Difethialone (Generation) - NYSDEC Approves Registration 3/96
New York State Department of Environmental Conservation
Division of Solid & Hazardous Materials
50 Wolf Road, Albany, New York 12233-7250
Phone 518 457-6934 FAX 518 457-4629
March 25, 1996
Ms. Kristin Sobocinski
Senior Regulatory Specialist
3600 West Elm Street
Milwaukee, WI 53209
Dear Ms. Sobocinski:
Re: Registration of Generation Pellets (EPA Reg. No.7173-205),
Generation Rodenticide Bait Packs (EPA Reg. No. 7173-211),
and Generation Pellets Placepack (EPA. Reg. No. 7173-206),
Containing the New Active Ingredient Difethialone (Chemical Code=128967)
The New York State Department of Environmental Conservation
(NYSDEC) has accepted your application for the registration of the new
active ingredient Difethialone contained in the pesticide products
Generation Pellets (EPA Reg. No 7173-205), Generation Rodenticide
Bait Packs (EPA Reg. No. 7173-211), and Generation Pellets Placepacks
(7173-206) in New York State. Generation rodenticides contain 0.0025
Difethialone used for control of roof rats, Norway rats, house mice
and warfarin resistant house mice.
The data package for this product was reviewed by the Division of
Fish & Wildlife (DF&W), the Geotechnical Support Section (GTS), and
the New York State Department of Health (NYSDOH).
The DF&W Bureau of Environmental Protection (BEP) did not object
to registration for indoor use or in tamper-resistant bait stations
out of reach of non-target wildlife. However, if Difethialone comes
in for outdoor use registration, BEP would need more data, including
pertinent United States Environmental Protection Agency (USEPA) branch
reviews and Data Evaluation Records (DERs), in order to properly
assess the risk to fish and wildlife.
The NYSDOH stated in their review that the registration package
provided did not contain USEPA DERs for the toxicology studies
conducted; however, NYSDOH did review the study reports. The study
reports provided indicate that technical difethialone is highly toxic
on an acute basis. The formulated products contain only 0.0025
percent difethialone and had an oral rat LD50 of greater than 5
grams/kilogram body weight. The formulated products were slightly to
moderately irritating to the eyes of rabbits and produced slight
reversible skin irritation. Neither difethialone nor the formulations
were reported to produce dermal sensitization. In a 90-day oral rat
study, difethialone caused increased coagulation times at a dose of 8
micrograms/kilogram/day (ug/kg/day); the no-observed-effect-level was
4 ug/kg/day. Hemorrhagic changes were also reported and 100 percent
mortality occurred at doses above 8 ug/kg/day. In a 90-day oral dog
study, decreased hemoglobin, increased coagulation times and
hemorrhagic changes were reported at a dose of 20 ug/kg/day, but not
at 10 ug/kg/day. No teratogenic or fetotoxic effects were reported in
offspring of pregnant rats or rabbits exposed to difethialone during
gestation at doses up to 50 ug/kg/day, respectively.
The federal labels require that Generation products be placed in
either inaccessible areas or in tamper-resistant bait stations. In
addition, they must be stored in the original container in a locked
storage area. Proper use of the Generation products is not likely to
pose a significant exposure potential or risk to the general public.
A groundwater review revealed that consideration of the application
methods, analysis of the provided adsorption/desorption study and
analysis of the results of the hydrolysis study show that the active
ingredient difethialone, when used as directed, is very unlikely to
adversely impact groundwater. However, an application for outdoor use
of difethialone would require additional data to properly assess
difethialone's impact on groundwater.
After consideration of the reviews by NYSDOH, F&W, and by our
Geotechnical Suppport Section, the Department accepted for
registration the pesticide products Generation Pellets (EPA Reg. No.
7173-205), Generation Rodenticide Bait Packs (EPA Reg. No. 7173-211),
and Generation Pellets Placepacks (EPA Reg. No. 7173-206) containing
difethialone for use in New York State as labeled.
Enclosed for your records are the stamped-accepted labels and the
certificate of registration for the above Generation Products.
If you have any questions on this matter, please contact Maureen
Serafini, Supervisor of our Pesticide Product Registration Section, at
Norman H. Nosenchuck, P.E.
Division of Solid & Hazardous Materials
cc: w/enc. - D. Rutz/W. Smith, Cornell University
N. Rudgers, NYS Dept. of Ag. & Mkts.
N. Kim/A. Grey, NYS Dept. of Health