Prenatal Mercury Research Articles

Incidence of attention-deficit and hyperactivity disorder among school children in Riyadh city and its association with body burden of mercury leached from dental amalgam fillings: A cross-sectional study

Objectives: The objectives of this study are to determine the association between the incidence of attention-deficit and hyperactivity disorder (ADHD) in children of mothers with and without amalgam fillings. Design: The study design was a cross-sectional descriptive study. Setting: The study was conducted at a dental college's clinic in Riyadh, Saudi Arabia. Participants: In total, 869 children (512 males and 357 females) aged 6–12 years and 796 mothers were included. Children suffering from hearing impairment, language impairment, or learning disabilities or those diagnosed with mental health problems were excluded from the study. Primary and Secondary Outcome Measures: The primary outcome measures included the results of the Vanderbilt scale used for ADHD diagnosis in children and the mercury concentration in 1 ml saliva samples obtained from both the mother and the children. The secondary outcome measures included the number of dental amalgam restorations in the oral cavity determined through a dental examination of children and their mothers. Methodology: A consent form was signed by the mothers who agreed to participate in our study, they were all examined for amalgam presence and a saliva samples were collected and digested. Results: Children with ADHD showed significantly higher levels of mercury in saliva than did children without ADHD. The mothers who had dental amalgam fillings during pregnancy had significantly higher mercury levels than did the mothers who did not have dental amalgam fillings. Conclusion: Prenatal mercury exposure is associated with a higher risk of ADHD behavior. Further research can be carried out to identify the toxic effects of mercury on different body organs owing to dental amalgam fillings. The study scale can be further increased to obtain a more accurate percentage of ADHD cases in Saudi Arabia.

Diffusion Imaging of the Corpus Callous in Inuit Adolescents Chronically Exposed to Methylmercury

Background: In comparison to the general population, the Inuit community of Northern Quebec (Nunavik) is highly exposed to environmental contaminants, in particular methylmercury. Impairments of cognitive and sensory functions in association with prenatal mercury (Hg) exposure have been previously reported in a longitudinal mother-child cohort study, the Nunavik Child Development Study (NCDS), but the brain substrates of these deficits remain to be elucidated.Methods: This study aimed at determining whether microstructural integrity of the corpus callosum, a structure implied in several brain functions, is altered by Hg exposure in 75 NCDS adolescent/young-adult participants (Mean age=18.4y; Range=16.2 to 21.9y) using diffusion Magnetic Resonance Imaging (MRI). The general fractional anisotropy (GFA) metric was extracted for 7 sections of the corpus callosum. The association between GFA and Hg blood levels at birth and at the time of MRI assessment was determine using multiple linear regressions after controlling for sex, age, alcohol/drugs dependence and co-exposure to selenium.Results: Results show that cord Hg was associated with a decrease of GFA in the rostrum (β = -.33, p = .02), i.e., the anterior part of the corpus callosum that connect the frontal lobes. This result remained significant after controlling for Hg level at time of assessment (β = -.35, p = .03). Hg level at time of assessment was associated with splenium GFA (β = .30, p = .03), the posterior section of the corpus callosum that connect the occipital cortices. However, this association was no longer significant after controlling for cord Hg (β = .26, p = .11).Conclusions: Exposure to Hg, especially exposure during fetal development, is associated with microstructural alterations of the corpus callosum in NCDS adolescents. These results are in agreement with previous findings reporting that prenatal exposure to Hg was associated with a decreased IQ and alterations in visual processing.

Prenatal mercury exposure and child neurodevelopment outcomes at 18 months: Results from the Mediterranean PHIME cohort.

Neurotoxicity due to acute prenatal exposure to high-dose of mercury (Hg) is well documented. However, the effect of prenatal exposure to low Hg levels on child neurodevelopment and the question about "safety" of fish-eating during pregnancy remain controversial. International comparisons of Hg concentrations in mother-child biological samples and neurodevelopmental scores embedded in birth cohort studies may provide useful evidence to explore this issue. The Mediterranean (Italy, Slovenia, Croatia, and Greece) cohort study included 1308 mother-child pairs enrolled in the Public Health Impact of long-term, low-level, Mixed Element exposure in a susceptible population EU Sixth Framework Programme (PHIME). Maternal hair and venous blood, cord blood and breast milk samples were collected, and total Hg (THg) levels were measured. Demographic and socioeconomic information, lifestyles and nutritional habits were collected through questionnaires at different phases of follow-up. Children at 18 months of age underwent neurodevelopmental testing using the Bayley Scales of Infant and Toddler Development, Third Edition (BSID-III). Multivariate linear and logistic regressions were performed, for each country, to assess the association between THg and BSID-III scores, obtaining adjusted β coefficients and odds ratios (ORs). These values were used to conduct a meta-analysis, to explore possible heterogeneity among countries and to obtain combined estimates of the association between THg exposure and BSID-III scores. Median THg (ng/g) was: 704 in maternal hair, 2.4 in maternal blood, 3.6 in cord blood, and 0.6 in breast milk. THg concentrations were highest in Greece and lowest in Slovenia. BSID-III neurodevelopmental scores were higher in Croatia and Slovenia. The meta-analysis of multivariate linear models found an overall positive association between language composite score and receptive communication scaled score and increasing THg in maternal hair (n = 1086; β = 0.55; 95%CI: 0.05-1.05 and n = 1075; β = 0.12; 95%CI: 0.02-0.22, respectively). The meta-analysis of logistic regression models showed that the overall adjusted OR between THg in cord blood and suboptimal gross motor score was borderline significant (n = 882; OR = 1.03; 95%CI: 1.00-1.07). Heterogeneity was found across the four sub-cohorts for language composite score in maternal blood, and for fine motor scaled score in cord blood and breast milk. Language composite score and THg concentrations in maternal venous blood were positively related (n = 58; β = 4.29; CI95% (-0.02, 8.60)) in Croatia and an increase of 1 ng/g of THg in maternal venous blood was associated with a reduced risk for children to fall in the lowest quintile of language score by 31% (n = 58; OR = 0.69; CI 95%: 0.37, 1.01). The comparison of β coefficients obtained by multiple linear regression model showed an inverse association between fine motor score and THg concentrations in cord blood for Croatia (n = 54; β = -0.53; CI 95%: -1.10, 0.04) and Slovenia (n = 225; β = -0.25; CI 95%: -0.49, -0.01). In Slovenia THg level in breast milk was associated with suboptimal fine motor performance (n = 195; OR = 5.25; CI 95%: 1.36, 21.10). This study showed an inverse relation between THg levels and developmental motor scores at 18 months, although the evidence was weak and partially internally and externally inconsistent. No evidence of detrimental effects of THg was found for cognitive and language outcomes at these concentrations and age.

Prenatal lead, cadmium and mercury exposure and associations with motor skills at age 7 years in a UK observational birth cohort

BackgroundLead and mercury are freely transferred across the placenta, while cadmium tends to accumulate in the placenta. Each contributes to adverse neurological outcomes for the child. Although prenatal heavy metal exposure has been linked with an array of neurodevelopmental outcomes in childhood, its association with the development of motor skills in children has not been robustly studied. Aims/objectiveThe aim of the present study was to investigate the association between prenatal exposure to lead, cadmium and mercury, measured as maternal blood concentrations during pregnancy, and motor skills, measured as subtests of the Movement Assessment Battery for Children (Movement ABC) at age 7 years in a large sample of mother–child pairs enrolled in a UK observational birth cohort study (Avon Longitudinal Study of Parents and Children, ALSPAC). MethodsWhole blood samples from pregnant women enrolled in ALSPAC were analysed for lead, cadmium and mercury. In a complete case analysis (n = 1558), associations between prenatal blood concentrations and child motor skills assessed by Movement ABC subtests of manual dexterity, ball skills and balance at 7 years were examined in adjusted regression models. Associations with probable developmental coordination disorder (DCD) were also investigated. ResultsThe mean prenatal blood levels were: lead 3.66 ± 1.55 μg/dl; cadmium 0.45 ± 0.54 μg/l; mercury 2.23 ± 1.14 μg/l. There was no evidence for any adverse associations of prenatal lead, cadmium or mercury exposure with motor skills measured at age 7 years with Movement ABC subtests in adjusted regression models. Further, there were no associations with probable DCD. ConclusionsThere was no evidence to support a role of prenatal exposure to heavy metals at these levels on motor skills in the child at age 7 years measured using the Movement ABC. Early identification of symptoms of motor skills impairment is important, however, to enable investigation, assessment and treatment.

Prenatal mercury exposure and features of autism: a prospective population study

BackgroundMercury (Hg) has been suspected of causing autism in the past, especially a suspected link with vaccinations containing thiomersal, but a review of the literature shows that has been largely repudiated. Of more significant burden is the total quantity of Hg in the environment. Here, we have used the Avon Longitudinal Study of Parents and Children (ALSPAC) to test whether prenatal exposure from total maternal blood Hg in the first half of pregnancy is associated with the risk of autism or of extreme levels of autistic traits. This is the largest longitudinal study to date to have tested this hypothesis and the only one to have considered early pregnancy.MethodsWe have used three strategies: (1) direct comparison of 45 pregnancies resulting in children with diagnosed autism from a population of 3840, (2) comparison of high scores on each of the four autistic traits within the population at risk (n~2800), and (3) indirect measures of association of these outcomes with proxies for increased Hg levels such as frequency of fish consumption and exposure to dental amalgam (n > 8000). Logistic regression adjusted for social conditions including maternal age, housing circumstances, maternal education, and parity. Interactions were tested between risks to offspring of fish and non-fish eaters.ResultsThere was no suggestion of an adverse effect of total prenatal blood Hg levels on diagnosed autism (AOR 0.89; 95% CI 0.65, 1.22) per SD of Hg (P = 0.485). The only indication of adverse effects concerned a measure of poor social cognition when the mother ate no fish, where the AOR was 1.63 [95% CI 1.02, 2.62] per SD of Hg (P = 0.041), significantly different from the association among the offspring of fish-eaters (AOR = 0.74 [95% CI 0.41, 1.35]).ConclusionIn conclusion, our study identifies no adverse effect of prenatal total blood Hg on autism or autistic traits provided the mother ate fish. Although these results should be confirmed in other populations, accumulating evidence substantiates the recommendation to eat fish during pregnancy.

Total mercury exposure in early pregnancy has no adverse association with scholastic ability of the offspring particularly if the mother eats fish

There is a public perception that relatively low doses of mercury found in seafood are harmful to the fetal brain but little consistent evidence to support this. In earlier publications we have shown no adverse associations between maternal total blood mercury levels and child behaviour, early development or cognitive function as measured by IQ. However, for IQ the lack of adverse association was conditional upon the mother being a fish eater.In this paper we analyse further data from the Avon Longitudinal Study of Parents and Children (ALSPAC), this time examining whether prenatal exposure to total mercury is associated with the child's scholastic abilities in reading, spelling, phoneme awareness, mathematics and science; the number of participants with prenatal mercury and relevant test results varied from 1500 to 2200. Multiple regression was used to assess relationships between prenatal total blood mercury concentrations and 16 different test results, after taking account of a variety of potential confounders; in parallel, logistic regression was used to determine associations with the risk of the child being in the lowest 15% of each score. Analyses were repeated stratifying for fish consumption and sex of the child.There was no evidence of harm associated with the level of total mercury, provided the mother ate fish during pregnancy. This was particularly true for tests of mathematics and science. We conclude that women should be confident that eating fish in pregnancy is beneficial for their unborn child.

Prenatal mercury exposure and birth weight

Adverse effects of prenatal mercury exposure on pregnancy outcomes remain a public health concern. We assessed the relationship between prenatal mercury exposure and newborn anthropometric characteristics in 334 mother-child pairs from the early stages of pregnancy to delivery in Tokyo, Japan, between December 2010 and October 2012. We found a negative correlation between blood mercury levels during the first and second trimesters of gestation and birth weight (r = −0.134 and −0.119, respectively; p < 0.05). Multiple linear regression analysis confirmed the relationship between first-trimester maternal blood mercury levels and birth weight when adjusted for independent variables (β = −0.170, t = −2.762; p = 0.006). Mean mercury levels in umbilical cord blood were twice as high as maternal blood levels (10.15 ± 7.74 and 4.97 ± 3.25 μg/L, respectively; r = 0.974, p < 0.001). Our findings suggest that pregnant women and women of reproductive age should avoid mercury exposure, even at low levels, because of its potentially adverse effects on fetal development.

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

BackgroundLeukocyte 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. ObjectiveThe 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. MethodsBlood 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. ResultsNeither 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 (β = 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 (β = 0.005, P = 0.03). ConclusionsWe 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.

Prenatal mercury exposure, maternal seafood consumption and associations with child language at five years

BackgroundMethyl mercury (MeHg) is a well-known neurotoxin and evidence suggests that also low level exposure may affect prenatal neurodevelopment. Uncertainty exists as to whether the maternal MeHg burden in Norway might affect child neurodevelopment. ObjectiveTo evaluate the association between prenatal mercury exposure, maternal seafood consumption and child language and communication skills at age five. MethodsThe study sample comprised 38,581 mother-child pairs in the Norwegian Mother and Child Cohort Study. Maternal mercury blood concentration in gestational week 17 was analysed in a sub-sample of 2239 women. Prenatal mercury exposure from maternal diet was calculated from a validated FFQ answered in mid-pregnancy. Mothers reported children's language and communications skills at age five by a questionnaire including questions from the Ages and Stages Questionnaire (ASQ), the Speech and Language Assessment Scale (SLAS) and the Twenty Statements about Language-Related Difficulties (language 20). We performed linear regression analyses adjusting for maternal characteristics, nutritional status and socioeconomic factors. ResultsMedian maternal blood mercury concentration was 1.03μg/L, dietary mercury exposure was 0.15μg/kgbw/wk, and seafood intake was 217g/wk. Blood mercury concentrations were not associated with any language and communication scales. Increased dietary mercury exposure was significantly associated with improved SLAS scores when mothers had a seafood intake below 400g/wk in the adjusted analysis. Sibling matched analysis showed a small significant adverse association between those above the 90th percentile dietary mercury exposure and the SLAS scores. Maternal seafood intake during pregnancy was positively associated with the language and communication scales. ConclusionLow levels of prenatal mercury exposure were positively associated with language and communication skills at five years. However, the matched sibling analyses suggested an adverse association between mercury and child language skills in the highest exposure group. This indicates that prenatal low level mercury exposure still needs our attention.

Prenatal mercury exposure, fish intake and neurocognitive development during first three years of life: Prospective cohort mothers and Children's environmental health (MOCEH) study

ObjectivesIn this prospective cohort study, the effects of prenatal Hg exposure on neurocognitive development during the first 3years of life were investigated. MethodsThe maternal blood levels of Hg were assessed during pregnancy and in cord blood. Maternal fish intake was assessed by interviewing the weekly frequency of fish intake during pregnancy. Maternal n-3 and n-6 fatty acid intake was estimated based on 24h recall food intake interview. The mental (MDI) and psychomotor (PDI) development index scores were assessed using the Bayley Scales of Infant Development at 6, 12, 24, 36months of age. ResultsThe geometric mean of the maternal blood Hg concentration was 3.3μg/L (10th percentile=1.81; 90th=5.91) during the early pregnancy, 3.0μg/L (10th=1.68; 90th=5.57) during late pregnancy, and 5.1μg/L (10th=2.94; 90th=8.93) in cord blood. After adjusting for weekly frequency of fish intake, the blood Hg concentrations during early pregnancy showed association with the adjusted MDI (β=−0.408, p=0.048) and PDI scores (β=−0.550, p=0.031) at 6months. After further adjusting for n-3 and n-6 fatty acids estimated based on 24h recall of food intake, the blood Hg concentrations during early pregnancy showed association with the MDI (β=−0.489, p=0.026) and PDI (β=−0.664, p=0.015) at 6months. ConclusionThese results show that prenatal Hg exposure during early pregnancy adversely associated with early neurodevelopment during infancy, after adjusting for fish and n-3, n-6 fatty acid intake. Consuming fish high in fatty acids and low in Hg during early pregnancy may be important to neurocognitive development at early infancy.

Maternal prenatal blood mercury is not adversely associated with offspring IQ at 8 years provided the mother eats fish: A British prebirth cohort study.

BackgroundConflicting evidence concerning possible harm from mercury (Hg) in regard to offspring cognition if the woman eats fish has prompted this study to examine evidence from a British pre-birth cohort to investigate the relationship between the two.MethodsPregnant women (median prenatal blood mercury 1.86 μg/L) resident in the study area with delivery between April 1991 and December 1992 were followed up and verbal, performance and total intelligence quotient (IQ) of 2062 offspring were measured at age 8. Analysis treated IQ as (a) continuous and (b) the lowest 25% of the distribution. Multiple and logistic regression analyses took account of social and demographic variables. Stratification considered children of fish eaters separately.ResultsBefore adjustment, mean full-scale IQ increased with increasing Hg (change with 1SD of Hg = +2.02; 95%CI +1.40,+2.64 IQ points; P < 0.0001); after adjustment effect size was reduced although still positive (+0.61;95%CI -0.06,+1.29 IQ points; P = 0.073). The adjusted positive relationship was stronger when fish-eating mothers were considered separately (+0.84:95%CI +0.13,+1.56 IQ points; P = 0.021) in comparison with the outcomes for non-fish eaters, where the adjusted relationship was negative (-2.22;95%CI -5.00,+0.56 IQ points; P = 0.117). The binary outcome showed a similar pattern with the adjusted OR for non-fish-eaters 1.79 (95%CI 1.10,2.93; P = 0.019) per SD of Hg, significantly different from that for fish consumers (0.94;95%CI:0.82,1.08)(Pinteraction<0.05). There were no differences between the sexes in the associations, nor did the level of the mother’s blood selenium change the effect sizes.ConclusionThe relationship between intrauterine exposure to mercury and offspring IQ appears to be benign provided the mother consumes fish.

Path analysis of prenatal mercury levels and birth weights in Korean and Taiwanese birth cohorts

Prospective cohort studies of the effect of mercury (Hg) exposure on birth weight have shown conflicting results. We combined data from Taiwanese and Korean birth cohorts, and assessed the effects of Hg exposure on birth weight. The first cohort was drawn from the Mothers and Children's Environmental Health (MOCEH) study performed in Korea from 2006 to 2010. The second cohort was enrolled from 2004 to 2005 and included singleton term births from the Taiwan Birth Panel Study (TBPS). In total, 1147 pregnant women were included in this study. A pooled analysis was performed to obtain combined estimates of the association between prenatal total Hg exposure and birth weight. A significant negative association between maternal and cord blood Hg and birth weight in the high-Hg group (Hg level>25th percentile) was detected (maternal blood: β=−0.056; 95% CI, −0.100 to −0.013, cord blood: β=−0.075; 95% CI, −0.121 to −0.028). Hg level showed a negative coefficient in the path analysis, indicating an adverse effect on birth weight (total effects: β=−0.177, P=0.01 in MOCEH, β=−0.204, P=0.03 in TBPS), but fish consumption exhibited a strong positive coefficient. In addition, fish consumption exerted a significant indirect effect on birth weight through exposure to cord blood Hg. Exposure to hazardous contaminants and beneficial nutrients may be highly correlated in those who frequently consume fish. Moreover, Hg in cord blood may adversely affect birth weight.

Associations of prenatal and early childhood mercury exposure with autistic behaviors at 5 years of age: The Mothers and Children's Environmental Health (MOCEH) study

BackgroundAlthough mercury is an established neurotoxin, only few longitudinal studies have investigated the association between prenatal and early childhood mercury exposure and autistic behaviors. MethodsWe conducted a longitudinal cohort study using an ongoing prospective birth cohort initiated in 2006, wherein blood mercury levels were measured at early and late pregnancy; in cord blood; and at 2 and 3years of age. We analyzed 458 mother-child pairs. Autistic behaviors were assessed using the Social Responsiveness Scale (SRS) at 5years of age. Both continuous SRS T-scores and T-scores dichotomized by a score of ≥60 or <60 were used as outcomes. ResultsThe geometric mean of mercury concentrations in cord blood was 5.52μg/L. In adjusted models, a doubling of blood mercury levels at late pregnancy (β=1.84, 95% confidence interval [CI]: 0.39, 3.29), in cord blood (β=2.24, 95% CI: 0.22, 4.27), and at 2years (β=2.12, 95% CI: 0.54, 3.70) and 3years (β=2.80, 95% CI: 0.89, 4.72) of age was positively associated with the SRS T-scores. When the SRS T-scores were dichotomized, we observed positive associations with mercury levels at late pregnancy (relative risk [RR]=1.31, 95% CI: 1.08, 1.60) and in cord blood (RR=1.28, 95% CI: 1.01, 1.63). ConclusionWe found that blood mercury levels at late pregnancy and early childhood were associated with more autistic behaviors in children at 5years of age. Further study on the long-term effects of mercury exposure is recommended.

Factors associated with mercury levels in human placenta and the relationship to neonatal anthropometry in Jamaica and Trinidad & Tobago

The aim of this study was to investigate the mercury levels in human placenta and its relationship to neonatal anthropometry for a group of selected pregnant women in Kingston and Manchester in Jamaica and St. Joseph in Trinidad & Tobago.The participants were interviewed on their fish intake. Neonatal anthropometric data were also recorded. The placental mercury concentrations ranged from 0.64±0.5μg/kg to 1.4±0.6μg/kg. The most significant associated factor for prenatal mercury exposure was maternal fish intake. Those pregnant women who regularly ate shark recorded the highest placenta mercury concentrations. Their neonates also had slightly smaller mean head circumference and lower birth weight.The mean placental mercury concentrations in this study were found to be lower than the literature values. Therefore it was difficult to detect any significant changes in neonatal anthropometry. This type of study can contribute to the extent of mercury exposure in the region.

Persistent DNA methylation changes associated with prenatal mercury exposure and cognitive performance during childhood

Prenatal exposure to mercury, a known neurotoxic metal, is associated with lower cognitive performance during childhood. Disruption of fetal epigenetic programming could explain mercury’s neurodevelopmental effects. We screened for epigenome-wide methylation differences associated with maternal prenatal blood mercury levels in 321 cord blood DNA samples and examined the persistence of these alterations during early (n = 75; 2.9–4.9 years) and mid-childhood (n = 291; 6.7–10.5 years). Among males, prenatal mercury levels were associated with lower regional cord blood DNA methylation at the Paraoxonase 1 gene (PON1) that persisted in early childhood and was attenuated in mid-childhood blood. Cord blood methylation at the PON1 locus predicted lower cognitive test scores measured during early childhood. Methylation at the PON1 locus was associated with PON1 expression in an independent set of cord blood samples. The observed persistent epigenetic disruption of the PON1 gene may modulate mercury toxicity in humans and might serve as a biomarker of exposure and disease susceptibility.

Are prenatal mercury levels associated with subsequent blood pressure in childhood and adolescence? The Avon prebirth cohort study

ObjectivesThere have been conflicting data suggesting that prenatal mercury exposure is associated with adverse cardiovascular measures in children. We therefore analysed a large prospective population study to investigate whether prenatal...

Prenatal mercury exposure and offspring behaviour in childhood and adolescence

BackgroundThere is considerable discussion over the possible harm caused by fetal exposure to mercury, but evidence of such harm is contradictory at levels commonly found in populations with moderate intakes of fish. Further information is needed to inform debate and clarify policy recommendations. MaterialData were collected prospectively for the Avon Longitudinal Study of Parents and Children (ALSPAC). Whole blood taken in the first half of pregnancy was assayed for mercury. The outcomes were offspring behavioural assessments collected using the Strengths and Difficulties Questionnaire at seven time points between ages 4 and 16–17 years; five were completed by the mother and two by the teacher. Socioeconomic and biological confounders were first taken into account; further analyses added maternal blood selenium. Separate analyses compared the relationships between prenatal mercury levels and behaviour traits treated as continuous measures in women who ate fish with those who ate no fish in order to determine whether the relationships differed; the hypothesis was that fish consumption had benefits on the brain and masked any mercury effects. In order to prevent Type II errors, the P value for significance was set at 0.10. ResultsPrenatal mercury measurements and offspring behaviour results were available for between 2776 (at 47 months) to 1599 mother-child pairs (at 16–17 years). Even given a P value of 0.10, the number of significant results was no greater than expected apart from the relationships with peer problems at 4, 6 and 10–11 years where the relationships with prenatal mercury were negative (i.e. the greater the level of mercury the fewer the problems the child had with his/her peers). There were no significant differences between the associations with mercury found among the offspring of women who ate fish in pregnancy and those who did not, nor did adjustment for selenium make a difference. ConclusionsThere were no adverse effects of maternal prenatal mercury levels on the behaviour of the offspring. A similar lack of relationship was found when the analyses were confined to those offspring whose mothers had eaten fish in pregnancy, and no consistent differences were found between the fish and non-fish eaters.

Prenatal mercury exposure, neurodevelopment and apolipoprotein E genetic polymorphism

The aim of the present study was to evaluate the association between prenatal exposure to mercury (Hg) and neurodevelopment of the child, taking into account genetic polymorphism of apolipoprotein E (Apoe) and other relevant confounders. Six hundred and one mother-child pairs were recruited from the central Slovenia region and 243 from Rijeka, on the Croatian coast of the northern Adriatic. The total Hg in cord blood, Bayley Scales of Infant and Toddler Development, Third Edition (Bayley-III) assessment at 18 months of age and Apoe genotyping was performed on 361 children; 237 of them were from Slovenia and 124 from Croatia. The results showed negative association between low-to-moderate Hg exposure in children with normal neurodevelopmental outcome and cognitive and fine motor scores at 18 months of age as assessed by Bayley III. The Hg-related decrease in cognitive score was observed only in children carrying at least one Apoe ε4 allele, while the decrease in fine motor scores was independent of the Apoe genotype. Adjusting for selenium (Se) and lead (Pb) levels, a positive association between Se and the language score and a negative association between Pb and the motor score was observed, but not in the subgroup of children carrying the ε4 allele.

Assessment of fish consumption and mercury exposure among pregnant women in Jamaica and Trinidad & Tobago

BackgroundFish is an essential and traditional element in the diet of most Caribbean people. However it also contains methylmercury which can have severe effects on fetal neurodevelopment. The objective of this study was to assess the fish intake of a selected group of pregnant women from Jamaica and Trinidad & Tobago and evaluate prenatal mercury exposure, using the placenta as a biomarker. MethodFood frequency questionnaires and placental samples were obtained from participating parturients at the time of delivery at the University Hospital of the West Indies in Kingston, Jamaica (N = 100, from November 2012 to March 2013) and the Mt Hope Women's hospital in St Joseph, Trinidad & Tobago (N = 30, in June 2015). The participants were asked to identify the species of fish and the frequency of consumption. Placental samples were analysed for mercury using cold vapour atomic absorption. ResultsThe fish consumption preferences for pregnant women, varies based on the marine fish catch production of each country. The main fish species that contributed to the highest estimated methylmercury exposure in Jamaica and Trinidad & Tobago were cod and shark, respectively. There was a weak association between maternal fish intake and placental mercury concentrations. The mean placental mercury concentrations in Jamaica and Trinidad & Tobago were 0.74 ± 0.5 μg/kg and 1.46 ± 0.6 μg/kg, wet weight respectively. ConclusionThe results from this study showed an influence of Caribbean fish intake preferences on mercury exposure and thus a recommendation for continuous bio-monitoring for public health purposes.

Mercury exposure of late pregnancy contributes to early childhood intelligence at 60 months

Introduction: Many of the studies showed that prenatal mercury exposure have been adversely associated with early childhood intelligence. This study was designed to investigate the relationship whether prenatal mercury exposure at late pregnancy affects their 60 month old children’s intelligence by Mothers and Children’s environmental health (MOCEH) cohort study in Korea. Methods: A multi-center birth cohort project in Korea that began in 2006. We collected the 1202 mother’s blood sample from third trimester pregnant woman and compared the relative contribution of prenatal blood mercury (Hg) to 60 month old children’s intelligence. Mercury level was analyzed by AAS (atomic absorption spectrometry). In sub study(n=518) of this cohort, children of mothers were evaluated their intelligence using the Korean version of the Wechsler Preschool and Primary Scale of Intelligence, revised edition (WPPSI-R) at 60 months of age. Results: The arithmetic mean of log-transformed mercury blood concentration of late pregnancy and the total IQ of 60 month old children were 0.514mg/dL (10th percentile = 1.168; 90th percentile = 0.761; range = -1.456–1.167) and 103.5. In the Linear regression analysis, it showed negative association between prenatal log mercury level and performance (p=0.025), verbal (p=0.022), and total IQ scores (p=0.010) of children after controlling for maternal age, education, income, geographical region, status of breastfeeding, and gender of baby. Conclusions: In conclusion, mercury exposure during late pregnancy is associated with significant reduction in IQ scores at 60 month old children. Pregnant woman should be aware of mercury exposure during their pregnancy to prevent adverse effect of children’s intelligence.