Environmental Engineering Reference
In-Depth Information
Table 31
Growth and survival of
Hyallela azteca
exposed in the water column to chlordane.
Table 23 reproduced from Cardwell et al. (
1977
)
Table 23 Relative survival and growth of
Hyallela azteca exposed to technical chlordane
Measured co
ncentration of technical chlordane,
ʼ
g/L
Parameter
Control
1.4
2.6
5.3
11.5
20.5
Replicate I
No. survivors
a
27
23
23
24
3
0
% Survivors
108
92
92
96
12
0
Wet body weight, mg
b
6.3 ± 1.3
6.2 ± 1.5
6.4 ± 1.2
5.1 ± 0.9
3.8 ± 0.7
…
Dry weight, mg
b
1.58
1.49
1.57
1.37
0.87
…
Replicate II
No. survivors
a
22
25
25
24
9
0
% Survivors
88
100
100
96
36
0
Wet body weight, mg
b
7.5 ± 1.3
5.8 ± 1.3
5.8 ± 1.6
5.5 ± 1.6
5.3 ± 1.0
…
Dry weight, mg
b
1.92
1.55
1.53
1.35
1.33
…
a
25 individuals introduced initially per chamber
b
Average calculated weight per individual
In a 65 day study of mortality and weight gain, the NOEL appears to be 2.6 ppb
in water. Using equilibrium partitioning to estimate the sediment concentration of
chlordane required to reach 2.6 ppb in water, gives a sediment level of 42,172 ppb
at 1% OC (2.6
ʼ
ʼ
ʼ
ʼ
g/kg).
The US Fish and Wildlife Service (Eisler
1990
) reviewed the aquatic toxicity of
chlordane. Eisler reported an LC
50
of 40 ppb for the amphipod
Gammarus fasciatus
.
The equivalent LC
50
for sediment at equilibrium would be 649,000 ppb. Other sensi-
tive aquatic species include the pink shrimp (LC
10
of 0.24 ppb in water), planarian
(5 day NOEL of 0.2 ppb in water), and dungeness crab survival and molting (37 day
NOEL of 0.015 ppb in water). The dungeness crab bioassay appears to be the most
sensitive; the equilibrium NOEL in sediment calculated out to be 243 ppb chlordane
in sediment.
The triad analysis, although representing one kind of weight-of-evidence analy-
sis, is incomplete and fl awed as it was used to assess impairment of aquatic biota by
chlordane in Newport Bay. Relying on the mere presence of chlordane along with
hundreds of other chemicals in toxic sediments constitutes an incomplete weight-
of-evidence analysis. The chlordane ERM is not a reliable measure of toxicity
thresholds and should not be used in a weight-of-evidence analysis to assess impair-
ment of aquatic biota. Most importantly, one should consider the results of dose-
response bioassays. Valid spiked sediment bioassays could not be found for
chlordane. Therefore, the triad analysis should have relied on spiked water bioas-
says and equilibrium partitioning to estimate toxicity thresholds for chlordane in
sediments. The available aquatic toxicity bioassay data do not support an effect of
chlordane on benthic organisms at the level of approximately 10 ppb (<1-55 ppb)
as measured in sediments from Newport Bay. The lowest effect level exceeded
1,000 ppb and the NOEL in the most sensitive species and life stage was 243 ppb.
g/L × 1,622,000 L/kg × 0.01
g OC/
g sediment = 42,172
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