Environmental Justice - Mercury in the Environment - page 311

table 15.1 (continued)

Ethnic
group

Geometric
mean

Sample
type

Year
collected

No. of
subjects Location Reference

Disko Bay Inuit 12.8 Maternal 1994-1996 Bjerregaard and

Hansen (2000)

Ilullisat Inuit 25.3 Cord 1994-1996 Bjerre gaard and

Hansen (2000)

Finland (average)

1.4 Maternal 1996 -1998 130 AMAP (2003)

Russia (Siberia)

Taymir Indigenous 2.7 Maternal 1995-1996 18 AMAP (2003)

Taymir Indigenous 2.9 Maternal 1996 -1998 12 AMAP (2003)

Norilsk Nonindigenous 1.4 Maternal 1995-1996 49 AMAP (2003)

United States (Alaska) (average)

Inuit 5.5 Maternal 2000 23

Bethel Inuit 1.3 Maternal 2000 23 AMAP (2003)

Barrow AMAP (2003)

SOURCES : 1

Deutch et al., 2007. 2 Wheatley (1994). 3 Dewilly et al. (2001). 4a Muckle et al. (2001). 4b Muckle et al. (2001b). 5 Rhainds et al.

(1999). 6 Kearney et al. (1995). 7 Walker et al. (2006). 8 Bjerregaard and Hansen (2000). 9 AMAP (2003).

in Greenland that have been studied, maternal exceed-
ances of the 5.8 µg/L threshold were 68% and 80% (AMAP,
2003). An epidemiologic study of 510 men and women in
six Greenland districts found that human blood mercury
levels were very high (mean values ranged from 3.3 to
69.8 µg/L, especially in the northern communities, where
people depended on local foods for their diet (Deutch et al.,
2007). Except for women from Nuuk, the mean blood mer-
cury levels were found to be above the 5.8 µg/L guideline,
while values above 20 µg/L were recorded in four of the
six districts for men and women (see Table 15.1).
Methylmercury crosses the placental barrier and is able to
penetrate the blood-brain barrier. The fetus is thus particu-
larly vulnerable to the risk of mercury exposure; therefore,
the accumulation of mercury in the Arctic food must be
viewed with some concern. A number of studies have deter-
mined the mercury level in cord blood to be a bioindicator of
fetal exposure. In one of the fi rst such studies, the analysis of
2405 umbilical cord blood samples taken from communities
in the Arctic regions of Canada found that 22% of the sam-
ples had mercury levels

signifi cantly higher in Inuit samples than in the rest of the eth-
nic groups (see Table 15.1). Considerable individual variability
was found in cord-blood mercury levels among the Inuit, with
values ranging from 0.0 to 70 µg/L, as well as marked regional
differences, with the levels of participants from the Baffi n
Region being signifi cantly higher than those for Inuit partici-
pants from the Inuvik Region. The study showed that 56% of
Inuit and 5% of Dene/Métis cord-blood samples were greater
than the 5.8 µg/L threshold for methylmercury (Walker et
al., 2006). There were signifi cant and important regional dif-
ferences in the exceedance of the 5.8 µg/L threshold, such
as the 11-58% rate for maternal samples from Kitikmeot and
Baffi n participants and the 20-75% for samples from Inuvik,
the Baffi n, and Kivalliq regions (see Table 15.1). In contrast to
Canada, nearly 75% of the children born in Greenland are esti-
mated to have cord-blood mercury levels 5.8 µg/L (Hylander

and Goodsite, 2006).
The ratio of total mercury in cord blood to the level in
maternal blood for communities in Canada ranged from
0.44 to 4.5, with a geometric mean value of 1.4, while the
corresponding methylmercury ratio ranged from 0.15 to
10.3, with a mean value of 1.6 (Walker et al., 2006). Studies
of other biomarkers of mercury exposure are consistent
with the blood data in showing disproportionate exposure
for indigenous people that consume traditional foods. A
study of autopsy samples from 102 ethnic Greenlanders
found the highest levels of mercury in kidney (1.4 µg/g wet
weight) followed by liver (0.53 to 1.4 µg/g wet weight) and

20 µg/L, with the highest recorded
concentration being 224 µg/L (Wheatley and Wheatley,
2000). In a subsequent study, Walker et al. (2006) found the
geometric mean total mercury concentration in cord blood
from different indigenous communities in Canada to be
2.7 µg/L. The geometric mean concentration of methylmer-
cury in cord blood ranged from 1.14 µg/L in Caucasians to 6.16
µg/L in Inuit participants, with the mean concentration being