Risk to Pollinators from the Use of Chlorpyrifos in the United States - Reviews of Environmental Contamination and Toxicology - page 232

Table 4 Dissipation and concentration of dislodgeable foliar residues following application of
chlorpyrifos (CPY) to different plants

Application
rate (kg ha −1 )

Half- life
(d)

Time
(d)

Residue
(μg cm −2 )

Adjusted to
1.12 kg ha −1 Plant Reference

Cotton 1.12 - 0 3.64 3.64 Buck et al.

( 1980 )

1 0.13 0.13

2 0.071 0.071

3 0.055 0.055

4 0.034 0.034

Cotton 1.12 <1 0 3.62 3.62 Ware et al.

( 1980 )

1 0.3 0.3

2 0.191 0.191

3 0.069 0.069

4 0.068 0.068

Orange 5.6 - 4 0.013 0.003 Iwata et al.

( 1983 )

10 0.005 0.001

11.21 - 4 0.031 0.003

10 0.012 0.001

17 0.006 0.0006

11.21 (ULV) - 4 0.08 0.008

10 0.021 0.002

17 0.015 0.001

31 0.008 0.0008

Grape fruit 5.6 2.4 3 0.035 0.007

11.21 3.4 3 0.061 0.006

Cranberry 2.0 3.8 0 (2 h) 52.5 28.9 Putnam

et al.
( 2003 )

3 23.95 13.2

15 6.14 3.4

Kentucky
bluegrass

2.2 0.1-0.3 0 0.14 0.07 Goh et al.

( 1986 )

1 0.04 0.02

2 0.03 0.015

3 0.018 0.009

4 0.013 0.007

Kentucky
bluegrass

2 <1 0.456 0.251 Sears et al.

( 1987 )

An estimate of the upper-bound concentration of CPY likely to be on flowers can
be obtained from the results of dislodgeable foliar residue studies (USEPA 2012 ).
These studies show that CPY does not persist on plant surfaces. In some studies,
dissipation was too rapid to produce meaningful dissipation curves (Iwata et al.
1983 ), but the average half-life was 1.5 d (Racke 1993 ; Solomon et al. 2001 ). The
upper 90% confidence limit on the mean foliar half-life was 3.28 d (Williams et al.
2014 ). CPY that drifts onto non-target plants should dissipate at a similar rate, but
initial concentrations would be less. Initial concentrations recorded for most crops
were <4 μg cm 2 , but were considerably larger for cranberry (Table 4 ). In a field