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Thiamethoxam - Registration of Special Local Need Labeling for Actara Insecticide (EPA Reg. No. 100-938) 6/02

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

June 14, 2002


John D. Abbott, Ph.D., CPH
Syngenta Crop Protection, Inc.
P.O. Box 18300
Greensboro, North Carolina 27419-8300

Dear Dr. Abbott:

Re: Registration of Special Local Need Labeling (SLN) for Actara Insecticide (EPA Reg. No. 100-938) Containing the New Active Ingredient Thiamethoxam Active Ingredient # 060109

    The New York State Department of Environmental Conservation (Department) has reviewed your application, received May 31, 2002, to register a Special Local Need (SLN) label for Actara Insecticide (EPA Reg. No. 100-938) in New York State.

    The SLN prohibits the use of Actara Insecticide in Nassau and Suffolk Counties and allows only one application on pome fruits at a maximum rate of 5.5 ounces (0.086 pounds of thiamethoxam) of product per acre per year. The federally registered label allows two applications per year at a maximum rate of 8.0 ounces (0.125 pounds of thiamethoxam) of product per acre per year on pome fruits.

    The Department has received numerous correspondence from concerned stakeholders regarding the need for Actara Insecticide to support New York State's pome fruit industry. There appears to be a specific need for the Actara product as an early season control of insect pests and a consequent lack of New York State registered products to combat these pests. Cornell research staff have provided supporting documentation regarding the need for Actara Insecticide in controlling plum curculio. The plum curculio lives in adjoining hedgerows and woodlands of the apple orchards but move into the orchards to oviposit in newly set fruit. The end result is scarred and deformed fruit which cannot be sold in the fresh fruit market. The registration of the proposed Actara SLN label in New York State will counter the impending loss of certain pesticide products, including the removal of methyl parathion, from use on apples, the restrictions placed on chlorpyrifos and the eventual cancellation of two organo-phosphorous pesticides, azinphos-methyl and Phosmet.

    A review of the current literature indicates that there are several active ingredients which control sucking and chewing insects. However, there are few products that provide effective control of plum curculio. Beyond the OP's and carbamates that are being phased out due to Worker Protection Standards concerns and market pressures, there are synthetic pyrethroids such as esfenvalerate, permethrin, and fenpropathrin, which may lose effect if over-used and may also negatively impact non-target organisms.

    The Department has evaluated groundwater impacts specific to the use of the Actara product for one early Spring application to pome fruit. The following assumptions were used in modeling groundwater impact: The product is applied as a foliar spray to the tree canopy; the ground below the trees in fruit orchards is primarily overgrown with grasses; and the orchard manager would not apply the Actara product close to a rain event as a matter of effective cultural practice. The likelihood of the active ingredient (thiamethoxam) impacting groundwater would be reduced due to absorption into tree leaves and over spray being absorbed into the groundcover. Other uses of thiamethoxam (Actara, Platinum, and Cruiser 5FS) direct the product to be applied to bare ground such as with row crops, in-furrow treatment, and pre-plant seed treatment thereby increasing the potential impact to groundwater.

    Therefore, under the authority of Section 24(c) of FIFRA, the Department hereby grants a Special Local Need (SLN) registration for Actara Insecticide for one early season application on pome fruits. The registration of the Actara Insecticide product will address the critical need for alternatives to current methods for early season control of plum curculio and other labeled pests on pome fruits. The following conditions apply for this SLN registration:

Thiamethoxam New Active Ingredient Review:

    The Department received three new active ingredient (NAI) applications on October 11, 2001 and one NAI application was submitted on December 6, 2001, and has completed its technical review of these applications to register Actara (EPA Reg. No. 100-938), Platinum (EPA Reg. No. 100-939), Platinum Ridomil Gold (EPA Reg. No. 100-974) and Cruiser 5FS (EPA Reg. No. 100-941). The Department has a number of unresolved issues concerning the use of these products as submitted, and has determined that use of these products in certain geographic areas of New York State, could result in significant impacts to groundwater and have potential carcinogenic effects at low levels of detection (part per billion) in drinking water.

    Pursuant to the review time frame specified in Environmental Conservation Law (ECL) §33-0704.2, a registration decision date of May 17, 2002 was established for the first group of three products (Actara, Platinum, and Cruiser). Syngenta waived the requirement of a registration decision by May 17, 2002 and requested an extension in order to address concerns raised during the Department's meeting with Syngenta on May 10, 2002. Although Syngenta submitted further information in correspondence dated May 31, 2002, the data was not enough to substantially change our findings. The Department is required to make a registration decision by June 17, 2002. However, we cannot grant registration of these products at this time due to the lack of completed groundwater monitoring studies and the concern of potential carcinogenic effects to humans from contaminated drinking water.

    Thiamethoxam belongs to a new class of insecticides known as neonictinoids. Laboratory data indicates that thiamethoxam kills insects by interfering with the nicotinic acetylcholine receptors of the insect's nervous system.

    Actara is a water dispersible granule and is labeled to control, as a foliar spray, many sucking and chewing insects infesting cucurbit vegetables, fruiting vegetables, tuberous and corm vegetables, cotton, tobacco, and pome fruit.

    Platinum is a water soluble concentrate which is applied to soil (in-furrow treatment) and is labeled to control certain insect pests infesting cucurbit vegetables, fruiting vegetables, tuberous and corm vegetables and tobacco.

    Cruiser is a seed treatment product for control of certain insects on barley, cotton, sorghum and wheat.

    The maximum application rate for Actara and Platinum is 0.125 lb. of active ingredient per acre per year, while Cruiser is applied as a seed treatment at approximately half of the rate of Actara and Platinum.

    Platinum Ridomil Gold (EPA Reg. No. 100-974) is a water soluble liquid formulation for use on potatoes at a maximum product application rate of 38 fluid ounces and one application per season. This product contains the new active ingredient thiamethoxam (4H-1,3,5-oxadiazin-4-imine,3-[(2-chloro-5-thiazolyl)methyl] tetrahydro-5-methyl-N-nitro) at 4.5% and is labeled for control of certain insect pests and diseases of potatoes. Platinum Ridomil Gold also contains the active ingredient mefenoxam at 9.0%. This active ingredient is currently registered in New York State for use on a variety of crops including potatoes.

    The following is a summary of the technical reviews conducted by the Department which support the Department's decision to not register the new active ingredient thiamethoxam in New York State other than for the special local need labeling for one early season application on pome fruits. The technical reviews assess impacts to non-target organisms, human health, and the environment:

Non-Target Organisms Review:

    Thiamethoxam caused an increased occurrence of liver tumors in mice exposed to 500 ppm in feed for 78 weeks. This exposure is far in excess to what herbivorous mammals would be exposed to by feeding in treated vegetation, so it was not considered to be a serious impact to wildlife. Rats exposed to similar concentrations of thiamethoxam food for 12 months did not develop tumors. Metabolism studies showed that mice and rats process thiamethoxam different ways metabolically. Rats excrete much more thiamethoxam in urine than in feces than do mice. Most aquatic organisms were very insensitive to thiamethoxam. Aquatic insects, as represented by Chironomus riparius, were highly sensitive.


    For aquatic modeling, the highest seasonal application rate of 0.125 lbs AI/acre was used with a runoff percentage of five percent. No allowance for foliar intercept was given. For mammalian and avian modeling, vegetation residues were determined using the highest seasonal application rate of 0.125 lbs AI/acre and the Hoerger and Kenaga (1978) nomograph for "typical" residue estimates.

Summary: There is a very slight risk that some aquatic insects could be harmed by runoff from thiamethoxam treated fields, if a large precipitation event occurs shortly after the material is applied. This risk is too slight to warrant denial of the product.

Human Health Review:

    Neither thiamethoxam nor the Actara, Platinum or Cruiser products were very toxic, irritating or caused skin sensitization following acute exposures in laboratory animals. However, thiamethoxam caused reproductive and other non-cancer effects, including effects on several endocrine tissues, at relatively low doses. In addition, the active ingredient caused liver tumors in mice and the United States Environmental Protection Agency (USEPA) classified thiamethoxam as "likely to be carcinogenic to humans." While the estimated dietary and occupational risks posed by the Actara, Platinum and Cruiser pesticide products are within the USEPA acceptable range, there are concerns for registering pesticide products that have carcinogenic potential and cause effects on endocrine tissues unless either the needs for the products are significant or they replace products that pose greater risks.

    In addition, there are concerns about the potential for thiamethoxam use to contaminate groundwater and drinking water as the environmental fate data indicate high mobility in some soils. While these concerns may be somewhat offset by the low application rates of the Actara and Platinum products and the use pattern of Cruiser, the toxicity data would suggest relatively low screening values as determined in the following paragraph.

    There are no chemical specific federal or State drinking water/groundwater standards for thiamethoxam. 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). If one uses the cPAD derived for the general population (0.0006 mg/kg/day) and procedures for deriving ambient water quality standards and guidelines based on nononcogenic effects (6 NYCRR Part 702.5), a value of four micrograms per liter can be derived. Using the USEPA cancer potency slope factor of 0.0377 (mg/kg/day)-1 and 6 NYCRR Part 702.4 procedures for deriving ambient water quality standards and guidelines based on oncogenic effects, the ambient water quality value associated with a one in one million increased lifetime cancer risk is 0.94 micrograms per liter for thiamethoxam. This value could be used to derive a screening value for comparison to estimated impacts to groundwater and surface water.

Environmental Fate Review:

Hydrolysis: Thiamethoxam was stable at pHs 5 and 7 (693 days), but hydrolyzed rapidly at pH 9 (8.4 days). Major transformation products were CGA 355190 at 59.4% and NOA 404617 at 27.8%. A second study indicated that thiamethoxam was stable at pHs 5 and 7 (572 days), but hydrolyzed rapidly at pH 9 (4.2 days). Major transformation products were CGA 355190 at 54.34%, CGA 404617 (35.2%) and CGA 309995 (9.1%).

Aqueous Photolysis: Thiamethoxam had a half-life in irradiated pH 5 buffered water of 3.36 days. The nonirradiated thiamethoxam was stable. There were 22 degradates, and major transformation products were CGA 355190, CGA 353968, CGA 322704, NOA 407475 and CGA 353042. In a second study, the half-life was 3.9 days and there were 25 degradates.

Soil Photolysis: Thiamethoxam had a half-life 54 days in a sandy loam soil. There were 14 degradates, and the only ones in sufficient quantity to be identified were CGA 355190, CGA 353968, CGA 322704, and CGA 282149. In a second study, the half-life was 47 days. There were 14 degradates, and the only ones in sufficient quantity to be identified were CGA 355190, CGA 353968, and CGA 322704.

Aerobic Soil Metabolism: Thiamethoxam had an EFED calculated half-life of 385 days in a sandy loam soil. Thirty (30) minor degradates were found, but none accumulated. In a second study, the EFED calculated a half-life of 408 days in a sandy loam soil. Several minor degradates were found, but none accumulated. In a third study, the EFED calculated a half-life of 112 days in a clay loam soil. One major degradate was found CGA 355190 at 23%, and several minor degradates were detected. CGA 355190 broke down further into CGA 353968 with a registrant calculated half-life of 459 days.

Anaerobic Aquatic Metabolism: Thiamethoxam degraded in a flooded sandy loam with an EFED calculated half-life of 35.5 days. Multiple degradates were found, but only two major degradates were noted, NOA 407475 at 62.3% and CGA 355190 at 4.8%. In a second study, the half-life in a flooded sandy loam was 38.7 days. Multiple degradates were found, but only two major degradates were noted, NOA 407475 at 58.9% and CGA 355190 at 5.4%. In a third study, pond water and sediment, the EFED half-life was 43.9 days. Degradate NOA 407475 was detected at 66.5% and CGA 355190 was a minor degradate at < two percent. Degradates from the fulvic acid fraction of the bound residues (68.7%) were CGA 293343 (68.6% of bound or 47% of total) and NOA-407745 (16.5% of bound or 11% of total). The degradation was faster in the pond water than in the sediment/water samples. The EFED calculated half-life in pond water was 9.8 days with hydrolysis of the guanidine ring to NOA 404617 (68.8%) and CGA 355190 (18.7%). The pH of the pond water under the anaerobic conditions was > nine.

Aerobic Aquatic Metabolism: Thiamethoxam had an EFED calculated half-life of 16.8 and 13.8 days for the guanidine and thiazole labeled samples in aerobic sediment/water systems. The primary route of degradation was the nitro group to NOA 407475 at 50.5% in the guanidine samples and 34.9% in the thiazole samples. CGA 355190 was found at 8.7 and 15% and NOA 404617 at < five percent. For pond water samples, the registrant calculated half-life was 21.9 and 9.5 days for guanidine and thiazole samples, respectively. The major degradate was CGA 355190 at 73.2% and 59.6% respectively. NOA 404617 reached 25.4% and 32.9%, respectively. CGA 355190 degrades by hydrolysis of the guanidine ring to CGA 353968. An unknown, possibly intermediate degradate, was 14.9% in the thiazole sample.

Adsorption/Desorption: Thiamethoxam was found to have a high to very high potential for mobility in six different soils with Kocs from 43 to 77. There was no correlation found between the Kd and the % organic carbon, so Koc use is not appropriate. Mobility of CGA 3555190 and CGA 353968 was not investigated. The soils were sandy clay loam, loam, sandy loam, sand, loam and silty clay loam. Desorption values tended to be higher than adsorption values.

Aged Leaching: Aged leaching is not discussed in any of the USEPA memorandum, but it is discussed in the registrant's Environmental Fate Summary and Assessment. The registrant claims that aged leaching studies indicate a Koc of 1301 to 28837.

Field Dissipation: Field studies done on the seed treatment found that thiamethoxam has a half-life ranging from 72 to 111 days. Major degradates were CGA 355190 and 322704. The degradates were expected to be more persistent than the parent.

In various types of soils, the parent was generally not found below zero to six inches, and the potential degradates CGA 355190, CGA 353042, NOA 404617 and NOA 407475 were not detected above the five ppb LOQ at any sampling interval or depth. Parent concentrations in the zero- to six-inch depth ranged from 39ppb after application to 9.4 at 86 days, 44 ppb after application to 5.1 at 179 days, 82.7ppb after application to 5.3 at 360 days, 173 ppb after application to 7.3 at 515 days, and 7.6 ppb after treatment to 1.4 ppb at 50 days (turf application).

Registrant calculated half-lives ranged from 13 days in sand, 30 days in sand, 70.7 days in sandy loam, 100.4 days in loamy sand, and 78.8 days in silt loam.

Label Statements: The following statements appear on each label: Conditions of Registration: The following conditions of registration were found in the Notice of Registration for Actara Insecticide (EPA Reg. No. 100-938) and Platinum Insecticide (EPA Reg. No. 100-939):

Submit the following information to satisfy the data gaps in the data base for Thiamethoxam and its metabolite.

    Syngenta Crop Protection, Inc., on May 31, 2002, submitted "Preliminary Information on a Thiamethoxam Seed Treatment Lysimeter Study." The information was preliminary, however, the data did not effectively change the Department's conclusion that thiamethoxam is highly mobile and persistent in the environment.

    Given the surface and groundwater advisories on the label, the requirement for prospective groundwater monitoring studies, the requirement for community and private well monitoring, the very low Kocs, the aerobic half-life of up to 385 days, the modeling that indicates leaching of between 0.25 to 14 ppb in sandy areas and the ambient water quality value calculated by the New York State Department of Health (NYSDOH) of 0.94 g/l, the Department has strong reservations, until additional data is submitted, to the registration of Actara, Platinum, Platinum Ridomil Gold or Cruiser 5FS in New York State. However, the use of Actara for one pre-bloom application in pome fruit orchards, except for those located in Nassau and Suffolk Counties, to meet a Special Local Need, is acceptable for a limited time period pending the submittal of the two prospective groundwater monitoring studies as referred to in the USEPA conditional registration of these products.

    The Department stands behind its methods for modeling impacts to groundwater in New York State. Staff have reviewed a number of products using the same model parameters. Table A (enclosed) lists a number of active ingredients which have been reviewed for environmental fate similar to the approach taken in the review of thiamethoxam. Table A reports both the Koc and half-life used in modeling these active ingredients and the modeled range of leachability for each active ingredient.

    The State's geography is varied and in certain cases, such as Long Island, very sensitive to groundwater impact from application of pesticides. There are also many sandy aquifers in upstate New York and the Department must protect these vulnerable aquifers as well.

Table A is attached and identifies several active ingredients which have been evaluated for impact to groundwater using the LEACHM model and criteria which customize the results to address New York State specific concerns. As an example, imidacloprid was modeled and evaluated at a medium level of leachability and has been detected in groundwater on Long Island. Thiamethoxam was modeled and evaluated at a high level of leachability using the same model and New York State specific criteria.


    The Department has received your request, dated June 12, 2002, to withdraw the applications for the full labeled uses of Actara, Platinum, Platinum Ridomil Gold and Cruiser 5FS. Therefore, the Department hereby accepts your withdrawal of the applications, as submitted, to register Actara (EPA Reg. No. 100-938), Platinum (EPA Reg. No. 100-939) Cruiser 5FS (EPA Reg. No. 100-941) and Platinum Ridomil Gold (EPA Reg. No. 100-974) in New York State. Your application to register the Actara Insecticide SLN label (SLN# NY 020001) for early season use on pome fruit has been accepted, until such time as Syngenta Crop Protection can submit additional data for review by this Department.

    Syngenta Crop Protection, Inc. may reapply to register the subject products. Such an application must be accompanied by a new application fee and meet the requirements listed in Appendix 1.A. of "New York State Pesticide Product Registration Procedures" (August 1996). The following items will also be required for the specific review of the new active ingredient, thiamethoxam.

    Should you have any questions regarding this matter, you may contact Samuel Jackling, Chief of our Pesticide Product Registration Section, at (518) 402-8768.


Maureen P. Serafini
Bureau of Pesticides Management

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

table A:
New York State LEACHM Modeling of Active Ingredients
Aldicarb 0-80 7-84 very high
Cryolite 1318-3000 3000 high?
Dicrotophos injection only   high
Dimethoate     high
Methomyl     high
Thiamethoxam 43-77 385-408 high

155 365 medium
Oxamyl 9 15 medium?
3-300 3 days low
Avermectin 4949 40-60 low
Azinphos-methyl 467-1282 44 low
Carbaryl 288 17 low
Copper     low?
Diazinon 1539 39 low
Disulfoton     low
Esfenvalerate 5273 163 low
Mineral Oil     low?
Phorate 628 3 low
Phosmet 668 14 low
Pymetrozine 181-7875 52 low
Beauvaria Bassiana     very low
Bt (various species)     very low
Canola Oil     very low
Chlorpyrifos 9930 14 very low
Cinnamaldehyde     very low
Cyfluthrin 3700 63 very low
Endosulfan 12,400 27 very low
Harpin Protein     very low
Kaolin     very low
Malathion 1,200 4-6 very low
Methamidophos <1 4-11 very low
Methoxychlor 76,000 128 very low
Permethrin 39,300 30 very low
Rotenone 10,000 3 very low
Spinosad immobile   very low
      very low
Piperonyl butoxide      
Potassium oleate      
Potassium salts of fatty acids      
Soybean oil      
Triphenyltin hydroxide