PMEP Home Page --> Pesticide Active Ingredient Information --> Herbicides, Growth Regulators, and Desiccants --> Herbicides, D to E --> Diquat Dibromide --> Diquat Dibromide - Razorooter II Major Change in Labeling 4/01

Diquat Dibromide - Major Change in Labeling for Razorooter II (EPA Reg. No. 64898-8) 4/01

April 11, 2001


Ms. Margery M. Exton
Pesticide Regulatory Affairs
3719 Thomasson Crossing Drive
Triangle, VA 22172

Dear Ms. Exton:

Re: Registration of One New Pesticide Product, Razorooter II (EPA Reg. No. 64898-8), Which Represents a Major Change in Labeling for the Active Ingredient Diquat Dibromide

    The New York State Department of Environmental Conservation (the Department) has reviewed your application, received April 5, 2000, and additional information, received September 8, 2000 and September 19, 2000, to register one new pesticide product, Razorooter II (EPA Reg. No. 64898-8) in New York State. The product represents a major change in labeling for the active ingredient diquat dibromide. The application was deemed complete for purposes of review November 20, 2000 and a registration decision is due by April 19, 2001.

    Razorooter II is labeled for control of tree root intrusions in sanitary sewers, storm drains, and other drainage systems. The diquat dibromide containing products currently registered in New York State are labeled for agricultural use and for use on non-crop or non-planted areas and aquatic sites.

    The Department has reviewed the information supplied to date in support of the pesticide product registration application for Razorooter II (EPA Reg. No. 64898-8).

    The New York State Department of Health (DOH), the Department's Division of Fish, Wildlife & Marine Resources' Bureau of Habitat and the Department's groundwater staff have reviewed the information submitted to date in support of the application for registration of Razorooter II (EPA Reg. No. 64898-8).

    The DOH stated that the formulated product was not very toxic in acute exposure laboratory animal studies by the oral or inhalation routes. This material was moderately toxic following acute dermal exposure on rabbits and was slightly irritating to the skin. It also caused severe eye irritation. The active ingredient was not a dermal sensitizer (guinea pigs).

    Diquat dibromide did not cause oncogenic effects in either rat or mouse chronic feeding studies. It also was negative in most of the genotoxicity tests conducted (positive results were reported in a mouse lymphoma cell forward mutation assay and at high doses in a human lymphocyte clastogenicity assay). The United States Environmental Protection Agency (USEPA) classified diquat dibromide as a Group E (no evidence of carcinogenicity for humans) carcinogen.

    The USEPA drinking water standard (maximum contaminant level), for the parent compound diquat is 0.02 milligrams per liter. This value is also the New York State (10 NYCRR Part 5, Public Water Systems) drinking water maximum contaminant level.

    The data indicate that the formulated end product Razorooter II and its active ingredient diquat dibromide are overall not very toxic following acute oral or inhalation exposure in laboratory animals. They, however, have the potential to cause significant eye irritation and to be moderately toxic following acute dermal contact. In addition, diquat dibromide has the potential to cause certain ocular and developmental effects, the latter occurring only at doses that also were parentally toxic. To mitigate exposure to applicators and other handlers, the label for the formulated product requires the use of considerable personal protective equipment which includes waterproof gloves, protective eyewear, long-sleeved shirt and pants and chemical resistant footwear and socks. The label also requires that those involved in application have specific respirators immediately available. Based on the inaccessible use sites of Razorooter II, there also appears to be minimal exposure potential to this pesticide product by the general public.

    Our groundwater staff stated that the primary route of environmental dissipation of diquat is strong adsorption to soil particles. Diquat does not hydrolyze or photodegrade and is resistant to microbial degradation under aerobic and anaerobic conditions. There were no major degradates isolated from any of the environmental fate studies. Any diquat not adsorbed or taken up by the plant roots will be removed from the water column by adsorption to soil sediments, aquatic vegetation, and organic matter upon discharge from the pipe. Adsorbed diquat is persistent and immobile, and is not expected to be a groundwater contaminant. The use of the product as labeled should not cause an impact to ground or surface water in New York State.

    The Bureau of Habitat stated that Razorooter II cannot be used in sewer systems that do not convey effluent into a treatment system and the product cannot be discharged into open water without a SPDES (NPDES) permit. Under these use limitations, non-target fish, aquatic invertebrates, or aquatic plants will not be exposed.

    Therefore, the Department hereby accepts for registration Razorooter II (EPA Reg. No. 64898-8).

    Due to the extensive personal protective equipment required, the quantities of product (and diluted product) applied, the use sites and the risks such a product could pose to untrained and unprotected applicators, Razorooter II is classified as restricted use in New York State in accordance with rules and regulations 6 NYCRR 326.2(g). As such the product is restricted in its purchase, distribution, sale, use, and possession in New York State. According to the New York State Department of Environmental Conservation Regulations 6 NYCRR 326.3 (a): "It shall be unlawful for any person to distribute, sell, offer for sale, purchase for the purpose of resale, or possess for the purpose of resale, any restricted pesticide unless said person shall have applied for, and been issued a commercial permit."

    Furthermore, the product may only be purchased and used by certified applicators in New York State.

    Please contact the Pesticide Certification Section, at (518) 457-7482, if you require information concerning commercial permits or pesticide applicator certification.

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

    If you have any questions, please contact Francis X. Hegener, Chief of our Pesticide Product Registration Section, at (518) 457-7446.


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