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 assessm ent. 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 expe rimental 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 eff ect 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 appropr iate 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 andhow 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 (EC

50 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 EC 50 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 need s 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 EC 50 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 EC 50 value than the 0.06 mg ai/L. Munkegaard et al. (2007) reported an EC 50 of 0.051 mg ai/L for a test of the toxicity of bent azon (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 blueg ill sunfish/rainbow trout study MRID 00041076 state that the test material was BAS 3517-H (although the DER inaccu rately states that the test material was BAS 351-H). This report states that the test mate rial 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) LD

50 only test. The test method selected will depend on whether or not a definitive median dose (LD

50 ) 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 LD 50 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.