Risk to Pollinators from the Use of Chlorpyrifos in the United States - Reviews of Environmental Contamination and Toxicology - page 226

linkages to assessment endpoints are lacking (Alix and Lewis 2010 ; Fischer and
Moriarty 2011 ). Given the limited number of such studies that were found and the
high degree of variability in methods among these studies, chronic laboratory
studies were not used in this risk assessment. Since the focus of this risk assessment
was on endpoints and assessment measures related to survival, development, repro-
duction, and colony strength, studies that examined effects of CPY on pollinators
using endpoints such as oxidative stress (Shafiq ur 2009 ) and localized cell death
(Gregoric and Ellis 2011 ) were not included.
Available higher-tier semi-field and field-tests provide data on mortality, foraging
behavior, brood development, and overall vigor. These should receive greater weight
than the results of sublethal testing because the net effect of multiple stressors and
modes of action are integrated into these higher-tier tests (Thompson and Maus 2007 ).
Semi-field and field tests were an important line of evidence in this risk assessment.
The analysis conducted here consisted of four parts recommended by the USEPA
Risk Assessment Framework (Fischer and Moriarty 2011 ; USEPA 1998 , 2012 ): (1)
characterization of the stressor; (2) characterization of potential exposures by
various pathways; (3) characterization of effects in pollinator or surrogate species;
and (4) risk characterization.

2.5 Sources of Information

Data on exposure and toxicity were mainly obtained from reports in the peer-
reviewed literature, the USEPA ECOTOX database ( http://cfpub.epa.gov/ecotox/
quick_query.htm ), and internal reports obtained from Dow AgroSciences. Peer-
reviewed articles were searched mainly through the ISI Web of Knowledge and
SciVerse Scopus databases. Incident reports for the years 1990 to present were
obtained from the Environmental Fate and Effects Division, USEPA Office of
Pesticide Programs (USEPA 2013 ). Additional incident reports were obtained from
the Health Canada PMRA.

2.6 Risk Assessment Approach

The risk characterization scheme applied was that used by the USEPA Office of
Chemical Safety and Pollution Prevention for assessing risks of foliar sprayed
pesticides to pollinators (USEPA 2012 ). The process is iterative, relying on multiple
lines of evidence to refine and characterize risk. The scheme incorporates Tier-1
(worst case) screening-level assessments that calculate risk quotients (RQ) based on
ratios of estimated exposure by contact exposure and oral uptake of CPY-
contaminated nectar and pollen, and effects determined by corresponding toxicity
tests. Strictly speaking, a RQ should refer to a value calculated on the basis of prob-
abilities. European terminology favors “hazard quotient” (HQ) to represent this as a
deterministic ratio. The OCSPP convention RQ was used in this document.