Long term neurocognitive impact of low dose prenatal methylmercury exposure in Hong Kong

Lam, Hugh Simon; Kwok, Ka Ming; Chan, Peggy Hiu Ying; So, Hung‐Kwan; Li, Albert Martin; Ng, Pak Cheung; Fok, Tai Fai

doi:10.1016/j.envint.2013.01.005

Cited by 37 publications

(25 citation statements)

References 25 publications

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“…In contrast to the associations with visual memory found in our study and others (Cordier et al 2002; Grandjean et al 1999b; Lam et al 2013), no significant MeHg associations were found with the Design Memory subtest of the WRAML Visual Memory Index (Myers et al 2003) in the Seychelles Islands (mean maternal hair Hg, 6.9 μg/g). However, potential confounding by the beneficial effects of polyunsaturated fatty acids were not taken into account in these Seychelles analyses; this may partly account for null associations (Davidson et al 2008; Oken et al 2005).…”

Section: Discussioncontrasting

confidence: 99%

“…These results are consistent with a study conducted in Hong Kong in which low-dose prenatal MeHg exposure was adversely associated with a visual sequencing task among 6- to 10-year-olds (Lam et al 2013). Additionally, decreased performance on the Stanford–Binet copying tests, which measures visuospatial performance, was associated with maternal hair mercury in 5- to 6-year-olds in French Guiana (Cordier et al 2002), and with child hair mercury in a population of 7- to 12-year-olds in the Amazon Basin (Grandjean et al 1999b).…”

Section: Discussionsupporting

confidence: 91%

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Prenatal Organochlorine and Methylmercury Exposure and Memory and Learning in School-Age Children in Communities Near the New Bedford Harbor Superfund Site, Massachusetts

Orenstein

Thurston

Bellinger

et al. 2014

Environ Health Perspect

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Background: Polychlorinated biphenyls (PCBs), organochlorine pesticides, and methylmercury (MeHg) are environmentally persistent with adverse effects on neurodevelopment. However, especially among populations with commonly experienced low levels of exposure, research on neurodevelopmental effects of these toxicants has produced conflicting results.Objectives: We assessed the association of low-level prenatal exposure to these contaminants with memory and learning.Methods: We studied 393 children, born between 1993 and 1998 to mothers residing near a PCB-contaminated harbor in New Bedford, Massachusetts. Cord serum PCB, DDE (dichlorodiphenyldichloroethylene), and maternal peripartum hair mercury (Hg) levels were measured to estimate prenatal exposure. Memory and learning were assessed at 8 years of age (range, 7–11 years) using the Wide Range Assessment of Memory and Learning (WRAML), age-standardized to a mean ± SD of 100 ± 15. Associations with each WRAML index—Visual Memory, Verbal Memory, and Learning—were examined with multivariable linear regression, controlling for potential confounders.Results: Although cord serum PCB levels were low (sum of four PCBs: mean, 0.3 ng/g serum; range, 0.01–4.4), hair Hg levels were typical of the U.S. fish-eating population (mean, 0.6 μg/g; range, 0.3–5.1). In multivariable models, each microgram per gram increase in hair Hg was associated with, on average, decrements of –2.8 on Visual Memory (95% CI: –5.0, –0.6, p = 0.01), –2.2 on Learning (95% CI: –4.6, 0.2, p = 0.08), and –1.7 on Verbal Memory (95% CI: –3.9, 0.6, p = 0.14). There were no significant adverse associations of PCBs or DDE with WRAML indices.Conclusions: These results support an adverse relationship between low-level prenatal MeHg exposure and childhood memory and learning, particularly visual memory.Citation: Orenstein ST, Thurston SW, Bellinger DC, Schwartz JD, Amarasiriwardena CJ, Altshul LM, Korrick SA. 2014. Prenatal organochlorine and methylmercury exposure and memory and learning in school-age children in communities near the New Bedford Harbor Superfund Site, Massachusetts. Environ Health Perspect 122:1253–1259; http://dx.doi.org/10.1289/ehp.1307804

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Section: Discussioncontrasting

confidence: 99%

Section: Discussionsupporting

confidence: 91%

Prenatal Organochlorine and Methylmercury Exposure and Memory and Learning in School-Age Children in Communities Near the New Bedford Harbor Superfund Site, Massachusetts

Orenstein

Thurston

Bellinger

et al. 2014

Environ Health Perspect

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“…No association was found between prenatal MeHg exposure and WISC-III full-scale, performance, or verbal IQ at 7-9 years in the Italian cohort or between prenatal mercury and WISC scores at 8 years in a Hong Kong cohort (Deroma et al, 2013; Lam et al, 2013). …”

Section: Mercurymentioning

confidence: 77%

“…At 14 years of age, there was an association with cued but not non-cued naming (Debes et al, 2006). Finally, in a Hong Kong cohort, there were no associations between prenatal mercury exposure and either non-cued or cued naming at 8 years (Lam et al, 2013). …”

Section: Mercurymentioning

confidence: 99%

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Prenatal chemical exposures and child language development

Dzwilewski

Schantz

2015

Journal of Communication Disorders

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The goal of this review is to summarize the evidence that prenatal and/or early postnatal exposure to certain chemicals, both man made (insulating materials, flame retardants, pesticides) and naturally occurring (e.g. lead, mercury), may be associated with delays or impairments in language development. We focus primarily on a subset of more extensively studied chemicals—polychlorinated biphenyls (PCBs), lead, and methyl mercury—for which a reasonable body of literature on neurodevelopmental outcomes is available. We also briefly summarize the smaller body of evidence for other chemicals including polybrominated diphenyl ether flame retardants (PBDEs) and organophosphate pesticides. Very few studies have used specific assessments of language development and function. Therefore, we included discussion of aspects of cognitive development such as overall intellectual functioning and verbal abilities that rely on language, as well as aspects of cognition such as verbal and auditory working memory that are critical underpinnings of language development. A high percentage of prospective birth cohort studies of PCBs, lead and mercury have reported exposure-related reductions in overall IQ and/or verbal IQ that persist into middle or late childhood. Given these findings, it is important that clinicians and researchers in communication sciences and disorders are aware of the potential for environmental chemicals to impact language development.

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Mercury and Pregnancy

Bellinger

2014

Birth Defects Research

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Long term neurocognitive impact of low dose prenatal methylmercury exposure in Hong Kong

Cited by 37 publications

References 25 publications

Prenatal Organochlorine and Methylmercury Exposure and Memory and Learning in School-Age Children in Communities Near the New Bedford Harbor Superfund Site, Massachusetts

Prenatal Organochlorine and Methylmercury Exposure and Memory and Learning in School-Age Children in Communities Near the New Bedford Harbor Superfund Site, Massachusetts

Prenatal chemical exposures and child language development

Mercury and Pregnancy

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