Environmental Engineering Reference
In-Depth Information
conducting research on causes and prevention of disease
and injury. We can measure public health achievements by
tracking exposures and related health outcomes. The dra-
matic success in lowering childhood and adult blood lead
levels that occurred by eliminating lead from automobile
gas and house paint has been well documented by sequen-
tial, population-based studies (Pirkle et al., 1994). Mercury
is currently a component of biomonitoring efforts in North
America, Europe, and Asia (CDC, 2012; Schulz et al., 2007b;
Wong and Lye, 2008; Son et al., 2009).
2008). An estimate of geometric mean total blood mercury
among adults in the Czech Republic was 0.82 (based on
measurements from 1188 blood donors during 2001-2003)
(Batariova et al., 2006). These estimates represent relatively
low average exposure.
Mercury concentrations in hair specimens collected
from women and children were measured in the 1999-
2000 NHANES (McDowell et al., 2004). Women had a
geometric mean hair mercury concentration of 0.20 ppm;
the geometric mean in children was 0.12 ppm. Similar
to results for blood mercury, average levels were low, but
the 95th percentiles for women and children who con-
sumed fi sh most frequently (at least three times in the past
30 days) were higher (2.75 and 2.00 ppm, respectively),
probably refl ecting the presence of small groups with high
fi sh consumption.
Estimates of mean values can obscure heterogeneity of
exposures within a population, especially in countries that
are culturally diverse. Regional differences in blood mer-
cury levels have been noted in both the United States and
Germany (Schulz et al., 2007b ; Mahaffey et al., 2009). A
local HANES conducted in New York City in 2004 reported
higher total blood mercury levels than the national HANES
(McKelvey et al., 2007). About 25% of adult New Yorkers
had levels that equaled or exceeded the New York State
reportable level (5 µg/L), as compared with about 10% of
adults nationally in 1999-2000 (Mahaffey et al., 2004).
Data from NHANES suggest that the northeast United
States and coastal regions, in general, may have similarly
elevated levels (Mahaffey et al., 2009). In New York City,
Asian and foreign-born Chinese New Yorkers had an even
higher prevalence of elevated blood mercury levels. An
estimated 72% of foreign-born Chinese residents had levels
of 5.0 µg/L and above (McKelvey et al., 2007). A 2003-2004
study conducted among children 1.5 to 5 years of age liv-
ing in Vancouver, Canada, also reported the highest blood
mercury concentrations in the Chinese, as compared with
the other racial/ethnic groups sampled (Innis et al., 2006).
These differences were all attributed to more frequent fi sh
consumption.
In general, studies conducted in communities where
fi sh constitute an important part of the diet have reported
higher blood and hair mercury levels. A 2000-2001 study
of 1057 consecutive births in Hong Kong found that 78%
of the neonates had cord-blood mercury concentrations
greater than or equal to 5.8 µg/L (Fok et al., 2007), as com-
pared with 10% of US women from the combined 1999-
2004 NHANES, who had levels greater than or equal to
3.5 µg/L (assuming a ratio of about 1.7 for cord:maternal
blood concentration) (Mahaffey et al., 2009). Mean fi sh
consumption in Hong Kong was 67 g/day based on a food-
frequency questionnaire, whereas dietary recall studies of
adults in the United States estimate an average consump-
tion rate of approximately 15 g/day (weight after cook-
ing) (US EPA, 2002). In a 2000-2002 survey of 3686 par-
ticipants from fi ve districts in Japan, the geometric mean
Mercury Levels in Blood and Hair
Mercury exposure in the general population can vary enor-
mously, and it does so primarily as a function of type and
frequency of fi sh consumption (NRC, 2000). Blood concen-
trations range from well under 1.0 µg/L in those who eat
fi sh infrequently to more than 8 µg/L in frequent consum-
ers (Brune et al., 1991).
Germany began conducting population-based biomoni-
toring for mercury as part of its German Environmental
Surveys (GerES) in the western part of the country in
1985-1986, and upon reunifi cation, in the eastern part in
1990-1992. In 1998, the estimated geometric mean total
blood mercury concentration (based on measurements in
3973 adults aged 25-69 years from both parts of the coun-
try) was 0.61 µg/L (Schulz et al., 2007b). The 2003-2006
estimate in children aged 6-14 years (based on 1240 mea-
surements) was 0.24 µg/L. The 95th percentiles for adults
and children, respectively, were 2.4 µg/L and 1.0 µg/L.
In the United States, the National Health and Nutrition
Examination Survey (NHANES) began population-based
mercury biomonitoring in 1999-2000 (CDC, 2012). During
1999-2002, the survey measured mercury levels in women
of reproductive age (16-49 years) and children (ages 1-5
years); more recent data include men and older ages. In
2003-2006, the geometric mean total blood mercury con-
centration in males and females 1 year of age or older was
0.83 µg/L (based on 16,780 measurements); the median
concentration in the subset of 1879 children 1 to 5 years
of age was 0.30 µg/L (Caldwell et al., 2009). The 95th per-
centiles were 4.76 and 1.60 µg/L, respectively. An assess-
ment of changes over time suggests that geometric mean
mercury levels have been stable since 1999-2000, how-
ever, the upper end of the distribution (95th percentile)
may be decreasing (Caldwell et al., 2009; Mahaffey et al.,
2009). The 95th percentile from data collected on women
in 1999-2000 was 7.2 µg/L (95% confi dence interval, 5.30-
11.30), as compared with 4.48 µg/L (95% confi dence inter-
val, 3.88-5.60) in 2005-2006.
Other Western countries have reported average mercury
levels similar to those in Germany and the United States.
The Canadian Health Measures Survey measured total
blood mercury concentration in Canadians 6 to 79 years
of age. The 2007-2009 estimated geometric mean was
0.76 µg/L (based on 2678 measurements) (Wong and Lye,
