Prenatal exposure to methyl mercury from fish consumption and polyunsaturated fatty acids: associations with child development at 20 mo of age in an observational study in the Republic of Seychelles.
BACKGROUND
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.


OBJECTIVE
The objective was to investigate the associations of prenatal MeHg exposure and maternal PUFA status with child development at 20 mo of age.


METHODS
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.


RESULTS
Prenatal MeHg exposure had no direct associations with neurodevelopmental outcomes. Significant interactions were found between MeHg and PUFAs on the Psychomotor Developmental Index (PDI) of the BSID-II. Increasing MeHg was associated with lower PDI but only in children of mothers with higher n-6/n-3. Among mothers with higher n-3 PUFAs, increasing MeHg was associated with improved PDI. Higher maternal docosahexaenoic acid (DHA) was associated with improved CDI total gestures (language development) but was significantly adversely associated with the Mental Development Index (MDI), both with and without MeHg adjustment. Higher n-6:n-3 ratios were associated with poorer scores on all 3 CDI outcomes.


CONCLUSIONS
We found no overall adverse association between prenatal MeHg exposure and neurodevelopmental outcomes. However, maternal PUFA status as a putative marker of the inflammatory milieu appeared to modify the associations of prenatal MeHg exposure with the PDI. Increasing DHA status was positively associated with language development yet negatively associated with the MDI. These findings may indicate the existence of an optimal DHA balance with respect to arachidonic acid for different aspects of neurodevelopment.
From the Northern Ireland Centre for Food and Health (NICHE), School of Biomedical Sciences, University of Ulster (JJS, AJY, MSM, and EMM); the School of Medicine and Dentistry, University of Rochester, Rochester, NY (EvW, SWT, GEW, TML, THS, KY, DH, GJM, and PWD); and the Child Development Centre, Ministry of Health, Mahé, Republic of Seychelles (CFS and JH).
J J
JJ
Strain
From the Northern Ireland Centre for Food and Health (NICHE), School of Biomedical Sciences, University of Ulster (JJS, AJY, MSM, and EMM); the School of Medicine and Dentistry, University of Rochester, Rochester, NY (EvW, SWT, GEW, TML, THS, KY, DH, GJM, and PWD); and the Child Development Centre, Ministry of Health, Mahé, Republic of Seychelles (CFS and JH).
Alison J
AJ
Yeates
From the Northern Ireland Centre for Food and Health (NICHE), School of Biomedical Sciences, University of Ulster (JJS, AJY, MSM, and EMM); the School of Medicine and Dentistry, University of Rochester, Rochester, NY (EvW, SWT, GEW, TML, THS, KY, DH, GJM, and PWD); and the Child Development Centre, Ministry of Health, Mahé, Republic of Seychelles (CFS and JH).
Edwin
E
van Wijngaarden
From the Northern Ireland Centre for Food and Health (NICHE), School of Biomedical Sciences, University of Ulster (JJS, AJY, MSM, and EMM); the School of Medicine and Dentistry, University of Rochester, Rochester, NY (EvW, SWT, GEW, TML, THS, KY, DH, GJM, and PWD); and the Child Development Centre, Ministry of Health, Mahé, Republic of Seychelles (CFS and JH).
Sally W
SW
Thurston
From the Northern Ireland Centre for Food and Health (NICHE), School of Biomedical Sciences, University of Ulster (JJS, AJY, MSM, and EMM); the School of Medicine and Dentistry, University of Rochester, Rochester, NY (EvW, SWT, GEW, TML, THS, KY, DH, GJM, and PWD); and the Child Development Centre, Ministry of Health, Mahé, Republic of Seychelles (CFS and JH).
Maria S
MS
Mulhern
From the Northern Ireland Centre for Food and Health (NICHE), School of Biomedical Sciences, University of Ulster (JJS, AJY, MSM, and EMM); the School of Medicine and Dentistry, University of Rochester, Rochester, NY (EvW, SWT, GEW, TML, THS, KY, DH, GJM, and PWD); and the Child Development Centre, Ministry of Health, Mahé, Republic of Seychelles (CFS and JH).
Emeir M
EM
McSorley
From the Northern Ireland Centre for Food and Health (NICHE), School of Biomedical Sciences, University of Ulster (JJS, AJY, MSM, and EMM); the School of Medicine and Dentistry, University of Rochester, Rochester, NY (EvW, SWT, GEW, TML, THS, KY, DH, GJM, and PWD); and the Child Development Centre, Ministry of Health, Mahé, Republic of Seychelles (CFS and JH).
Gene E
GE
Watson
From the Northern Ireland Centre for Food and Health (NICHE), School of Biomedical Sciences, University of Ulster (JJS, AJY, MSM, and EMM); the School of Medicine and Dentistry, University of Rochester, Rochester, NY (EvW, SWT, GEW, TML, THS, KY, DH, GJM, and PWD); and the Child Development Centre, Ministry of Health, Mahé, Republic of Seychelles (CFS and JH).
Tanzy M
TM
Love
From the Northern Ireland Centre for Food and Health (NICHE), School of Biomedical Sciences, University of Ulster (JJS, AJY, MSM, and EMM); the School of Medicine and Dentistry, University of Rochester, Rochester, NY (EvW, SWT, GEW, TML, THS, KY, DH, GJM, and PWD); and the Child Development Centre, Ministry of Health, Mahé, Republic of Seychelles (CFS and JH).
Tristram H
TH
Smith
From the Northern Ireland Centre for Food and Health (NICHE), School of Biomedical Sciences, University of Ulster (JJS, AJY, MSM, and EMM); the School of Medicine and Dentistry, University of Rochester, Rochester, NY (EvW, SWT, GEW, TML, THS, KY, DH, GJM, and PWD); and the Child Development Centre, Ministry of Health, Mahé, Republic of Seychelles (CFS and JH).
Kelley
K
Yost
From the Northern Ireland Centre for Food and Health (NICHE), School of Biomedical Sciences, University of Ulster (JJS, AJY, MSM, and EMM); the School of Medicine and Dentistry, University of Rochester, Rochester, NY (EvW, SWT, GEW, TML, THS, KY, DH, GJM, and PWD); and the Child Development Centre, Ministry of Health, Mahé, Republic of Seychelles (CFS and JH).
Donald
D
Harrington
From the Northern Ireland Centre for Food and Health (NICHE), School of Biomedical Sciences, University of Ulster (JJS, AJY, MSM, and EMM); the School of Medicine and Dentistry, University of Rochester, Rochester, NY (EvW, SWT, GEW, TML, THS, KY, DH, GJM, and PWD); and the Child Development Centre, Ministry of Health, Mahé, Republic of Seychelles (CFS and JH).
Conrad F
CF
Shamlaye
From the Northern Ireland Centre for Food and Health (NICHE), School of Biomedical Sciences, University of Ulster (JJS, AJY, MSM, and EMM); the School of Medicine and Dentistry, University of Rochester, Rochester, NY (EvW, SWT, GEW, TML, THS, KY, DH, GJM, and PWD); and the Child Development Centre, Ministry of Health, Mahé, Republic of Seychelles (CFS and JH).
Juliette
J
Henderson
From the Northern Ireland Centre for Food and Health (NICHE), School of Biomedical Sciences, University of Ulster (JJS, AJY, MSM, and EMM); the School of Medicine and Dentistry, University of Rochester, Rochester, NY (EvW, SWT, GEW, TML, THS, KY, DH, GJM, and PWD); and the Child Development Centre, Ministry of Health, Mahé, Republic of Seychelles (CFS and JH).
Gary J
GJ
Myers
From the Northern Ireland Centre for Food and Health (NICHE), School of Biomedical Sciences, University of Ulster (JJS, AJY, MSM, and EMM); the School of Medicine and Dentistry, University of Rochester, Rochester, NY (EvW, SWT, GEW, TML, THS, KY, DH, GJM, and PWD); and the Child Development Centre, Ministry of Health, Mahé, Republic of Seychelles (CFS and JH).
Philip W
PW
Davidson
D000328:Adult; D000818:Animals; D002657:Child Development / Q000187:drug effects; D015331:Cohort Studies; D004281:Docosahexaenoic Acids / Q000008:administration & dosage / Q000009:adverse effects / Q000627:therapeutic use; D015525:Fatty Acids, Omega-3 / Q000008:administration & dosage / Q000009:adverse effects / Q000627:therapeutic use*; D005260:Female; D005399:Fishes; D005506:Food Contamination; D006801:Humans; D007223:Infant; D007805:Language Development Disorders / Q000209:etiology / Q000517:prevention & control; D008297:Male; D039382:Maternal Nutritional Physiological Phenomena; D001523:Mental Disorders / Q000209:etiology / Q000517:prevention & control; D008630:Mercury Poisoning / Q000209:etiology / Q000503:physiopathology / Q000517:prevention & control*; D008767:Methylmercury Compounds / Q000037:antagonists & inhibitors* / Q000633:toxicity; D055495:Neurogenesis / Q000187:drug effects; D011247:Pregnancy; D011297:Prenatal Exposure Delayed Effects / Q000209:etiology / Q000503:physiopathology / Q000517:prevention & control*; D011596:Psychomotor Disorders / Q000209:etiology / Q000517:prevention & control; D017747:Seafood; D012750:Seychelles
D015525:Fatty Acids, Omega-3; D008767:Methylmercury Compounds; D004281:Docosahexaenoic Acids
Mental Developmental Index; Psychomotor Developmental Index; arachidonic acid; child development; docosahexaenoic acid; language development; maternal fish consumption; methyl mercury; n–6:n–3 ratio; polyunsaturated fatty acids