1

OFFICE OF CHEMICAL SAFETY AND POLLUTION PREVENTION

UNITED STATES ENVIRONMENTAL PROTECTION AGENCY

WASHINGTON, D.C. 20460

PC Code: 103901

 DP Barcode: 426367

Date: April 17, 2015

MEMORANDUM

SUBJECT: Response to Public Comments on the EFED’s Preliminary Risk Assessment on 

the Registration Review of Sodium Bentazon

FROM: He Zhong, Ph.D., Biologist

Stephen Wente, Ph.D., Biologist

Environmental Risk Branch 1

Environmental Fate and Effects Division (7507P)

THROUGH: Sujatha Sankula, Ph.D., Branch Chief

Environmental Risk Branch 1

Environmental Fate and Effects Division (7507P)

TO: Moana Appleyard, Chemical Review Manager

Linda Arrington, Branch Chief

Risk Management and Implementation Branch V

Pesticide Re-Evaluation Division (7508P)

In response to the preliminary “Registration Review Ecological Risk Assessment and Effects 

Determination for Sodium Bentazon” (DP 417314), BASF provided informal comments after the 

public comment period. Additionally, the North Dakota Department of Agriculture provided 

Bentazon water quality monitoring data. The Agency appreciates receiving these data and 

comments. The purpose of the remainder of this memorandum is to address comments that are 

applicable to the ecological risk assessment and effects determination by Environmental Fate and 

Effects Division (EFED) for the herbicide sodium bentazon.

BASF Comments: 

Page 3, 3rd paragraph: The following two sentences seem at odds. "Bentazon is hydrolytically 

stable in pH 5, 7, and 9 buffered solutions and is also stable in sandy loam soil and clay soil 

under anaerobic or aerobic conditions. Bentazon degrades (t1/2 = 4.3 to 68 days) in aerobic 

mineral soils." As it reads the first sentence indicates bentazon is stable in soil and the next 

sentence indicates it is not stable in soil by citing short half-lives. The first sentence refers to the 

aerobic and anaerobic aquatic studies where soils from rice growing areas were flooded with 
2

water and incubated. The second sentence refers to the aerobic (unflooded) soil studies. 

Therefore, BASF suggests the first sentence is changed as follows " ...... is also stable in flooded 

sandy loam and clay soil under anaerobic or aerobic conditions."

• Page 8, top of page: The following is stated "Bentazon degradates were also not analyzed in 

any of the terrestrial field studies." Based on the titles for the TFD studies cited in Table 3.1 (see 

table on page 13 and refs on pages 51-53), the metabolite AIBA was included in all except 

MRID 00044401 .

• Page 72, Appendix C, bottom line in Table C-1 carrying over to next page: The structure for 

AIBA is corrupted and needs to be replaced. 

• Page 73, Appendix C, bottom line in Table C-1 carrying over to next page: The structure for 

Photoproduct 12 is corrupted and needs to be replaced.

EFED Response: EFED agrees with these comments. However on page 72, the structure that 

appears to be corrupted is O-nitro-N-isopropyl benzamide, rather than AIBA. The corrupted 

chemical structures from Appendix C are presented in Figure 1.

O-nitro-N-isopropyl benzamide Photoproduct 12

Figure 1.Chemical structures of Sodium Bentazon Degradates that were corrupted in the Registration Review 

Ecological Risk Assessment and Effects Determination for Sodium Bentazon.

BASF Comment: 

• Page 8, 2nd bullet from top of page: "The potential for endocrine disruptor-related effects was 

observed in mammalian and avian reproduction toxicity studies using bentazon. There is also a 

potential for endocrine disruptor-related effects due to the toxicity of the degradates of 

bentazon." BASF disputes this statement, as there were no avian reproduction effects in either 

submitted study, and no mention nor evidence of endocrine disruption effects in the HED 

assessment "Sodium Bentazon - Preliminary Human Health Risk Assessment for Registration 

Review." BASF respectfully requests that this bullet point be removed from the document.

EFED Response:

The sentences are a recap from the previous risk assessment findings (pages 3 and 17 USEPA 

2005, DP 314025). The Agency is unable to remove the previous conclusion without new 

evidence. Currently, bentazon is not subject to the endocrine screening part of the Agency’s 

Endocrine Disruptor Screening Program (EDSP). 

N

H

NO2

O

CH3

CH3

N

N

SO2

O

CH3

CH3

N

H

N

SO2

O

CH3

CH3
3

As the ecological risk assessment stated (USEPA 2014, DP 417314) “Bentazon is not on the 

first or second list chemicals for which EPA intends to issue test orders/data call-ins in the near 

future. For further information on the status of the EDSP, the policies and procedures, the lists 

of chemicals, future lists, the test guidelines and the Tier 1 screening battery, please visit the 

website, http://www.epa.gov/endo/”.

References

USEPA. 2005. Ecological Risk Assessment for the IR-4 Use of the Herbicide, Bentazon. DP 

Barcode 314025. 128pp.

USEPA. 2014. Registration Review Ecological Risk Assessment and Effects Determination for 

Sodium Bentazon. DP Barcode 417314. 140pp