Environmental Engineering Reference
In-Depth Information
8
Summary
Refi ned risk assessments for birds exposed to fl owable and granular formulations of
CPY were conducted for a range of current use patterns in the United States. Overall,
the collective evidence from the modeling and fi eld study lines of evidence indicate
that fl owable and granular CPY do not pose signifi cant risks to the bird communities
foraging in agro-ecosystems in the United States. The available information indi-
cates that avian incidents resulting from the legal, registered uses of CPY have been
very infrequent since 2002 (see SI Appendix 3). The small number of recent inci-
dents suggests that the current labels for CPY are generally protective of birds.
However, incident data are uncertain because of the diffi culties associated with fi nding
dead birds in the fi eld and linking any mortality observed to CPY.
Flowable CPY is registered for a variety of crops in the United States including
alfalfa, brassica vegetables, citrus, corn, cotton, grape, mint, onion, peanut, pome and
stone fruits, soybean, sugar beet, sunfl ower, sweet potato, tree nuts, and wheat under
the trade name Lorsban Advanced. The major routes of exposure for birds to fl ow-
able CPY were consumption of treated dietary items and drinking water. The Liquid
Pesticide Avian Risk Assessment Model (LiquidPARAM) was used to simulate
avian ingestion of CPY by these routes of exposure. For acute exposure,
LiquidPARAM estimated the maximum retained dose in each of 20 birds on each of
1,000 fi elds that were treated with CPY over the 60-d period following initial appli-
cation. The model used a 1-h time step. For species lacking acceptable acute oral
toxicity data (all focal species except northern bobwhite ( C. virginianus ) and red-
winged blackbird ( A. phoeniceus )), a species sensitivity distribution (SSD) approach
was used to generate hypothetical dose-response curves assuming high, median and
low sensitivity to CPY. For acute risk, risk curves were generated for each use pattern
and exposure scenario. The risk curves show the relationship between exceedence
probability and percent mortality. The results of the LiquidPARAM modeling exer-
cise indicate that fl owable CPY poses an acute risk to some bird species, particularly
those species that are highly sensitive and that forage extensively in crops with high
maximum application rates (e.g., grapefruit, orange). Overall, most bird species
would not experience signifi cant mortality as a result of exposure to fl owable CPY.
The results of a number of fi eld studies conducted at application rates comparable to
those on the Lorsban Advanced label indicate that fl owable CPY rarely causes
avian mortality. The results of the fi eld studies suggest that LiquidPARAM is likely
over-estimating acute risk to birds for fl owable CPY.
For chronic exposure, LiquidPARAM estimated the maximum total daily
intake (TDI) over a user-specifi ed exposure duration (28-d in the case of CPY).
The maximum average TDI was compared to the chronic NOEL and LOEL from
the most sensitive species tested for CPY, the mallard. This comparison was
done for each of the 20 birds in each of the 1000 fi elds simulated in LiquidPARAM.
The outputs are estimates of the probabilities of exceeding the NOEL and LOEL.
LiquidPARAM did not predict signifi cant adverse effects resulting from chronic
exposure to fl owable CPY. The small number of incidents (2) involving CPY
reported since 2002 suggests that the current labels for CPY are generally protective
of birds.
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