Separation of Risks and Benefits of Seafood Intake (original) (raw)
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Effects of Prenatal and Postnatal Methylmercury Exposure From Fish Consumption on Neurodevelopment
JAMA, 1998
Context.-Human neurodevelopmental consequences of exposure to methylmercury (MeHg) from eating fish remain a question of public health concern. Objective.-To study the association between MeHg exposure and the developmental outcomes of children in the Republic of Seychelles at 66 months of age. Design.-A prospective longitudinal cohort study. Participants.-A total of 711 of 779 cohort mother-child pairs initially enrolled in the Seychelles Child Development Study in 1989. Setting.-The Republic of Seychelles, an archipelago in the Indian Ocean where 85% of the population consumes ocean fish daily. Main Outcome Measures.-Prenatal and postnatal MeHg exposure and 6 age-appropriate neurodevelopmental tests: the McCarthy Scales of Children's Abilities, the Preschool Language Scale, the Woodcock-Johnson Applied Problems and Letter and Word Recognition Tests of Achievement, the Bender Gestalt test, and the Child Behavior Checklist. Results.-The mean maternal hair total mercury level was 6.8 ppm and the mean child hair total mercury level at age 66 months was 6.5 ppm. No adverse outcomes at 66 months were associated with either prenatal or postnatal MeHg exposure. Conclusion.-In the population studied, consumption of a diet high in ocean fish appears to pose no threat to developmental outcomes through 66 months of age.
Journal of Epidemiology, 2013
Background: Mercury is a neurotoxin, and limited prenatal exposure to it can affect long-term child neurodevelopment. However, results of epidemiologic studies of such exposure have been inconsistent. We examined the association of prenatal mercury exposure from maternal fish consumption with child neurodevelopment in northern Italy. Methods: A population-based cohort of 606 children and their mothers was studied from pregnancy to age 18 months. Mercury levels were measured in maternal hair and blood during pregnancy and in umbilical cord blood and breast milk. Levels of polyunsaturated fatty acids (PUFAs) were measured in maternal serum. Maternal and child intakes of fish were assessed by using a food frequency questionnaire. The Bayley Scales of Infant and Toddler Development, Third Edition (BSID-III) was used to evaluate child neurodevelopment. Multivariate linear regression was used to examine the association of mercury exposure with BSID-III scores, after controlling for maternal fish intake, PUFAs during pregnancy, and several other confounders. Results: Mean weekly fish intake during pregnancy was less than 2 servings. Mercury concentrations in biological samples were low (mean, 1061 ng/g in hair) and moderately correlated with fish intake, particularly of carnivorous species. Maternal ω-3 PUFA concentrations were poorly correlated with fish intake. Maternal intelligence quotient (IQ) and child intake of fish were significantly associated with neurodevelopment scores. In multivariate models, the level of Hg exposure was not associated with neurodevelopmental performance at 18 months. Conclusions: In this Italian population, neurodevelopment at 18 months was associated with child intake of fresh fish and maternal IQ rather than with mercury exposure. The expected beneficial effect of maternal fish intake (from maternal ω-3 PUFAs) was not found.
Nutrient and Methyl Mercury Exposure from Consuming Fish
The Journal of Nutrition, 2007
There is controversy about the risks and benefits of consuming fish. Fish consumption provides nutrients, some of which are essential for brain growth and development. All fish, however, contain methyl mercury (MeHg), a known neurotoxicant. The toxic effect of MeHg seems most damaging during brain development, and thus, prenatal exposure is of greatest concern. At present the level of prenatal exposure associated with risk to a child's neurodevelopment is not known. Balancing the rewards and possible risks of fish consumption presents a dilemma to consumers and regulatory authorities. We review the nutrients in fish that are important in brain development and the current evidence of risk from MeHg at exposure levels achieved by consuming fish. We then review the findings from a large prospective cohort study of a population that consumes fish daily, the Seychelles Child Development Study. The MeHg content of the fish consumed in the Seychelles is similar to that of ocean fish available in industrialized countries, so they represent a sentinel population for any risk from fish consumption. In the Seychelles, evaluations of the children through 9 y of age show no consistent pattern of adverse associations with prenatal MeHg exposure. Recent studies in the Seychelles have focused on nutrients in fish that might influence a child's development, including long-chain polyunsaturated fatty acids, iodine, iron, and choline. Preliminary findings from this study suggest that the beneficial influence of nutrients from fish may counter any adverse effects of MeHg on the developing nervous system.
NeuroToxicology, 2008
Fish contain nutrients that promote optimal brain growth and development but also contain methylmercury (MeHg) that can have toxic effects. The present study tested the hypothesis that the intake of selected nutrients in fish or measures of maternal nutritional status may represent important confounders when estimating the effects of prenatal methylmercury exposure on child development. The study took place in the Republic of Seychelles, an Indian Ocean archipelago where fish consumption is high. A longitudinal cohort study design was used. A total of 300 mothers were enrolled early in pregnancy. Nutrients considered to be important for brain development were measured during pregnancy along with prenatal MeHg exposure. The children were evaluated periodically to age 30 months. There were 229 children with complete outcome and covariate data for analysis. The primary endpoint was the Bayley Scales of Infant Development-II (BSID-II), administered at 9 and 30 months of age. Combinations of four secondary measures of infant cognition and memory were also given at 5, 9 and 25 months. Cohort mothers consumed an average of 537 gm of fish (9 meals containing fish) per week. The average prenatal MeHg exposure was 5.9 ppm in maternal hair. The primary analysis examined the associations between MeHg, maternal nutritional measures and children's scores on the BSID-II and showed an adverse association between MeHg and the mean Psychomotor Developmental Index (PDI) score at 30 months. Secondary analyses of the association between the PDI and only MeHg alone or nutritional factors alone showed only a borderline significant association between MeHg and the PDI at 30 months and no associations with nutritional factors. One experimental measure at 5 months of age was positively associated with iodine status, but not prenatal MeHg exposure. These findings suggest a possible confounding role of maternal nutrition in studies examining associations between prenatal MeHg exposures and developmental outcomes in children.
The American journal of clinical nutrition, 2015
Fish is a rich source of n-3 polyunsaturated fatty acids (PUFAs) but also contains the neurotoxicant methyl mercury (MeHg). PUFAs may modify the relation between prenatal MeHg exposure and child development either directly by enhancing neurodevelopment or indirectly through the inflammatory milieu. The objective was to investigate the associations of prenatal MeHg exposure and maternal PUFA status with child development at 20 mo of age. The Seychelles Child Development Study Nutrition Cohort 2 is an observational study in the Republic of Seychelles, a high-fish-eating population. Mothers were enrolled during pregnancy and their children evaluated at 20 mo of age by using the Bayley Scales of Infant Development II (BSID-II), the MacArthur Bates Communicative Development Inventories (CDI), and the Infant Behavior Questionnaire-Revised. There were 1265 mother-child pairs with complete data. Prenatal MeHg exposure had no direct associations with neurodevelopmental outcomes. Significant ...
NeuroToxicology, 2009
Background-Fish is an important source of nutrition worldwide. Fish contain both the neurotoxin methyl mercury (MeHg) and nutrients important for brain development. The developing brain appears to be most sensitive to MeHg toxicity and mothers who consume fish during pregnancy expose their fetus prenatally. Although brain development is most dramatic during fetal life, it continues for years postnatally and additional exposure can occur when a mother breast feeds or the child consumes fish. This raises the possibility that MeHg might influence brain development after birth and thus adversely affect children's developmental outcomes. We reviewed postnatal MeHg exposure and the associations that have been published to determine the issues associated with it and then carried out a series of analyses involving alternative metrics of postnatal MeHg exposure in the Seychelles Child Development Study (SCDS) Main Cohort. Methods-The SCDS is a prospective longitudinal evaluation of prenatal MeHg exposure from fish consumption. The Main Cohort includes 779 subjects on whom recent postnatal exposure data were collected at the 6, 19, 29, 66, and 107 month evaluations. We examined the association of recent postnatal MeHg exposure with multiple 66 and 107-month outcomes and then used three types of alternative postnatal exposure metrics to examine their association with the children's intelligence quotient (IQ) at 107 months of age. Results-Recent postnatal exposure at 107 months of age was adversely associated with four endpoints, three in females only. One alternative postnatal metric was beneficially associated with 9-year IQ in males only.
Bulletin of the World Health Organization, 2014
Systematic reviews Global mercury exposure from seafood Mary C Sheehan et al. 1. "fetus" OR "infant" OR "newborn" OR "maternal" OR "mother" OR "pregnant" OR "women" 2. "fish" OR "marine" OR "shellfish" OR "seafood" 3. "mercury" OR "methylmercury" OR "methyl AND mercury" OR "biomonitoring" Combined terms: 1 AND 2 AND 3. Note: The following databases were searched for studies published from January 1991 to September 2013: PubMed, Embase, SCOPUS, Web of Science, TOXNET and LILACS. References were hand-checked and there were no restrictions on language or study design. Systematic reviews Global mercury exposure from seafood Mary C Sheehan et al.
International Journal of Epidemiology, 2016
Background: Vulnerability of the central nervous system to mercury exposure is increased during early development. The aim of this study is to evaluate the association between prenatal exposure to mercury and child neuropsychological development in high-fish-intake areas in Spain. Methods: Study subjects were 1362 children, participants in the INMA (Environment and Childhood) birth cohort study. Cord blood total mercury (CB-Hg) and cord polyunsaturated fatty acids (PUFA) concentrations were analysed in samples collected between 2004 and 2008. Child neuropsychological development was assessed at age 4-5 years by the McCarthy Scales of Children's Abilities (MSCA). Socio-demographic, lifestyle and dietary information was obtained by questionnaires administered during pregnancy and childhood. Results: The geometric mean of CB-Hg was 8.8 mg/L [95% confidence interval (CI) 8.4, 9.2]. A doubling in CB-Hg was associated with higher scores in most of the MSCA scales (b¼1.29; 95% CI 0.28, 2.31 for the general cognitive scale). The association between
The Lancet, 2003
Exposure to methylmercury (MeHg) before birth can adversely affect children's neurodevelopment. The most common form of prenatal exposure is maternal fish consumption, but whether such exposure harms the fetus is unknown. We aimed to identify adverse neurodevelopmental effects in a fish-consuming population. We investigated 779 mother-infant pairs residing in the Republic of Seychelles. Mothers reported consuming fish on average 12 meals per week. Fish in Seychelles contain much the same concentrations of MeHg as commercial ocean fish elsewhere. Prenatal MeHg exposure was determined from maternal hair growing during pregnancy. We assessed neurocognitive, language, memory, motor, perceptual-motor, and behavioural functions in children at age 9 years. The association between prenatal MeHg exposure and the primary endpoints was investigated with multiple linear regression with adjustment for covariates that affect child development. Mean prenatal MeHg exposure was 6.9 parts per million (SD 4.5 ppm). Only two endpoints were associated with prenatal MeHg exposure. Increased exposure was associated with decreased performance in the grooved pegboard using the non-dominant hand in males and improved scores in the hyperactivity index of the Conner's teacher rating scale. Covariates affecting child development were appropriately associated with endpoints. These data do not support the hypothesis that there is a neurodevelopmental risk from prenatal MeHg exposure resulting solely from ocean fish consumption.