UNITED STATES ENVIRONMENTAL PROTECTION AGENCY

  SEQ CHAPTER \h \r 1 WASHINGTON, D.C.  20460

		

							            OFFICE OF

						                 PREVENTION, PESTICIDES

							AND TOXIC SUBSTANCES 

April 16, 2007

  SEQ CHAPTER \h \r 1 MEMORANDUM

SUBJECT:	2,4-D: HED Response to Irrigated Crop Waiver Request.   

		PC Code: 030001, DP Barcode: D336596.				

		

FROM:	Toiya Goodlow, Chemist

		Reregistration Branch 1

		Health Effects Division (7509P)

THROUGH:	Michael S. Metzger, Branch Chief

		Reregistration Branch 1

		Health Effects Division (7509P)

TO:		Katie Hall, Chemical Review Manager		

Special Review and Reregistration Division (7508P)

This document was written in response to an irrigated crop waiver
request submitted by the 2,4-D Task Force. 

The 2005 Reregistration Eligibility Decision Document (RED) for 2,4-D
included a data requirement for Guideline 860.1400 Water, fish, and
irrigated crops.  Although irrigated crop data has been submitted for a
variety of crops, supplemental irrigated crop data were required for
strawberries and sugar beets (roots and tops).  Irrigated crop data for
strawberries were required to support tolerance reassessment for
irrigated perennial crops (pome fruit, stone fruit, and grapes); sugar
beet data were required to support tolerance reassessment for root and
tuber vegetables, excluding potatoes (Crop Group 1) and the leaves of
root and tuber vegetables (Crop Group 2).  After reevaluating the
existing irrigated crop data and given the significant amount of 2,4-D
data currently available to the Agency, it was determined that
additional irrigated crop data would not negate the current data or
significantly impact the risk assessment.  Therefore, no additional
irrigated crop data are required. 

Aquatic use patterns supported by the 2,4-D Task Force prohibit the use
of 2,4-D treated water for irrigation unless an approved assay indicates
that 2,4-D concentrations are <0.1 ppm.  Based on the 2,4-D data
available including terrestrial and aquatic half-life information,
metabolism data, and the irrigated crop residue data for other crops, 
it is unlikely that irrigation with water containing 2,4-D at <0.1 ppm
would result in inadvertent residues exceeding 0.1 ppm (two times the
limit of quantification, 0.05 ppm). Therefore, a tolerance value of 0.1
ppm is appropriate, and should be set for residues of 2,4-D in/on
strawberries and perennial crops, as well as Crop Groups 1 and 2, root
and tuber vegetables (excluding potatoes) and the leaves of root and
tuber vegetables, respectively.

Table 1.  Summary of Reassessed Tolerances for 2,4-D, Post-RED

Commodity/ Crop Group	Reassessed Tolerance (ppm)

Tolerances Needed Under 40 CFR §180.142(a)1

Fruit, pome, group 11	0.1

Fruit, stone, group 12	0.1

Grape	0.1

Strawberry	0.1

Vegetable, leaves of root and tuber, except potato, group 2	0.1

Vegetable, root and tuber, except potato, group 1	0.1

1 Part (a) is reserved for commodities with permanent tolerances
reflecting at least one preharvest (field) or postharvest use. For the
commodities above, tolerances resulting from the primary use of 2,4-D
are high enough  to cover any inadvertent residues that may result from
the use of 2,4-D treated irrigation water.  Therefore, separate
tolerances for inadvertent residues in/on these crops are not required.

cc:  T. Goodlow/HED/RRB1.

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