Prenatal mercury and cadmium exposure and neurodevelopment Público

Abstract

Prenatal exposures to toxic metals are associated with neurodevelopment effects in children. Heavy metals have different mechanisms of neurotoxic action including effects on the placenta. This organ plays an important role in the transference of the metal from the mother to the infant as well as in orchestrating appropriate development. The present study aims to investigate the potential association between exposure to cadmium and mercury and neurodevelopmental outcomes in the Rhode Island Child Health Study (RICHS). The sub-cohort included 316 participants that were assessed with the NICU Network Neurobehavioral Scale (NNNS) and have available biomarkers of exposure. Differences in the concentrations of metals across neurobehavioral profiles were initially examined, and followed by logistic regression to examine the association between metals exposure and membership in a neurobehavioral profile with the poorest performance. We found elevated odds of membership in a neurobehavioral profile characterized by increased excitability, poor quality of movement and reduced self-regulation associated with Cd and Hg exposures in models controlling for infant birthweight, gestational age, sex, maternal age, level of education and smoking status during pregnancy, but this relationship was not statistically significant. The use of the NNNS might not be suitable for populations with low exposures to heavy metals that do not display extreme neurobehavioral features but opens the possibility to further investigation related to the use of this assessment as a neurobehavioral predictive tool under the right conditions.

Table of Contents

1. INTRODUCTION ........................................................................................................... 1

1.1. Prenatal exposure to cadmium and mercury .................................................................. 1

1.2. Placental transfer of cadmium and mercury ................................................................... 2

1.3. Neurodevelopmental effects of cadmium and mercury ................................................. 3

1.4. Effects on the Placenta .................................................................................................... 4

1.5. Biomarkers used for cadmium and mercury detection ................................................... 5

1.6. Neurodevelopment Assessment ...................................................................................... 5

1.7. Rhode Island Birth Cohort ................................................................................................ 7

2. AIM AND HYPOTHESIS ................................................................................................. 7

3. METHODS .................................................................................................................... 8

3.1. Study Population .............................................................................................................. 8

3.2. Data Abstraction .............................................................................................................. 8

1.1.1. Exposure Assessment ............................................................................................... 8

1.1.2. Outcome Assessment .............................................................................................. 9

3.3. Covariates ........................................................................................................................ 9

3.4. Data Analysis .................................................................................................................. 10

4. RESULTS ..................................................................................................................... 10

4.1. Demographic characteristics of the participants ........................................................... 10

4.2. NNNS Summary Scores .................................................................................................. 12

4.3. Heavy metal levels ......................................................................................................... 14

1.1.3. Placental cadmium ................................................................................................. 14

1.1.4. Placental mercury .................................................................................................. 15

1.1.5. Cadmium in infant toenails .................................................................................... 15

1.1.6. Mercury in infant toenails ...................................................................................... 16

1.1.7. Correlations between metals ................................................................................. 17

4.4. Logistic regression model .............................................................................................. 17

5. DISCUSSION ............................................................................................................... 19

6. CONCLUSION AND RECOMMENDATIONS ................................................................. 22

About this Master's Thesis

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School	Rollins School of Public Health
Department	Environmental Health
Degree	M.P.H.
Submission	Master's Thesis
Language	English
Research Field	Environmental Health
Palavra-chave	Neurobehavior, cadmium, mercury, placenta, Heavy metals, Exposure, toenails
Committee Chair / Thesis Advisor	Marsit, Carmen, Emory University
Partnering Agencies	Does not apply (no collaborating organization)

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