Environmental Engineering Reference
In-Depth Information
Table 4
(continued)
Ave. lbs. a.i.
applied (NASS
program states
-latest year)
b
(USDA
2012
)
Ave. %
crop treated
(NASS)
(USDA
2012
)
Ave. lbs.
a
a.i.
applied
(Gomez
2009
)
from Doane
Ave. %
crop treated
(USEPA
2008
)
Ave. lbs. a.i.
applied
(USEPA
2008
)
Crop
Soybeans
1,017,953
700,000
<1
Strawberries
10,043
9,000
15
7,700
15
Sugar Beets
138,020
100,000
10
Sunflowers
34,857
20,000
<1
Sweet Corn
120,881
100,000
10
36,500
13-23
Sweet potatoes
100,000
65
Tangelos &
tangerines
8,000
10
8,300
7-19
Tobacco
98,468
100,000
15
Walnuts
195,505
400,000
45
Wheat
288,751
300,000
<1
577,000
2-3
Total
a
To maintain consistency with uses and the labels of formulated products sold in the U.S., amounts
of CPY applied are given in imperial units (pounds (lbs.))
b
Generally this is 2011 for fruits and 2010 for other crop
c
Special Label Needs
4.4
Timing of the Use of Chlorpyrifos
CPY is normally applied to coincide with infestations of pests, which vary from one
location to another. Timing of application of CPY in relation to local climatic condi-
tions, rainfall, and patterns of weather might have significant effects on the degradation,
potential for movement, and exposures of non-target organisms. To properly character-
ize timing of the use of CPY, we relied on the USDA publication “Usual Planting and
Harvesting Dates for U.S. Field Crops” (USDA
2010
) and other sources (i.e., mainly
state extension services and the internet). These data are summarized in Table
5
for
crops that are in the field year round, and in Table
6
for crops that are seasonal.
From these data, it is apparent that there is no strong seasonal use of CPY,
although there is a somewhat greater usage in winter months for tree crops in
California and greater use in summer for certain field crops (e.g., corn). These use
patterns and how they affect scenarios for exposures are discussed in more detail in
the companion papers of this volume (Moore et al.
2014
; Williams et al.
2014
).
5
Summary
Physical properties and use data provide the basis for estimating environmental
exposures to chlorpyrifos (CPY) and for assessing its risks. The vapor pressure of
CPY is low, solubility in water is <1 mg L
−1
, and its log K
OW
is 5. Chlorpyrifos has
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