Exposures of Aquatic Organisms to the Organophosphorus Insecticide, Chlorpyrifos Resulting from Use in the United States - Reviews of Environmental Contamination and Toxicology - page 77

Fig. 1 Geographical distribution of chlorpyrifos use in the United States from 2010 to 2011. Derived
from confidential sales data (from Dow AgroSciences, 2012; see SI for a color version of this Figure)

the implementation of other label changes for environmental stewardship that were
implemented in 2001. The objective of this study was to characterize likely exposures
of aquatic organisms to CPY in the U.S. by evaluating patterns of use, environmental
chemistry, available monitoring data, and via simulation modeling. The results of the
data analyses and simulation modeling are a key component of the CPY risk assess-
ment described in the companion paper (Giddings et al. 2014 ).

1.1 Distribution of Use of Chlorpyrifos

CPY is one of the insecticides most widely used throughout the world to limit insect
and mite damage to a number of important crops, including soybeans, corn, tree
nuts, alfalfa, wheat, citrus, peanuts, and vegetables, among others (Solomon et al.
2014 ). Regions in the U.S. with the largest use of CPY in 2010-2011, expressed as
percent of insecticide, include the Central Valley of California; the Snake River
basin in Oregon and southwestern Idaho; parts of Minnesota, Iowa, Wisconsin,
Illinois, Indiana, Ohio and Michigan in the central and eastern corn belt; and areas
in Georgia and North Carolina along the Atlantic and Gulf coastal plain (Fig. 1 ).
Soybeans, corn, tree nuts (almonds, pecans and walnuts), apples, alfalfa, wheat, and
sugar beets accounted for approximately 80% of the use of CPY in 2007 (Fig. 2 ).
CPY is available as a granular product for soil treatment, or several flowable
formulations (all formulations that are sprayed) that can be applied to foliage, soil,