2

1). Data Waiver Req uest for Aquatic Field Dissipation Study (835.6200)

BCS comments (page s 2 6 and 2 7 ):

 Mesosulfuron

- methyl has no registered use in aquatic systems.

 While water soluble, mesosulfuron

- methyl degrades fast both under aerobic soil and aerobic aquatic conditions, and it is not persistent.

 Mesosulfuron

- methyl and major degradates have intermediate or immobile characteristics, and in field dissipation studies quantifiable residues were not detected below 7.5 to 30 cm depths.

 Mesosulfuron

- methyl has been extensively studie d in environmental fate studies and data indicate it will not likely persist or move to aquatic environments.

EFED response: EFED acknowledges BCS’s presentation on environmental fate profile of mesosulfuron

- methyl (page 5

– 2 2 ). T he submitted data showed that mesosulfuron

- methyl is persistent with aerobic soil DT 50 up to 199 days (MRID 45386425) and with DT 50 up to 100 days in aerobic aquatic system (MRID 45386430). T he FAO mobility classification showed mesosulfuron

- methyl (Koc = 93) and its major degradate, AE F145851

, (Koc = 78) (Page 14) are highly mobile, which are likely e nter ing the aquatic environments through runoff , erosion or leaching

. EFED concurs that “mesosulfuron

- methyl has no regi stered use in aquatic systems ”. Not having a direct application to water registered does not automatically exclude a chemical from needing this study. EFED is concerned about what happens wh en the chemical gets into
water

. However, i n considering m esosulfuron

- methyl has relative ly low toxicity to aquatic fish and invertebrates and the annual application rate is low

, the aquatic field dissipation study will not be needed for R egistration R eview. Therefore, EFED recommends the aquatic field dissipation study (835.6200) to be waived

.
2). Data Waiver Request for Environmental Chemistry Method (ECM) and Independent Laboratory Validation (ILV) Study (850.6100)

BCS comments (page 2) :

 BCS is requesting the data requirements for all degradates except for parent mesosulfuron

- methyl, and metabolite AE

- F092944 be waived (Option 9). Justification for this request is included in this package. BCS intends to conduct the study for the parent, mesosulfuron

- methyl (Option 1; time frame: 12 months). Additionally, as AE

F092944 is a common metabolite with foramsulfuron, BCS will submit this data with the foramsulfuron DCI data package (Option 4; time fr ame: 12 months, with foramsulfuron data).

EFED response: BCS’s justification for th e ECM/ILV data waive r request was not found from the submitted package. EFED reviewed two previous submitted ECM/ILV (MRIDs 46451701 and 46451702) and conclude d that the y can only be used for monitoring parent mesosulfuron

methyl in water. A new ECM/ILV

, with the m ajor degradates to be included, is recommended. Each ECM should be able to analyze both the parent and the major degradates at the same time. It is not acceptable for mesosulfuron D CI to have one common degradate AE F092944 to be included in the foramsulfuron DCI data package However, foramsulfuron ECM/ILV may include parent mesosulfuron

- methyl and i t s major degradates listed below ( e.g.: a n an a ly tical3

method for multiple chemicals and their degra dates)

. Based on a re cent review o f new ly submitted aquatic plant toxicity data (USEPA 2014, DP 422361), t wo major degradates, BCS

CV14885 (benzoic acid with guanidine), and BCS

- CO60720 (methyl ester of benzoic acid with guanidine)

, are not recommend ed to be included in the ECM/ILV (water) study. EFED reiterates the previous recommendation ( USEPA 2013, DP 414767) that the ECM/ILV (850.6100 ) studies (water and soil), including the major degradates, should not to be waived (see below)

.
1) ECM/ILV (water) (8 50.6100)

- to include the major degradates observed in aquatic environments (AE F160459, AE F160460, AE F140584, AE F147447, AE F092944,

2) ECM/ILV (soil) (850.6100)

- to include the major degradates observed in soil environments (AE F154851, AE F099095, an d AE F092944).

References

USEPA. 2013. Response to Public Comments on the Mesosulfuron

- methyl Registration

Review Problem Formulation. DP 414767. 6pp

USEPA. 2014. Review of BCS

– CO60720 (Degradate of Mesosulfuron

- methyl) Vascular Aquatic Plant Toxicity Study (MRID 49447202) in Support of Registration Review and EFED responses to Registrant’s Data Waiver Request for Vascular Aquatic Plant Toxicity Testing with BCS

- CV 1488 5 , a Degradation Product of Mesosulfuron methyl. DP 422361. 2pp.

Bayer C ropScience. 2014. Mesosulfuron

- methyl: (EPA Reg Nos. 264

- 694, 264

- 802, 264

- 847, and 264

- 801); 90

- Day Response to Generic Data Call

- In for Mesosulfuron

- methyl Generic ID: DCI

- 122009

- 1369. MRID 49447200. 42pp.