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

MERCURY 472
5. POTENTIAL FOR HUMAN EXPOSURE
milk of women living in coastal areas (7.6±2.7 ppb) than in breast milk of Inuit women living in the interior
(3.2±0.8 ppb) or in urban areas (3.3±0.5 ppb). In addition, mercury red blood cell concentrations were also
higher in Inuit women living in coastal areas (33.5±5.1 ppb), as compared to those living in the interior
(22.6±3.0 ppb) or in urban areas (8.9±0.9 ppb). Higher mercury levels in coastal populations were attributed
to higher consumption of seal meat and oil and marine fish (Galster 1976). By analogy to the Canadian
populations of native peoples (Wheatley and Paradis 1995a, 1995b), it is anticipated that methylmercury
concentrations in these tissues are likely to be higher among individuals who consume large quantities of
marine mammal species with high concentrations of methylmercury (as well as inorganic mercury) in their
tissues than among members of the general population. In a study of subsistence economies in the State of
Alaska, Wolfe and Walker (1987) reported that total annual per capita harvest of wild game species
(including land mammals, marine mammals, and fish) ranged from 10 to 1,498 pounds (median harvest of
252 pounds), compared to 222 pounds of meat, fish, and poultry (combined) consumed each year per
individual in the western United States. The wild game harvest in 84% of the 98 Alaskan subsistence
communities surveyed was at least half or greater than the 222 pounds consumed in the western United
States. Because hunters often share wild game they harvest with other family members, the amount
harvested may not represent the actual amount consumed (Egeland et al. 1998). The average daily per capita
consumption was estimated to be 0.67 pounds of fish and 0.23 pounds of land mammals based on all
98 communities, and 0.2 pounds of marine mammals based on the 41 coastal communities surveyed. Marine
mammals consumed in these communities included seal, walrus, and whales. Subsistence hunters and their
families are a population at potentially higher risk of mercury exposure, if the wild game species they
consume are contaminated with high concentrations of inorganic and methylmercury. Although the
existence of larger amounts of mercury in subsistence diets does give cause for concern, the available
Alaskan data do not support the conclusion that current exposures are a serious problem for Alaskan
subsistence hunters (Egeland et al. 1998).
Individuals with Large Numbers of Dental Amalgams. Individuals with dental amalgams have
greater exposure to elemental mercury than members of the general population that do not have dental
amalgams. Richardson (1995) computed a release rate per filled tooth surface of 0.73 µg/day-surface, with a
standard deviation of 0.3 µg/day-surface and a “stimulation magnification factor” of 5.3, based on a weighed
average enhancement of mercury vapor concentration following chewing, eating, or tooth brushing