Mr. Harry Radke
State Registration Project Manager
Valent U.S.A. Corporation
1333 North California Blvd., Suite 600
P.O. Box 8025
Walnut Creek, CA 94596-8025
Dear Mr. Radke:
Re: Registration of a Major Change in Labeled (MCL) Use Pattern for the Active
Ingredient Pyriproxyfen Contained in the Pesticide Product Esteem® 0.86 EC Insect
Growth Regulator (EPA Reg. No. 59639-95)
The New York State Department of Environmental Conservation
("The Department") has completed review of your application (received 09/30/99)
and supplemental information supplied to date regarding registration of the
referenced pesticide product in New York State. The subject application and
data package were deemed complete for purposes of technical review on March
15, 2000 following one determination of incompleteness. Pursuant to the review
time frame specified in ECL §33-0704.2, a registration decision date of August
12, 2000 was established. By mutual agreement, the registration decision date
was subsequently waived to allow Valent U.S.A. Corporation (Valent) to respond
to issues raised in the ecological effects risk assessment.
Esteem® 0.86 EC Insect Growth Regulator (11.23% pyriproxyfen)
is an alternate brand name for Knack® Insect Growth Regulator (EPA Reg. No.
59639-95). Esteem® is labeled to control certain insects on apples, pears
and walnuts. During the technical review, Valent submitted amended product
labeling bearing new almond and citrus crop uses. The maximum Esteem® application
rate on crops (apples and pears) relevant to New York State is 32 fluid ounces
per acre per season, which is equivalent to 0.22 pounds pyriproxyfen per acre
Previously registered use patterns for the active ingredient
pyriproxyfen include products for indoor non-food/feed, indoor residential,
domestic animal, indoor (greenhouse, lath and shadehouse) and outdoor ornamental,
and outdoor perimeter area applications. The proposal to register a pesticide
product bearing terrestrial food crop uses represents a MCL for pyriproxyfen in
New York State.
The Department conducted toxicological, environmental fate and
ecological effects risk assessments for pyriproxyfen and the Esteem®
TOXICOLOGICAL RISK ASSESSMENT:
Esteem® 0.86 EC Insect Growth Regulator is identical in formulation to
Distance® Insect Growth Regulator (EPA Reg. No. 59639-96). The toxicological
properties of Distance® and the active ingredient pyriproxyfen were previously
reviewed by the Department (reference correspondence from S. Hammond to H.
Radke and M. Serafini to H. Radke, October 19, 1999 and June 29, 2000,
Neither the formulated product nor the active ingredient was very
toxic on an acute basis to laboratory animals by the oral, dermal or inhalation
routes of exposure. Whereas, the formulated product was moderately irritating
to rabbit skin and mildly to moderately irritating to their eyes, the active
ingredient was not very irritating to animal eyes or skin. Neither the
formulated product nor the active ingredient caused dermal sensitization
(tested in guinea pigs). In addition, the active ingredient pyriproxyfen did not
cause oncogenic or reproductive effects and was negative in several genotoxicity
studies. Some developmental effects (at maternally toxic doses) were reported
in rats, but not in rabbits. The United States Environmental Protection Agency's
(USEPA) Office of Pesticide Programs developed a reference dose (RfD) of 0.35
milligrams per kilogram body weight per day (mg/kg/day) based on a
no-observed-effect level (NOEL) of 35 mg/kg/day in a two-year rat feeding study
(decreased body weight of female rats at 183 mg/kg/day) and an uncertainty
factor of 100.
The USEPA established tolerances for pyriproxyfen in or on wet
apple pomace at 0.8 parts per million (ppm), pome fruits at 0.2 ppm and walnuts
at 0.02 ppm. The USEPA estimated that chronic dietary exposure to these residues
would be 0.8 percent of the RfD for the general United States population, 1.2
percent for non-nursing infants and 2.2 percent for children 1 to 6 years old.
This chronic exposure analysis is based on the assumption that 100 percent of crops
are treated and contain tolerance level residues.
There are no chemical-specific federal or State drinking
water/groundwater standards for pyriproxyfen. Based on its chemical structure,
pyriproxyfen falls under the 50 micrograms per liter (μg/L) general New York
State drinking water standard for an "unspecified organic contaminant"
(10 NYCRR Part 5, Public Water Systems).
The available information indicates that use of pyriproxyfen
for control of certain insects on apples, pears, and walnuts should not pose
significant risks to workers or the general public. While the Esteem® product
can be somewhat irritating to eyes and skin, the label requires that applicators
wear a considerable amount of personal protective equipment, which should
mitigate direct contact.
ENVIRONMENTAL FATE RISK ASSESSMENT:
Certain required USEPA Data Evaluation Records (DERs) were not
available, however, sufficient information was available to determine potential
impacts to ground and surface water.
The input parameters for the Department's groundwater model
(LEACHM) were taken from the DERs or from USEPA's Environmental Fate and Effects
Division (EFED) memoranda dated March 27, 1996 and July 13, 1999. Using Riverhead
soil, an application rate of 0.215 pounds pyriproxyfen/acre/year, a Koc of 11,600
for the parent and 85 for the degradate PYPAC (7.6%) and an aerobic half-life of
9 days, the modeling indicated no parent or degradate in the leachate in the ten
year modeling cycle.
Based on the low application rate, very high parent Koc, very short
half-life and LEACHM modeling, it does not appear that use of Esteem®, as labeled,
will impact ground or surface water in New York State.
ECOLOGICAL EFFECTS RISK ASSESSMENT:
Esteem® is labeled for control of Codling moths, leaf rollers,
scale insects, leaf miners, aphids, and pear psylla on pome fruits. Applications
of 10 to 16 fluid ounces per acre in 75 to 400 gallons of water are made at
targeted pest life stages. No more than two applications or 32 fluid ounces may
be applied per season. Esteem® may not be applied within 45 days of harvest.
Pyriproxyfen is practically non-toxic to birds or mammals. It is
highly toxic to fish and freshwater invertebrates, and very highly toxic to
marine invertebrates. Freshwater fish reproduction is affected at low ppb
concentrations. Freshwater invertebrate reproduction is affected at low part
per trillion concentrations. Freshwater invertebrate life cycle studies were
conducted with two major degradates identified as PYPAC and 4'-OH-pyr; both
affected reproduction at low ppb concentrations. PYPAC may be highly mobile
in soil, 4'-OH-pyr is likely to exhibit low mobility. The environmental fate
of both is poorly characterized.
Potential ecological impacts of Esteem® were modeled using the
Department's MAMTOX, AVTOX and AQUALIFE models. All toxicity and fate
parameters for modeling inputs were taken from the data package.
MAMTOX and AVTOX modeling indicate low potential for mammalian or
AQUALIFE runoff modeling was conducted for a single application
at the 10 oz/acre rate and two applications at 16 oz/acre. It was assumed that
50% of the applied material was intercepted by the target plants and was
unavailable for runoff. The 36-day field dissipation rate was used to calculate
the parent compound residue remaining from the first application in the two
application scenario. Of the applied precipitation, 60% was assumed to reach
the model pond.
The mean aqueous photolysis half-life of pyriproxyfen in shallow
clear water is 4 days, other aquatic degradation pathways are considerably slower
so it is possible for it to persist in deeper waters. The AQUALIFE model does
not consider chronic effects if a chemicals shortest aquatic half-life is
less than 10 days. If the predicted water concentrations exceed toxicity
thresholds by a large degree it is possible to get chronic exposures even
with compounds with relatively short half lives. Given the extreme
reproductive sensitivity of aquatic invertebrates to this compound, the half-life
in water was set at 11 days to evaluate the potential for chronic effects in
situations where photolysis is reduced, and to determine if chronic exposures
might occur before water concentrations fall below effects thresholds through
No acute toxicity thresholds were exceeded in either modeled
scenario. The predicted pyriproxyfen concentration in the model pond resulting
from a runoff event occurring after one application at the lowest label rate
exceeds the daphnia chronic lowest-observed-effect level (LOEL) and NOEL at all
three runoff levels and in all pond depths, except at the lowest runoff rate
in the 6 foot depth. The concentration in 6 feet of water at the low runoff
rate is predicted to be 30 parts per trillion (ppt). The daphnid LOEL is 31
ppt. Although technically the concentration did not exceed the threshold,
being only one part per trillion lower it can be considered equal to it. The
pyriproxyfen water concentrations ranged from being equal to the daphnid LOEL
to a level 13 times the LOEL.
Following the second allowed application of Esteem® at the
16 oz/acre rate, a runoff event is predicted to result in model pond
pyriproxyfen concentrations that exceed the daphnid chronic LOEL by
2.6 to 39 times. Labeled use of Esteem® is not likely to cause acute
toxicity to fish or wildlife resources, however, the risk of significant
freshwater aquatic invertebrate reproductive impairment is high.
None of the materials submitted in support of registration of
Esteem® establish how long of an exposure of adult aquatic invertebrates is
needed to impede reproduction. However, in a discussion of the risks posed
to freshwater invertebrates (reference USEPA Environmental Fate and Effects
Division risk assessment for pyriproxyfen use on citrus, almonds and fruiting
vegetables, dated 07/13/99), the reviewer reports that an analysis of the
daphnia and mysid shrimp toxicity test results shows that the effects on
reproduction for both species are likely to be occurring in the relatively
short time period between egg fertilization and hatching. That is, with 4
to 9 days of exposure or less.
The pyriproxyfen concentration predicted by AQUALIFE at the
lowest runoff rate in one foot of water is three times the daphnia chronic LOEL
following one Esteem® application at the lowest labeled pome fruit rate. As
described previously, the fastest degradation pathway for pyriproxyfen in water
is via photolysis with a half-life of approximately four days. Even under
optimum photolytic conditions in the one foot depth model pond the pyriproxyfen
concentration might remain above effective concentrations for 8 to 12 days. In
deeper waters where degradation will occur by other slower degradation pathways
it may persist far longer.
The ecological effects review concluded that use of Esteem® on
an agricultural scale will adversely impact aquatic invertebrate populations
in waters near use sites and may produce indirect trophic effects on other
aquatic species. In order to more effectively assess the impacts likely
to be caused by the labeled use of Esteem®, Valent was granted the opportunity
to submit any additional information that addressed the following areas:
Pyriproxyfen field runoff studies.
Chronic toxicity data for additional aquatic invertebrate taxa.
Studies defining the length of exposure necessary to result in invertebrate
Aquatic field dissipation studies.
Aquatic mesocosm or pond studies.
By mutual agreement, the established registration decision date was
waived to allow Valent to provide additional data and information which could
affect the Department's current understanding of the impact of pyriproxyfen on
aquatic organisms. The data package, received on September 14, 2000, was
forwarded to the Department's Division of Fish, Wildlife & Marine Resources
The following information prompted the DFW&MR to refine their
initial risk assessment for Esteem®:
Researchers at a California mosquito control research lab made
pyriproxyfen applications directly to the surface of rice plots. The
pyriproxyfen water column concentrations decreased by an average of
roughly 11 fold per day before dropping below their method detection
limit of 50 ng/L. In low application rate plots no measurable pyriproxyfen
was present past day 1. In high rate plots none was detected after day 2.
Dip, drag net, and trap samples yielded sufficient numbers in 14 of 23
invertebrate taxa to analyze statistically for treatment effects. Four groups
were affected. Approximately 13 percent of newly emerged Odonate adults
captured 4-10 days post application were deformed. Daphnoid cladocerans and
ostracods experienced slightly depressed reproduction. Fourth-instar
chironomids collected 5 hours after the second application and reared in
the lab all died during the pupal-adult edysis. Chironomid larvae collected
from control plots emerged normally. While the number of replicates for each
treatment level is low, the mean number of chironomids drag netted in both
the low and high dose plots recovered to levels above control means within 11
days after dosing, and remained higher through the end of the study. Additional
sources from the literature and 2000 national Society of Environmental Toxicology
and Chemistry (SETAC) conference presentations serve to characterize
pyriproxyfen's effects on different species of invertebrates and at different
The Department's initial ecological effects risk
assessment determined that use of Esteem®, as labeled, will adversely impact
aquatic invertebrate populations in waters near use sites and may produce
indirect trophic effects on other aquatic species. A combination of information
submitted by Valent, a literature search, and recently completed work presented
at the SETAC meeting has allowed for refinement of the initial risk assessment
and mitigates concerns for major aquatic impacts. When used as labeled, Esteem®
0.86 EC Insect Growth Regulator should not cause unreasonable adverse effects to
humans or the environment.
The Department hereby accepts Esteem® 0.86 EC Insect Growth Regulator
(EPA Reg. No. 59639-95) for registration in New York State. Enclosed for your
files are the Certificate of Pesticide Registration and New York State stamped
-'ACCEPTED' labeling (Form 1283-D).
Please note that a proposal by Valent or any other registrant to
register a product containing pyriproxyfen, whose labeled uses are likely to
increase the potential for significant impact to humans, property or the
environment, would constitute a major change in labeled (MCL) use pattern.
Such an application must be accompanied by a new application fee and meet the
requirements listed in Appendix 1.B. of "New York State Pesticide Product
Registration Procedures" (August 1996).
Please contact Frank Hegener, Chief of our Pesticide Product
Registration Section, at (518) 457-7446, if you have any questions.
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 PMEP