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Imidacloprid - Status of Imidacloprid in New York State 10/03

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

October 3, 2003


Ms. Karen Cain
Product Manager, State Regulatory Affairs
Bayer CropScience
2 T.W. Alexander Drive
Research Triangle Park, North Carolina 27709

Dear Ms. Cain:

Re: Status of Imidacloprid in New York State

    The New York State Department of Environmental Conservation (Department) has received your letter, dated August 13, 2003, which summarizes the meeting the Department held on July 29, 2003 with you and four other representatives of Bayer CropScience, and with two representatives of Bayer Environmental Science to discuss the registration status of imidacloprid in New York State. A copy of Bayer CropSciences' July 29, 2003 presentation, which includes your initial draft of the Best Management Practices (BMPs) for use of imidacloprid on Long Island, was also received.

    The Department has unresolved concerns regarding the continued use of imidacloprid in Nassau and Suffolk Counties as currently labeled.

    As a result of these concerns, staff of the Bureau of Pesticides Management met previously with you and other various representatives of Bayer CropScience on July 30, 2002 and October 1, 2002 to discuss groundwater monitoring results and possible label and use pattern modifications. The Department, in our letter dated July 17, 2002, stated that we will not register any additional imidacloprid containing products to either Bayer CropScience or your distributors/formulators until our concerns are adequately addressed.


    The Department registered the active ingredient imidacloprid in March 1995. In the absence of actual groundwater data, the Department utilized computer modeling to predict the leachability of the parent compound and degradates. Groundwater modeling performed by the Department prior to the registration of imidacloprid, indicated the potential for accumulation and persistence of imidacloprid and its degradates over an extended period of continued yearly use at maximum labeled rates. The Department, as stated in our registration letter, was especially concerned about the use of imidacloprid on Long Island (Nassau and Suffolk Counties) which is a vulnerable sole source drinking water aquifer.

    Therefore, as a condition of registration, Bayer CropScience (formerly known as Bayer Corporation) agreed to establish appropriate monitoring wells on Long Island within typical use sites with use patterns consistent with label directions.

    Bayer CropScience was informed that continued registration of all imidacloprid products within New York State would be dependent upon the annual review of groundwater monitoring data collected within the Long Island aquifer immediately beneath the use sites and compliance with requirements outlined in various New York State registration letters.

    In conjunction with groundwater data provided by Bayer, the Department has also been working closely with the Suffolk County Department of Health Services (SCDHS) to monitor imidacloprid. The SCDHS's goal is to identify potentially significant pesticide contaminant plumes throughout Nassau and Suffolk Counties by sampling approximately 2,000 public and private water supply and monitoring wells.


    To date, imidacloprid has been identified at low levels (parts per billion), in groundwater samples from approximately twenty monitoring and private wells in Nassau and Suffolk Counties. Most groundwater detections have been very low, ranging from 0.1 ppb to 2.0 ppb. However, imidacloprid has been found in clusters of private wells down-gradient of farms, and a recent private well sample in Suffolk County contained 6.7 ppb imidacloprid. Additionally, imidacloprid has now been detected at a golf course monitoring well and at monitoring wells near trees that have been treated with imidacloprid by injection.

    The United States Environmental Protection Agency (USEPA) Health Advisory Level (HAL) for imidacloprid is 399 ug/l. There are no chemical specific New York State drinking water standards for imidacloprid. Based on its chemical structure imidacloprid falls under the 50 micrograms/liter New York State drinking water standard for an "unspecified organic contaminant" (NYCRR Part 5 - Public Water Systems).

    When the "Imidacloprid Groundwater Monitoring Project Plan" was established in 1996, an "action threshold" of 25 ppb (half of the New York State drinking water standard) was discussed and agreed upon. This "action threshold" was intended for the groundwater samples taken from the monitoring wells established for the imidacloprid groundwater monitoring project. The intent of the study was to monitor levels of imidacloprid in the groundwater directly beneath the site specified and used in conjunction with the groundwater monitoring project. Ideally, imidacloprid was to be used yearly at maximum labeled rates.

    During the course of the study, it was reported that at all of the established monitoring sites, imidacloprid products were either not being used or the products were being used at a fraction of the maximum labeled rate. Also, during this time, SCDHS added imidacloprid to their routine analysis of public and private water supply and monitoring wells.

    Since the product has not been used at labeled rate throughout the groundwater monitoring program, it has been difficult to provide a realistic interpretation of the impact of imidacloprid.

    While the detected level of imidacloprid in groundwater samples is not currently a health concern, the Department is troubled about the increasing frequency of detections of the parent compound with respect to the short duration of registration and use at less than maximum labeled rates in New York State. The Department is particularly concerned about the increasing number of detections in samples from private drinking water wells down gradient of fields where the product was applied.

    Due to the high profile of pesticide and groundwater issues on Long Island, the Department intends to take a pro-active approach to the use of imidacloprid in New York State to limit continued environmental load.

    The Department's goal is to manage the current labeled uses of all imidacloprid products in order to protect the groundwater resources of Long Island and at the same time, preserve its use for crops and other use patterns where no alternatives for insect control exist.

    Discussions about our concerns have been held with the USEPA and various user groups.

    Various user groups are very interested in maintaining imidacloprid as an insect control option. As provided in our meeting held on October 1, 2002, the Department has received input from numerous sources regarding possible label modifications. Some modifications suggested are:
  1. Eliminate all drench uses in greenhouses and nursery production.
  2. Allow use of granular imidacloprid only in enclosed structures (greenhouses, overwintering houses, etc.) and address watering practices through Best Management Practices (BMPs) and educational programs.
  3. Limit Admire use in cucurbits to no more than 1.1 fl. oz. per 1000 ft. of row.
  4. All in-furrow applications of Admire in potatoes and vegetables must be made in 4 to 8 inch bands depending on width of seed furrow. Also, eliminate narrow dribble application.
  5. Require the use of reduced-pressure shut-off valves (anti-drip valves) to prevent overspray at the ends of rows.
  6. Require a minimum distance of 200 feet from mixing and loading area to sump, water source, field drain, etc., or use of a containment pad.
  7. Require a minimum distance of 75 feet from the area of application to sump, water source, field drain, etc.
  8. Delay field applications of imidacloprid if heavy rains (greater than one inch) are expected within 24 to 48 hours.
    The Department intends to protect the groundwater/drinking water of Long Island, while still preserving the use of imidacloprid where no viable alternatives exist.

    Bayer CropScience, in December of 2001, committed to the production of product stewardship brochures regarding the use of imidacloprid products in vulnerable soils and sole source aquifers. Prior to the July 29, 2003 meeting, the Department had received no evidence of progress in this area. The Department is encouraged that Bayer CropScience is now developing BMPs. Bayer CropScience, in their August 13, 2003 letter, promised to submit the following:
  1. Cumulative annual sales, in the form of total active ingredient, in New York State of Bayer's imidacloprid products. Sales information for the 3rd party-registered imidacloprid products will be provided directly to the Department from the sub-registrants/distributors. This information will be considered Confidential Business Information (CBI) by the Department. In addition the Department would prefer to see a breakdown of sales for Long Island.
  2. Data to support the adequacy of a mixing/loading and application buffer zone of 25 feet for the protection of nearby water resources.
  3. Efficacy data for application rates for imidacloprid.
  4. Peer reviewed and finalized product specific Best Management Plans for imidacloprid products labeled for agricultural, greenhouse and nursery, professional turf and ornamental, and professional tree and shrub uses.
    The Department will not register any additional imidacloprid products or approve amended labels with expanded uses until the above-mentioned items are received and deemed acceptable by the Department.

    Bayer has proposed the following schedule in order to complete the BMPs by the end of 2003:
  1. By September 1st, Bayer will revise the initial draft of the imidacloprid-specific BMPs to reflect the format utilized in BMPs drafted by Bartlett Tree Service. The Department has received this item.
  2. During the period of September through October, Bayer will have the imidacloprid-specific BMPs, in the updated format, peer-reviewed by the Department, Bayer CropScience/Bayer Environmental Science (BCS/BES), stakeholders, Cornell, the New York State Department of Agriculture and Markets, and other appropriate researchers. The Department requests copies of comments received.
  3. During the period of September through October, Bayer will explore with industry the concepts for generic BMPs targeted to the retailers and homeowners. Bayer will be consulting with trade associations, in addition to other interested parties.
  4. During the period from November through December, Bayer will refine the imidacloprid-specific BMPs based on comments received during the peer review process.
  5. Imidacloprid-specific BMPs will be finalized in time for presentations to the user communities at the winter meetings which begin in January, 2004.
  6. Stewardship materials (slide sets, brochures, etc.) and training presentations will be finalized for use during the winter user meetings which begin in January, 2004. Please inform the Department of the locations and dates of these meetings.
    The submitted BMPs are an initial step. As Bayer CropScience reviews and modifies the BMPs, we suggest they include aspects that the Department considers crucial to successful BMPs. Please see the enclosed Essential Elements of a Best Management Plan. Specifically the BMPs should:
  1. Be specific to Long Island, describe the need to protect its sole source drinking water aquifer, and explain the need to limit the environmental load of imidacloprid.
  2. Identify critical pests and use sites where no other products are available to assist in control.
  3. Identify pests that can be controlled by other products.
  4. Be more specific in the timing of applications, especially with respect to weather conditions.
  5. Specify soil conditions where imidacloprid should not be used (eg., when the water table is <3 feet below the soil surface).
    The Department reiterates that the continued registration of all imidacloprid products within New York State will be dependent upon the ongoing review of groundwater monitoring data collected within the Long Island sole source aquifer. The Department will continue to evaluate the various use patterns. Our evaluation may result in the establishment of narrow allowable use patterns and rates and/or the classification of certain imidacloprid products as Restricted Use Pesticides in New York State.

    The protection of the drinking water resources and the health of the residents of Nassau and Suffolk Counties is of the utmost importance.

    The Department looks forward to working with you, your associates and other interested stakeholders to refine and produce the BMPs which have been received to date. Also, we look forward to receiving and reviewing the concepts developed for generic BMPs targeted to the retailers and homeowners.

    If you have any questions, please call Samuel Jackling, Chief of our Pesticide Product Registration Section, at (518) 402-8768, or me, at (518) 402-8788.


Maureen P. Serafini
Bureau of Pesticides Management

cc: Meredith Laws - USEPA - Chief, Insecticide-Rodenticide Branch, Registration Division