              UNITED STATES ENVIRONMENTAL PROTECTION AGENCY

                                     WASHINGTON, D.C.  20460												
						                                                                  
                                                                        
                                                   						         				  
           OFFICE OF							PREVENTION, PESTICIDES AND

									       TOXIC SUBSTANCES

DATE:  September 25, 2006

MEMORANDUM

SUBJECT:	MCPB: Response to Comments on Reregistration Eligibility
Decision (RED) for MCPB and Salts.  PC Code: 019201 (MCPB Acid) and
019202 (MCPB Sodium Salt).  DP Barcode: D331675

		Regulatory Action:  Phase 4 Reregistration Action

		Risk Assessment Type: Single Chemical Aggregate

FROM: 	Elizabeth Méndez, PhD

		Risk Assessor

		Reregistration Branch I

		Health Effects Division (7509P)

			AND

		Kit Farwell, DVM – Toxicologist

		Felecia Fort – Chemist

		Timothy Dole, CIH – ORE Assessor

		Reregistration Branch I

		Health Effects Division (7509P)

THROUGH:	Christine Olinger 

		Senior Scientist

		Reregistration Branch I

		Health Effects Division (7509P)

TO:		James Parker

		Chemical Review Manager

		Reregistration Branch I

		SRRD (7508P)

The MCPB Task Force has submitted comments on the Agency’s
Reregistration

Eligibility Decision released to the public on June 21, 2006.  Two
comments in particular

referred to the Health Effects Division’s (HED) chapter.  

The Task Force comments on the Agency requirement for a Developmental

Neurotoxicity on MCPB stating “…the logic of the statement also
indicates that a

developmental neurotoxicity study would most appropriately be conducted
on

MCPA rather than MCPB, as this is the molecule of concern. Submitting a
DNT

study with MCPA was included as a requirement in the Data Call-In Notice
for

MCPA; this should then fulfill the requirement for a DNT study on
MCPB.”

Response:  The Agency stated in section 4.4 of HED’s chapter for the

Reregistration Eligibility Decision (RED) document that a requirement
for a DNT study on MCPB “can be satisfied with a developmental
neurotoxicity study with MCPA if this study becomes available.”

The Task Force has requested a waiver for Data Requirement 860.1850 –
Confined Accumulation in Rotational Crops.

Response:  The Agency is currently requiring a Confined Accumulation in
Rotational Crops study for MCPB.  However, this requirement may be
satisfied with a Confined Accumulation in Rotational Crops study with
MCPA since this compound is the major metabolite for MCPB.

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