Environmental Engineering Reference
In-Depth Information
table 12.5a
Mercury Concentration in Five Commonly Eaten Fish from the Savannah
River and Percentage of Fish Exceeding 0.5 ppm and 1.0 ppm
Mean Hg (
SE)
in ppm wet
weight
%
exceeding
0.5 ppm
%
exceeding
1.0 ppm
g of
mercury in
8 oz (227 g)
Species
No.
Bowfi n
(Amia calva)
58
0.94
0.05
81%
45%
214
Largemouth Bass
(Micropterus
salmoides)
48
0.46
0.04
38%
4%
105
Yellow Perch
(Perca fl avescens)
39
0.28
0.02
10%
0%
64
Black Crappie
(Pomoxis
nigromaculatus)
53
0.24
0.02
9%
0%
55
Channel Catfi sh
(Ictalurus punctatus)
45
0.20
0.02
1%
0%
46
note:
These values are for total mercury (about 90% of which is methylmercury). (Additional data are provided in Burger et al., 2001a).
table 12.5b
Distribution of Fish Intake (g/day) for Fishermen and Women Interviewed along the Savannah River (from
Burger et al., 1999)
95th
percentile
Fish eaters
Median
Mean
Black males
51.8
70.1
187.9
White females
12.8
26.1
90
note:
Of the four groups tested (black males and females and white males and females), black males reported the highest and
white females the lowest fi sh consumption.
We calculated mercury intake using the median, mean,
and 95th percentile of the fi sh consumption estimates
from our interview studies (see Table 12.6). It should be
noted that some risk evaluations are based on much lower
default assumptions derived from the general population,
whereas fi sh consumption risks fall mainly on the large
number of people who are population outliers (high fi sh
consumers). We illustrate the risk evaluation using Bowfi n
(see Table 12.6), the fi sh with the highest mercury content
(mean 0.94 µg/g [ppm]). Of the four populations—white
male and female and black male and female—the black
males had the highest average consumption and white
females the lowest. Using their median, mean and 95th
percentile consumption in grams per day, the table shows
the mercury intake in micrograms per day. This is then
converted to methylmercury using a conversion value of
90% (from many published studies). We then divided the
daily intake by 70 kg for males and 60 kg for females to
arrive at a daily intake in micrograms per kilogram of body
weight. These are the units that both the ATSDR and the
Data on the distribution of mercury levels in fi sh com-
monly caught and eaten by local anglers along the Savannah
River is provided in Table 12.5a, b. We interviewed the anglers
for many features, including the amount of fi sh that they and
their family members consumed. To stabilize the estimate of
meal size we showed them a model equivalent to about 8 oz
(227 g) of fi sh. Table 12.6 combines mercury concentration
data with fi sh consumption data to estimate the hazard quo-
tient (daily mercury intake divided by both the ATSDR MRL
(0.3 µg/kg/day) and the EPA's RfD (0.1 µg/kg/day).
Table 12.5 shows the sample size and average total mercury
concentration (micrograms per gram, or parts per million
[ppm], of muscle on a wet weight basis) in fi ve of the fi sh
species we sampled from the Savannah River, as well as the
number (and percent) exceeding a conservative action level
of 0.5 ppm and the current USFDA action level of 1.0 ppm.
The fi nal column is the amount of mercury (micrograms of
total mercury) in an 8 oz (227 g) serving. On average, about
90% of this mercury would be methylmercury. We provide
more details on the data and methods in Burger et al. (2001c).
