Environmental Engineering Reference
In-Depth Information
Table 3
Toxicity values for chlorpyrifos in
benthic organisms
Geomean
μ
Test
item
Expos.
type
Species
Resp.
a
Test sub.
Expos. (d)
Endpoint
g kg
−1
n
Inc. Medium
Crustacea
Hyalella
azteca
Mort
7-14 d
10
LC50
399
1
A
F
Y
FW
Insects
Chironomus
dilutus
Mort
Larv 3rd
10
LC50
377
3
A
F
Y
FW
from 0.53 to >806
μ
g CPY L
−1
and the HC5 (95%CI) was 0.812 (0.507-1.298)
μ
g
CPY L
−1
(SI Table
4
).
Aquatic stages of amphibians
. Of the seven species assessed, only three studies
met the QC criteria, and one of these was questionable. The range of LC
50
s was
from 19 to a questionable value of 5,174
g CPY L
−1
(Table
2
). Because of the
paucity of data, an SSD was not constructed. Larval stages of amphibians have
been observed to be less sensitive than fi sh to a range of chemicals (Weltje et al.
2013
), and the toxicity data for fi sh can be extrapolated to and be protective of
amphibians. Therefore, aquatic stages of amphibians were not considered further
in the ERA.
μ
Other invertebrates
. Toxicity data for four other invertebrates were found (Table
2
).
The LC
50
of 12,000
g CPY L
−1
for
Brachionus calycifl orus
is consistent with the
lack of sensitivity of rotifers to pesticides in general (Brock et al.
2000
). Similarly,
the three LC/EC
50
values for aquatic mollusks ranged from 154 to >806
μ
g CPY L
−1
,
which also is consistent with general lack of sensitivity of this taxon to insecticides
(Brock et al.
2000
). Because of general lack of sensitivity, these taxa were not con-
sidered further in the ERA.
μ
Toxicity of CPY to benthos
. There were few acute toxicity data for benthic organisms.
Data from two species met the QC criteria (Table
3
). LC
50
s for
Hyalella azteca
and
Chironomus dilutus
were 399 and 377
g CPY kg
−1
(dwt), respectively, or expressed
in terms of organic carbon content of the sediment 2,122 and 4,815 ng g
−1
organic
carbon (OC), respectively. There were too few data to derive an SSD. Given that the
concentration measured in the pore-water at the LC
50
was close to the water-only
LC
50
(Ankley et al.
1994
), it was previously concluded (Giesy et al.
1999
) that the
risk assessment for aquatic organisms could be applied to benthos on the basis of
equilibrium partitioning and that risk of CPY to benthos could be extrapolated from
organisms in the water column.
μ
Toxicity of CPYO
. Insuffi cient toxicity data on the biologically active metabolite,
CPYO, were available (Table
4
) to construct an SSD. The LC
50
values relevant to
risks to surface-water organisms were a 48-h LC
50
for
D. magna
of 1.9
μ
g CPYO L
−1
and 96-h LC
50
of 1.1
g CPYO L
−1
in the bluegill sunfi sh
L. macrochirus
. The only
toxicity value reported for amphibians was in larval
Rana boylii
, but the reported
LC
50
value of >5
μ
g CPYO L
−1
was from a study that did not meet the criteria for
inclusion in the ERA. The LC
50
value for CPYO in
D. magna
was larger than CPY
μ
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