UNITED STATES ENVIRONMENTAL PROTECTION AGENCY

WASHINGTON D.C., 20460

Chemical Code: 036602

DP Barcode: 345152

October 19, 2007

MEMORANDUM

SUBJECT:	EFED’s Response to Syngenta’s Request to Upgrade Several
Mandipropamid Aquatic Toxicity Studies.

TO:			Tony Kish, Risk Manager

Registration Division (7505P)

FROM:		Fred Jenkins, Biologist

Environmental Fate and Effects Division

THROUGH:		Dana Spatz, Acting Branch Chief

Environmental Risk Branch II

Environmental Fate and Effects Division (7507P)

In response to Syngenta’s request for a classification upgrade of
several aquatic toxicity studies testing mandipropamid, please see below
EFED’s conclusions.  These conclusions do not impact the overall
findings of EFED’s Screening Level Ecological Risk Assessment for
Mandipropamid dated on July 24, 2007. 

Syngenta Request 1

Syngenta requested that EFED upgrade several fish acute toxicity studies
from invalid to valid.  These studies included MRID’s 468001-03,
468001-04, 468001-05, and 468001-06.

EFED Response

EFED agrees that the studies may be upgraded from invalid to acceptable.
 The studies were initially deemed invalid by EFED because their
measured concentrations appeared to be less than 80% of the nominal
concentrations throughout the duration of the study.  Guideline 850-1075
requires that the mean measured concentrations remain 80% of the nominal
concentrations throughout the study.   The registrant claims that
although the measured concentrations varied substantially from the
nominal concentrations, the mean-measured concentrations were an
accurate representation of the exposure of the test species throughout
the duration of the study (as required by Guideline 850-1075).  EFED
agrees with the registrant’s position based on information presented
in their submittal (see attached) which demonstrates that although the
mean-measured concentration deviated substantially from the nominal
concentrations, the mean-measured concentration remained an accurate
representation of what the test animals were consistently exposed to
throughout the duration of the study.

Syngenta Request 2

Syngenta requests that EFED upgrade the freshwater invertebrate chronic
toxicity study, MRID 468001-07, from invalid to valid.

EFED’s Response

EFED disagrees with the registrant’s request to upgrade this study. 
EFED invalidated the study because there was a significant difference in
the number of offspring produced between the negative control and the
solvent control.  Syngenta contends that: 

“…the study is VALID and it was appropriate to use the solvent
control for statistical comparisons. All test item treatments contained
the same amount of solvent as the solvent control. Therefore it is
scientifically robust to make treatment comparisons with the solvent.
The only variable that was different between solvent control and
treatment is the test item itself; as such, the solvent controls were
identical to the test treatments in every way except that the solvent
controls contained no test material. In contrast, the negative controls
were not identical to the treatments. Both solvent and negative controls
met data quality objectives for control survival and number of young
produced per female. Since the objective of the test is to determine the
influence of the test item on Daphnia, this long-established approach
reduces the experimental variance, increasing the probability of
detecting a true treatment-related effect.”

EFED does not agree with the registrant’s position because the results
of the study indicate that the solvent, in comparison to the negative
control, had an adverse effect on the test organisms’ ability to
reproduce.  In a scientifically valid study, the solvent should not have
an adverse effect on the test organisms.  The objective of the study is
to measure the effect of the test substance alone.  If the solvent has
an effect on the test organisms, the results of the study are confounded
with uncertainty because the true measured effects of the test substance
cannot be verified.

This study (MRID 468001-07) remains invalid.

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OFFICE OF

PREVENTION, PESTICIDES AND

TOXIC SUBSTANCES

