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
RETURN RECEIPT REQUESTED
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
The Department has reviewed the information supplied to date in support of
the pesticide product registration application for Razorooter II (EPA Reg. No.
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
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
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
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