Page 4, Section 6(a): 

EPA cites an NOEL of 7.04 μg/L reported for oyster spat by StachowskiHaberhorn, et al., 2008. BASF does not believe that this value is 

appropriate for use in a quantitative risk assessment. The 

formulation that was tested in the cited study is not registered in 

the United States. This formulation contains a built-in spray 

adjuvant and in this way is unlike any Bentazon-containing products 

that are registered in the United States. Spray adjuvants can 

significantly alter the aquatic toxicology properties of a chemical 

mixture. Beyond this fact, this non-guideline test appears to have 

been intended as a method development exercise, not as an evaluation 

of the toxicity of Bentazon. Only two concentrations were tested and 

these were greater than 2X apart from each other. The effect cited at 

the higher concentration was a “slight” reduction in growth at test 

termination (day 13) compared to the control. This observation does 

not demonstrate a significant long-term effect upon the test organism 

and has not been shown to be dose-responsive. Data from the report by 

Stachowski-Haberhorn should not be used by the EPA in its risk 

assessment of Bentazon. 

EFED Response #1: 

The Agency routinely searches the open literature for published studies that yield results showing 

greater toxicity than submitted guideline studies. When found, such studies are evaluated for 

acceptability prior to use of the results in risk assessment. The cited paper of Statchowski-Haberkorn et 

al. (2008) was identified as potentially useful study in preparation of the problem formulation of sodium 

bentazon, but has not yet been formally reviewed for acceptability. Preliminary review of this paper 

suggests that, while the study was conducted as an evaluation of a novel microcosm method, it did yield 

valid results that show the toxicity of exposure of Basamais (a formulated product of bentazon) to oyster 

spat. The description of the methodology and experimental method gave no reason not to accept the 

results of this study for quantitative risk assessment. One of the three endpoints measured, growth 

measured by area index, is an acceptable endpoint for use in our quantitative assessment. The study 

found that a concentration of 10 μg ai/L did not effect growth, whereas a concentration of 70 μg ai/L 

produced a significant reduction in the area index when compared to the control (P = 0.0049). The area 

index for this treatment group was 108, compared to 126 in the control, a 14% decrease. The results of 

this study are considered to be valid measurements of the chronic toxicity of the test material to 

marine/estuarine mollusks. 

As BASF states, however, the test material used in this study was Basamais®, a formulated product of 

bentazon sold in France. BASF’s comment that use of a study testing a formulated product to assess the 

chronic toxicity of the active ingredient is not appropriate is noted. Since this formulated product is not 

registered in the United States, its use to assess risk of typical end-use products sold in the United States 

may not be appropriate. The Agency needs to review the formulation of Basamais® to confirm the 

claim that it is substantially different than formulations sold in the United States. Additionally, the 

Agency is unclear if the active ingredient of Basamais® is sodium bentazon (103901) or bentazon 

(275200). Therefore, the Agency requests that BASF submits the confidential statement of formulation 

(CSF) of Besamais® to the Agency so that we can evaluate the formulation, identify the exact active 

ingredient as well as the inerts, and confirm the claim that it is unlike any formulation of sodium 

bentazon registered in the United States. Upon review of this CSF, the Agency will then decide if and 
how the results of this study will be used in the Registration Review risk assessment for sodium 

bentazon.

BASF Comment #2: 

Page 5, Section 6(b).: 

The EPA cites an EC50 of 0.06 mg/L for the marine diatom (Chaetoceros 

gracilis) reported by Hourmant, et al., 2009. BASF does not believe 

that this value is appropriate for use in a quantitative risk 

assessment. This study uses the same formulation of Bentazon that was 

used by Stachowski-Haberhorn, et al., that is not registered in the 

United States. This formulation contains a built-in spray adjuvant 

and in this way is unlike any Bentazon-containing products that are 

registered in the United States. However, the green algae (EC50 of 4.9 

mg ai/L) cited in row 6 of Table 5 (MRID 42129603) is the most 

sensitive species. Therefore, green algae are the most appropriate 

algal species for use in quantitative risk assessment of Bentazon.

EFED Response #2: 

The cited paper of Hourmant et al. (2009) was identified as a potentially useful study in preparation of 

the problem formulation of sodium bentazon, but has not yet been formally reviewed for acceptability. 

Upon conducting a preliminary review, EFED found the comment of BASF to be correct. The EC50

value of 0.06 mg ai/L was for the formulated product Basamais®, a product not registered in the United 

States. As previously stated, the Agency needs the registrant to provide documentation of the 

ingredients of the formulated product to confirm that the formulation is substantially different from 

those sold in the United States. If this is not confirmed, then the EFED may use the data to assess the 

potential risks the formulated product from spray drift exposure. In any case, however, the 0.06 mg ai/L 

result will not be used to assess the risk of the active ingredient. As pointed out in the comments, the 

paper reports the much higher EC50 of 150 mg/L in a test of the active ingredient bentazon. 

Upon review of results reported for bentazon in the ECOTOX database, another study was identified 

that yielded an even lower EC50 value than the 0.06 mg ai/L. Munkegaard et al. (2007) reported an EC50

of 0.051 mg ai/L for a test of the toxicity of bentazon (technical grade, 95% purity) to the green alga 

Pseudokirchneriella subcapitata. Therefore, this study will be reviewed by the agency, and if found 

acceptable, the value of 0.051 mg ai/L will be used as the algal toxicity endpoint in the risk assessment 

for sodium bentazon. 

BASF Comment #3: 

Page 5, Section 6(c): 

EPA states that the freshwater diatom (e.g. Navicula pelliculosa) 

study (MRID 42129608) is invalid and must be repeated. BASF requests 

the Data Evaluation Record (DER) for this study. 

EFED Response #3: 

A copy of the requested Data Evaluation Record (MRID 42129608) is attached to this memo. 
BASF Comment #4: 

Page 5, Section 6(d): 

EPA requests the registrant to provide additional information on the 

purity of the test substance used in acute toxicity studies on avian 

and aquatic species. BASF is searching the ecological database for 

these studies to identify the purity of the test substances and will 

provide the additional information that EPA requests. However, BASF 

questions the assumed 42 and 44 (%AE) test substance purity that EPA 

lists in Table 8 and therefore requests EPA to identify the study (or 

studies) that references 42% or 44% at the test substance purity. 

EFED Response #4: 

For the two avian acute oral tests, MRID 0018850 and 0018851, the test material is only identified as 

“Basagran®.” The report on the Daphnia magna with MRID 00106240 and the bluegill 

sunfish/rainbow trout study MRID 00041075 state that the test material was BAS 351-H, but gave no 

indication of the percent purity. Another bluegill sunfish/rainbow trout study MRID 00041076 state that 

the test material was BAS 3517-H (although the DER inaccurately states that the test material was BAS 

351-H). This report states that the test material was a “soluble concentrate containing 4 lbs 

active/gallon,” which is equivalent of 0.479 kg/L, or approximately 47.9 %. EFED will therefore 

assume 47.9% AE for MRID 00041076, which was conducted using BAS 3517-H, but not for the other 

studies since there were not identified as having the same test material. For the other studies (MRID 

0018850, 0018851, 00106240, and 00041075) the AE will be assumed to be 42%, which is the smallest 

percent AE of any “Basagran” product registered by BASF (e.g., EPA Reg. No. AR820028). 

Earlier DERs and reviews assumed that the percent purity was 42% for the avian studies and was 44.3% 

or 48.9% for the fish and aquatic invertebrate studies; however, the basis for these assumptions was not 

documented. 

Comments from Physicians Committee for Responsible Medicine 

The Physicians Committee for Responsible Medicine (PCRM) submitted the following comments 

concerning: 

PCRM Comment: 

The Summary Document indicates that the Agency may request testing for 

avian acute oral toxicity. We strongly support the use of the newly 

revised OECD test guideline for the acute avian oral toxicity, which 

is on the verge of official adaptation by the OECD. The new approach 

could reduce the total number of animals by up to approximately 90%. 

The approach provides three testing options: (1) limit dose test, (2) 

LD50-slope test, and (3) LD50 only test. The test method selected will 

depend on whether or not a definitive median dose (LD50) and slope of 

the dose-response curve are both needed. ... We hope the Agency will use 

the OECD’s draft test guideline to minimize the number of animals used 

while still accounting for the safety of wild birds. 
EFED Response: 

The Agency requires a toxicity test be conducted to estimate the acute oral LD50 of sodium bentazon to a 

passerine species. PCRM recommends that the new OECD test guideline be used for this test because it 

uses considerably fewer animals than the traditional LD50 test described by Test Guideline 850.2100. 

The new OECD test guideline for measuring avian acute oral toxicity with a sequential dosing 

procedure is Test Guideline (TG) 223. Current policy within the Office of Pesticide 

Programs/Environmental Fate and Effects Division (EFED) regarding the acceptance of avian acute 

effects studies conducted using the TG 223 protocol states the following: 

Until the OECD TG 223 validation process is completed and 

the guideline has been approved by OECD, studies that 

utilize this guideline should not be classified; pending 

results of the validation, they may then be classified as 

‘acceptable,’ assuming that they meet all other guideline 

requirements. 

To date the OECD has adopted the TG 223 guideline and has issued a validation report. At this time 

EFED is actively evaluating the results of the OECD validation report to determine if the TG 223 effects 

endpoints and dose/response information adequately address the purposes of the avian acute oral data 

requirement as described in 40 CFR Part 158. Until the Agency’s evaluation of that validation report is 

completed, EFED will not classify avian toxicity studies performed using the TG223 protocol and the 

studies cannot be used to fulfill data requirements. Therefore, we cannot say at this time whether or not 

avian toxicity studies done under TG 223 will be acceptable to meet our data requirements. 

Validation work conducted on TG 223 test guideline to date has been limited to studies with the upland 

game birds (e.g., northern bobwhite). Because no work has been to date to validate this guideline for 

passerine species, it is doubtful that we would accept studies done under this guideline for fulfilling 

requirements for passerine acute toxicity data unless additional validation work with passerines is done.