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

MERCURY 481
5. POTENTIAL FOR HUMAN EXPOSURE
turned on and the windows are closed, so data that reflect a variety of possible exposure scenarios are also
needed.
Results of the Total Diet Study conducted by the FDA suggest that two-year-old children differ in their weight-
adjusted intake of mercury, based on the assumption that 50% of the fish consumed were locally caught species
(Clarkson 1990; Gunderson 1988). Additional information on weight adjusted intakes would be helpful for the
general population, and particularly in determining the health risks for young children in Native American
populations. Children in these populations may consume relatively large quantities of locally caught fish as part
of their traditional ceremonial practices (CRITFC 1994) or may consume large quantities of marine mammal
tissues (blubber, muscle, and organ meats) if they are in subsistence fishing or hunting populations.
One childhood-specific means of decreasing exposure scenarios for children is through better education of
school age children and their parents on the health risks particularly of metallic mercury exposure from
accidental spillage, intentional uses, or from improper industrial exposures.
Exposure Registries. New York State has instituted a Heavy Metals Registry that monitors occupational
exposure to heavy metals, including mercury. Cases are reported when mercury exposure is equal to or exceeds
50 µg/L (ppb) in blood or 20 µg/L (ppb) in urine. Between 1982 and 1986, 1,000 cases of mercury exposure
were reported and linked to 47 companies. Most exposures (494 cases) occurred in workers in the alkali and
chlorine industry, where mercury is used as a cathode because exposure occurs when the cells are opened; the
median blood mercury concentration was 76 µg/L (ppb) (maximum concentration 916 µg/L [ppb]). The
second most frequent exposure category (213 cases) was the manufacture of industrial instruments, such as the
manual assembly and fabrication of thermometers; median blood mercury concentration was 145 µg/L (ppb)
and the maximum concentration was 889 µg/L (ppb) (Baser and Marion 1990).
This substance is not currently one of the compounds for which a subregistry has been established in the
National Exposure Registry. The substance will be considered in the future when chemical selection is made
for subregistries to be established. The information that is amassed in the National Exposure Registry facilitates
the epidemiological research needed to assess adverse health outcomes that may be related to exposure to this
substance.