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carfentrazone-ethyl
NYS DEC Letter - New Product Registration and Major Label Change 1/03

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

Bureau of Pesticides Management, 9th Floor
625 Broadway, Albany, New York 12233-7254
Phone: (518) 402-8788     FAX: (518) 402-9024
Website: www.dec.state.ny.us

January 16, 2003

CERTIFIED MAIL
RETURN RECEIPT REQUESTED


Ms. Linda Dannaldson
Regulatory Affairs Specialist
PBI/Gordon Corporation
1217 West 12th Street
Kansas City, Missouri 64101-0090

Dear Ms. Dannaldson:

Re: Registration of Two New Pesticide Products, Speed Zone Broadleaf Herbicide for Turf (EPA Reg. No. 2217-833) and Power Zone Broadleaf Herbicide for Turf (EPA Reg. No. 2217-834), Which Represents a Major Change in Labeled Use for the Active Ingredient Carfentrazone-ethyl

    The New York State Department of Environmental Conservation (Department) has reviewed the application, received October 31, 2001, from PBI/Gordon Corporation, to register the above mentioned products in New York State. At that time, the application was submitted as a routine initial registration of pesticide products. As of November 21, 2001, PBI/Gordon was notified that use on turf is considered a major change in labeled use pattern for this active ingredient in New York State. Additional data was submitted and the application was deemed complete for purposes of review on September 3, 2002 with a registration decision due by January 31, 2003.

    Speed Zone Broadleaf Herbicide for Turf (EPA Reg. No. 2217-833) and Power Zone Broadleaf Herbicide for Turf (EPA Reg. No. 2217-834) contain the active ingredient carfentrazone-ethyl, which is currently registered in New York State for selective postemergence control of broadleaf weeds in corn (field, seed, popcorn, and silage). The product applications for Speed Zone Broadleaf Herbicide for Turf and Power Zone Broadleaf Herbicide for Turf for uuse on turf is a major change in labeled use pattern for this active ingredient in New York State. Speed Zone also contains the active ingredients 2,4-D, MCPP and dicamba. Power Zone also contains the active ingredients MCPA, MCPP and dicamba.

HEALTH EFFECTS:
    On an acute basis Speed Zone Broadleaf Herbicide for Turf and Power Zone Broadleaf Herbicide for Turf were not very toxic to laboratory animals by the oral, dermal or inhalation routes of exposure. These pesticide products were moderately irritating to the eyes and skin (tested on rabbits), and they caused dermal sensitization (tested on guinea pigs).

    In November 1999, the Department reviewed carfentrazone-ethyl in another pesticide product. The review indicated that carfentrazone-ethyl was not very acutely toxic to laboratory animals via the oral, dermal or inhalation routes of exposure and was not very irritating to animal eyes or skin. This active ingredient was not a skin sensitizer. In addition, carfentrazone-ethyl did not cause oncogenic effects and gave negative results in all, but one genotoxicity study Carfentrazone-ethyl did not cause reproductive effects in rats nor developmental effects in rabbits; minor developmental effects were reported in a rat study at doses exceeding those that caused effects in maternal animals. The United States Environmental Protection Agency (USEPA) calculated an oral reference dose (RfD) for carfentrazone-ethyl of 0.03 milligrams per kilogram body weight per day (mg/kg/day) based on the no-observed-effect level (NOEL) of 3 mg/kg/day from a chronic feeding/oncogenicity study in rats (microscopic signs of liver toxicity and increases in urinary porphyrins) and an uncertainty factor of 100. A current search of the toxicological literature did not find any new information on the toxicity of carfentrazone-ethyl.

    The USEPA did not require a worker exposure risk assessment for carfentrazone-ethyl in the Speed Zone and Power Zone products since no systemic toxicity was observed in a 21-day dermal toxicity study in rats (the highest dose tested was 1,000 mg/kg/day) and it did not cause developmental effects except at doses above those that caused effects in maternal animals. In addition, this chemical was not very acutely toxic by the inhalation route of exposure. Moreover, the labeled application rate of carfentrazone-ethyl for both the Speed Zone and Power Zone products is quite low (28.1 and 27.2 grams of carfentrazone-ethyl per acre per season for the Speed Zone and Power Zone products, respectively).

    The USEPA evaluated residential non-dietary exposures from incidental ingestion via hand-to-mouth contact by children up to six years old. Estimated margins of exposure (MOE) from short-term exposure to carfentrazone-ethyl were greater than 47,000. Generally, the USEPA considers MOEs of 100-fold or greater to provide adequate protection.

    In the previous evaluation, the department briefly reviewed the environmental fate data for carfentrazone-ethyl. These data indicated that although this chemical is not very mobile in the soils tested, it rapidly degrades to compounds that have the potential to be mobile or very mobile: the benzoic acid degradates, the propionic acid degradates and the cinnamic acid degradates. Given this information, drinking water/groundwater contamination may be a concern if the Speed Zone and Power Zone products are registered in the State unless the low application rates of these two products and subsequent rate of breakdown to the mobile degradates preclude significant environmental concentrations.

    There are no federal or State drinking water/groundwater standards for carfentrazone-ethyl or its above noted degradates. Based on their chemical structures, these compounds fall under the 50 microgram per liter (_g/L) general New York State drinking water standard for "unspecified organic contaminants" (10 NYCRR Part 5, Public Water Systems). The New York State drinking water standard for the sum of "unspecified organic contaminants" and "principal organic contaminants" is 100 _g/L.

    The available information on carfentrazone-ethyl and the formulated products Speed Zone Broadleaf Herbicide for Turf and Power Zone Broadleaf Herbicide for Turf indicates that they were not very acutely toxic in laboratory animals. Furthermore, carfentrazone-ethyl did not cause carcinogenic effects and expected exposures to this chemical from use of the Speed Zone and Power Zone products should not pose a significant health risk to workers or the general public. Although both pesticide products showed skin sensitization properties, this potential adverse effect should be mitigated by following the product labels which caution that "Prolonged or frequently repeated skin contact may cause allergic reactions in some individuals." and require users to wear a long-sleeved shirt, long pants and chemical-resistant gloves.

ECOLOGICAL EFFECTS:
    The Department's Division of Fish, Wildlife & Marine Resources' Bureau of Habitat (BOH) stated that the review of Speed Zone and Power Zone Herbicide completed to date suggests that neither product represents a significant threat to fish or wildlife resources.

ENVIRONMENTAL FATE AND GROUNDWATER IMPACTS:
    PBI/Gordon is applying to use this active ingredient on turf. Carfentrazone-ethyl is currently registered in New York State for selected postemergence control of broadleaf weeds in corn (field, seed, pop and silage). The application rate on corn is 0.3 oz product four times per year (40% ai) for a total of 0.03 lb ai/a/yr.

    Speed Zone Broadleaf Herbicide for Turf contains 0.62% by weight active ingredient, or 0.5 pounds of active ingredient per gallon. The maximum application rate is 0.062 lb ai/a/year applied in two applications of five pints of product or 0.031 lb ai/a, two to six weeks apart. The inerts include 50% by weight of a hydrogenated aliphatic solvent, or a total of five pints of hydrogenated aliphatic solvent per year applied in two applications.

    Power Zone Broadleaf Herbicide for Turf contains 0.48% by weight active ingredient, or 0.4 pounds of active ingredient per gallon. The maximum application rate is 0.06 lb ai/a/year applied in two applications of 6 pints of product or 0.03 lb ai/a, two to six weeks apart. The inerts include 38% by weight of a hydrogenated aliphatic solvent, or a total of five pints of hydrogenated aliphatic solvent per year applied in two applications.

    Carfentrazone-ethyl is in the aryl triazolinone family and inhibits protoporphyrinogen oxidase, a pivotal enzyme in chlorophyll production. The label has a ground water advisory for the 2,4-D and the MCPP-p, but not for the carfentrazone-ethyl or the dicamba acid. The maximum application rate of product is limited by the amount of 2,4-D that may legally be applied. This product may be foliarly applied by ground equipment only.

    Information for this review was taken from the DERs, the Pesticide Fact Sheet dated September 30, 1998, and from unreviewed study summaries provided by FMC for the first review. Many of the DERs found the studies to be unacceptable; however, PBI/Gordon is registering an active ingredient originally registered by FMC. Since we were not able to get any updated information from FMC in 1999, it is unlikely we can get updated information from PBI/Gordon now.

Technical Review
Parent = F8426 degrades to
F8426-cl = F8426 chlorpropionic acid which degrades to
F8426-p = F8426 propionic acid and
F8426-b = F8426 benzoic acid and
F8426-c = F8426 cinnamic acid

Hydrolysis: A DER was submitted for this study, which USEPA found acceptable. The parent is stable at pH 5, has a half-life of 8.6 days at pH 7, and a half-life of 3.6 days at pH 9. The degradate F8426-cl is stable under hydrolysis at neutral and acidic pH's, but was unstable at alkaline pH's.

Aqueous Photolysis: A DER was submitted for this study, but USEPA found the study unacceptable. An initial number of 8.3 days was determined for the parent. F8426-cl had a half life of 5.7 days in pH 5, 5.4 days in pH 7 and 6.0 days in pH 9.

Soil Photolysis: A DER was submitted for this study, but USEPA found the study unacceptable. The parent was found to be stable to photolysis on a loamy sand.

Aerobic Soil Metabolism: A DER was submitted for this study, which USEPA found acceptable. The half-life of the parent is 0.3 days to 1.1 days on a US loamy sand. The parent degrades to a maximum of 49% F8426-cl. The loamy sand half-life of F8426-cl was 161.2 to 391.4 days, F8426-b was 770.2 days, F8426-p was 210 to 364.8 days and F8426-c was 433.2 days.

Aerobic Aquatic Metabolism: The half-life is 0.3 to 0.8 days for the parent, and 245 days for F8426-cl.

Anaerobic Soil Metabolism: A DER was submitted for this study, but USEPA found the study unacceptable. Half-life in a loamy sand soil for F8426 was found to be <1 day.

Anaerobic Aquatic Metabolism: The parent has a half-life of <1 day. The half-life of F8426-Cl was four to eight days in water and 36-54 days in the soil. For the parent and the degradates together, the half-life in water was five to nine days, and 40-59 days in the sediment. In another study, in water the parent had a half-life of two to five days, F8426-Cl was four to ten days and the parent and all metabolites was four to ten days. In the sediment, the parent had a half-life of <1-2 days, F8426-Cl was 12-25 days and the parent and all metabolites was 23-53 days.

Adsorption/Desorption: A DER was submitted for the degradates, but the study was found to be only partially acceptable to the USEPA. The Koc of the parent could not be determined because carfentrazone-ethyl is very short-lived in soil. A DER was submitted for the degradate F8426-cl, which was found to be partially acceptable to the USEPA. Degradate F8426-cl is very mobile with a Koc of 6-48. F8426-b had a Koc of 1-9, F8426-c had a Koc of 94-474, and F8426-p had a Koc of 47-349.

Aged Leaching: A DER was submitted for this study, but USEPA found the study unacceptable. The parent appeared to be immobile under study conditions.

Terrestrial Field Dissipation: A DER was submitted for this study, but USEPA indicated that more information was needed before the study could be found acceptable. The parent had a half-life of two to five days in bare ground studies in Kansas and Minnesota. Parent and degradates were found sporadically in the 10-20 cm range, and not below that depth.

USEPA Comments: Carfentrazone-ethyl breaks down rapidly in the environment, while its degradates are persistent in aquatic and terrestrial environments. Because of its low application rate, carfentrazone-ethyl residues are expected to occur at low levels in surface water and ground water and are not expected to trigger acute or chronic risk for non-target plants or animals.

    Even though this product has a low Koc, it is not expected to impact ground water because of the low application rate and the short half-life of this active ingredient.

    The Department concludes that Speed Zone Broadleaf Herbicide for Turf and Power Zone Broadleaf Herbicide for Turf should not have an adverse effect on the health of workers or the general public, the fish and wildlife resources, or the ground and surface water of New York State when used as labeled.

    Therefore, the Department hereby accepts for general use registration in New York State the major change in labeling application of Speed Zone Broadleaf Herbicide for Turf (EPA Reg. No. 2217-833) and Power Zone Broadleaf Herbicide for Turf (EPA Reg. No.2217-834) which contains the active ingredient carfentrazone-ethyl.

    Enclosed are your Certificate of Registration and New York State stamped "ACCEPTED" label.

    If you have any questions, please contact Samuel Jackling, Chief of our Pesticide Product Registration Section, at (518) 402-8768.

Sincerely,

Maureen P. Serafini
Director, Bureau of Pesticides Management
Division of Solid & Hazardous Materials

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