Risk to Pollinators from the Use of Chlorpyrifos in the United States - Reviews of Environmental Contamination and Toxicology - page 247

Table 11 Reported chlorpyrifos (CPY) incidents with honey bees in the U.S., 1990-present
(USEPA 2013 )

Reported CPY Incidents with Honey Bees

Crop 1990-1999 2000-2009 2010- present No date Specified

Agricultural area
(not specified)

4 0 0 2

Alfalfa 1 1 0

Apple 1 0 0

Bean 1 0 0

Carrot 2 0 0

Carrot seed 1 0 0

Cherry 0 0 0 2

Corn 0 1 0

Cotton 0 0 1

Orchard 4 0 0

Orchard (unspecified) 5 0 0

Soybean 0 1 0

Not reported 7 1 0

TOTALS 26 4 1 4

portion of bee samples collected from hives throughout the U.S., at concentrations
up to 10.7 μg CPY kg −1 . Samples consisted of live adult nurse bees removed from
brood nests (Mullin et al. 2010 ). Live worker bees were collected several times dur-
ing the season from hives in France, but CPY was not detected in any samples
(Chauzat et al. 2011 ). In Italy, CPY in bees was detected in only a small portion of
samples (Ghini et al. 2004 ) (Table 10 ). Thus, detection of CPY in honey bees col-
lected in the field was infrequent. Assuming an adult worker honey bee weighs
93 mg (Winston 1987 ), a honey bee worker is estimated to contain up to 9 × 10 −4 μg
CPY, based on the 95th centile estimate of 9.7 μg CPY kg −1 reported by Mullin et al.
( 2010 ). The median concentration of 2.2 μg CPY kg −1 reported by Mullin et al.
( 2010 ) provides an estimate of 2 × 10 −4 μg CPY bee −1 .
In an experiment where nucleus colonies (five frames with 3000 adults, a queen,
larvae) of honey bees were held in cages and fed almond pollen from trees previously
sprayed with CPY, or CPY and boscalid + pyraclostrobin, concentrations in bodies of
nurse bees were 80.6 and 72.7 μg CPY kg −1 (wwt), respectively (DeGrandi-Hoffman
et al. 2013 ). Because bees were held in cages and only had access to trays of pollen
from almond trees intentionally treated with CPY, it is not surprising that these values
are higher than concentrations reported from field monitoring surveys (Table 10 ).

Incident Reports . Considering the widespread use of CPY in agriculture in the U.S.,
data obtained from the USEPA Office of Pesticide Programs show that the number
of honey bee incidents reported is very low, and has decreased over the past two
decades (USEPA 2013 ). Reported incidents range from those involving a few to
hundreds of honey bee colonies, and involve exposure following registered uses and
misuse of CPY. As well, the level of certainty as to whether or not CPY caused the
reported incidents was variable, ranging from “unlikely” to “highly probable”. The
reported incidents since 1990 are listed in Table 11 .