To examine whether in utero exposure to mercury (Hg), cadmium (Cd), lead (Pb) and arsenic (As) is associated with an elevated neural tube defects (NTDs) risk, placental concentrations of total Hg, Cd, Pb and As were measured with an inductively coupled plasma mass spectrometer (ICP-MS) in 36 anencephaly and 44 spina bifida cases as well as in 50 healthy controls.
- Subjects – 608 children from a cohort with 1057 mother-infant pairs recruited from Jul 2000 to Dec 2001.
- Key measurements – maternal fish intake, cord blood mercury concentration, neurocognitive assessment (verbal skills and non-verbal skills, i.e. ability to transfer visual information).
- Key findings:
- Average maternal marine fish consumption during pregnancy = 1196 +/- 2094 g per month.
- The mercury levels of 491 out of 608 children were in "high-level" group (cord blood mercury concentration >/= 29 nmol/L).
- Cord blood mercury concentration was significantly associated with 3 subsets of neurocognitive assessment (visual sequencing task, short and long retention ability of verbal memory):
- Performance worsened with increasing prenatal mercury exposure.
- Unable to find a beneficial neurocognitive effect of maternal fish consumption.
- Despite the low prenatal mercury exposure in Hong Kong, small and significant adverse associations have been noted between prenatal mercury exposure and long-term neurocognitive effects.
- Safe strategies to further reduce prenatal mercury exposure in Hong Kong are suggested.
Lam HS, Kwok KM, Chan PH, So HK, Li AM, Ng PC, Fok TF. Long term neurocognitive impact of low dose prenatal methylmercury exposure in Hong Kong. Environ Int. 2013 Feb 13;54C:59-64. Link to PubMed