Strong Center for Developmental Disabilities, Golisano
Children's Hospital at Strong, University of Rochester School of
Medicine and Dentistry, Rochester, New York 14642, USA.
phil_davidson@urmc.rochester.edu
Mercury is ubiquitous in the
global environment, ensuring universal exposure. Some forms of mercury
are especially neurotoxic, including clinical signs at high doses.
However, typical human exposures occur at low to moderate doses. Only
limited data about neurotoxicity at low doses are available, and
scientists differ in their interpretation. Dose-response data on
neurodevelopment are particularly limited. Despite or perhaps because of
the lack of sufficient or consistent scientific data, public concern
about a link between mercury exposure and developmental disabilities has
been rising. After reviewing the data, the US Environmental Protection
Agency proposed a reference dose (an estimate of a daily dose that is
likely to be without a risk of adverse effects over a lifetime) for
methyl mercury that is substantially lower than previous guidelines from
the World Health Organization, the US Agency for Toxic Substances and
Disease Registry, and the US Food and Drug Administration. Some
questions have been raised about the Environmental Protection Agency's
guidelines, but the issue remains unresolved. Meanwhile, consumer groups
have raised questions about the potential link between mercury exposure
and autism spectrum disorders as well as other adverse
neurodevelopmental outcomes. This hypothesis has prompted some parents
to seek regulatory, legal, or medical remedies in the absence of firm
evidence. This article reviews what is known about mercury neurotoxicity
and neurodevelopmental risk. Our intent is to focus the debate about
mercury on 1) additional research that should be sought and 2) defining
the principal issues that public policy makers face.