Department of Neurology, Massachusetts General Hospital,
Harvard Biological Laboratories, Harvard Medical School, Cambridge, MA
02138, USA. allen_Counter@harvard.edu
Exposure to toxic mercury
(Hg) is a growing health hazard throughout the world today. Recent
studies show that mercury exposure may occur in the environment, and
increasingly in occupational and domestic settings. Children are
particularly vulnerable to Hg intoxication, which may lead to impairment
of the developing central nervous system, as well as pulmonary and
nephrotic damage. Several sources of toxic Hg exposure in children have
been reported in biomedical literature: (1) methylmercury, the most
widespread source of Hg exposure, is most commonly the result of
consumption of contaminated foods, primarily fish; (2) ethylmercury,
which has been the subject of recent scientific inquiry in relation to
the controversial pediatric vaccine preservative thimerosal; (3)
elemental Hg vapor exposure through accidents and occupational and
ritualistic practices; (4) inorganic Hg through the use of topical
Hg-based skin creams and in infant teething powders; (5) metallic Hg in
dental amalgams, which release Hg vapors, and Hg2+ in tissues. This
review examines recent epidemiological studies of methylmercury exposure
in children. Reports of elemental Hg vapor exposure in children through
accidents and occupational practices, and the more recent observations
of the increasing use of elemental Hg for magico-religious purposes in
urban communities are also discussed. Studies of inorganic Hg exposure
from the widespread use of topical beauty creams and teething powders,
and fetal/neonatal Hg exposure from maternal dental amalgam fillings are
reviewed. Considerable attention was given in this review to pediatric
methylmercury exposure and neurodevelopment because it is the most
thoroughly investigated Hg species. Each source of Hg exposure is
reviewed in relation to specific pediatric health effects, particularly
subtle neurodevelopmental disorders.