NYS DEC Letter - Denial of Applications for Registration 2/00
New York State Department of Environmental Conservation
Division of Solid and Hazardous Materials
50 Wolf Road, Albany, New York 12233-7250
Phone: (518) 457-6934 - FAX: (518) 457-0629
February 23, 2000
RETURN RECEIPT REQUESTED
Ms. Linda H. Aschbrenner
State Registration Specialist
Rhone-Poulenc Ag Company
P.O. Box 12014
Research Triangle Park, NC 27709-2014
Dear Ms. Aschbrenner:
Re: Denial of Applications for Registration of Two New Pesticide Products, Regent 80 WG
Insecticide (EPA Reg. No. 264-570) and Regent 4 SC Insecticide (EPA Reg. No. 264-582),
which Represent a Major Change in Labeling for the Active Ingredient Fipronil
The Department of Environmental Conservation (the Department) has completed the review of
your applications, received June 30, 1998 and September 29, 1998, for the registration of
Regent 80 WG Insecticide (EPA Reg. No. 264-570) and Regent 4 SC Insecticide (EPA Reg. No.
264-582), respectively, in New York State. Additional information, received September 22,
1998, May 24, 1999, June 4, 1999, August 10, 1999 and November 2, 1999, submitted in support
of the applications for registration of the above-mentioned products has also been reviewed.
The Regent products are labeled to control insect pests on field corn. Fipronil is currently
registered in New York State for use in products labeled to control fleas and ticks on dogs,
puppies, cats and kittens, and to control indoor/outdoor household insects. The proposed
use of the Regent products on field corn represents a major new use pattern for the active
ingredient fipronil in New York State.
The applications were deemed complete on November 20, 1998 with a legislatively mandated
registration decision due by April 16, 1999. Rhone-Poulenc Ag Company waived the registration
decision date on April 14, 1999 with a future registration decision date to be determined by
A meeting was held with Larry Hodges, Bob Theissen, Lisa Ortego and Linda Burgess of
Rhone-Poulenc Ag Company, on May 27, 1999, in order to discuss the Department's concerns
regarding the registration of the Regent products in New York State. Additional information
was submitted on June 4, 1999 and August 10, 1999 in response to the May 27, 1999 meeting.
The Department had unmitigated concerns regarding the use of the Regent products near
sensitive aquatic areas. A conference call was held on October 29, 1999 with Larry Hodges,
Rodney Schmidt and Bob Theissen of Rhone-Poulenc Ag Company in order to discuss the
Departments concerns. Additional information was submitted on November 2, 1999 in response
to the October 29, 1999 conference call. A final registration decision date for Regent 80
WG Insecticide (EPA Reg. No. 264-570) and Regent 4 SC Insecticide (EPA Reg. No. 264-582) is
February 29, 2000.
The Department has reviewed the information supplied to date in support of the major change
in labeling applications for Regent 80 WG Insecticide (EPA Reg. No. 264-570) and Regent 4
SC Insecticide (EPA Reg. No. 264-582).
The formulated Regent products were moderately toxic to laboratory animals by the oral,
inhalation and dermal routes of exposure, were mildly irritating to rabbit eyes and skin
and were not skin sensitizers. While fipronil is relatively toxic, exposure potential from
the use of the Regent products on field corn is limited. The products are directly applied
to soil furrows only at the time of planting and the application rate is relatively low.
The labels of these products also require that the applicators and other handlers wear
coveralls over short-sleeved shirts and short pants, waterproof gloves, chemical-resistant
footwear plus socks, chemical-resistant headgear for overhead exposure, protective eyewear,
a dust/mist filtering respirator and a chemical-resistant apron when cleaning or mixing and
There are no chemical-specific federal or State drinking water/groundwater standards for
fipronil. Based on its chemical structure, fipronil falls under the 50 micrograms per
liter general New York State drinking water standard for "unspecified organic contaminants"
(10 NYCRR Part 5 - Public Water Systems).
Available laboratory data indicate that below the soil surface fipronil dissipates by soil
binding followed by slower biotic mediated processes. The major route of degradation on the
soil surface may be photolysis and/or soil binding followed by slower biotic mediated
processes. These data indicate that fipronil is slightly mobile to relatively non-mobile
in soils tested, but may be moderately persistent under some environmental conditions.
Laboratory data indicate that fipronil degrades slowly under alkaline hydrolytic conditions,
but appears to be stable to hydrolysis at pHs five and seven. Field data appear to support
these laboratory data. Half-lives of 1.1 to 1.5 months for bare soil and 0.4 to 0.5 months
for turfed soil were reported in field data. Half-lives of 3.4 to 7.3 months were reported
for in-furrow applications. In bare soil and in-furrow applications, fipronil residues were
detectable mainly in the 0 to 0.15 meter (m) soil depth. Field data for in-furrow applications
did report limited fipronil residues in the 0.15 to 0.45 m soil depth segments. Since fipronil
absorbs to soil/sediment, the potential for groundwater contamination is considered relatively
low in most soils. Movement off-target would appear to be associated with sediment contained
in surface water and runoff water.
Based on the environmental fate data, the Regent products, when used as labeled, will not
have a significant impact on the groundwater of New York State.
Fipronil is extremely toxic to marine invertebrates. Marine invertebrates will be impacted
at water concentrations three orders of magnitude lower than those affecting freshwater
organisms. Transport to aquatic habitats with surface runoff of even a minute percentage of
the applied fipronil or metabolites will negatively impact them.
The Department, as a result of the review of additional information submitted by
Rhone-Poulenc Ag Company on fipronil degradate toxicity and avian dietary toxicity,
requested additional label language in order to insure the protection of sensitive aquatic
life in New York State. The Department has, in the past, required that identical exclusionary
100-foot buffer zones around surface waters be added to product labels. The intent, as
explained to Rhone-Poulenc representatives during the October 29, 1999 teleconference, is
to exclude the use of products as toxic as Regent from areas bordering surface waters. The
Department has determined that 100 feet is a reasonable distance for eliminating the
potential for harm from extremely toxic comp u s and is intended to steer a user to a
different, lower risk product. In a follow-up letter to the teleconference, Rhone-Poulenc
Ag Company stated that they did not intend to amend their label because there was no
scientific rationale supporting the 100-foot buffer as opposed to the 60-foot buffer
currently on the Regent label. They indicated that they were forwarding three documents or
portions thereof that support their position that the 60-foot buffer currently on the label
Use of Regent as directed on the label will result in an unacceptable level of risk to
marine invertebrates on both an acute and chronic basis. The Mysid shrimp acute Lethal
Concentration 50 (LC50) (median lethal concentration) for fipronil is 140 parts per
trillion (ppt), the chronic Lowest Observed Effect Concentration (LOEC) is 5 ppt. With
this extreme toxicity transport to aquatic habitats of parent and/or metabolites, at
levels typical of compounds with fipronil's chemical characteristics, will result in adverse
Once in surface waters, the only significant degradation pathway of fipronil or metabolites
is via photolysis. While their aqueous photolysis half-life is relatively short they may
persist in deeper or turbid water for extended periods before adsorbing to the water column
or sediment organic carbon.
Rhone-Poulenc Ag Company submitted three items in support of your position that the current
20-yard buffer is adequate for protection of aquatic resources. The first item consisted of
selected pages from a terrestrial soil dissipation study dated September 1994. The second
item was a United States Environmental Protection Agency (USEPA) Data Evaluation Record (DER)
report, dated March 28, 1997, which included the above-mentioned soil dissipation study. The
third item was the paper "Reducing Herbicide Runoff. Role of Best Management Practices" by
J.L. Baker et al, 1995, Brighton Crop Protection Conference.
The soil dissipation study was conducted at locations in California, Nebraska, North
Carolina and Washington State. Fipronil was applied in furrow with corn seed at 0.13 pound
of active ingredient per acre. Replicate soil core samples were taken immediately after
planting and at intervals over the next eighteen months from three locations; in the row,
in the trough between rows, and at a point midway between the trough and the row cores.
Parent fipronil was detected at the Washington site after four months in the 15-30
centimeter (cm) depth in four-row samples. Parent fipronil was found after six months
at the 30-45 cm depth in one sample and the 15-30 cm depth in two others. By the 16
month samples, it was detected at the 30-45 cm depth in all four-row cores collected.
No parent or metabolites were detected in any trough samples. Nonetheless, the vertical
movement of fipronil in the coarse sandy loam Washington soil demonstrates that there can
be, limited as expected, movement with water. The USEPA study evaluation indicates that
the mobility of fipronil at the Washington site appeared to correlate with the spring thaw.
The November 1997 USEPA Environmental Fate and Effects Division Section 3 Eligibility
Decision Chapter for Fipronil Use on Corn which considered laboratory data, the above
study plus others, stated that "based on the environmental fate assessment, fipronil and
its degradates (MB46513, MB46136 and MB45950) can potentially move into surface waters."
Later in the surface water assessment section; "Although fipronil and its degradates exhibit
moderate soil sorption affinities, these compounds are expected to exist in runoff waters
primarily in the dissolved state."
The current federal label's Environmental Hazards section states; "Runoff from treated
areas may be hazardous to aquatic and estuarine organisms ... Protection of aquatic areas
may be enhanced by maintaining all or a portion of this buffer in vegetative cover." The
1995 J.L. Baker paper, provided by the applicant, is part of a large volume of work in this
area demonstrating that properly maintained vegetated buffer strips can substantially reduce
pesticide loading to surface waters. However, to rely on there being properly constructed
and maintained buffers in place for protection of sensitive organisms at all locations where
a given product may be used is imprudent. They can be effective and their use should be
encouraged, but any breach in a buffer, such as a low spot, tire rut, drainage tile etc.,
can largely negate its function.
In your October 29, 1999 letter to the Department, Rhone-Poulenc Ag Company indicated that
the company is conducting a water monitoring program in corn growing areas where Regent is
currently being used. The fact that a study is being conducted is an indication of the level
of concern associated with this product. You state that in the first two years of the
three-year study, fipronil residues have not been detected in any water samples using an
analytical method that can detect down to 3 ppt of fipronil. No details on the study
location, design, soil conditions, or methods are given.
The current federally accepted Regent labels contain the following language: "Runoff
from treated areas may be hazardous to aquatic and estuarine organisms in adjacent aquatic
and estuarine sites. Do not apply within 20 yards of lakes, reservoirs, rivers, permanent
streams, marshes, natural ponds, estuaries, commercial aquaculture facilities or other bodies
of water that convey water to these areas. Protection of aquatic areas may be enhanced by
maintaining all or a portion of this buffer in vegetative cover. "
The Department requested that Rhone-Poulenc Ag Company simply increase the buffer zone
from 60 feet (20 yards) to 100 feet, or add a statement that specifies a 100-foot buffer
zone in New York State.
The Department maintains that increasing the buffer zone which appears on the existing
label by 40 feet; to a 100-foot buffer zone around sur waters, is required to be added to
the Regent product labels in order to insure the protection of sensitive
aquatic areas. The Mysid shrimp acute LC50 for fipronil is 140 ppt and the chronic
LOEC is 5 ppt. The runoff modeling conducted by the Department included the fipronil
metabolites of aquatic toxicological concern produced via aerobic soil metabolism.
Metabolite MB46136 is 6.6 times more toxic and metabolite MB45950 is 1.9 times more toxic
to Daphnia than the parent fipronil compound. A similar toxicity differential between parent
and metabolites was assumed for Mysidopsis, the marine test organism. The extremely high
level of toxicity and the fraction of applied fipronil and degradates that is likely to be
transported in runoff poses an unacceptable level of risk to marine invertebrates.
The materials provided by Rhone-Poulenc Ag Company in response to the October 29, 1999
teleconference do not provide any information that was not previously considered in the
review of this product, including the label's standard 20-yard (60 foot)
corn insecticide cluster buffer zone. Maintenance of properly vegetated buffer zones while
effective, is unenforceable, particularly given the label language which vaguely suggests
that protection of aquatic areas "may be enhanced by maintaining all or a portion of the
buffer in vegetative cover." In rare cases where a combination of a product's toxicity and
persistence warrants, the Department has and will request a 100-foot buffer to reduce or
eliminate its use in fields bordering surface waters.
The Department continues to have unmitigated concerns regarding the potential of fipronil
to impact aquatic and estuarine organisms with a buffer zone of 20 yards
(60 feet). A buffer zone of 100 feet is required to be added to the existing label in order
to insure the protection of aquatic and estuarine organisms in New York State.
Therefore, your application for registration of Regent 80 WG Insecticide (EPA Reg. No.
264-570) and Regent 4 SC Insecticide (EPA Reg. No. 264-582) in New York State is denied.
You may pursue the options available under Article 33-0711 of the New York State
Environmental Conservation Law.
Please be reminded that the application fee is nonrefundable. If you wish to reapply,
you must submit a new application for registration as a Major Change in Labeling,
applicable application fee and all required documents.
If you have any questions, please contact Maureen Serafini, Chief of our Pesticide
Product Registration Section, at (518) 457-7446.
Stephen Hammond, P.E.
Division of Solid & Hazardous Materials
cc: N. Kim/D. Luttinger - NYS Dept. of Health
R. Zimmerman/R. Mungari - NYS Dept. of Ag. & Markets
G. Good/W. Smith - Cornell University, PMEP