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

MERCURY 457
5. POTENTIAL FOR HUMAN EXPOSURE
exposures (see Section 5.7). Children can be exposed to various forms of mercury in a variety of ways,
including playing with unsecured elemental mercury, inhalation of mercury vapors via the religious or ethnic
practices of their parents or unintentional spills of elemental mercury, oral ingestion of herbal or ethnic
remedies or mercury-containing consumer products, consumption of methylmercury-contaminated fish and
wildlife, and dermal or oral exposure to contaminated soils and sediments.
Mercury concentrations have been measured in cord blood in one study in the United States with levels that
suggest prenatal exposure. Pitkin et al. (1976) measured concentrations of total mercury in cord blood
samples from 100 maternal cord blood pairs from a population in rural Iowa. The mean cord blood total
mercury concentration was 1.24 ppb, while the mean of the paired maternal blood samples was 1.01 ppb.
More recently, Wheatley and Paradis (1995a, 1995b) reported on the analysis of 2,405 cord blood samples
collected from Canadian aboriginal peoples over the last 20 years. Of these cord blood samples, 523
(21.8%) were found to have total mercury levels greater than 20 ppb, with the highest cord blood sample
containing 224 ppb. These latter samples were from populations that routinely consumed fish and marine
mammal tissues. Grandjean et al. (1997b) measured cord blood samples from 894 Faroe Islands children
whose mothers consumed large amounts of fish and pilot whale meat. The methylmercury exposure in the
Faroe Island population is mainly from eating pilot whale meat. The geometric mean concentration of total
mercury in these cord blood samples was 22.9 ppb.
Concentrations of mercury have also been measured in breast milk from several populations in the United
States as well as other countries (see Table 5-17). Breast milk concentrations have been reported for two
U.S. populations; one in rural Iowa (Pitkin et al. 1976) and the other from Alaska (Galster 1976). Pitkin et
al. (1976) reported a total mean mercury concentration in breast milk of 0.9±0.23 ppb (range, 0.8–1.6 ppb).
The mean total mercury concentrations in the Alaskan populations were 3.3± 0.5 ppb for the urban
population, 3.2±0.8 ppb for the interior population, and 7.6±2.7 ppb for the coastal population that consumed
fish and marine mammals.
Total mercury concentrations in breast milk from other countries and exposure scenarios were 3.6±2.2 ppb
for an urban population in Tokyo, Japan (Fujita and Takabatake 1977), 0.6±0.4 ppb for Swedish women that
were fish consumers with 12 dental amalgams (Oskarsson et al. 1996), 0.2–6.3 ppb (range) for Swedish
women that consumed fish (Skerfving 1988), and 9.5±5.5 ppb for an urban population of women in Madrid,
Spain (Baluja et al. 1982) (Table 5-17). Some of the highest levels were reported in fish eaters, and about
20% of the total mercury content of the milk was methylmercury. The median and maximum mercury