for methylated mercury species in seawater

BACKGROUND

The relative distribution and importance of monomethylmercury (MMHg) and dimethylmercury (DMHg) in seawater is still under debate. A lack of comparability between measurements at sub-picomolar levels hampered the further understanding of the biogeochemical Hg cycle. To overcome this, we assessed the relative standard measurement uncertainties (Uex,r) for direct measurements of MMHg and DMHg by species-specific isotope dilution ICP-MS and cryo-focusing GC-ICP-MS at femtomolar concentrations. Furthermore, Uex,r was determined for the indirect determination of DMHg (DMHgcalc = MeHg - MMHg) and MeHg (MeHgcalc = MMHg + DMHg) to compare the two methodologies.

RESULTS

Expanded Uex,r (confidence interval of 95%) for cryo-focusing GC-ICP-MS was 14.4 (<50 fM) and 14.2% (>50 fM) and for SS-ID GC-ICP-MS 5.6 (<50 fM) and 3.7% (>50 fM). For concentrations above 50 fM, Uex,r for DMHgcalc was always lower than for direct measurements (14.2%). For MeHgcalc, on the other hand, Uex,r was always higher for concentrations above 115 fM (range: 3.7-13.9%) than for direct measurements (3.7%). We evaluated the comparability of directly measured and calculated DMHg and MeHg concentrations based on Hg speciation measurements for two vertical profiles in the Mediterranean Sea. We show that directly measured and indirectly determined DMHg and MeHg concentrations yield comparable results.

SIGNIFICANCE

Our results validate the application of the indirect method for the determination of DMHg if a direct measurement method with a low Uex,r such as isotope dilution is used for MMHg and MeHg measurements. The validation of the indirect measurement approach opens new possibilities to generate more precise and accurate DMHg data in the global ocean.

Mercury Sources and Fate in a Large Brackish Ecosystem (the Baltic Sea) Depicted by Stable Isotopes

Identifying Hg sources to aquatic ecosystems and processes controlling the levels of monomethylmercury (MMHg) is critical for developing efficient policies of Hg emissions reduction. Here we measured Hg concentrations and stable isotopes in sediment, seston, and fishes from the various basins of the Baltic Sea, a large brackish ecosystem presenting extensive gradients in salinity, redox conditions, dissolved organic matter (DOM) composition, and biological activities. We found that Hg mass dependent fractionation (Hg-MDF) values in sediments mostly reflect a mixing between light terrestrial Hg and heavier industrial sources, whereas odd Hg isotope mass independent fractionation (odd Hg-MIF) reveals atmospheric inputs. Seston presents intermediate Hg-MDF and odd Hg-MIF values falling between sediments and fish, but in northern basins, high even Hg-MIF values suggest the preferential accumulation of wet-deposited Hg. Odd Hg-MIF values in fish indicate an overall low extent of MMHg photodegradation due to limited sunlight exposure and penetration but also reveal large spatial differences. The photodegradation extent is lowest in the central basin with recurrent algal blooms due to their shading effect and is highest in the northern, least saline basin with high concentrations of terrestrial DOM. As increased loads of terrestrial DOM are expected in many coastal areas due to global changes, its impact on MMHg photodegradation needs to be better understood and accounted for when predicting future MMHg concentrations in aquatic ecosystems.

Fish muscle mercury concentration and bioaccumulation fluctuate year-round - Insights from cyprinid and percid fishes in a humic boreal lake

Boreal lakes demonstrate pronounced seasonality, where the warm open-water season and subsequent cold and ice-covered season dominate natural cycles. While fish muscle total mercury concentration (mg/kg) [THg] is well documented in open-water summer months, there is limited knowledge on the ice-covered winter and spring mercury dynamics in fish from various foraging and thermal guilds. This year-round study tested how seasonality influences [THg] and its bioaccumulation in three percids, perch (Perca fluviatilis), pikeperch (Sander lucioperca), ruffe (Gymnocephalus cernua), and three cyprinids, roach (Rutilus rutilus), bleak (Alburnus alburnus), and bream (Abramis brama) in deep boreal mesotrophic Lake Pääjärvi, southern Finland. Fish were sampled and [THg] was quantified in the dorsal muscle during four seasons in this humic lake. Bioaccumulation regression slopes (mean ± STD, 0.039 ± 0.030, range 0.013-0.114) between [THg] and fish length were steepest during and after spawning and shallowest during autumn and winter for all species. Fish [THg] was significantly higher in the winter-spring than summer-autumn in all percids, however, not in cyprinids. The lowest [THg] was observed in summer and autumn, likely due to recovery from spring spawning, somatic growth and lipid accumulation. Fish [THg] was best described by multiple regression models (R2adj: 52-76%) which included total length and varying combinations of seasonally changing environmental (water temperature, total carbon, total nitrogen, and oxygen saturation) and biotic factors (gonadosomatic index, and sex) in all species. The seasonal variation in [THg] and bioaccumulation slopes across multiple species suggests a need for standardized sampling seasons in long-term monitoring to avoid any seasonality bias. From the fisheries and fish consumption perspective in seasonally ice-covered lakes, monitoring of both winter-spring and summer-autumn would improve knowledge of [THg] variation in fish muscle.

Risk assessment of toxic residues among some freshwater and marine water fish species

Egypt has several beaches, as well as the Nile River and a few lakes; therefore, it could compensate for the lack of protein in red meat with fish. Fish, however, may become a source of heavy metal exposure in humans. The current study was to assess the level of five toxic metals, lead (Pb), cadmium (Cd), mercury (Hg), arsenic (As), and aluminum (Al), in six species, namely, Oreochromis niloticus (O. niloticus), Mugil cephalus (M. cephalus), Lates niloticus (L. niloticus), Plectropomus leopardus (P. leopardus), Epinephelus tauvina (E. tauvina), and Lethrinus nebulosus (L. nebulosus), collected from the El-Obour fish market in Egypt. The residual concentrations of the tested toxic metals in the examined O. niloticus, M. cephalus, L. niloticus, E. tauvina, P. leopardus, and L. nebulosus species were found to be higher than the European Commission's maximum permissible limits (MPL) for Pb and Cd by 10 and 20%, 15 and 65%, 75 and 15%, 20 and 65%, 15 and 40%, and 25 and 5%. In contrast, 30% of L. niloticus exceeded the MPL for Hg. It was shown that the average estimated daily intake (EDI) and the target hazard quotient (THQ) in fish samples are below safety levels for human consumption and hazard index (HI < 1). From the human health point of view, this study showed that there was no possible health risk to people due to the intake of any studied species under the current consumption rate in the country.

Mining-impacted rice paddies select for Archaeal methylators and reveal a putative (Archaeal) regulator of mercury methylation

Methylmercury (MeHg) is a microbially produced neurotoxin derived from inorganic mercury (Hg), which accumulation in rice represents a major health concern to humans. However, the microbial control of MeHg dynamics in the environment remains elusive. Here, leveraging three rice paddy fields with distinct concentrations of Hg (Total Hg (THg): 0.21-513 mg kg-1 dry wt. soil; MeHg: 1.21-6.82 ng g-1 dry wt. soil), we resorted to metagenomics to determine the microbial determinants involved in MeHg production under contrasted contamination settings. We show that Hg methylating Archaea, along with methane-cycling genes, were enriched in severely contaminated paddy soils. Metagenome-resolved Genomes of novel putative Hg methylators belonging to Nitrospinota (UBA7883), with poorly resolved taxonomy despite high completeness, showed evidence of facultative anaerobic metabolism and adaptations to fluctuating redox potential. Furthermore, we found evidence of environmental filtering effects that influenced the phylogenies of not only hgcA genes under different THg concentrations, but also of two housekeeping genes, rpoB and glnA, highlighting the need for further experimental validation of whether THg drives the evolution of hgcAB. Finally, assessment of the genomic environment surrounding hgcAB suggests that this gene pair may be regulated by an archaeal toxin-antitoxin (TA) system, instead of the more frequently found arsR-like genes in bacterial methylators. This suggests the presence of distinct hgcAB regulation systems in bacteria and archaea. Our results support the emerging role of Archaea in MeHg cycling under mining-impacted environments and shed light on the differential control of the expression of genes involved in MeHg formation between Archaea and Bacteria.

Noise, Air, and Heavy Metal Pollution as Risk Factors for Endothelial Dysfunction

During the last two decades, large epidemiological studies have shown that the physical environment, including noise, air pollution or heavy metals, have a considerable impact on human health. It is known that the most common cardiovascular risk factors are all associated with endothelial dysfunction. Vascular tone, circulation of blood cells, inflammation, and platelet activity are some of the most essential functions regulated by the endothelium that suffer negative effects as a consequence of environmental pollution, causing endothelial dysfunction. In this review, we delineate the impact of environmental risk factors in connection to endothelial function. On a mechanistic level, a significant number of studies suggest the involvement of endothelial dysfunction to fundamentally drive the adverse endothelium health effects of the different pollutants. We focus on well-established studies that demonstrate the negative effects on the endothelium, with a focus on air, noise, and heavy metal pollution. This in-depth review on endothelial dysfunction as a consequence of the physical environment aims to contribute to the associated research needs by evaluating current findings from human and animal studies. From a public health perspective, these findings may also help to reinforce efforts promoting the research for adequate promising biomarkers for cardiovascular diseases since endothelial function is considered a hallmark of environmental stressor health effects.

The role and mechanism of unfolded protein response signaling pathway in methylmercury-induced apoptosis of mouse spermatocytes germ cell-2 cells

The study aimed to explore the role and mechanism of unfolded protein response (UPR) in methylmercury (MeHg)-induced Mouse Spermatocytes (GC-2spd[ts]) apoptosis. Methods such as MTT, flow cytometry, and Western Blot were used to evaluate the cell viability, membrane potential (MMP), reactive oxygen species (ROS), calcium ion (Ca²⁺ ), rate of cell apoptosis, and the expression of apoptosis-related and UPR-related protein. The results showed that with the increase of MeHg concentration, cell viability and MMP decreased, ROS, Ca²⁺ , rate of cell apoptosis, and the expression of apoptosis-related protein and UPR-related protein increased. To further explore the effect of ROS-induced oxidative damage on it, the ROS inhibitor N-acetyl-L-cysteine (NAC) was used. The effects of MeHg on germ cell (GC-2) cells were partially inhibited after NAC pretreatment. Our present study proved that MeHg might induce cell apoptosis by activating the UPR signaling pathway in GC-2 cells and affect normal reproductive function.

MRTCM: A comprehensive dataset for probabilistic risk assessment of metals and metalloids in traditional Chinese medicine

Traditional Chinese medicine (TCM) is still considered a global complementary or alternative medical system, but exogenous hazardous contaminants remain in TCM even after decocting. Besides, it is time-consuming to conduct a risk assessment of trace elements in TCMs with a non-automatic approach due to the wide variety of TCMs. Here, we present MRTCM, a cloud-computing infrastructure for automating the probabilistic risk assessment of metals and metalloids in TCM. MRTCM includes a consumption database and a pollutant database involving forty million rows of consumption data and fourteen types of TCM potentially toxic elements concentrations. The algorithm of probabilistic risk assessment was also packaged in MRTCM to assess the risks of eight elements with Monte Carlo simulation. The results demonstrated that 96.64% and 99.46% had no non-carcinogenic risk (hazard indices (HI) were < 1.0) for animal and herbal medicines consumers, respectively. After twenty years of exposure, less than 1% of the total carcinogenic risk (CR_t) was > 10^-4 for TCM consumers, indicating that they are at potential risk for carcinogenicity. Sensitivity analysis revealed that annual consumption and concentration were the main variables affecting the assessment results. Ultimately, a priority management list of TCMs was also generated, indicating that more attention should be paid to the non-carcinogenic risks of As, Mn, and Hg and the carcinogenic risks of As and Cr in Pheretima and Cr in Arcae Conch. In general, MRTCM could significantly enhance the efficiency of risk assessment in TCM and provide reasonable guidance for policymakers to optimize risk management.

Potential Association between Methylmercury Neurotoxicity and Inflammation

Methylmercury (MeHg) is the causal substrate of Minamata disease and a major environmental toxicant. MeHg is widely distributed, mainly in the ocean, meaning its bioaccumulation in seafood is a considerable problem for human health. MeHg has been intensively investigated and is known to induce inflammatory responses and neurodegeneration. However, the relationship between MeHg-induced inflammatory responses and neurodegeneration is not understood. In the present review, we first describe recent findings showing an association between inflammatory responses and certain MeHg-unrelated neurological diseases caused by neurodegeneration. In addition, cell-specific MeHg-induced inflammatory responses are summarized for the central nervous system including those of microglia, astrocytes, and neurons. We also describe MeHg-induced inflammatory responses in peripheral cells and tissue, such as macrophages and blood. These findings provide a concept of the relationship between MeHg-induced inflammatory responses and neurodegeneration, as well as direction for future research of MeHg-induced neurotoxicity.

Elucidations of Molecular Mechanism and Mechanistic Effects of Environmental Toxicants in Neurological Disorders

Due to rising environmental and global public health concerns associated with environmental contamination, human populations are continually being exposed to environmental toxicants, including physical chemical mutagens widespread in our environment causing adverse consequences and inducing a variety of neurological disorders in humans. Physical mutagens comprise ionizing and non-ionizing radiation, such as UV rays, IR rays, X-rays, which produces a broad spectrum of neuronal destruction, including neuroinflammation, genetic instability, enhanced oxidative stress driving mitochondrial damage in the human neuronal antecedent cells, cognitive impairment due to alterations in neuronal function, especially in synaptic plasticity, neurogenesis repression, modifications in mature neuronal networks drives to enhanced neurodegenerative risk. Chemical Mutagens including alkylating agents (EMS, NM, MMS, and NTG), Hydroxylamine, nitrous acid, sodium azide, halouracils are the major toxic mutagen in our environment and have been associated with neurological disorders. These chemical mutagens create dimers of pyrimidine that cause DNA damage that leads to ROS generation producing mutations, chromosomal abnormalities, genotoxicity which leads to increased neurodegenerative risk. The toxicity of four heavy metal including Cd, As, Pb, Hg is mostly responsible for complicated neurological disorders in humans. Cadmium exposure can enhance the permeability of the BBB and penetrate the brain, driving brain intracellular accumulation, cellular dysfunction, and cerebral edema. Arsenic exerts its toxic effect by induction of ROS production in neuronal cells. In this review, we summarize the molecular mechanism and mechanistic effects of mutagens in the environment and their role in multiple neurological disorders.

Association Between Essential and Non-essential Metals, Body Composition, and Metabolic Syndrome in Adults

Growing evidence indicates that metal exposure is associated with metabolic syndrome (MetS); however, mixed results have been reported. The aim of this study was to clarify associations of exposure to essential and non-essential metals with body composition and risks of obesity and MetS. Anthropometry and blood biochemistry of metabolic parameters were obtained from 150 middle-aged Taiwanese adults. Plasma metals were assessed using inductively coupled plasma mass spectrometry, and body compositions were measured by a bioelectrical impedance analysis (BIA). The essential metals of copper (Cu), manganese (Mn), and chromium (Cr) were positively correlated with the body fat mass but inversely correlated with the skeletal muscle mass (all p < 0.05). An adjusted logistic regression showed that Mn [odds ratio (OR) = 1.624 (95% confidence interval 1.072, 2.462), p = 0.02] and, to a lesser extent, Cu [OR = 1.501 (0.985, 2.292), p = 0.059] predicted abdominal obesity, while plasma Cu [OR = 2.211 (1.146, 4.266), p = 0.02] and zinc (Zn) [OR = 2.228 (1.048, 4.736) p = 0.04] predicted MetS. Significant correlations between dyslipidemia and lithium [OR = 1.716 (1.080, 2.726)], Cu [OR = 2.210 (1.415, 3.454)], Mn [OR = 2.200 (1.320, 3.666)], molybdenum [OR = 1.853 (1.160, 2.958)], and Zn [OR = 1.993 (1.186, 3.349)], and between boron [OR = 2.583 (1.137, 5.868)] and hyperglycemia were observed (all p < 0.05). Exposure to essential metals may affect the body composition and metabolic profiles, exacerbating the risk of MetS.

Biochemical Parameters of Female Wistar Rats and Their Offspring Exposed to Inorganic Mercury in Drinking Water during the Gestational and Lactational Periods

The aim of this study was to investigate the effects of inorganic mercury (Hg²⁺) exposure on biochemical parameters of dams and their offspring exposed to metal in drinking water. Female Wistar rats were exposed to 0, 10, and 50 µg Hg²⁺/mL (as HgCl₂) for 42 days corresponding to gestational (21 days) and lactational (21 days) periods. The offspring were sacrificed on postnatal days 10, 20, 30, and 40. Dams exposed to Hg²⁺ presented a decrease in water intake in gestation [total: F(2,19) = 15.84; p ≤ 0.0001; daily: F(2,21) = 12.71; p = 0.0002] and lactation [total: F(2,19) = 4.619; p = 0.024; daily: F(2,21) = 5.309; p = 0.0136] without alteration in food intake. Dams exposed to 50 µg Hg²⁺/mL had an increase in kidney total [F(2,21) = 8.081; p = 0.0025] and relative [F(2,21) = 14.11; p = 0.0001] weight without changes in biochemical markers of nephrotoxicity. Moreover, dams had an increase in hepatic [F(2,10) = 3.847; p = 0.0577] and renal [F(2,11) = 6.267; p = 0.0152] metallothionein content concomitantly with an increase in renal Hg levels after Hg²⁺ exposure. Regarding offspring, the exposure to Hg²⁺in utero and breast milk increased the relative liver [F(2,18) = 5.33; p = 0.0152] and kidney [F(2,18) = 3.819; p = 0.0415] weight only on the postnatal day 40. In conclusion, dams were able to handle the Hg²⁺ avoiding the classic Hg²⁺ toxic effects as well as protecting the offspring. We suggest that this protection is related to the hepatic and renal metallothionein content increase.

A Systematic Review of Mercury Exposures from Skin-Lightening Products

BACKGROUND

The Minamata Convention on Mercury (Article 4) prohibits the manufacture, import, or export of skin-lightening products containing mercury concentrations above 1 ppm. However, there is a lack of knowledge surrounding the global prevalence of mercury-added skin-lightening products.

OBJECTIVE

The objective of this study was to increase our understanding of worldwide human mercury exposure from skin-lightening products.

METHODS

A systematic search of peer-reviewed scientific literature was performed for relevant articles in four databases (PubMed, Web of Science Core Collection, Scopus, and TOXLINE). The search strategy, eligibility criteria, and data-extraction methods were established a priori. The search identified 2,303 unique scientific articles, of which 41 were ultimately deemed eligible for inclusion after iterative screens at the title, abstract, and whole-text levels. To facilitate data extraction and synthesis, all papers were organized according to four data groups a) "Mercury in products," b) "Usage of products," c) "Human biomarkers of exposure," and d) "Health impacts."

RESULTS

This review was based on data contained in 41 peer-reviewed scientific papers from 22 countries worldwide published between 2000 and 2022. In total, we captured mercury concentration values from 787 skin-lightening product samples [overall pooled central median mercury level was 0.49μg/g; interquartile range (IQR): 0.02-5.9] and 1,042 human biomarker measurements from 863 individuals. We also synthesized usage information from 3,898 individuals and self-reported health impacts associated with using mercury-added products from 832 individuals.

DISCUSSION

This review suggests that mercury widely exists as an active ingredient in many skin-lightening products worldwide and that users are at risk of variable and often high exposures. These synthesized findings identify data gaps and help increase our understanding of the health risks associated with the use of these products. https://doi.org/10.1289/EHP10808.

Systematic Review and Meta-Analysis of Mercury Exposure among Populations and Environments in Contact with Electronic Waste

Electronic waste (e-waste) recycling releases mercury (Hg) into the environment, though to our knowledge Hg levels at such sites have yet to be examined on a worldwide basis. A systematic review of scientific studies was conducted to extract, analyze, and synthesize data on Hg levels in e-waste products, environments near recycling sites, and in people. Data were extracted from 78 studies from 20 countries, and these included Hg levels in 1103 electrical and electronic products, 2072 environmental samples (soil, air, plant, food, water, dust), and 2330 human biomarkers (blood, hair, urine). The average Hg level in products was 0.65 μg/g, with the highest levels found in lamps (578 μg/g). Average soil and sediment Hg levels (1.86 μg/g) at e-waste sites were at least eight times higher than at control sites. Average urinary Hg levels (0.93 μg/g creatinine) were approximately two-fold higher among e-waste workers versus control groups. Collectively, these findings demonstrate that e-waste recycling may lead to Hg contamination in environments and human populations in close proximity to processing sites. These findings contribute to a growing knowledge base of mercury exposure through diverse source-exposure pathways, and the work has potential policy implications in the context of the Minamata Convention.

A Call for Biomonitoring Systems in Latin America and the Caribbean: Considerations for Potentially Toxic Metals/Metalloids

The Latin America and the Caribbean (LAC) region makes up 8.4% of the world’s population. Human biomonitoring (HBM) programs, which can shed light on population-level exposure to environmental contaminants such as toxic metals and thus, improve the health of the populations are inexistent in LAC countries. We call for the creation of HBM programs in the region and identify three viable design options for HBM at the individual level, through national surveys, newborn blood collection, and biobanks. We highlight some of challenges to the implementation of HBM programs, including financial and human resources, technical constrains (laboratory), sample, and data logistics. Finally, we provide the case studies of Brazil, Chile, Mexico, and Uruguay, to illustrate a range of responses to toxic metal exposure in non-occupational populations. Although different in many respects, the individual country responses share two commonalities: 1) academic centers drive the research to raise awareness of governmental entities; 2) reference levels are adapted from international norms rather than arising from the studied populations. Well-designed and sufficiently funded biomonitoring systems need to be established in each country of the LAC region. HBM programs are key to promoting human health by informing the public and contributing to policy processes that establish sustainable environmental controls and health prevention programs.

Methylmercury-induced DNA methylation—From epidemiological observations to experimental evidence

Methylmercury (MeHg) is a developmental neurotoxicant, and one potential mechanism of MeHg toxicity is epigenetic dysregulation. In a recent meta-analysis of epigenome-wide association studies (EWAS), associations between prenatal MeHg exposure and DNA methylation at several genomic sites were identified in blood from newborns and children. While EWASs reveal human-relevant associations, experimental studies are required to validate the relationship between exposure and DNA methylation changes, and to assess if such changes have implications for gene expression. Herein, we studied DNA methylation and gene expression of five of the top genes identified in the EWAS meta-analysis, MED31, MRPL19, GGH, GRK1, and LYSMD3, upon MeHg exposure in human SH-SY5Y cells exposed to 8 or 40 nM of MeHg during differentiation, using bisulfite-pyrosequencing and qPCR, respectively. The concentrations were selected to cover the range of MeHg concentrations in cord blood (2–8.5 μg/L) observed in the cohorts included in the EWAS. Exposure to MeHg increased DNA methylation at MED31, a transcriptional regulator essential for fetal development. The results were in concordance with the epidemiological findings where more MED31 methylation was associated with higher concentrations of MeHg. Additionally, we found a non-significant decrease in DNA methylation at GGH, which corresponds to the direction of change observed in the EWAS, and a significant correlation of GGH methylation with its expression. In conclusion, this study corroborates some of the EWAS findings and puts forward candidate genes involved in MeHg’s effects on the developing brain, thus highlighting the value of experimental validation of epidemiological association studies.

Deciphering the Global Proteomic Profile Involved in Methylmercury-Induced Cerebellar Neurodegeneration and Motor Dysfunction in Adult Rats

Mercury is a ubiquitous pollutant in the environment with potential neurotoxic effects. Several populations are susceptible to mercurial exposure, especially methylmercury (MeHg) at low doses for long periods through food consumption. Given this, the present work aimed to assess the effects of long-term MeHg exposure on the cerebellum of rats from a translational perspective using a representative dose, assessing molecular, biochemical, morphological, and behavioral parameters. The model was produced by administering 40 µg/kg of MeHg for 60 days to adult male Wistar rats by oral gavage. As a result of this exposure, the animals presented motor deficits in open field and rotarod tests which were associated with an increase in total mercury content in cerebellar parenchyma, a reduction in antioxidant competence against peroxyl radicals, and increased nitrite and lipid peroxidation levels. The proteomic approach showed 317 modulated proteins. Such findings were associated with reductions in mature neuron and Purkinje cell densities and glial fibrillary acidic protein immunostained areas and increased microglial density. In addition, decreases in myelin basic protein and synaptophysin immunostaining were also observed. The results thus provided new evidence of the mechanisms underlying complex MeHg-induced neurodegeneration, especially the proteins underlying the biochemical and morphological features associated with motor dysfunction.

Total Blood Mercury Predicts Methylmercury Exposure in Fish and Shellfish Consumers

Many studies evaluating methylmercury (MeHg) toxicity rely on whole blood total mercury (THg) measurements to estimate MeHg exposure. However, whole blood THg includes other forms of mercury (Hg), such as inorganic Hg, which have different exposure sources and toxicological effects than MeHg. Therefore, estimating the whole blood MeHg/THg ratio is critical to predicting MeHg exposure and, subsequently, efforts to establish an exposure-response relationship for use in risk assessment. A large, representative dataset (National Health and Nutrition Examination Survey (NHANES) 2011-2016) was used to determine the whole blood MeHg/THg ratio among (a) self-reported fish and shellfish consumers, ≥ 15 years of age (the "full adult" population (N = 5268 training dataset; N = 2336 test dataset)) and (b) female fish and shellfish consumers, 15-44 years of age (the "women of reproductive age" population (N = 1285 training dataset; N = 560 test dataset)). Unadjusted and adjusted linear and spline models with direct measurements for both THg and MeHg were evaluated. The mean whole blood MeHg/THg ratio was 0.75 (95% confidence interval (CI): 0.74, 0.75). This ratio was significantly higher among those with higher THg concentrations. All models exhibited excellent fit (adjusted R² from 0.957 to 0.982). Performance was slightly improved in spline versus linear models. For the full adult population and women of reproductive age, the unadjusted spline model predicted whole blood MeHg concentrations of 5.65 µg/L and 5.55 µg/L, respectively, when the THg concentration was 5.80 µg/L. These results suggest that whole blood THg is a good predictor of whole blood MeHg among fish and shellfish consumers.

The impact of mercury contamination on human health in the Arctic: A state of the science review

The 2021 Arctic Monitoring and Assessment Programme (AMAP) Mercury (Hg) Assessment is motivated by Arctic populations, and most notably Indigenous Peoples in the region, who are particularly vulnerable to Hg pollution. The objective of this review paper is to answer the following AMAP policy-relevant question: what is the human health impact of Hg pollution in the Arctic? In doing so, this state of the science review paper builds on information published 10 years ago in the last AMAP Hg assessment. The synthesized results demonstrate that: a) global influences (e.g., sources and transport pathways, biogeochemical processes, climate change, globalization) drive Hg exposures into human communities; b) Hg exposures are realized through dietary intake of certain country food items, and that new exposure science approaches are helping to deepen understandings; c) the nutritional and cultural benefits of country foods are immense, though a dietary transition is underway raising concerns over metabolic syndrome and broader issues of food security as well as cultural and social well-being; d) blood Hg measures are among the highest worldwide based on the results of human biomonitoring studies; e) Hg exposures are associated with adverse health outcomes across life stages (e.g., neurodevelopmental outcomes in young children to cardiovascular disease in adults); and f) risk communication needs to be balanced, targeted and clear, culturally appropriate, and be done collaboratively. These synthesized findings are particularly timely and policy-relevant given that the Minamata Convention entered into legal force worldwide in 2017 as a regulatory scheme to reduce the use and environmental release of Hg in order to protect human health and the environment. The Convention was influenced by health concerns raised by northern populations as indicated in the preamble text which makes reference to "the particular vulnerabilities of Arctic ecosystems and Indigenous communities".

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.

Protective actions of nuclear factor erythroid 2-related factor 2 (NRF2) and downstream pathways against environmental stressors

Environmental risk factors, including noise, air pollution, chemical agents, ultraviolet radiation (UVR) and mental stress have a considerable impact on human health. Oxidative stress and inflammation are key players in molecular pathomechanisms of environmental pollution and risk factors. In this review, we delineate the impact of environmental risk factors and the protective actions of the nuclear factor erythroid 2-related factor 2 (NRF2) in connection to oxidative stress and inflammation. We focus on well-established studies that demonstrate the protective actions of NRF2 and its downstream pathways against different environmental stressors. State-of-the-art mechanistic considerations on NRF2 signaling are discussed in detail, e.g. classical concepts like KEAP1 oxidation/electrophilic modification, NRF2 ubiquitination and degradation. Specific focus is also laid on NRF2-dependent heme oxygenase-1 induction with detailed presentation of the protective down-stream pathways of heme oxygenase-1, including interaction with BACH1 system. The significant impact of all environmental stressors on the circadian rhythm and the interactions of NRF2 with the circadian clock will also be considered here. A broad range of NRF2 activators is discussed in relation to environmental stressor-induced health side effects, thereby suggesting promising new mitigation strategies (e.g. by nutraceuticals) to fight the negative effects of the environment on our health.

Potential Application of Living Microorganisms in the Detoxification of Heavy Metals

Heavy metal (HM) exposure remains a global occupational and environmental problem that creates a hazard to general health. Even low-level exposure to toxic metals contributes to the pathogenesis of various metabolic and immunological diseases, whereas, in this process, the gut microbiota serves as a major target and mediator of HM bioavailability and toxicity. Specifically, a picture is emerging from recent investigations identifying specific probiotic species to counteract the noxious effect of HM within the intestinal tract via a series of HM-resistant mechanisms. More encouragingly, aided by genetic engineering techniques, novel HM-bioremediation strategies using recombinant microorganisms have been fruitful and may provide access to promising biological medicines for HM poisoning. In this review, we summarized the pivotal mutualistic relationship between HM exposure and the gut microbiota, the probiotic-based protective strategies against HM-induced gut dysbiosis, with reference to recent advancements in developing engineered microorganisms for medically alleviating HM toxicity.

Understanding among-lake variability of mercury concentrations in Northern Pike (Esox lucius): A whole-ecosystem study in subarctic lakes

Mercury concentrations ([Hg]) in fish reflect complex biogeochemical and ecological interactions that occur at a range of spatial and biological scales. Elucidating these interactions is crucial to understanding and predicting fish [Hg], particularly at northern latitudes, where environmental perturbations are having profound effects on land-water-animal interactions, and where fish are a critical subsistence food source. Using data from eleven subarctic lakes that span an area of ~60,000 km² in the Dehcho Region of Northwest Territories (Canada), we investigated how trophic ecology and growth rates of fish, lake water chemistry, and catchment characteristics interact to affect [Hg] in Northern Pike (Esox lucius), a predatory fish of widespread subsistence and commercial importance. Results from linear regression and piecewise structural equation models showed that 83% of among-lake variability in Northern Pike [Hg] was explained by fish growth rates (negative) and concentrations of methyl Hg ([MeHg]) in benthic invertebrates (positive). These variables were in turn influenced by concentrations of dissolved organic carbon, MeHg (water), and total Hg (sediment) in lakes, which were ultimately driven by catchment characteristics. Lakes in relatively larger catchments and with more temperate/subpolar needleleaf and mixed forests had higher [Hg] in Northern Pike. Our results provide a plausible mechanistic understanding of how interacting processes at scales ranging from whole catchments to individual organisms influence fish [Hg], and give insight into factors that could be considered for prioritizing lakes for monitoring in subarctic regions.

Mercury biomonitoring in German adults using volumetric absorptive microsampling

Mercury (Hg) is a global pollutant and a danger to human health. Human biomonitoring of Hg using a dried blood matrix instead of venous blood sampling for exposure assessment is of growing interest. This study aims to develop, validate, and evaluate the application of volumetric absorptive microsampling (VAMS) for Hg biomonitoring in humans. Sampling, drying, and storage conditions were evaluated during method development. Storage in pre-cleaned glass vials after drying for 2 h in a desiccator ensured analyte stability for at least 4 weeks. Sixty-eight paired capillary VAMS and venous blood samples from volunteers in Munich, Germany, were used for method validation. Hg levels in VAMS and venous blood samples were determined by direct mercury analysis. The limits of detection and quantitation for VAMS were 0.18 and 0.61 µg/l, respectively. However, sensitivity could be improved by using two microsamples for analysis instead of one. Hg levels in VAMS samples correlated very well with Hg levels in venous blood samples (R² = 0.958). Furthermore, VAMS showed a high accuracy (median recovery: 117%) and precision (median relative standard deviation: 8.7%), especially for Hg concentrations above 1.0 µg/l. In fact, accuracy and precision of VAMS improved with increasing Hg concentrations. In conclusion, VAMS in combination with direct mercury analysis is an accurate and viable alternative for human biomonitoring of Hg.

Selecting the best non-invasive matrix to measure mercury exposure in human biomonitoring surveys

Exposure to mercury, even at low doses, can affect human health, well-being and life quality at a broad scale. Human biomonitoring is the most straightforward approach to measure and quantify mercury exposure in humans. The objective of the present study is to compare and discuss the relationships between Hg levels in the most used matrices, hair, urine and blood, with the aim to ascertain to what extent mercury exposure and internal mercury levels could be predicted by monitoring non-invasive matrices. The study population (n = 527) is a subsample from Spanish BIOAMBIENT. ES study (18-65 y, both sexes), with data of Hg levels in blood, hair, and urine from the same individuals. We found strong inter-matrix Spearman correlations between blood and hair mercury (r² = 0.84), while the correlations for urine and blood mercury (r²⁼0.64) and urine and hair mercury (r²⁼0.65) were weaker. The geometric mean of the ratios between matrices were (GM, 95%CI): Hair/Blood 280 (271-290), Urine/Blood 0.174 (0.163-0.186) and Hair/Urine 2070 (1953-2194) and Urine/Blood 0.135 (0.128-0.144) for urine corrected by creatinine. High individual variation was observed particularly in those ratios involving urine. Considering the wide range of values observed in the ratios, we do not recommend applying them at individual level. The predictive models indicate that hair Hg was a more accurate predictor than urine. The inclusion of urine values did not increase the predictive accuracy, so, we recommend a cautious interpretation of urine mercury levels. Our study presents clear evidence that in a population highly exposed to food-borne mercury, a large portion of urinary mercury primarily emanates from methylmercury demethylation. We conclude that urine, as a non-invasive matrix, can be used as a reliable qualitative biomarker for Hg exposure when hair measurements not are available. For quantitative individual assessments, still blood measurements are to be preferred.

DNA methylation changes associated with prenatal mercury exposure: A meta-analysis of prospective cohort studies from PACE consortium

Mercury (Hg) is a ubiquitous heavy metal that originates from both natural and anthropogenic sources and is transformed in the environment to its most toxicant form, methylmercury (MeHg). Recent studies suggest that MeHg exposure can alter epigenetic modifications during embryogenesis. In this study, we examined associations between prenatal MeHg exposure and levels of cord blood DNA methylation (DNAm) by meta-analysis in up to seven independent studies (n = 1462) as well as persistence of those relationships in blood from 7 to 8 year-old children (n = 794). In cord blood, we found limited evidence of differential DNAm at cg24184221 in MED31 (β = 2.28 × 10-4, p-value = 5.87 × 10-5) in relation to prenatal MeHg exposure. In child blood, we identified differential DNAm at cg15288800 (β = 0.004, p-value = 4.97 × 10-5), also located in MED31. This repeated link to MED31, a gene involved in lipid metabolism and RNA Polymerase II transcription function, may suggest a DNAm perturbation related to MeHg exposure that persists into early childhood. Further, we found evidence for association between prenatal MeHg exposure and child blood DNAm levels at two additional CpGs: cg12204245 (β = 0.002, p-value = 4.81 × 10-7) in GRK1 and cg02212000 (β = -0.001, p-value = 8.13 × 10-7) in GGH. Prenatal MeHg exposure was associated with DNAm modifications that may influence health outcomes, such as cognitive or anthropometric development, in different populations.

Oyster arsenic, cadmium, copper, mercury, lead and zinc levels in the northern South China Sea: long-term spatiotemporal distributions, combined effects, and risk assessment to human health

Estuarine and coastal ecosystems are often considered vulnerable due to the complex biogeochemical processes and the human disturbances through a variety of pollution. Among environmental contaminants, heavy metals in estuarine and coastal ecosystems have been of increasing concern in environmental conservation. Long-term exposure to heavy metal contamination, mainly through food and water, could be harmful to human health. It is therefore critical to understand the quantitative comparisons and combined effects of different heavy metals in common seafood species, such as oysters. This work studied the long-term spatiotemporal trends and health risk assessment of oyster arsenic (As), cadmium (Cd), copper (Cu), mercury (Hg), lead (Pb), and zinc (Zn) levels in the coastal waters of northern South China Sea. Cultured oysters (Crassostrea rivularis) from 23 estuaries and harbors in the coastal areas of northern South China Sea in 1989-2015 were analyzed for the spatiotemporal trends of the six heavy metal levels. Metal pollution index (MPI), target hazard quotient (THQ), and hazard index (HI) were used for quantifying the exposure of the six heavy metals to human health through oyster consumption. Principal component analysis (PCA) was used for assessing the relative importance of the six metals in oyster heavy metal distribution patterns in the northern South China Sea. Overall, the As, Cd, Cu, Hg, Pb, and Zn levels in oysters from the northern South China Sea generally declined from 1989 to 2015, stayed relatively high (MPI = 2.42-3.68) during 1989-2000, gradually decreased since 2000, and slightly increased after 2010. Oyster heavy metal levels were highest in the Pearl River Estuary (MPI = 1.20-5.52), followed by west Guangdong and east Guangdong, Guangxi, and Hainan coastal waters. This pattern is probably because economics and industry around the Pearl River Estuary have been growing faster than the other areas of this work in the recent two decades, and it should be taken as a hotspot for the monitoring of seafood safety in southern China. Principal component analysis indicated that Cu, Zn, and Cd were the most important metals in the long-term distributions of oyster heavy metal levels in the northern South China Sea. Health risk assessment suggested that the risk of the six heavy metals exposure through oyster consumption were relatively high during 1989-2005 (THQ = 1.01-5.82), significantly decreased since 2005 (THQ < 1), and slightly increased after 2010.

Toward Food Sovereignty for Coastal Communities of Eastern Québec: Co-designing A Website to Support Consumption of Edible Resources from the St. Lawrence River, Estuary, and Gulf

Background. Despite the abundance and proximity of edible marine resources, coastal communities along the St. Lawrence in Eastern Québec rarely consume these resources. Within a community-based food sovereignty project, Manger notre Saint-Laurent (“Sustenance from our St. Lawrence”), members of participating communities (3 non-Indigenous, 1 Indigenous) identified a need for a web-based decision tool to help make informed consumption choices. Methods. We thus aimed to co-design a prototype website that facilitates informed choices about consuming local edible marine resources based on seasonal and regional availability, food safety, nutrition, and sustainability, with community members, regional stakeholders, and experts in user experience design and web development. We conducted 48 interviews with a variety of people over 3 iterative cycles, assessing the prototype’s ease of use with a validated measure, the System Usability Scale. Results. Community members, regional stakeholders, and other experts identified problematic elements in initial versions of the website (e.g., confusing symbols). We resolved issues and added features people identified as useful. Usability scores reached “best imaginable” for both the second and the third versions and did not differ significantly between sociodemographic groups. The final prototype includes a tool to explore each species and index cards to regroup accurate evidence relevant to each species. Conclusions. Engaging co-designers with different sociodemographic characteristics brought together a variety of perspectives. Several components would not have been included without co-designers’ input; other components were greatly improved thanks to their feedback. Co-design approaches in research and intervention development are preferable to foster the inclusion of a variety of people. Once the prototype is programmed and available online, we hope to evaluate the website to determine its effects on food choices.

Uma revisão de escopo de revisões sistemáticas sobre exposição humana ao mercúrio

Resumo: Introdução: a promulgação da Convenção de Minamata no Brasil em 2018 incentivou o cumprimento dos seus objetivos em reduzir o uso e a poluição por mercúrio. Objetivo: caracterizar a produção científica sobre exposição humana ao mercúrio e identificar lacunas de conhecimento a fim de subsidiar a tomada de decisão em saúde. Métodos: revisão de escopo de revisões sistemáticas e metanálises, sem restrição de idioma ou data de publicação, utilizando as bases PubMed, BVS e Cochrane Library. Resultados: 71 estudos atenderam aos critérios de elegibilidade, com 40 revisões sistemáticas, 30 metanálises e 1 overview. Amálgama dentário e contaminação alimentar e ambiental por atividades que utilizam mercúrio foram as fontes de exposição mais mencionadas. Os temas mais estudados contaram com transtornos mentais e comportamentais, assim como uso de biomarcadores e testes neurocomportamentais relacionados à exposição ao mercúrio. Discussão: lacunas como a exposição ocupacional ao mercúrio, uso em práticas tradicionais e em cosméticos apontam para a necessidade de mais estudos. As revisões identificadas podem oferecer subsídios para sínteses de evidências e protocolos de atenção à saúde de populações expostas, assim como para a elaboração de políticas públicas que visem o controle do uso e da exposição ao mercúrio.

Genotoxicity of Mercury and Its Derivatives Demonstrated In Vitro and In Vivo in Human Populations Studies. Systematic Review

Beside partial coverage in three reviews so far (1994, 2009, 2019), there is no review on genotoxic studies dealing with mercury (Hg) and human exposure using the most usual genotoxic assays: sister chromatid exchanges (SCE), chromosomal aberrations (CA), cytochalasin B blocked micronucleus assay (CBMN), and single-cell gel electrophoresis (SCGE or alkaline comet assay). Fifty years from the first Hg genotoxicity study and with the Minamata Convention in force, the genotoxic potential of Hg and its derivatives is still controversial. Considering these antecedents, we present this first systematic literature overview of genotoxic studies dealing with Hg and human exposure that used the standard genotoxic assays. To date, there is not sufficient evidence for Hg human carcinogen classification, so the new data collections can be of great help. A review was made of the studies available (those published before the end of October 2021 on PubMed or Web of Science in English or Spanish language) in the scientific literature dealing with genotoxic assays and human sample exposure ex vivo, in vivo, and in vitro. Results from a total of 66 articles selected are presented. Organic (o)Hg compounds were more toxic than inorganic and/or elemental ones, without ruling out that all represent a risk. The most studied inorganic (i)Hg compounds in populations exposed accidentally, occupationally, or iatrogenically, and/or in human cells, were Hg chloride and Hg nitrate and of the organic compounds, were methylmercury, thimerosal, methylmercury chloride, phenylmercuric acetate, and methylmercury hydroxide.

Children with Amalgam Dental Restorations Have Significantly Elevated Blood and Urine Mercury Levels

Human exposure to organic mercury (Hg) as methylmercury (MeHg) from seafood consumption is widely considered a health risk because pure methylmercury is extremely neurotoxic. In contrast, the clinical significance of Hg exposure from amalgam (AMG) dental restorations, the only other major nonoccupational source of Hg exposure, has long been debated. Here, we examined data from the two most recent National Health and Nutrition Examination Surveys (NHANES) on 14 181 subjects to assess the contributions of seafood consumption versus AMG to blood total mercury (THg), inorganic mercury (IHg), and methyl mercury (MeHg) and to urine creatinine corrected mercury (UTHg). All subjects were also classified as to their self-reported qualitative consumption of seafood (59% fish and 44% shellfish). Subjects with restorations were grouped into three groups (0) those without AMG (64.4%), (1) those with 1-5 dental AMG restorations (19.7%), (2) those with more than five AMG (16%). Seafood consumption increased total mercury in urine (UTHg) and total mercury (THg) and methyl mercury (MeHg) in blood, but unlike AMG, seafood did not increase blood inorganic mercury (IHg). Using stratified covariate (ANOVA) and multivariate (GLM) analyses revealed a strong correlation of blood (THg and IHg) and urine (UTHg) levels with the number of AMGs. In a subpopulation without fish consumption, having more than five AMG restorations raised blood THg (103%), IHg (221%), and urine UTHg (221%) over the group without AMG. The most striking difference was noted in classification by age: subjects under 6 years old with more than five AMG restorations had the highest blood IHg and urine UTHg among all age groups. Elevation of bivalent IHg on a large scale in children warrants urgent in-depth risk assessment with specific attention to genetic- and gender-associated vulnerabilities.

High variability of mercury content in the hair of Russia Northwest population: the role of the environment and social factors

PURPOSE

The purpose of this work is to study mercury levels in the hair of different social and demographic groups of the population of the Vologda region in Northwest Russia. This region is selected due to a heterogeneous distribution of rivers and lakes-a resource base for fishing.

METHODS

The mercury content was determined in the hair from the root with a length of about 2 cm. The concentration of total mercury in human hair was determined by the atomic absorption method without preliminary sample preparation using an RA-915M mercury analyzer and a PYRO-915 + pyrolysis unit.

RESULTS

The average level of mercury in the human hair was 0.445 μg/g (median 0.220 μg/g). The concentration of mercury in the hair of people older than 44 years (0.875 μg/g) was three times higher than in the hair of children under 18 years of age (0.270 μg/g). People who eat fish less than once per month had a hair mercury concentration of 0.172 μg/g, for 1-2 times a month 0.409 μg/g, once a week 0.555 μg/g, and several times a week 0.995 μg/g. The concentration of mercury in the hair of smokers (0.514 μg/g) was higher than in the hair of non-smokers (0.426 μg/g).

CONCLUSION

Significantly higher concentrations of mercury were observed in the hair of participants from the western part of the region, where reservoirs are the main commercial sources of fish products. The data showed that the main source of people's mercury intake was fish.

Latent effects of early-life methylmercury exposure on motor function in Drosophila

The developmental toxicant, methylmercury (MeHg), can elicit motor deficits that last well into adulthood. Recent studies using Drosophila showed that the developing musculature is sensitive to high doses of MeHg, where a larval feeding paradigm resulted in compromised myotendinous junction (MTJ) formation during development, by a mechanism involving the NG2 homologue, kon-tiki (kon). Low-dose exposures to MeHg that do not produce muscle pathology during development, nevertheless result in impaired flight behavior later in adult life. The present study evaluated the potential for relatively low-dose exposure to produce latent adult muscle pathology and motor impairments, as assayed by climbing and flight, as well as to evaluate molecular mechanisms that may contribute to motor deficits. Wildtype larvae were fed 0, 2, 2.5, or 5 μM MeHg laden food until eclosion. The effect of 5 μM MeHg on MTJ-related gene expression during pupal development was assessed via quantitative RT-qPCR analysis. Upon eclosion, adults were transferred to standard food bottles for 4, 11, or 30 days prior to motor testing. Survivorship (%) was determined from a subset of 200 flies per treatment. Average climbing speed (cm/s) was quantified 4-days post-eclosion (PE). Flight ability was assayed 11- or 30-days PE by measuring landing height (cm) of flies dropped into an adhesive-lined vertical column. In parallel, total body mercury was measured to estimate the influence of residual MeHg at the time of motor testing. Muscle morphology was assessed using immuno-fluorescence microscopy. Exposure to 5uM MeHg significantly reduced climbing speed, and flight ability 4 and 11 - days PE, respectively. While age-related flight deficits were seen in each sex, flight deficits due to MeHg persisted to 30-day PE timepoints exclusively in males. Expression of kon was upregulated across the window of pupal development essential to establishing adult MTJ. However, experimentally restricting the induction of comparable levels of kon to muscle during the same periods did not recapitulate the flight deficits, indicating that muscle-specific induction of kon alone is not sufficient to contribute to latent flight impairments. Adult flight muscle morphology of 11-day PE flies treated with 5 μM MeHg was indistinct from controls, implying muscle structure is not grossly perturbed to impair flight. Collectively, the current data suggest that developmental exposure to 5 μM MeHg reduces flight ability in each sex at 11 day-PE and that latent deficits at 30-day PE are male-specific. It remains to be determined whether the developing MTJ of Drosophila is a sensitive target of MeHg, and whether or not kon acts in conjunction with additional MTJ factors to constitute a MeHg target.

Developmental Exposure to Low Concentrations of Methylmercury Causes Increase in Anxiety-Related Behaviour and Locomotor Impairments in Zebrafish

Methylmercury (MeHg) is a ubiquitous pollutant shown to cause developmental neurotoxicity, even at low levels. However, there is still a large gap in our understanding of the mechanisms linking early-life exposure to life-long behavioural impairments. Our aim was to characterise the short- and long-term effects of developmental exposure to low doses of MeHg on anxiety-related behaviours in zebrafish, and to test the involvement of neurological pathways related to stress-response. Zebrafish embryos were exposed to sub-acute doses of MeHg (0, 5, 10, 15, 30 nM) throughout embryo-development, and tested for anxiety-related behaviours and locomotor activity at larval (light/dark locomotor activity) and adult (novel tank and tap assays) life-stages. Exposure to all doses of MeHg caused increased anxiety-related responses; heightened response to the transition from light to dark in larvae, and a stronger dive response in adults. In addition, impairment in locomotor activity was observed in the higher doses in both larvae and adults. Finally, the expressions of several neural stress-response genes from the HPI-axis and dopaminergic system were found to be disrupted in both life-stages. Our results provide important insights into dose-dependent differences in exposure outcomes, the development of delayed effects over the life-time of exposed individuals and the potential mechanisms underlying these effects.

Mercury stable isotopes constrain atmospheric sources to the ocean

Human exposure to toxic mercury (Hg) is dominated by the consumption of seafood^1,2. Earth system models suggest that Hg in marine ecosystems is supplied by atmospheric wet and dry Hg(II) deposition, with a three times smaller contribution from gaseous Hg(0) uptake^3,4. Observations of marine Hg(II) deposition and Hg(0) gas exchange are sparse, however⁵, leaving the suggested importance of Hg(II) deposition⁶ ill-constrained. Here we present the first Hg stable isotope measurements of total Hg (tHg) in surface and deep Atlantic and Mediterranean seawater and use them to quantify atmospheric Hg deposition pathways. We observe overall similar tHg isotope compositions, with median Δ²⁰⁰Hg signatures of 0.02‰, lying in between atmospheric Hg(0) and Hg(II) deposition end-members. We use a Δ²⁰⁰Hg isotope mass balance to estimate that seawater tHg can be explained by the mixing of 42% (median; interquartile range, 24-50%) atmospheric Hg(II) gross deposition and 58% (50-76%) Hg(0) gross uptake. We measure and compile additional, global marine Hg isotope data including particulate Hg, sediments and biota and observe a latitudinal Δ²⁰⁰Hg gradient that indicates larger ocean Hg(0) uptake at high latitudes. Our findings suggest that global atmospheric Hg(0) uptake by the oceans is equal to Hg(II) deposition, which has implications for our understanding of atmospheric Hg dispersal and marine ecosystem recovery.

Methylmercury Measurements in Dried Blood Spots from Electronic Waste Workers Sampled from Agbogbloshie, Ghana

Biomonitoring methylmercury (MeHg) exposure is problematic in resource-limited settings and with difficult-to-access populations where traditional biomarker approaches present logistical, economic, and ethical issues. The present study aimed to validate the use of dried blood spots (DBS) to assess MeHg exposure in a real-world contaminated field setting. Whole-blood and DBS samples were collected from electronic waste workers (n = 20) from Agbogbloshie (Ghana) in 2017, and DBS were also artificially created in the laboratory using the field-collected blood. Whole-blood MeHg concentrations averaged 0.84 µg/L, which was not different from levels measured in the corresponding DBS samples (field-collected or artificially created). Whole-blood MeHg comprised 61% of the blood total Hg concentrations. Linear regression analysis revealed no differences in MeHg concentrations between whole-blood samples and field-collected DBS (slope 0.89, R²  = 0.94) and between field and laboratory DBS (slope 0.89, R²  = 0.96). The MeHg content in DBS punch blanks averaged 0.86 pg and thus was not of concern. These findings indicate that DBS are a suitable tool for assessing MeHg exposure in real-world environmental settings that may be heavily contaminated.  Environ Toxicol Chem 2021;40:2183-2188. © 2021 SETAC.

Total mercury and methylmercury in human hair and food: Implications for the exposure and health risk to residents in the Three Gorges Reservoir Region, China

Three Gorges Dam (TGD) is the largest hydroelectric construction in the world, and its potential impacts on the ecological environment and human health risks have invoked considerable global concern. However, as a mercury (Hg) sensitive system, limited work was conducted on the Hg exposure level of local residents around the Three Gorges Reservoir (TGR). Thus, 540 human hair samples and 22 species of local food samples were collected to assess the Hg exposure and human health risk to the residents located in the Three Gorges Reservoir Region (TGRR) and to investigate their dietary exposure to Hg. The results showed that the geometric mean concentrations of total mercury (THg) and methylmercury (MeHg) in hair were 0.42 ± 0.43 μg g^-1 and 0.23 ± 0.32 μg g^-1, respectively, lower than the reference level (1.0 μg g^-1) recommended by the United States Environmental Protection Agency (US EPA), indicating a low level Hg exposure for residents around the TGR. No significant difference in the accumulation of Hg in hair between the gender subgroups was observed, whereas age difference, smoking and alcohol drinking behavior, and fish consumption frequency were significant predictors of hair Hg level. Besides, THg and MeHg of all the investigated food samples did not exceed the corresponding Chinese national standard. The average probable daily intakes (PDIs) of THg and MeHg were 0.032 μg kg^-1 day^-1 and 0.007 μg kg^-1 day^-1, which were obviously below the recommended values of 0.57 μg kg^-1 day^-1 and 0.1 μg kg^-1 day^-1, respectively. The cereal (mainly rice) contribution of THg (76.0%) and MeHg (74.4%) intakes to the local residents around the TGR was much higher than that of fish (10.7% and 22.9%, respectively) due to the considerable rice consumption. Overall, residents around the TGR were at a low Hg exposure and rice consumption was the major pathway for Hg exposure.

The Role of Human LRRK2 in Acute Methylmercury Toxicity in Caenorhabditis elegans

Methylmercury (MeHg) exposure and its harmful effects on the developing brain continue to be a global environmental health concern. Decline in mitochondrial function is central to the toxic effects of MeHg and pathogenesis of mitochondria-related diseases including Parkinson's disease (PD). LRRK2 (Leucine-rich repeat kinase 2) mutation is one of the most common genetic risk factors for PD. In this study, we utilize an acute toxicity model of MeHg exposure in the model organism Caenorhabditis elegans (C. elegans) to compare lifespan, developmental progression, mitochondrial membrane potential and reactive oxygen species (ROS) between the wild-type N2 strain, wild-type LRRK2 transgenic strain (WLZ1), and mutant LRRK2(G2019S) transgenic strain (WLZ3). Additionally, the expression levels of skn-1 and gst-4 were investigated. Our results show that acute MeHg exposure (5 and 10 µM) caused a significant developmental delay in the N2 and WLZ3 worms. Notably, the worms expressing wild-type LRRK2 were resistant to 5 µM MeHg- induced developmental retardation. ROS levels in response to MeHg exposure were increased in the N2 worms, but not in the WLZ1 or WLZ3 worms. The mitochondrial membrane potential was decreased in the N2 worms but increased in the WLZ1 and WLZ3 worms following MeHg exposure. Furthermore, MeHg exposure increased the expression of skn-1 in N2, but not in WLZ1 worms. Although skn-1 expression was increased in the WLZ3 worms following MeHg exposure, gst-4 expression was not induced. Both skn-1 and gst-4 had higher basal expression levels in LRRK2s transgenic than wild-type N2 worms. Knocking down of skn-1 with feeding RNAi had a significant developmental effect in WLZ1 worms; however, the effect was not found in WLZ3 worms. These results suggest that mitochondrial dysfunction and a defect in the SKN-1 signaling in the LRRK2 G2019S worms contribute to the severe developmental delay, establishing a modulatory role of LRRK2 mutation in MeHg-induced acute toxicity.

Characterizing the Low-Dose Effects of Methylmercury on the Early Stages of Embryo Development Using Cultured Human Embryonic Stem Cells

BACKGROUND

Global concerns of methylmercury (MeHg) exposure have been raised, especially on its effects on pregnant women. Recent epidemiological studies have revealed associations between maternal blood/hair MeHg concentrations, adverse pregnancy outcomes, and developmental deficits. However, the underlying mechanisms remain unclear.

OBJECTIVES

In this study, we characterized the effects of MeHg exposure on undifferentiated human embryonic stem cells (hESCs) and extrapolated the effects to human embryonic development.

METHODS

hESCs were exposed to 0, 1, 5, 10, 50, 100 or 200nM MeHg for 24 h or 6 d. Cell adherence and colony formation and expansion were examined under the microscope. Cell attachment, viability/proliferation, apoptosis, stress response, cell cycle, autophagy, and expression of cell lineage marker genes and proteins were measured at the end of exposures.

RESULTS

Our results indicated that exposure to nanomolar concentrations of MeHg was associated with a) higher levels of reactive oxygen species (ROS) and hemeoxygenase-1 (HO-1), suggesting increased stress and adaptive responses; b) lower cellular adhesion, viability/proliferation, and colony formation and expansion; c) higher levels of apoptosis, reflected by higher cleaved caspase-3 expression and Annexin V binding; d) higher levels of cytoskeleton protein α-tubulin expression; e) higher rates of G1/S phase cell cycle arrest; and f) autophagy inhibition, as shown by a lower LC3BII/LC3BI ratio and accumulation of SQSTM1 (p62). These outcomes were accompanied by higher expressions of self-renewal genes or proteins or both, including OCT4, SOX2, NANOG, and cytokine receptor IL6ST, as well as pluripotency and the cell fate regulator cyclin D1.

DISCUSSION

These results revealed that under the selection pressure of exposure to low doses of MeHg, some hESCs underwent apoptosis, whereas others adapted and survived with enhanced self-renewal gene expression and specific morphological phenotypes. Findings from the present study provide in vitro evidence that low doses of MeHg adversely affect hESCs when exposed during a period of time that models embryonic pre-, during, and early postimplantation stages. https://doi.org/10.1289/EHP7349.

DHA ameliorates MeHg‑induced PC12 cell apoptosis by inhibiting the ROS/JNK signaling pathway

Recent studies have reported that methylmercury (MeHg) induces neuronal apoptosis, which is accompanied by abnormal neurological development. Despite the important role of docosahexaenoic acid (DHA) in maintaining the structure and function of the brain, as well as improving neuronal apoptosis induced by MeHg, the exact mechanism remains unknown. The present study hypothesized that the reactive oxygen species (ROS)-mediated JNK signaling pathway may be associated with the protective effect of DHA against MeHg-induced PC12 cell apoptosis. Cell Counting Kit-8, TUNEL staining, flow cytometry, ROS detection, PCR and western blot analysis were performed. The results demonstrated that MeHg inhibited the activity of PC12 cells, causing oxidative damage and promoting apoptosis; however, DHA significantly attenuated this effect. Mechanistic studies revealed that MeHg increased intracellular ROS levels and JNK protein phosphorylation, and decreased the expression levels of the anti-apoptotic protein Bcl-2, whereas DHA reduced ROS levels and JNK phosphorylation, and increased Bcl-2 expression. In addition, the ROS inhibitor N-acetyl-l-cysteine (NAC) was used to verify the experimental results. After pretreatment with NAC, expression levels of Bcl-2, Bax, phosphorylated-JNK and JNK were assessed. Bcl-2 protein expression was increased and the Bcl-2/Bax ratio was increased. Moreover, the high expression levels of phosphorylated-JNK induced by MeHg were significantly decreased. Based on the aforementioned results, the present study indicated that the effects of DHA against MeHg-induced PC12 cell apoptosis may be mediated via the ROS/JNK signaling pathway.

Heavy metals and PAHs in mussels on the Serbian market and consumer exposure

The goal of the study was to investigate the concentration of heavy metals and polycyclic aromatic hydrocarbons (PAHs) in 84 samples of mussels, collected from supermarkets and fish markets in Serbia. Lead, cadmium, mercury and arsenic concentrations were determined using an inductive coupled plasma mass spectrometry method. Sixteen PAHs were determined using a gas chromatography-mass spectrometry method. Heavy metals in the mussels were in the range (mg/kg) of 0.01-0.74 for lead, 0.01-0.38 for cadmium, 0.01-0.15 for mercury and 1.12-5.87 for arsenic. Metals and PAHs levels in all analysed samples were under the legal European and Serbian legislation limits. The provisional tolerable intake values were calculated on the base of the obtainable values of heavy metals. Mussels are considered to be safe for human consumption. However, one should take care of the amount and frequency of mussel consumption, primarily due to consumer's cadmium and mercury burden.

Plasma and red blood cells distribution of total mercury, inorganic mercury, and selenium in maternal and cord blood from a group of Japanese women

Fetuses are a high-risk group for methylmercury (MeHg) exposure. The main objective of this study was to compare the characteristic profiles of total mercury (THg), inorganic mercury (IHg), MeHg, and selenium in plasma and red blood cells (RBCs) between maternal and cord blood at parturition collected from a group of Japanese women. Furthermore, correlations of THg in RBCs, which is a biomarker of MeHg, and THg in plasma, which is an IHg exposure biomarker, were examined in maternal and cord blood. Fifty-five pairs of maternal and cord blood samples obtained at parturition were collected from pregnant women in Fukuoka, Japan. THg in RBCs and plasma were significant correlated between maternal and cord blood. THg in RBCs was 13.9 ng/mL for cord and 9.16 ng/mL for maternal blood, with a cord:maternal RBCs ratio for THg of 1.58, suggesting that MeHg is actively transferred from the mother to the fetus via the placenta. THg in plasma showed a positive correlation with THg in RBCs for maternal and cord blood. This result suggests that measuring THg in plasma can overestimate the exposure level to IHg in fish-eating populations. The percentages of IHg in cord plasma and RBCs were 31% and 1.7%, respectively, and those in maternal plasma and RBCs were 46% and 5.9%, respectively. These results suggest that cord blood is rich in MeHg and can easily transfer to the fetal brain. Selenium in cord plasma was 67 ng/mL and that in maternal plasma was 97 ng/mL, with a cord:maternal plasma ratio for Se of 0.69, suggesting that the protective effects of Se against MeHg toxicity in fetuses may be weaker than those expected in adult mothers.

Associations of Fish Consumption With Risk of Cardiovascular Disease and Mortality Among Individuals With or Without Vascular Disease From 58 Countries

IMPORTANCE

Cohort studies report inconsistent associations between fish consumption, a major source of long-chain ω-3 fatty acids, and risk of cardiovascular disease (CVD) and mortality. Whether the associations vary between those with and those without vascular disease is unknown.

OBJECTIVE

To examine whether the associations of fish consumption with risk of CVD or of mortality differ between individuals with and individuals without vascular disease.

DESIGN, SETTING, AND PARTICIPANTS

This pooled analysis of individual participant data involved 191 558 individuals from 4 cohort studies-147 645 individuals (139 827 without CVD and 7818 with CVD) from 21 countries in the Prospective Urban Rural Epidemiology (PURE) study and 43 413 patients with vascular disease in 3 prospective studies from 40 countries. Adjusted hazard ratios (HRs) were calculated by multilevel Cox regression separately within each study and then pooled using random-effects meta-analysis. This analysis was conducted from January to June 2020.

EXPOSURES

Fish consumption was recorded using validated food frequency questionnaires. In 1 of the cohorts with vascular disease, a separate qualitative food frequency questionnaire was used to assess intake of individual types of fish.

MAIN OUTCOMES AND MEASURES

Mortality and major CVD events (including myocardial infarction, stroke, congestive heart failure, or sudden death).

RESULTS

Overall, 191 558 participants with a mean (SD) age of 54.1 (8.0) years (91 666 [47.9%] male) were included in the present analysis. During 9.1 years of follow-up in PURE, compared with little or no fish intake (≤50 g/mo), an intake of 350 g/wk or more was not associated with risk of major CVD (HR, 0.95; 95% CI, 0.86-1.04) or total mortality (HR, 0.96; 0.88-1.05). By contrast, in the 3 cohorts of patients with vascular disease, the HR for risk of major CVD (HR, 0.84; 95% CI, 0.73-0.96) and total mortality (HR, 0.82; 95% CI, 0.74-0.91) was lowest with intakes of at least 175 g/wk (or approximately 2 servings/wk) compared with 50 g/mo or lower, with no further apparent decrease in HR with consumption of 350 g/wk or higher. Fish with higher amounts of ω-3 fatty acids were strongly associated with a lower risk of CVD (HR, 0.94; 95% CI, 0.92-0.97 per 5-g increment of intake), whereas other fish were neutral (collected in 1 cohort of patients with vascular disease). The association between fish intake and each outcome varied by CVD status, with a lower risk found among patients with vascular disease but not in general populations (for major CVD, I2 = 82.6 [P = .02]; for death, I2 = 90.8 [P = .001]).

CONCLUSIONS AND RELEVANCE

Findings of this pooled analysis of 4 cohort studies indicated that a minimal fish intake of 175 g (approximately 2 servings) weekly is associated with lower risk of major CVD and mortality among patients with prior CVD but not in general populations. The consumption of fish (especially oily fish) should be evaluated in randomized trials of clinical outcomes among people with vascular disease.