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In the following sections, the specific argument presented by DAS is summarized in italics and is 

then followed by EFED’s response. 

1. DAS’s comment:

“DAS acknowledges that an independent laboratory validation for the specific water method 

(MRID 478242-01) is not available. However, an additional water method (RH-2485 Analytical 

Method for Water; MRID: 44617824) and its corresponding ILV (Independent Laboratory 

Method Validation Trials of RH-2485 Analytical Method for Water; MRID: 44617815) have 

been submitted to the USEPA. The two studies are in compliance with the OCSPP Guideline 

850.6100. Therefore, DAS believes that the requirement for an ILV to meet guideline 850.6100 

has already been met at this time by the submitted study, and no additional study would be 

required...”

EFED’s response: EFED received the analytical method and independent laboratory 

validation provided by the registrant. Both studies: “ILV Trials Analytical Methods in Water 

RH-2485” and “RH-2485 Analytical Method for Water” with MRIDs 492017-03 (previously 

446178-24) and 492017-02 (previously 446178-15) respectively, are currently under review; 

therefore, no additional studies are required at this time.

2. DAS’s comment:

 “DAS agrees that an anaerobic soil metabolism study has not been submitted to the EPA. 

DAS has an anaerobic soil metabolism study that was conducted for Europe that can potentially 

provide additional information for the risk assessment. We can provide the data for review 

should EPA require it for their registration review process.”

EFED’s response: EFED encourages DAS to submit data that can potentially provide 

more information about the anaerobic metabolism of methoxyfenozide. 

3. DAS’s comment:

“In Section 4.1, Table 3, the chronic midge Chironomus riparius toxicity value is stated 

as NOAEC = 0.0063 mg a.i./L. However, the Acute-to-Chronic Ratio (ACR) that estimates the 

acute toxicity for the midge has used a chronic midge endpoint of NOAEC =0.0026 mg a.i./L. It 

is unclear how the NOAEC of 0.0026 mg a.i./L has been derived from the midge life cycle study, 

and DAS believes that the wrong number was used in the calculation. The NOAEC that is used in 

the ACR effects the estimated toxicity value for the acute midge and the subsequent risk 

assessments. The toxicity value for the chronic midge is expected to be NOAEC = 0.0063 mg 

a.i./L and should be the number used for the ACR.”

EFED’s response: EFED agrees that the source of the NOAEC of 0.0026 mg a.i./L used in 

the ACR calculations is unclear. After closer examination, it appears that EFED’s review of the 

midge lifecycle study (MRID 450328-01) will need to be revised to reflect a different NOAEC 

based on the measured concentrations in pore water (0.0031 mg a.i./L). The NOAEC of 0.0063 

mg a.i./L is based on nominal concentrations. Typically, the Agency prefers measured 

concentration values to nominal concentration values. The value of 0.0031 mg a.i./L is the 28-

day NOAEC based on concentrations in pore water. This value should be used in the calculation 

of an ACR, and results in an EC50 of 0.05 mg a.i./L. The Agency notes that the NOAEC of 

0.0031 mg a.i./L is not substantially different than the value of 0.0026 mg a.i./L which has been 

used in the past.