Fate in the Environment and Long-Range Atmospheric Transport of the Organophosphorus Insecticide, Chlorpyrifos and Its Oxon - Reviews of Environmental Contamination and Toxicology - page 58

Concentrations of pesticides were measured in frogs at 7 high elevation sites in the
Sierra Nevada in 2009 and 2010 (Smalling et al. 2013 ). Although CPY was one of
the most heavily used pesticides in the area, it was not detected in frog tissues above
the LOD of 0.5 ng g −1 . In comparison, p,p ′ - DDE was widely detected with a 75th
centile of 40 ng g −1 and the fungicide, tebuconazole was detected with a 75th centile
of 120 ng g −1 . Concentrations of CPY in zooplankton in lakes in Ontario, expressed
on a wet weight basis, have been reported to be 0.004 ng CPY g −1 wwt, but concen-
trations as great as 0.08 ng CPY g −1 can occur (Kurt-Karakus et al. 2011 ).
Corresponding concentrations, normalized to the fraction of lipid (2%) in zooplank-
ton results in a range of concentrations of 0.2 and to 4 ng CPY g −1 lipid in lakes
distant from points of application of CPY. Corresponding fugacities for this range
of concentrations are 0.0064 and 0.13 nPa. Bioconcentration factors (BCF) are con-
siderably smaller than would be predicted from the octanol-water partition coeffi-
cient (K OW ) or from estimations based on simulation models such as BCFWIN.
These lesser values for site-specific BCF calculated from measured concentrations
are likely attributable to biotransformation. Aston and Seiber ( 1997 ) obtained pine
needle/air bioconcentration factors of 9,800 of CPY that might be a function of the
octanol/air partition coefficient and the quantity of lipid-like material in the cuticle.
In summary, fugacity can act as a bridge between monitored concentrations in biota,
air, and precipitation in regions subject to LRT in the atmosphere. The corollary is
that estimated concentrations in air can be used to estimate concentrations in biota
and possibly contribute to assessments of risk of adverse effects.

2.4 Long-Range Atmospheric Transport of Chlorpyrifos

and Its Oxon

It is useful to present a perspective on the relevant distances in regions of the U.S.
that have been monitored for CPY and CPYO. Much of the available data have been
collected from the Central Valley of CA and adjacent National Parks in the Sierra
Nevada. The Parks are 50-100 km from the areas of application in the Central
Valley and have altitudes from 600 to 4,000 m. The region is approximately 50 km
west of the border between California and Nevada, but the meteorology at higher
elevations is complex and simple estimates of concentration versus distance are
impossible. In Eastern and Midwest regions of the U.S., distances relative to appli-
cation areas are less defined and are probably several hundreds of km. For example,
the distance from central Iowa to the U.S. East Coast is approximately 1,000 km.
An example of monitored concentrations along a transect from source to destina-
tion is the work of Aston and Seiber ( 1997 ), who measured concentrations of CPY
in June 1994 over a transect from Lindcove, CA (elevation 114 m) to Ash Mountain
22 km distant (elevation 533 m) and to Kaweah a further 10 km distant (elevation
1,920 m). Concentrations decreased from approximately 100 ng CPY m −3 at Lindcove
to 0.1-0.5 ng CPY m −3 at Ash Mountain and to 0.1-0.3 ng CPY m −3 at Kaweah.