  SEQ CHAPTER \h \r 1 U. S. ENVIRONMENTAL PROTECTION AGENCY

Washington, D.C. 20460	

									                          

	

OFFICE OF PREVENTION, PESTICIDES AND TOXIC SUBSTANCES	



						             PC Code: 128974

                                                                        
                               DP 344482

                                                                        
                                       November 30, 2009

MEMORANDUM

DATE:         November 30, 2009

SUBJECT:   Completion of an aquatic acute toxicity study analyzing the
acute toxicity effects of  

                     Quinclorac on the swimming ability of the
freshwater invertebrate Daphnia magna

FROM:         Lewis Ross Brown, Environmental Biologist

                     Brian Anderson, RAPL Team Leader

                     Nancy Andrews, Branch Chief

                     Environmental Risk Branch I

                     Environmental Fate and Effects Division (7507P)

TO:               Robert McNally, Risk Manager

                       Joy Schnackenbeck, Risk Reviewer

                     Pesticide Re-evaluation Division (7509P)

                      

EFED-ERB 1 has completed the review and analysis of an aquatic acute
toxicity study exposing the freshwater invertebrate, known as the
Daphnia magna, to Quinclorac in order to analyzing the effects on
swimming ability of this organism. Below is short tabulation of our
findings:

MRID # 474210-01-“Quinclorac – Determination of the Acute Effect on
the Swimming Ability of the Water Flea Daphnia magna STRAUS”.-This
study is scientifically sound and meets the guideline requirements for
an acute toxicity study with freshwater invertebrates. The 48-hour EC50,
based on the sum of immobile daphnids, was >100 mg ai/L. The NOAEC was
100 mg ai/L. According to the results of this study, Quinclorac is
classified as practically non-toxic (based on the EC50 of the active
ingredient, >100 mg ai/L) to Daphnia magna on an acute toxicity basis,
in accordance with the classification system of the U.S. EPA.  This
study is categorized as “Acceptable”.

Results Synopsis:

Test Organism Age (e.g., 1st instar): neonates (2-24 hours)

Test Type (Flow-through, Static, Static Renewal): Static

EC50: >100 mg ai/L				95% C.I.: N/A 

NOAEC: 100 mg ai/L		

Probit Slope:	N/A				95% C.I.: N/A	

Endpoint(s) Affected:  None

Please contact Lewis Ross Brown at (703) 305-0278 with any questions or
comments.

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