We are pleased to introduce this special issue of Neurotoxicology. It reproduces Volume 7, Number 1 of the Seychelles Medical and Dental Journal (SMDJ), initially published in November, 2004. Publication of the SMDJ was discontinued in 2005 and the manuscripts it published are no longer accessible to the scientific community. The papers in this special issue lay the background for the Seychelles Child Development Study (SCDS) and provide valuable data on the MeHg exposures that occurred at Niigata, Japan. They are relevant to the ongoing debate over whether the consumption of fish and consequently low-level exposure to methylmercury (MeHg) is a risk to human health.