Milken Institute School of Public Health Poster Presentations (Marvin Center & Video)

Title

Prenatal and Postnatal Mercury Exposure on Neurodevelopment: A Systematic Review of Human Evidence

Document Type

Poster

Abstract Category

Environmental and Occupational Health

Keywords

mercury, neurodevelopment, methylmercury, development

Publication Date

Spring 5-1-2019

Abstract

Background: Evidence has reported the negative effects of prenatal mercury exposure on neurodevelopment, but evidence is limited and inconsistent regarding the effects of both prenatal and postnatal exposure. Objective: The Navigation Guide systematic review methodology was used to determine whether prenatal and/or postnatal exposure to mercury affects neurodevelopment in humans. The Navigation Guide is a systematic and transparent method for synthesizing environmental health research from multiple evidence streams. Methods: The first 3 steps of the Navigation Guide methodology were applied to human epidemiological data: 1) specify the study question, 2) select the evidence, and 3) rate the quality and strength of the evidence. To conduct a comprehensive and replicable search of the literature, a search protocol was developed to identify relevant studies using specific inclusion criteria. Each study was assessed for risk of bias and then the overall quality and strength of the body of evidence was determined. Results: The search resulted in 541 human studies, 8 of those studies met the inclusion criteria. Out of the 8 studies, 2 studies reported that both prenatal and postnatal exposure were associated with impaired neurodevelopment, 2 studies reported only a postnatal association, 1 study reported only a prenatal association, and the remaining 3 did not find a prenatal or postnatal association. The risk of bias across studies was “low” to “probably low”, but the overall quality of evidence was given a “low” rating due to inconsistency and imprecision across the body of evidence. Discussion and Conclusion: There is “inadequate” evidence of association between prenatal and postnatal exposure to mercury and neurodevelopment. The available evidence is insufficient to assess the effects of exposure. Generally, evidence that prenatal exposure to mercury has a toxic effect on neurodevelopment, is imprecise and unconvincing. The majority of studies reported postnatal mercury exposures were not associated with impaired neurodevelopment or the results were inconclusive. It is likely that a new study would change the certainty of the direction of the effect of exposure prenatally and postnatally on human neurodevelopment.

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Presented at Research Days 2019.

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Prenatal and Postnatal Mercury Exposure on Neurodevelopment: A Systematic Review of Human Evidence

Background: Evidence has reported the negative effects of prenatal mercury exposure on neurodevelopment, but evidence is limited and inconsistent regarding the effects of both prenatal and postnatal exposure. Objective: The Navigation Guide systematic review methodology was used to determine whether prenatal and/or postnatal exposure to mercury affects neurodevelopment in humans. The Navigation Guide is a systematic and transparent method for synthesizing environmental health research from multiple evidence streams. Methods: The first 3 steps of the Navigation Guide methodology were applied to human epidemiological data: 1) specify the study question, 2) select the evidence, and 3) rate the quality and strength of the evidence. To conduct a comprehensive and replicable search of the literature, a search protocol was developed to identify relevant studies using specific inclusion criteria. Each study was assessed for risk of bias and then the overall quality and strength of the body of evidence was determined. Results: The search resulted in 541 human studies, 8 of those studies met the inclusion criteria. Out of the 8 studies, 2 studies reported that both prenatal and postnatal exposure were associated with impaired neurodevelopment, 2 studies reported only a postnatal association, 1 study reported only a prenatal association, and the remaining 3 did not find a prenatal or postnatal association. The risk of bias across studies was “low” to “probably low”, but the overall quality of evidence was given a “low” rating due to inconsistency and imprecision across the body of evidence. Discussion and Conclusion: There is “inadequate” evidence of association between prenatal and postnatal exposure to mercury and neurodevelopment. The available evidence is insufficient to assess the effects of exposure. Generally, evidence that prenatal exposure to mercury has a toxic effect on neurodevelopment, is imprecise and unconvincing. The majority of studies reported postnatal mercury exposures were not associated with impaired neurodevelopment or the results were inconclusive. It is likely that a new study would change the certainty of the direction of the effect of exposure prenatally and postnatally on human neurodevelopment.