Environmental Engineering Reference
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Fig. 8
Productivity and population size of osprey in the region between New York City and
Boston. Figure 2 in Spitzer et al. (
1983
) reproduced with permission
levels and shell thinning were noted. Analysis of the DDE egg residue—shell thin-
ning relationship revealed 10% thinning at 2.0 ppm, 15% at 4.2 ppm and 20% at
8.7 ppm. Reproductive failure was attributed to DDE causing thinning of eggshells.
Ospreys were considered to be as sensitive as other sensitive species.
In his topic on ospreys, Poole (
1989
) published Figure 9.7 relating DDE residues
in osprey eggs with eggshell thinning as shown in Fig.
9
.
Poole's data illustrate the wide variability in eggshell thinning at each residue
level, explaining why populations increase even at levels of DDE that result in some
shells breaking and failing to produce viable young. Reproductive failure and mor-
tality due to high residues of dieldrin and PCBs, particularly in the 1960s and early
1970s, may account for some of this variability. Poole also reported on the DDE egg
residue—production dose-response as shown in Fig.
10
. Poole set the reproductive
effect threshold at 4.3 ppm DDE. This number compares with the 15% shell-
thinning value suggested by Wiemeyer et al. (
1988
) at 4.2 ppm DDE.
Schmitt et al. (
1990
) published the results of a national fresh water fi sh residue
survey for 1984. Total DDT residues in fi sh from the Connecticut River averaged
0.22 ppm. For all sites sampled nationwide, the trend of the geometric average total
DDT residue was 0.39 ppm in 1976-1977, 0.36 ppm in 1978-1979, 0.32 ppm in
1980-1981 and 0.28 ppm in 1984. Schmitt et al. (
1981
) had earlier published a
nationwide level of 1.08 ppm in fi sh collected between 1970 and 1974. Bilger et al.
(
1999
) discussed EPA analysis of multi-species composite analyses done in 1987.
The mean DDE concentration was 0.295 ppm in a nationwide sampling. The USGS
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