Environmental Engineering Reference
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will partition out of air into water, where it is less persistent. The overall persistence
in these two media is not suggestive of the characteristics of a POP. Concentrations
in surface waters in remote locations (Sect.
2.4
and Fig.
4
) are less than amounts
that would cause toxicity (Giddings et al.
2014
). In addition, adverse effects in
aquatic organisms have not been linked to exposures to CPY (Datta et al.
1998
;
Davidson et al.
2012
), and, by extension to the oxon that might be formed. Thus,
neither CPY nor CPYO trigger the criteria for POPs and LRT.
Classification as a PBT
. In terms of assessment of PBT under EC regulation No.
1107/2009, there is no guidance for using multiple values for P and B. However,
because of the multiple uses of CPY over a large number of agricultural sites, the
geometric mean is the most appropriate value to compare to the trigger value. In
addition, values derived under field conditions can be used for validation. For sur-
face waters, the geometric mean of laboratory-based half-lives was 21 d but, under
more realistic conditions in microcosms, half-lives were less than 10 d (Sect.
3
).
These are less than the trigger of 40 d. Based on these values, the trigger value for
P is not exceeded. Geometric mean half-lives in soil tested under laboratory and
field conditions were 32 and 22 d, respectively. These are less than the trigger of 120
d. The geometric mean DT
50dis
for CPY in sediments tested in the laboratory and
microcosms was 39 d, less than the trigger value of 120 d.
The geometric mean values for BCF or BAF tested in the laboratory and the field
were 848 and 935, respectively (Sect.
5
). These are less that the trigger value of
2,000. Moreover, CPY does not trigger the criterion for Pv or Bv. In addition, CPYO
also does not trigger the criteria for P and B or Pv or Bv.
The trigger of 10 μg L
−1
for T is exceeded for CPY; the most sensitive NOEC
reported for aquatic organisms is 0.005 μg L
−1
for
Simocephalus vetulus
in a micro-
cosm experiment (Daam and Van den Brink
2007
). Since CPY is an insecticide,
toxicity to arthropods is expected, however; the key question is the relevance of this
to the exposures in the general environment and, as discussed in the companion
papers (Giddings et al.
2014
; Williams et al.
2014
), this is not indicative of significant
ecotoxicological risks in the North-American environment, even in areas close to
where it is applied. In aquatic organisms, CPYO has similar toxicity to CPY (Giddings
et al.
2014
), but it is only infrequently found in surface waters and then only at very
small concentrations (Williams et al.
2013
). This is consistent with the greater reac-
tivity of CPYO and its rapid hydrolysis in the environment. Thus, although formed
from CPY in the atmosphere, CPYO is not persistent enough to present a risk to
aquatic organisms, although it does trigger the T criterion under EC 1107/2009.
7
Summary
The fate and movement of the organophosphorus insecticide chlorpyrifos (CPY;
CAS No.2921-88-2) and its metabolite chlorpyrifos-oxon (CPYO; CAS
No.5598-15-2) determine exposures in terrestrial and aquatic environments.
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