Environmental Engineering Reference
In-Depth Information
table 13.1
Summary of Risk Assessments for Methylmercury
Biomarker
and exposure
level
Critical
dose
Uncertainty
factor
Acceptable
level
Agency, year
Key studies
US EPA, 2001
Seychelles
(Davidson
et al., 1998); Faroe
Islands (Grandjean
et al., 1997); New
Zealand (Crump
et al., 1998). Final
value based on all
three studies.
Cord blood,
58
Benchmark
dose, 1.0
10
RfD, 0.1
g/
kg-bw/day
g/L
g/
kg-bw/day
European
Union, 2002
Seychelles study
(Davidson et al.,
1998); Faroe Islands
(Grandjean et al.,
1997). Final value
based on Faroes.
Cord blood,
58
Benchmark
dose, 1.0
10
NOAEL, 0.1
g/
g/L
g/
kg-bw/day
kg-bw/day
Health Canada,
2007
Seychelles study
(Davidson et al.,
1998); Faroe Islands
(Grandjean et al.,
1997); New Zealand
(Crump et al.,
1998). Final value
based on Faroes.
Maternal hair,
10 ppm
Benchmark
dose, 1.0
5
PTDI, 0.2
g/
kg-bw/day (for
women of
childbearing age
and young
children)
g/
kg-bw/day
WHO JECFA,
2003
Seychelles
(Davidson et al.,
1998); Faroe
Islands (Grandjean
et al., 1997); New
Zealand (Crump
et al., 1998). Final
value based on
Faroes and
Seychelles.
Maternal hair,
14 ppm
10.2
g/kg-bw/
wk (1.5
6.4
PTWI, 1.6
g/
g/
kg-bw/day)
kg-bw/wk
(equivalent to
0.23
g/kg-bw/
day)
US ATSDR,
1999
Seychelles
(Davidson et al.,
1998)
Maternal hair,
15.3 ppm
NOAEL,
1.3
4.5
MRL, 0.3
g/
g/
kg-bw/day
kg-bw/day
SOURCE
: NRC, 2000, Mahaffey et al. 2009.
NOTES
: MRL
minimal risk level; NOAEL
no observed adverse effect level; PTDI
provisional tolerable daily intake; PTWI
provisional
tolerable weekly intake; RfD
reference dose.
et al., 2006). The time between exposure and treatment
may also impact the effectiveness of chelation (NRC, 2000;
Clarkson et al., 2003). Chelation therapy is unlikely to reverse
damage to the central nervous system, particularly after
exposure to methylmercury, but it may prevent further
deterioration (Clarkson et al., 2003).
Biomonitoring for Mercury Exposure in
Human Populations
The mission of public health institutions is to protect and
improve the health of people and communities by educat-
ing, promoting healthy lifestyles and environments, and
