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

MERCURY 479
5. POTENTIAL FOR HUMAN EXPOSURE
influence the bioavailability of mercury. Additional studies are needed in order to understand why the
relatively high concentrations of mercury measured in marine mammal tissues do not appear to result in
elevation of hair mercury levels among Alaskan natives that consume marine mammal tissues.
Reliable monitoring data for the levels of mercury in contaminated media at hazardous waste sites are
needed so that the information obtained on levels of mercury in the environment can be used in combination
with the known body burden of mercury to assess the potential risk of adverse health effects in populations
living in the vicinity of hazardous waste sites.
Exposure Levels in Humans. Mercury has been measured in human blood, hair, breast milk, urine,
feces, and saliva (Bakir et al. 1973; EPA 1984b; Fujita and Takabatake 1977; Galster 1976; Oskarsson et al.
1996; Pitkin et al. 1976; Wheatley and Paradis 1995a, 1995b; WHO 1990). However, current information on
mercury levels in blood, hair, breast milk, and urine of members of the general U.S. population are almost
entirely lacking. Data are needed for the general population that measure the levels of mercury in blood, hair,
breast milk, and urine derived from dietary exposures (such as fish consumption) versus mercury derived from
dental amalgams in order to obtain additional information about the importance of each of these exposure
pathways to resulting mercury body burden. Additional information on mercury levels in urine of persons with
varying numbers of amalgam surfaces as well as in persons that have had amalgam fillings removed or replaced
would be useful in evaluating mercury exposure form this source. Data are available for some Native American
populations (Galster 1976) and several foreign populations that consume large amounts of locally caught fish
and wildlife (Airey 1983b; Fleming et al. 1995; Lasora and Citterman 1991). The most common method of
assessing human exposure in the workplace involves the measurement of mercury in urine (Baser and Marion
1990; Bell et al. 1973; Lindstedt et al. 1979; Roels et al. 1987; Rosenman et al. 1986). Urine mercury levels
have been correlated with ambient air exposure levels, particularly to mercury vapor. A longitudinal
epidemiological study that tracks individual exposure levels to metallic mercury vapors in occupational settings
(chloralkali industry workers, fluorescent lightbulb manufacturers, or other mercury utilizing industries) on a
daily basis and associated these exposure levels with weekly urine and blood samples for a period of 1–2 years
is needed. Neurobehavioral testing should also be conducted of these workers at 6-month intervals. Workers
new to these industries would make the best subjects since they could provide pre-exposure blood and urine
levels as a point of reference. Information is available on populations living near former production sites or
hazardous waste sites (Harnly et al. 1997; Nublein et al. 1995; Reif et al. 1993; Shaw et al. 1986). Additional
information on the biological monitoring of populations living in the vicinity of hazardous waste