As a result of problems perceived in the USA from widespread dispersal of mercury from fossil fuel burning, the USEPA was charged with controlling discharges from utilities. This entailed determining a scientifically sustainable mercury exposure reference dose (RfD). The National Academy of Sciences was charged with performing an independent study on the toxicological effects of MeHg and make appropriate recommendations. This was published in 2000 (see ref below.). Three epidemiological studies formed the main basis of this study (The Faroes, The Seychelles, New Zealand see ) along with reconsideration of Minamata and Iraq. Of the three large epidemiological studies, two studies (The Faroes and New Zealand) MeHg exposure was associated with poor neurodevelopmental outcomes. However, no relation with outcome was seen in the Seychelles study. It was concluded that this was not because of poor study design but may be due to differences in population sensitivity, environmental circumstances that they were exposed to or lack of statistical power to distinguish differences because of the distribution of the data. It was concluded that the Iraq study should no longer be considered to be the reference incident because of the major differences between that incident and the general exposure of US population. For the future, the Faroes data and analysis provided the soundest basis for progress although it was not necessary to change the RfD as a consequence.