Scientists know that mercury causes harmful changes in brain functions, and slows fetal and child development in ways that may have lifelong consequences. Second, mercury moves easily among air, water, and land, so coordinated actions are needed. And, third, it is the leading and fastest growing cause of fish consumption advisories in this country. Mercury is well known as a neurotoxin that slows fetal and child development and causes irreversible deficits in brain function. About that there is no dispute.
Scientific debate is ongoing about the level of mercury exposure at which effects begin to occur.
Many, but not all, of these existing studies show adverse human health effects at the level at which tens of thousands of Americans are exposed today, from fish consumption. I must note that scientists are still working on an important question, whether to revise the reference dose for mercury. By reference dose, we mean the amount which can be consumed for a lifetime without expectation of harmful effects. As many of you know, there is a meeting among researchers and risk assessors this week in North Carolina on the use of these new human studies. In addition, Congress has directed EPA to fund a study by the National Academy of Sciences to make a recommendation on the proper reference dose.