Maternal fish consumption and child neurodevelopment in Nutrition 1 Cohort: Seychelles Child Development Study.

Maternal fish consumption exposes the fetus to beneficial nutrients and potentially adverse neurotoxicants. The current study investigated associations between maternal fish consumption and child neurodevelopmental outcomes. Maternal fish consumption was assessed in the Seychelles Child Development Study Nutrition Cohort 1 (n 229) using 4-day food diaries. Neurodevelopment was evaluated at 9 and 30 months, and 5 and 9 years with test batteries assessing twenty-six endpoints and covering multiple neurodevelopmental domains. Analyses used multiple linear regression with adjustment for covariates known to influence child neurodevelopment. This cohort consumed an average of 8 fish meals/week and the total fish intake during pregnancy was 106·8 (sd 61·9) g/d. Among the twenty-six endpoints evaluated in the primary analysis there was one beneficial association. Children whose mothers consumed larger quantities of fish performed marginally better on the Kaufman Brief Intelligence Test (a test of nonverbal intelligence) at age 5 years (ß 0·003, 95 % CI (0, 0·005)). A secondary analysis dividing fish consumption into tertiles found no significant associations when comparing the highest and lowest consumption groups. In this cohort, where fish consumption is substantially higher than current global recommendations, maternal fish consumption during pregnancy was not beneficially or adversely associated with children's neurodevelopmental outcomes.

Serum cytokines are associated with n-3 polyunsaturated fatty acids and not with methylmercury measured in infant cord blood in the Seychelles child development study.

BACKGROUND: Maternal fish consumption increases infant methylmercury (MeHg) exposure and polyunsaturated fatty acid (PUFA) concentrations. The n-3 PUFA are regulators of inflammation while MeHg may impact the cord cytokine profile and, subsequently, contribute to immune mediated outcomes. This study aimed to investigate associations between infant MeHg exposure and cord cytokine concentrations while adjusting for cord PUFA. METHODS: We studied participants in the Seychelles Child Development Study (SCDS) Nutrition Cohort 2 (NC2), a large birth cohort in a high fish-eating population. Whole blood MeHg, serum PUFA and serum cytokine concentrations (IFN-γ, IL-1ß, IL-2, IL-12p70, TNF-α, IL-4, IL-10, IL-13, IL-6 and IL-8) were measured in cord blood collected at delivery (n = 878). Linear regression examined associations between infant MeHg exposure and cord cytokines concentrations, with and without adjustment for cord PUFA. An interaction model examined cord MeHg, cytokines and tertiles of the n-6:n-3 ratio (low/medium/high). RESULTS: There was no overall association between cord MeHg (34.08 ± 19.98 µg/L) and cytokine concentrations, with or without adjustment for PUFA. Increased total n-3 PUFA (DHA, EPA and ALA) was significantly associated with lower IL-10 (ß = -0.667; p = 0.007) and lower total Th2 (IL-4, IL-10 and IL-13) (ß = -0.715; p = 0.036). In the interaction model, MeHg and IL-1ß was positive and significantly different from zero in the lowest n-6:n-3 ratio tertile (ß = 0.002, p = 0.03). CONCLUSION: Methylmercury exposure from fish consumption does not appear to impact markers of inflammation in cord blood. The association of cord n-3 PUFA with lower IL-10 and total Th2 cytokines suggests that they may have a beneficial influence on the regulation of the inflammatory milieu. These findings are important for public health advice and deserve to be investigated in follow up studies.

The influence of fish consumption on serum n-3 polyunsaturated fatty acid (PUFA) concentrations in women of childbearing age: a randomised controlled trial (the iFish Study).

PURPOSE: Long-chain polyunsaturated fatty acids (LCPUFA) can be synthesised endogenously from linoleic acid (LA) and α-linolenic acid (ALA) in a pathway involving the fatty acid desaturase (FADS) genes. Endogenous synthesis is inefficient; therefore, dietary intake of preformed LCPUFA from their richest source of fish is preferred. This study investigated the effect of fish consumption on PUFA concentrations in women of childbearing age while stratifying by FADS genotype. The influence of fish consumption on lipid profile, and markers of inflammation and oxidative stress was also examined. METHODS: Healthy women (n = 49) provided a buccal swab which was analysed for FADS2 genotype (rs3834458; T/deletion). Participants were stratified according to genotype and randomised to an intervention group to receive either no fish (n = 18), 1 portion (n = 14) or 2 portions (n = 17) (140 g per portion) of fish per week for a period of 8 weeks. Serum PUFA was analysed at baseline and post-intervention. Lipid profile, and markers of inflammation and oxidative stress were also analysed. RESULTS: Participants consuming 2 portions of fish per week had significantly higher concentrations of eicosapentaenoic acid (EPA), docosahexaenoic acid (DHA) and total n-3 PUFA, and a lower n-6:n-3 ratio compared to those in the no fish or 1 portion per week group (all p < 0.05). Fish consumption did not have a significant effect on biomarkers of oxidative stress, inflammation and lipid profile in the current study. CONCLUSION: Consumption of 2 portions of fish per week has beneficial effects on biological n-3 PUFA concentrations in women of childbearing age; however, no effects on oxidative stress, inflammation or lipid profile were observed. This trial was registered at www.clinicaltrials.gov (NCT03765580), registered December 2018.

Maternal Long-Chain Polyunsaturated Fatty Acid Status, Methylmercury Exposure, and Birth Outcomes in a High-Fish-Eating Mother-Child Cohort.

BACKGROUND: Maternal status of long-chain PUFAs (LC-PUFAs) may be related to fetal growth. Maternal fish consumption exposes the mother to the neurotoxicant methylmercury (MeHg), which, in contrast, may restrict fetal growth. OBJECTIVE: Our aim was to examine relations between maternal LC-PUFA status at 28 wk and birth outcomes (birth weight, length, and head circumference), controlling for MeHg exposure throughout pregnancy, in the Seychelles Child Development Study Nutrition Cohort 2. Our secondary aim was to examine the influence of maternal variation in genes regulating the desaturation of LC-PUFAs [fatty acid desaturase (FADS)] on birth outcomes. METHODS: From nonfasting blood samples collected at 28 wk of gestation, we measured serum total LC-PUFA concentrations and FADS1 (rs174537, rs174561), FADS1-FADS2rs3834458, and FADS2rs174575 genotypes, with hair total mercury concentrations assessed at delivery. Data were available for n = 1236 mother-child pairs. Associations of maternal LC-PUFAs, MeHg, and FADS genotype with birth outcomes were assessed by multiple linear regression models, adjusting for child sex, gestational age, maternal age, BMI, alcohol use, socioeconomic status, and parity. RESULTS: In our cohort of healthy mothers, neither maternal LC-PUFA status nor MeHg exposure were significant determinants of birth outcomes. However, when compared with major allele homozygotes, mothers who were heterozygous for the minor allele of FADS1 (rs174537 and rs174561, GT compared with TT, ß = 0.205, P = 0.03; TC compared with CC, ß = 0.203, P = 0.04) and FADS1-FADS2 (rs3834458, Tdel compared with DelDel, ß = 0.197, P = 0.04) had infants with a greater head circumference (all P < 0.05). Homozygosity for the minor allele of FADS2 (rs174575) was associated with a greater birth weight (GG compared with CC, ß = 0.109, P = 0.04). CONCLUSIONS: In our mother-child cohort, neither maternal LC-PUFA status nor MeHg exposure was associated with birth outcomes. The observed associations of variation in maternal FADS genotype with birth outcomes should be confirmed in other populations.

Rethinking the Minamata Tragedy: What Mercury Species Was Really Responsible?

Industrial release of mercury into the local Minamata environment with consequent poisoning of local communities through contaminated fish and shellfish consumption is considered the classic case of environmental mercury poisoning. However, the mercury species in the factory effluent has proved controversial, originally suggested as inorganic, and more recently as methylmercury species. We used newly available methods to re-examine the cerebellum of historic Cat 717, which was fed factory effluent mixed with food to confirm the source. Synchrotron high-energy-resolution fluorescence detection-X-ray absorption spectroscopy revealed sulfur-bound organometallic mercury with a minor ß-HgS phase. Density functional theory indicated energetic preference for α-mercuri-acetaldehyde as a waste product of aldehyde production. The consequences of this alternative species in the "classic" mercury poisoning should be re-evaluated.

Methylmercury and long chain polyunsaturated fatty acids are associated with immune dysregulation in young adults from the Seychelles child development study.

BACKGROUND: Exposure to the environmental toxicant mercury (Hg) has been associated with immune dysregulation, including autoimmune disease, but few human studies have examined methylmercury (MeHg) exposure from fish consumption. OBJECTIVES: We examined associations between MeHg exposure and biological markers of autoimmunity and inflammation while adjusting for long chain polyunsaturated fatty acids (LCPUFA). METHOD: At age 19 years, hair total Hg (Y19Hg), LCPUFA status, a panel of 13 antinuclear antibodies (ANA), total serum immunoglobulins (Ig) IgG, IgA, and IgM and serum markers of inflammation (IL-1, IL-2, IL-6, IL-10, C-reactive protein (CRP), IFN-γ, TNF-α) were measured in the Seychelles Child Development Study (SCDS) Main Cohort (n = 497). Multivariable regression models investigated the association between Y19Hg and biomarkers, adjusting for prenatal total hair Hg (MatHg) and other relevant covariates, and with and without adjustment for LCPUFA. RESULTS: With each 1 ppm increase in Y19Hg (mean 10.23 (SD 6.02) ppm) we observed a 4% increased odds in a positive Combined ANA following adjustment for the n6:n3 LCPUFA ratio (ß = 0.036, 95%; CI: 0.001, 0.073). IgM was negatively associated with Y19Hg (ß = -0.016, 95%CI: 0.016, -0.002) in models adjusted for n-3, n-6 LCPUFA and when separately adjusted for the n-6:n-3 LCPUFA ratio. No associations were observed with MatHg. Total n-3 LCPUFA status was associated with reduced odds of a positive anti-ribonuclear protein (RNP) A. The n-3 LCPUFA were negatively associated with IL-6, IL-10, CRP, IFN-γ, TNF-α and positively with TNF-α:IL-10. There were positive associations between the n-6:n-3 ratio and IL-6, IL-10, CRP, IFN-γ, TNF-α and a negative association with TNF-α:IL-10. DISCUSSION: The Y19Hg exposure was associated with higher ANA and lower IgM albeit only following adjustment for the n-3 LCPUFA or the n-6:n-3 LCPUFA ratio. The clinical significance of these findings is unclear, but warrant follow up at an older age to determine any relationship to the onset of autoimmune disease.

PUFA Status and Methylmercury Exposure Are Not Associated with Leukocyte Telomere Length in Mothers or Their Children in the Seychelles Child Development Study.

Background: Leukocyte telomere length (TL) is associated with age-related diseases and early mortality, but there is a lack of data on the determinants of TL in early life. Evidence suggests that dietary intake of marine n-3 (ω-3) polyunsaturated fatty acids (PUFAs) is protective of telomere attrition, yet the effect of methylmercury exposure, also found in fish, on TL is unknown.Objective: The aim of this study was to investigate the associations between prenatal PUFA status, methylmercury exposure, and TL in mothers and children in the SCDS (Seychelles Child Development Study), for whom fish consumption is high.Methods: Blood samples collected from 229 mothers (at 28 wk gestation and delivery) and children (at 5 y of age) in the SCDS first nutrition cohort were analyzed for PUFA concentrations. Prenatal mercury was measured in maternal hair collected at delivery. Postnatal mercury was also measured in children's hair samples with the use of a cumulative metric derived from values obtained at 3-5 y of age. Relative TL was measured in blood obtained from mothers at delivery, in cord blood, and in children at 5 y of age by quantitative polymerase chain reaction. Linear regression models were used to investigate the associations between PUFA status, methylmercury exposure, and TL.Results: Neither prenatal PUFA status or methylmercury exposure was associated with TL of the mother or child or with TL attrition rate. However, a higher prenatal n-6:n-3 PUFA ratio was significantly associated with longer TLs in the mothers (ß = 0.001, P = 0.048). Child PUFA status and methylmercury exposure were not associated with child TL. However, higher family Hollingshead socioeconomic status (SES) scores at 9 mo of age were significantly associated with longer TLs in cord blood (ß = 0.005, P = 0.03).Conclusions: We found no evidence that PUFA status or methylmercury exposure are determinants of TL in either the mother or child. However, our results support the hypothesis that family SES may be associated with child TL.

The collagen binding protein Cnm contributes to oral colonization and cariogenicity of Streptococcus mutans OMZ175.

Streptococcus mutans is the etiological agent of dental caries and one of the many bacterial species implicated in infective endocarditis. The expression of the collagen-binding protein Cnm by S. mutans has been associated with extraoral infections, but its relevance for dental caries has only been theorized to date. Due to the collagenous composition of dentinal and root tissues, we hypothesized that Cnm may facilitate the colonization of these surfaces, thereby enhancing the pathogenic potential of S. mutans in advancing carious lesions. As shown for extraoral endothelial cell lines, Cnm mediates the invasion of oral keratinocytes and fibroblasts by S. mutans. In this study, we show that in the Cnm(+) native strain, OMZ175, Cnm mediates stringent adhesion to dentinal and root tissues as well as collagen-coated surfaces and promotes both cariogenicity and carriage in vivo. In vitro, ex vivo, and in vivo experiments revealed that while Cnm is not universally required for S. mutans cariogenicity, it contributes to (i) the invasion of the oral epithelium, (ii) enhanced binding on collagenous surfaces, (iii) implantation of oral biofilms, and (IV) the severity of caries due to a native Cnm(+) isolate. Taken together, our findings reveal that Cnm is a colonization factor that contributes to the pathogenicity of certain S. mutans strains in their native habitat, the oral cavity.

Implementation of a 4Ms approach in age-friendly oral health care at an Academic Specialty Care Dental Clinic.

BACKGROUND: Implementing the Age-Friendly Health System (AFHS) framework into dental care provides a significant opportunity to link oral health to healthy aging. This project aimed to implement the AFHS 4Ms (what matters, medications, mentation, and mobility) in the provision of oral health care. This article describes the planning, integration, training development, and outcome measurements supporting a 4Ms approach at an academic dental clinic. METHODS: The Eastman Institute for Oral Health (EIOH) implemented screening instruments based on the 4Ms framework recommended for ambulatory care clinics by the Institute for Health Care Improvement (IHI). These ambulatory instruments were integrated into the workflows of a Specialty Care Clinic through the development of a plan-do-study-act cycle, utilization of available clinic resources, and creation of interdisciplinary collaborations. RESULTS: This project demonstrated the feasibility of implementing an AFHS checklist and tracking forms in dental practice by integrating available resources and prioritizing the 4Ms elements. This effort necessitated interdisciplinary collaborations between dental, medical, and social service professionals. It also created a new age-friendly focused education and training curriculum for dental residents and faculty. CONCLUSIONS: This pilot project is the first to establish dental standards for AFHS implementation, adapting the 4Ms assessment and metrics to oral health. This AFHS underscores key oral health processes, including assessment, planning, and personalized oral health care, adapted to the unique needs of the older adult population, especially those with cognitive impairment.

Psychosocial Risk Exposure Limits Routine Pediatric Oral Health Care.

Introduction: This study aimed to identify social, psychological, and contextual factors that influenced attendance at routine oral health visits in a cohort of 189 preschool children who were followed over a 2-year period. Methods: Generalized estimating equation was used to examine the association between clinic attendance and the predictors. ORs and 95% CIs were reported in the multiple logistic regression models. The study was conducted in Rochester, New York, between February 2016 and February 2021. Results: Prior to the COVID-19 pandemic declaration, the rate of canceled and no-show appointments was greater for routine clinic visits (20% and 24%, respectively) than for research visits (14% and 9%, respectively) for the same participants; these rates increased during the pandemic. After adjusting for sociodemographic factors, the likelihood of a canceled or no-show appointment was associated with parental depression (OR=1.06, CI=1.03, 1.09), regardless of the type or occurrence of the visit. Conclusions: Findings from this study demonstrate that attendance to oral health care in young children is reliably reduced with parental depression and that this may provide one mechanism for early emerging health inequalities of oral health.

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.

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.

Autism spectrum disorder phenotypes and prenatal exposure to methylmercury.

BACKGROUND: There continues to be public concern that mercury exposure and autism spectrum disorder (ASD) may be associated. The primary source of exposure to organic mercury in humans is to methylmercury from fish consumption. We evaluated the association between prenatal methylmercury exposure and ASD phenotype in children and adolescents in the Republic of Seychelles, where fish consumption is high. METHODS: We administered the Social Communication Questionnaire to parents of a cohort of 1784 children, adolescents, and young adults. The Social Responsiveness Scale was administered to teachers of 537 cohort subjects at about 10 years of age. Prenatal exposure to methylmercury was measured in maternal hair samples collected at or near the time of birth. Multivariable regression models evaluated the relationship between prenatal methylmercury exposure and ASD phenotypic scores, adjusting for relevant covariates. RESULTS: The mean prenatal methylmercury exposure for subjects in the analysis was 8.4 ppm (standard deviation [SD] = 5.7). The mean Social Communication Questionnaire score was 8.0 (SD = 4.4). The mean prenatal methylmercury exposure for subjects with Social Responsiveness Scale scores was 6.7 ppm (SD = 4.4) and the mean Social Responsiveness Scale score was 57.6 (SD = 26.8). No consistent association between prenatal methylmercury exposure and ASD screening instrument was found, using linear and nonlinear regression analyses. CONCLUSIONS: Prenatal exposure to methylmercury was not associated with ASD phenotypic behaviors in our cohort of high fish consumers. Our findings contribute to the growing literature suggesting that exposure to methylmercury does not play an important role in the development of ASD phenotypic behavior.

Choline status and neurodevelopmental outcomes at 5 years of age in the Seychelles Child Development Nutrition Study.

Choline is an essential nutrient that is found in many food sources and plays a critical role in the development of the central nervous system. Animal studies have shown that choline status pre- and postnatally can have long-lasting effects on attention and memory; however, effects in human subjects have not been well studied. The aim of the present study was to examine the association between plasma concentrations of free choline and its related metabolites in children and their neurodevelopment in the Seychelles Child Development Nutrition Study, an ongoing longitudinal study assessing the development of children born to mothers with high fish consumption during pregnancy. Plasma concentrations of free choline, betaine, dimethylglycine (DMG), methionine and homocysteine and specific measures of neurodevelopment were measured in 210 children aged 5 years. The children's plasma free choline concentration (9·17 (sd 2·09) µmol/l) was moderately, but significantly, correlated with betaine (r 0·24; P= 0·0006), DMG (r 0·15; P= 0·03), methionine (r 0·24; P= 0·0005) and homocysteine (r 0·19; P= 0·006) concentrations. Adjusted multiple linear regression revealed that betaine concentrations were positively associated with Preschool Language Scale ­ total language scores (ß = 0·066; P= 0·04), but no other associations were evident. We found no indication that free choline concentration or its metabolites, within the normal physiological range, are associated with neurodevelopmental outcomes in children at 5 years of age. As there is considerable animal evidence suggesting that choline status during development is associated with cognitive outcome, the issue deserves further study in other cohorts.

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.

The association of auditory function measures with low-level methylmercury from oceanic fish consumption and mercury vapor from amalgam: The Seychelles Child Development Study Nutrition 1 Cohort.

BACKGROUND: Some authors have reported that low-level exposure to methylmercury (MeHg) adversely impacts measures of auditory function. These reports, however, are not consistent in their findings. Consequently, we examined auditory function in a population exposed to low-level methylmercury (MeHg) exposure from fish consumption and to mercury vapor (Hg0) from dental amalgams. We analyzed their associations with the participants hearing acuity, absolute and interwave ABR latencies, and otoacoustic emissions (distortion product/DPOAE and click evoked/CEOAE). DESIGN: We administered an audiometry test battery to 246 participants from the Seychelles Child Development Study (SCDS) Nutrition Cohort 1 (NC1) at 9 years of age. The test battery included standard pure-tone audiometry, tympanometry, Auditory Brainstem Responses (ABR) and Distortion Product and Click Evoked Otoacoustic Emissions (DPOAE and CEOAE) testing. We measured prenatal MeHg exposure in maternal hair and postnatal MeHg in children's hair. We approximated prenatal Hg0 exposure using maternal amalgam surface area and postnatal Hg0 using children amalgam surface area. Complete exposure records and audiometric data were available on 210 participants and in them we analyzed the association of MeHg and Hg0 exposures with auditory outcomes using covariate-adjusted linear regression models adjusted for sex and tympanometric pressure. RESULTS: Hg exposures were similar for both sexes. Seven of the 210 evaluable participants examined had either a mild (5) or moderate (2) hearing loss. Four had a mild monaural hearing loss and 3 had either a mild (1) or moderate (2) bilateral hearing loss. No participant had greater than a moderate hearing loss in either ear. Hg exposures were higher in participants with either a mild or moderate hearing loss, but these differences were not statistically significant. Among the 210 with complete data, neither prenatal nor postnatal MeHg nor Hg0 exposure was statistically significantly associated with any of the ABR endpoints (p > 0.05 for all 72 associations). Neither prenatal nor postnatal Hg0 exposure was associated with any of the OAE endpoints (p > 0.05). MeHg exposure was statistically associated with 6 of the 56 DPOAE endpoints (p-values between 0.0001 and 0.023), but none of the 40 CEOAE endpoints. Two of the associations occurred with prenatal MeHg exposures and 1 of those would suggest a beneficial effect. Four of the other associations occurred with postnatal MeHg exposures with only 2 found in left ears of both males and females and the other 2 in the left and right ear of females at only one frequency. CONCLUSION: Overall, these data do not present a clear and consistent pattern to suggest that the auditory system is negatively affected by low-level methylmercury exposure due to dietary consumption of oceanic fish or mercury vapor exposure from dental amalgams.

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.

Postnatal methylmercury exposure and neurodevelopmental outcomes at 7 years of age in the Seychelles Child Development Study Nutrition Cohort 2.

BACKGROUND: Consumption of fish yields many nutritional benefits, but also results in exposure to methylmercury (MeHg). The developing brain is known to be particularly susceptible to MeHg toxicity in high doses. However, the potential impact of low-level environmental exposure from fish consumption on children's neurodevelopment remains unclear. METHODS: We investigated postnatal MeHg exposure at 7 years and its association with a battery of 17 neurodevelopmental outcomes in a subset of children (n = 376) from 1535 enrolled mother-child pairs in Nutrition Cohort 2 of the Seychelles Child Development Study (SCDS NC2). Each outcome was modeled in relation to postnatal MeHg exposure using linear regression, adjusting for prenatal MeHg exposure, levels of maternal polyunsaturated fatty acids (PUFA), and several other covariates known to be associated with neurodevelopmental outcomes. RESULTS: Median postnatal MeHg exposure at 7 years was 2.5 ppm, while the median prenatal MeHg exposure was 3.5 ppm. We found no statistically significant associations between postnatal MeHg exposure and any of the 17 neurodevelopmental outcomes after adjusting for prenatal MeHg exposure and other covariates. CONCLUSIONS: These findings are consistent with previous cross-sectional analyses of the SCDS Main Cohort. Continued follow-up of the entire NC2 cohort at later ages with repeated exposure measures is needed to further confirm these findings.