Here is a short snip from
http://www.epa.gov/pesticides/about/intheworks/clothianidin-registration-status.html

-- begin excerpt ---

2010 Reclassification of Clothianidin Field Study for Pollinators

Though the registrant satisfied the basic study requirements for 
registration in 2003, we required an additional field study to address 
uncertainties about potential long-term effects of clothianidin on 
honeybees. In 2007, we reviewed this study and determined that it 
satisfied EPA’s field study guidelines. However, the Agency’s assessment 
of the usefulness of this study has changed since the initial 2007 
review, which is not unusual in the scientific field.

As EPA’s understanding of honeybee biology has improved, staff 
scientists have started to recognize the challenges associated with 
field pollinator study designs. While elaborate field studies can be 
designed, there may be confounding effects that limit the utility of a 
study but may not entirely discredit it.

It is clear that field pollinator studies cannot be viewed in the same 
context as laboratory studies where experimental conditions can be 
strictly manipulated. Recognizing the complexity of conducting field 
studies, EPA is endeavoring to make the best use of existing data to 
address uncertainties. Although EPA noted deficiencies in the 
clothianidin pollinator field study, including some cross contamination 
between treated and non-treated (control) experimental plots and 
inadequate separation between treated and control portions of the study, 
there was useful information that could be used to qualitatively 
describe hive survival following exposure to clothianidin.

The reevaluation of the study in question does not change the Agency’s 
conclusion that the registered uses of clothianidin meet the FIFRA 
risk/benefit standard for registration. Clothianidin generally poses 
less risk to agricultural workers and fish and wildlife when compared to 
the insecticide alternatives...

--- end excerpt ---

             ***********************************************
The BEE-L mailing list is powered by L-Soft's renowned
LISTSERV(R) list management software.  For more information, go to:
http://www.lsoft.com/LISTSERV-powered.html

Guidelines for posting to BEE-L can be found at:
http://honeybeeworld.com/bee-l/guidelines.htm