A research team from the University of Rochester, USA, with colleagues from the Seychelles investigated 779 mother-infant pairs enrolled in the Seychelles Childhood Development Study, established in 1989/1990. Mothers reported high fish consumption-12 meals a week compared with one meal a week on average in the USA. The fish in Seychelles contained similar concentrations of methylmercury as commercial ocean fish elsewhere. Prenatal MeHg exposure was determined from maternal hair growing during pregnancy.
The investigators assessed neurocognitive, language, memory, motor, perceptual-motor, and behavioural functions in children at nine years of age. Out of 21 endpoints, only two tests were associated with prenatal methylmercury exposure: decreased performance in a motor test (the grooved pegboard using the non-dominant hand in males), and improved scores in the hyperactivity index of the Conner's teacher rating scale The investigators comment, however, that these two results probably arose by chance, and conclude that there is no evidence of neurodevelopmental risk from prenatal methylmercury exposure resulting solely from ocean fish consumption.
In an accompanying Commentary (p 1667), Constantine Lyketsos from Johns Hopkins Hospital, Baltimore, USA, concludes: "On balance, the existing evidence suggests that methyl mercury exposure from fish consumption during pregnancy, of the level seen in most parts of the world, does not have measurable cognitive or behavioural effects in later childhood…For now, there is no reason for pregnant women to reduce fish consumption below current levels, which are probably safe."
Contact: Professor Gary J M Myers, University of Rochester Medical Center, Box 631,601 Elmwood Avenue, Rochester, New York 14642, USA;
T) 585-275-6222;
F) 585-275-3683;
E) gary_myers@urmc.rochester.edu
Dr Constantine G Lyketsos, Division of Geriatric Psychiatry and Neuropsychiatry, Johns Hopkins Hospital, Baltimore, MD 21287, USA;
T) 410-955-6158;
E) Kostas@jhmi.edu
Journal
The Lancet