Chemistry Reference
In-Depth Information
taBLe 5.6
results from an analytical Study of residues in Biota
Sampled from clear Lake, california
p,p
′
-ddd concentration
(ppm wet weight)
Species/Sample
Lake water
0.02
Plankton
5.0
Nonpredatory fish (fat)
40-1000
Predatory fish (fat)
80-2500
Predatory fish (flesh)
1-200
Western grebe (fat)
1600
Source:
From Hunt and Bischoff (1960).
bioconcentration due to direct uptake from water, both by plankton and fish. The
difference in concentration in body fat between predatory and nonpredatory fish is
not very large, so there is no clear evidence of strong bioaccumulation of
p,p
′-DDD
by the predatory fish from its food. A comparison of bioconcentration factors from
water for nonpredatory and predatory fish would be necessary to establish how much
bioaccumulation, if any, was achieved by the latter. The grebes, however, which were
not expected to take up substantial quantities of insecticide directly from water, con-
tained a mean level of
p,p
′-DDD in their depot fat well above the top of the range
for nonpredatory fish and not much below the highest value found in predatory fish,
suggesting some bioaccumulation in the last step of the food chain. Indeed, it seems
very probable that the birds died from DDD poisoning while the tissue levels of the
insecticide were still increasing (i.e., some time before a steady state was reached),
so that the level of bioaccumulation found was below what might have been achieved
at a lower level of exposure.
The two examples just given are of localized effects associated with the acute tox-
icity of DDT and DDD to organisms in higher trophic levels. A more wide-ranging
toxic effect associated with population decline was eggshell thinning caused by the
relatively high levels of
p,p
′-DDE in some predatory birds (see Table 5.7).
In North America, during the period late 1940s to late 1970s, the decline of
several species of birds of prey was associated with eggshell thinning caused by
p,p
′-DDE. Peregrine populations declined or were extirpated when eggshell thin-
ning of 18-25% occurred. This degree of eggshell thinning was associated with
DDE residues in excess of 10 ppm (wet weight) in the eggs (Peakall 1993). The bald
eagle showed a marked decline in many areas of North America, first reported in
Florida in 1946 (Broley 1958). Shell thinning of 15% was associated with residues
of 16 ppm
p,p
′-DDE in eggs of this species (Wiemeyer et al. 1993), and at the time
of the initial decline (1946-1957), shell thinning of 15-19% was associated with
diminished breeding success. In field studies carried out during 1969-1984, the
picture was complicated by the fact that, although breeding success was negatively
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