UNITED STATES ENVIRONMENTAL PROTECTION AGENCY

WASHINGTON, D.C. 20460      

	OFFICE OF CHEMICAL SAFETY 

AND POLLUTION PREVENTION

	

  SEQ CHAPTER \h \r 1 MEMORANDUM

Date: 8/9/12

		

SUBJECT:	Metconazole.   Summary of Risk Issues Associated With Increase
In Tolerance For Corn Stover.  

 

PC Code:  125619	DP Barcode:  D399532

Decision No.: 457152	Registration Nos.: 7969-246, 7969-263 

Petition No.: 1F7937	Regulatory Action: Section 3 Registration

Risk Assessment Type: NA	Case No.: NA

TXR No.: NA	CAS No.: 125116-23-6

MRID No.: 48639901	40 CFR: 180.617

		              									Ver.Apr.08

	          	

FROM:	Jeffrey L Dawson, Acting Branch Chief

		Registration Action Branch III (RAB3)

		Health Effects Division (HED; 7509P)

THROUGH:	Steve Funk, Senior Chemist

		RAB3/HED (7509P)

		

TO:		Mary Waller/Tamue Gibson, RM#21		  SEQ CHAPTER \h \r 1   SEQ
CHAPTER \h \r 1 

		Registration Division (7505P)

The petitioner, BASF Corporation, requested to increase the established
tolerance for sweet corn stover from 4.5 to 25 ppm as a result of the
additional data.  In order to support this BASF submitted additional
field trials for metconazole on corn stover.  These data were reviewed
and summarized in D399057.  

The analysis completed in D399057 concluded that the additional five
field trials on field corn stover, submitted to represent sweet corn
stover, resolve the deficiency regarding geographic representation of
sweet corn stover field trials and based on the Organisation for
Economic Co-operation and Development (OECD) tolerance calculation
procedures, the appropriate tolerance for sweet corn stover is 30 ppm. 
The petitioner proposed a tolerance of 25.0 ppm on corn, sweet, stover. 
All corn stover (sweet, field, and pop) can be harvested at the same
minimum preharvest interval.  The petitioner must submit a revised
Section F to propose a tolerance of 30 ppm on corn, sweet, stover; corn,
field, stover; and corn, pop, stover.

The impact on dietary risk estimates was also examined.  Submission of
additional corn stover residue data caused an increase in the maximum
reasonably balanced dietary burden for dairy cattle; no increase
occurred for beef cattle, swine, or poultry.  The increase was driven by
one in twenty-five field trials with a highest average field trial
(HAFT) of 22.7 ppm in corn stover; the remaining field trial residues
were 0.14 to 3.23 ppm.  Based on the cattle feeding study and the
calculated dietary burden based on the maximum reasonably balanced diet,
no changes are required in the established livestock tolerances as a
result of submission of the additional corn stover field trials.  If
additional uses increase the livestock dietary burdens, additional
livestock feeding studies conducted at higher rates may be needed. 
Since corn stover (a livestock feed item) is not included in the dietary
exposure assessment a revised dietary exposure assessment and a human
health risk assessment are not needed.  

Actions of this type trigger a review of the toxicological databases for
impacted chemicals.  In this case, data needs for metconazole were
examined in a meeting of the Hazard and Science Policy Council (HASPOC)
in order to determine if additional data were required in order to
adequately characterize the toxicity of metconazole.   In particular,
the need for an acute neurotoxicity study and a subchronic inhalation
toxicity study were examined.  When data are missing, additional
uncertainty factors can be applied as described in current policies. 
Based on a weight-of-evidence (WOE) approach and considering all the
available metconazole hazard and exposure information, the HASPOC
recommended that a subchronic inhalation toxicity study and an acute
neurotoxicity study are not required for metconazole at this time.  They
also indicated, however, these issues will be re-evaluated if the
metconazole use pattern changes.  

 Metconazole.   Additional Residue Data on Corn Stover.  Summary of
Residue Data. (N. Dodd, D399057,7/19/12).

 Metconazole: Summary of Hazard and Science Policy Council (HASPOC)
Meeting of July 19, 2012:  Recommendations on the Requirement of a
Subchronic Inhalation Study and an Acute Neurotoxicity Study. (Rury, K,.
TXR0056405, 8/9/12)

Page   PAGE  1  of   NUMPAGES  2 

