Mercury in the San Francisco Estuary - Reviews of Environmental Contamination and Toxicology - page 34

anglers representing 150 fishing sites visits, the study found that the five most popular
fish eaten by anglers, in order of preference, were striped bass, California halibut,
jacksmelt, white sturgeon, and white croaker, and that about 1 in 10 of the anglers ate
more than the amount recommended by the California Environmental Agency's Office
of Environmental Health Hazard Assessment (~6.2 g sportfish/kg body weight/mon).
Similarly, a fish consumption study on low-income persons in the Sacramento-San
Joaquin Delta region found that 2% of women exceeded the Office of Environmental
Health Hazard Assessment recommendation, and that 29% of women exceeded the
FDA/EPA advisory limits (48.6 g/d commercial fish, 24.3 g/d sportfish) via a combina-
tion of sport and commercial fish consumption (Silver et al. 2007).
In addition to studies related to fish consumption, there has been one published
study (Windham et al. 2006) suggesting a potential association between children
with autism spectrum disorders and emission of hazardous air pollutants, including
mercury, to ambient air in the San Francisco Bay area. However, this association,
based on limited data, should be reexamined and confirmed with a more refined
exposure assessment.
B EcosystemHealth
Birds
Studies of mercury in birds in the estuary have focused on measuring concentra-
tions and detecting the ecological impacts of contamination (Hoffman et al. 1998;
Hothem et al. 1995, 1998; Hui 1998; Hui et al. 2001; Lonzarich et al. 1992; Ohlendorf
et al. 1991; Schwarzbach et al. 2006; Takekawa et al. 2002); these have demon-
strated potentially toxic mercury concentrations in waterbirds around the estuary
(see Table 1), with diving ducks typically showing the highest level of contamina-
tion. The relationship between mercury and selenium has also been investigated
because the elements may offset each other's toxicity (Hothem et al. 1998; Hui et
al. 2001). Based on elevated concentrations of mercury, other recent studies of birds
in the estuary have sought to establish biomarkers of exposure, such as enzyme
activity and reproductive success. Ratios of glutathione reductase to oxidized
glutathione were used as a bioindicator to discriminate between mercury and sele-
nium effects (Hoffman et al. 1998). Schwarzbach et al. (2006) linked decreased egg
hatchability to mercury contamination in the California clapper rail ( Rallus
longirostris obsoletus ).
Mammals
There have been a few published studies on mercury concentration and toxicity in
mammals. A study of small mammals residing in pickleweed ( Salicornia virginica )