revised final - Agency for Toxic Substances and Disease Registry ...

MERCURY 462
5. POTENTIAL FOR HUMAN EXPOSURE
Children may be exposed to mercury during play at home or in school when using art supplies that contain
colors from mercury compounds. Rastogi and Pritzi (1996) reported the migration of several toxic metals
including mercury from crayons and artist watercolor paints (see Section 5.4). Migration of mercury from
these art supply products occurred in 57% of the samples tested. The authors believe that children might be
exposed not only to mercury, but to several other metals that can migrate from the paints. Grabo (1997) also
reported that artists may be exposed to mercury because it is a main component in airbrush and brush
painting pigments as well as a component of pastel chalks. Artist supplies that contain mercury should be
stored out of children’s reach to avoid accidental poisoning.
Infants and developing fetuses may be exposed to methylmercury if their mothers consume certain
methylmercury-contaminated fish, shellfish, or wildlife species from contaminated waters prior to their
pregnancy, during their pregnancy, or while nursing. Older children also may be exposed to methylmercury
by eating contaminated fish and wildlife species. Certain states, Native American tribes, and U.S. Territories
have issued fish and wildlife advisories for mercury in fresh water, estuarine, and saltwater fish and in
freshwater turtles (see Section 5.7).
In a study of lactating women, Oskarsson et al. (1996) assessed the total and inorganic mercury content in
breast milk and blood in relation to fish consumption and amalgam fillings (see Section 5.5). In breast milk
samples collected 6 weeks after delivery, about half of the total mercury was inorganic and half was
methylmercury, whereas in blood samples only 26% was inorganic and 74% was methylmercury. Exposure
of the infant to mercury from breast milk was calculated to range up to 0.3 µg/kg/day, of which
approximately one-half was inorganic mercury. This exposure corresponds to approximately one-half the
tolerable daily intake of total mercury for adults recommended by WHO. The authors concluded that efforts
should be made to decrease total mercury burden in women of reproductive age (Oskarsson et al. 1996).
Two-year-old children seem to be different in their weight-adjusted intake of methylmercury as shown by
the results of the FDA Total Diet Study. Expressed on a per weight basis, methylmercury intake for all age
groups except 2-year-old children was approximately 50 ng/kg/day (Clarkson 1990; Gunderson 1988). For
2-year-old children, the intake was estimated to be approximately 100 ng/kg/day (assuming 50% of the fish
intake was due to fish caught locally) or about twice as much methylmercury intake per body weight as for
other age groups. For additional details, see Section 5.5, General Population and Occupational Exposure.