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Flumioxazin
Registration of Payload Herbicide; Sureguard Herbicide; and Broadstar Herbicide & Approval of Aerial Application for Valor Herbicide 3/05

New York State Department of Environmental Conservation
Division of Solid & Hazardous Materials

Bureau of Pesticides Management
Pesticide Product Registration Section
625 Broadway, Albany, New York 12233-7257
Phone 518-402-8768     FAX 518-402-9024
Website: http://www.dec.state.ny.us/website/dshm/pesticid/pesticid.htm
E-Mail: ppr@gw.dec.state.ny.us

March 30, 2005

CERTIFIED MAIL
RETURN RECEIPT REQUESTED


Ms. Leslie Garcia
Registration Submission Specialist
Valent U.S.A. Corporation
1600 Riviera Avenue, Suite 200
P.O. Box 8025
Walnut Creek, California 94596-8025

Dear Ms. Garcia:

Re: Registration of Payload Herbicide (59639-120); Sureguard Herbicide (EPA Reg. No. 59639-120); and Broadstar Herbicide (EPA Reg. No. 59639-128). Approval of Aerial Application for Valor Herbicide (EPA Reg. No. 59639-99). Products Contain the Active Ingredient Flumioxazin. Chemical Code: 129034

The New York State Department of Environmental Conservation (Department) has completed its technical review of your application and data packages submitted in support of the registration of the above-referenced products. The Department has registered Payload Herbicide (59639-120); Sureguard Herbicide (EPA Reg. No. 59639-120); and Broadstar Herbicide (EPA Reg. No. 59639-128) for labeled use on the below-listed crops/sites and allowed aerial application on the Valor Herbicide label, which was previously registered (12/03/03) in New York State.

Valor Herbicide, Payload Herbicide and SureGuard Herbicide have identical formulations containing 51% flumioxazin as a granule to be mixed and sprayed with water. BroadStar Herbicide contains 0.25% flumioxazin as a ready-to-spread granular product. Valor Herbicide is currently registered in New York State for the control of susceptible weeds in peanuts and soybeans, and for use as part of an early preplant burn down program in cotton, field corn, rice, sorghum, sunflowers and wheat. The revised label adds aerial application directions to the currently registered product label. Payload Herbicide is labeled for weed control to maintain bareground and non-crop areas. SureGuard Herbicide is labeled for application to container and field grown ornamentals, conifers and deciduous trees for preemergent and post-emergent weed control. BroadStar Herbicide is labeled for preemergent weed control in container and field grown shrubs, trees and ground covers.

The active ingredient, flumioxazin, is a light-dependent peroxidizing herbicide (LDPH), which acts by blocking heme and chlorophyll biosynthesis resulting in an endogenous accumulation of phototoxic porphyrins. This class of herbicides are known to have a phototoxic mode of action in plants and possibly in fish. The Payload, SureGuard, and BroadStar Herbicide directions for use increase the maximum annual application rate to 0.76 lb. active ingredient/acre/year from the previously reviewed Valor Herbicide maximum application rate of 0.0956 lb. active ingredient/acre/year.

The initial application for Payload, SureGuard, and BroadStar Herbicides was submitted on March 26, 2004 with the addition of aerial application for Valor Herbicide submitted on April 14, 2004. The Department notified Valent U.S.A. Corporation of an incomplete application via letters dated March 26, 2004 and May 27, 2004. Valent U.S.A. Corporation submitted two data packages, received by the Department on June 29, 2004 and September 17, 2004. The application was declared complete as per Department letter dated November 1, 2004.

Pursuant to the review time frame specified in ECL §33-0704.2, a registration decision date of March 31, 2005 was established. The Department conducted the following technical reviews with regard to the registration of Payload, SureGuard, and BroadStar Herbicide and the addition of aerial application to the Valor Herbicide label. Review summaries for impacts to human health, nontarget organisms, and the environment are provided below:

HUMAN HEALTH REVIEW:
The New York State Department of Health (NYSDOH) previously reviewed Valor Herbicide and its active ingredient flumioxazin prior to registration (December 3, 2003). Neither Valor Herbicide nor flumioxazin was very toxic, irritating to the skin or eyes, or caused skin sensitization reactions following acute exposures in laboratory animals. Also, flumioxazin did not cause oncogenic effects and was negative in a number of genotoxicity studies. However, this chemical caused some chronic and developmental/reproductive effects in laboratory animals. A current search of the toxicological literature did not find any significant new information on the toxicity of flumioxazin.

On an acute basis, BroadStar Herbicide as a ready to use granular product, was not very toxic to laboratory animals by the oral, dermal or inhalation routes of exposure. It also was neither very irritating to the skin or eyes (tested on rabbits) nor did it cause dermal sensitization (tested on guinea pigs).

The United States Environmental Protection Agency (USEPA) calculated an oral reference dose (RfD) for flumioxazin of 0.02 milligrams per kilogram body weight per day (mg/kg/day) based on the no-observed-effect level (NOEL) of 2.2 mg/kg/day for hematological and kidney changes in a chronic feeding/oncogenicity study in rats and an uncertainty factor of 100. Previously, dietary risks from consumption of crops treated with Valor Herbicide were evaluated with a chronic population adjusted dose (cPAD) of 0.002 mg/kg/day. This value was based on the RfD of 0.02 mg/kg/day and an additional uncertainty factor 10 used to account for the greater sensitivity of the fetus in the rat developmental and reproductive studies (from previous review). In a more recent evaluation of the toxicological database for flumioxazin, the USEPA concluded that the developmental toxicity of flumioxazin is well characterized and that the additional uncertainty factor of 10 should be withdrawn (Federal Register, 69: 16,823-16832, March 31, 2004). Consequently, the cPAD increased to 0.02 mg/kg/day. The consequence of this increase in the cPAD is that the estimated chronic dietary exposure to flumioxazin residues by infants less than one year old is reduced from 2.3% to less than 1% of the revised cPAD. The subject major changes in labeled use would not significantly alter dietary flumioxazin exposure as the aerial application rate for Valor Herbicide is the same as the ground rate and the other products are not labeled for crop uses.

The registrant conducted risk assessments for dermal and inhalation exposures of workers to the labeled uses of flumioxazin in the BroadStar, Payload and SureGuard Herbicide products, as well as for the aerial application of Valor Herbicide. For the ground application of the Valor product, the USEPA conducted an occupational risk assessment which showed that this product should not pose significant risks to workers (previous NAI review). The more recently submitted risk assessments indicate that worker exposure to Valor Herbicide by aerial application, or to the BroadStar, Payload and SureGuard products also should not pose significant risks. For mixers/loaders/applicators involved in the aerial application of Valor Herbicide, margins of exposure (MOEs) were estimated to be about 170 and above for combined dermal and inhalation exposures. For these estimates, it was assumed that workers wore long pants, long-sleeved shirt and except for pilots, gloves (the label requires pants, shirt and gloves). The NOELs used for estimating the MOEs were 30 mg/kg/day from a rat dermal developmental toxicity study (for comparing to short-term dermal exposures), and 2.2 mg/kg/day from a rat oral chronic toxicity study (for comparing to short and intermediate-term inhalation exposures as well as intermediate-term dermal exposures). In regard to the labeled uses of flumioxazin in the BroadStar, Payload and SureGuard Herbicide products, for mixers/loaders/applicators, MOEs were estimated to be about 120 and above for combined dermal and inhalation exposures. For these estimates, it was assumed that workers wore the personal protective equipment (PPE) as required by the labels (long-sleeved shirt, long pants and gloves). The NOELs used for estimating these MOEs were 30 mg/kg/day from the rat dermal developmental toxicity study (for comparing to short- and intermediate-term dermal exposures), 3 mg/kg/day from a rat oral developmental toxicity study (for comparing to short-term inhalation exposures), and 2 (rounded off from 2.2) mg/kg/day from a rat oral chronic toxicity study (for comparing to intermediate-term inhalation exposures). Generally, the USEPA considers MOEs of 100-fold or greater to provide adequate worker protection.

There are no chemical specific federal or State drinking water/groundwater standards for flumioxazin. Based on its chemical structure, this compound falls under the 50 microgram per liter New York State drinking water standard for "unspecified organic contaminants" (10 NYCRR Part 5, Public Water Systems).

The information in this registration package for Valor Herbicide, BroadStar Herbicide, Payload Herbicide and SureGuard Herbicide, along with the information we previously reviewed for Valor Herbicide, indicate that the labeled uses of flumioxazin should not pose significant risks to workers or the general public.

NONTARGET ORGANISM REVIEW:
Department reviewers checked product labeling for instructions for aerial applications. The product labeling includes the following restrictions: "Do not apply this product by air within 40 feet of nontarget plants including nontarget crops"; "Do not apply this product by air within 40 feet of streams, wetlands, marshes, ponds, lakes, and reservoirs."

Model Parameters:
Models were run with the same parameters as described in the previous new active ingredient review of Valor Herbicide except the application rates and residue rates were increased.

Model Results:
The AVTOX model showed no risk to birds from the increased application rates of flumioxazin. The MAMTOX model showed marginal increases of chronic risk to mammals. Both chronic feeding and reproductive thresholds were marginally exceeded. Some aquatic risk thresholds were also exceeded. At a runoff rate of 3%, both LC50s and acute NOELS were exceeded in all pond depths for the most sensitive algae and the aquatic macrophyte. In the one foot pond depth, the chronic No Observed Effects Concentration (NOEC) and Lowest Observed Effects Concentration (LOEC) were exceeded for the rainbow trout. The rainbow trout chronic NOEC was also exceeded in the three foot deep pond. The mysid shrimp NOEC was also exceeded in the one foot deep pond. At the 1% runoff rate, the trout and mysid shrimp exceedances dropped out, and only nontarget plant thresholds were exceeded.

Model Analysis:
The MAMTOX model predicts a potential chronic risk quotient of 3.2 for mammals that consume short grass, 2.4 for mammals that consume long grass, and 1.1 for mammals that consume leafy vegetation. These risk quotients are based on an application rate of 0.76 lbs flumioxazin/acre. This is the maximum seasonal application rate, but only half that amount, 0.38 lbs AI/acre, can be applied at any one time. Flumioxazin degrades relatively rapidly on soil, so it is highly unlikely that as much as 0.76 lbs flumioxazin would ever accumulate as a result of multiple applications. The BroadStar label requires a minimum of eight weeks between consecutive applications. Also, flumioxazin is only applied to bare ground (preemergence treatment) or to rapidly growing weeds less than two inches high. Flumioxazin products are not applied to vegetated areas that birds and mammals would feed upon. Finally, these are chronic thresholds, and flumioxazin degrades too quickly to pose a significant risk of chronic toxicity.

The PONDTOX model predicts acute risks to nontarget aquatic vegetation and chronic risks to rainbow trout and mysid shrimp. However, flumioxazin is degraded extremely rapidly in water by multiple degradation pathways. The hydrolytic half-life of flumioxazin was found to be 21 to 24 hours at a pH 7 and 14 to 22 minutes at a pH of 9. At low pHs, the hydrolytic half-life was longer, 3 to 5 days. The photolytic half-life of flumioxazin in water at pH 5, the pH at which flumioxazin was most stable, was 20 to 26 hours. Given the rapid degradation of flumioxazin by multiple fate processes, it seems unlikely that a sufficient concentration of flumioxazin could be maintained in the water to cause harm to nontarget plants. Furthermore, flumioxazin degrades relatively rapidly on soil, thus further reducing the amount of active ingredient available to be removed by runoff.

Nontarget Organism Review Summary:
Because of the rapid degradation of flumioxazin in the environment, the labeled use of this product in unlikely to pose significant risks to fish, wildlife or nontarget plants.

ENVIRONMENTAL FATE REVIEW:

Solubility: The solubility of flumioxazin is 1.79 mg/L.

Hydrolysis: The DER for this study was not submitted. However, according to the USEPA memorandum dated July 21, 1993, this study was acceptable. Flumioxazin (or V-53482) had average calculated half-lives of 3.4 to 5.1 days, 21.4 to 24.6 hours and 14.6 to 22.0 minutes in solutions with pH of 5, 7, and 9, respectively. Two degradates were found in the phenyl-labeled ring study--7-fluoro-5[(2-carboxy-cyclohexenoyl)amino]-4-(2-propynyl)-1,4-benzoxazin-2(2H)-one or 482-HA, reached a maximum of 5.4 in the pH 5 solution, 60.2 in pH 7 solution, and 100% in pH 9 solution. The second degradate, 6-amino-7-fluoro-4-(2-propynyl)-1,4-benzoxazin-3(2H)-one, or APF, reached 90% in the pH 5 solution, 82.2% in the pH 7 and was ND in the pH 9. In the tetrahydrophthalimido ring-labeled study, three degradates were found: 482-HA at 6.7% in pH 5 solution, 70.3% in the pH 7 solution and 98% in the pH 9 solution. 3,4,5-6 tetrahydrophthalic acid or THPA as 96.6% in pH 5 solution, 84.2% in the pH 7 solution, and ND in the pH 9 solution. The third degradate, 3,4,5,6-tetrahydrophthalic acid anhydride or 1 -TPA reached 8.8% in pH 5 solution, 8.7% in pH 7 solution, and ND in the pH 9 solution.

Aqueous Photolysis: The original study did not meet Subdivision N Guidelines. The registrant-calculated half-life was 20.9 hours in a sterile pH 5 aqueous buffer solution. The reviewer-calculated half-life was 25.4 hours. Two unidentified major degradates were found. Unknown 1 reached 74.6% and Unknown 3 reached 16.8%. USEPA required that these studies be repeated and data submitted by April 12, 2003. The study submitted indicated that the parent degraded slowly by photolysis, with the major degradate 482-PHO, which degraded into 482-PHO-DC and 482-PHO-ISO and THPA, which degraded into 482-HA, 482-PO-HA, APF and 482-PHO-APF. A DER has not yet been issued for this study. The full degradate names were not provided.

Soil Photolysis: USEPA found this study partially acceptable. In the phenyl ring-labeled study, flumioxazin had a half-life of 3.2 days on a sandy loam soil. Five minor degradates were found. In the THP ring-labeled study, flumioxazin had a half-life of 8.4 days on a sandy loam soil. Five minor degradates were found. 1-TPA reached 21.6% of applied, and THPA reached 12.9% of applied.

Aerobic Soil Metabolism: Two studies were done, which together were found to be acceptable. Degradates were not determined. Flumioxazin had a half-life in sandy loam, clay loam, sand and loam of 5.0 days, 18.6 days, 18.9 days and 15.6 days, respectively.

Anaerobic Aquatic Metabolism: This study did not meet Subdivision N Guidelines. The data submission indicated that flumioxazin dissipated rapidly, with half-lives of 1.3 to 1.5 days in the water and 1.4 to 2.4 days in the sediment. Major degradates found were THPA, HPA, and APF.

Adsorption/Desorption: This study did not meet Subdivision N Guidelines. The Kocs of flumioxazin in sand, sandy loam, silt loam and clay loam were 265 to 277, 105 to 118, 675 to 1705 and 497 to 816, respectively. In a California sandy loam, the Koc was 11.9 to 17.5 days. No degradates were noted.

Mobility and Aged Leaching: No DER was submitted, but in the July 21, 1993 memorandum, USEPA indicated that this study was scientifically sound and partially acceptable. The USEPA memorandum did not indicate what the mobility of flumioxazin was. However, in an April 13, 1994 memorandum, USEPA indicated that due to the instability of the parent under hydrolysis, the use of adsorption/desorption methods were precluded.

Terrestrial Field Dissipation: MRID44295045 - This study did not meet Subdivision N Guidelines because the registrant did not analyze for degradates. USEPA felt the registrant- calculated half-life of 10.3 days was questionable for many reasons.

MRID44295047 - This study was partially acceptable. The registrant-calculated half-life was 4.8 days on a loam soil. Only minor degradates were found.

MRID44295043 - This study was partially acceptable. The registrant-calculated half-life was 27 days in a loamy sand soil. Only minor degradates were found.

MRID44295046 - This study did not meet Subdivision N Guidelines because the registrant did not analyze for degradates. The registrant-calculated half-life was 42 days in a silt loam soil.

MRID44295044 - This study did not meet Subdivision N Guidelines because the registrant did not analyze for degradates. USEPA felt the half-life was questionable. The registrant calculated half-life was 12.5 days in a silt loam soil.

An additional study was performed on a California sandy loam with 1.0% OM and 7.3 pH. Flumioxazin degraded rapidly with an estimated half-life of 5.1 days.

Modeling: Staff modeled flumioxazin on Riverhead soil using a Koc of 105, a half-life of 18.9 days and the maximum application rate of 0.76 lb ai/a/yr. The model projected several peaks, all less than 0.11 ppb.

The aerobic degradation study did not indicate major degradates, therefore, degradates were not modeled.

Environmental Fate Review Summary: The studies performed for this active ingredient were not, according to the USEPA, very well done. Even with the inadequate studies, though, it does appear that flumioxazin has a short half-life and very low application rate that offset the low Koc. No mobility information was presented for the degradates, however, groundwater reviews are predominantly concerned with major degradates from the aerobic metabolism study. Therefore, it is unlikely that use of these products per label direction will cause a significant impact to State groundwater resources.

REGISTRATION SUMMARY:
Enclosed for your record is a copy of the stamped accepted labeling for Payload Herbicide (59639-120); Sureguard Herbicide (EPA Reg. No. 59639-120); Broadstar Herbicide (EPA Reg. No. 59639-128); and Valor Herbicide (EPA Reg. No. 59639-99) with aerial application. Also, please find the Certificate of Registration for Payload Herbicide (59639-120); Sureguard Herbicide (EPA Reg. No. 59639-120); and Broadstar Herbicide (EPA Reg. No. 59639-128).

Please note that a proposal by Valent U.S.A. Corporation, or any other registrant, to register a product that contains flumioxazin homeowner use, use on other food crops, or any other labeled uses that are likely to increase the potential for significant impact to humans, nontarget organisms, or the environment, would constitute a major change in labeled (MCL) use pattern. Such an application must be accompanied by a new application fee and meet the requirements listed in Appendix 1.B. of "New York State Pesticide Product Registration Procedures" (August 1996). Such information, as well as forms, can be accessed at our website as listed in our letterhead.

Please be aware that any unregistered product may not be sold, offered for sale, distributed, or used in New York State.

If you have any questions on this matter, please contact our Pesticide Product Registration Section, at (518) 402-8768.

Sincerely,

Maureen P. Serafini
Director
Bureau of Pesticides Management

Enclosure
cc: w/enc. - N. Kim/D. Luttinger - NYS Dept. of Health
R. Zimmerman/R. Mungari - NYS Dept. of Ag. & Markets
W. Smith - Cornell University, PSUR