Download (MCL) for DuPont Matrix FNV Herbicide

New York State Department of Environmental Conservation
Division of Solid and Hazardous Materials
Bureau of Pesticides Management
Pesticide Product Registration Section
625 Broadway, Albany, New York 12233-7257
Phone: (518) 402-8788 • Fax: (518) 402-9024
Website: www.dec.ny.gov/chemical/298.html
E-mail: [email protected]
Alexander B. Grannis
Commissioner
May 15, 2009
DELIVERY CONFIRMATION (Co. No. 352)
Mr. Tim McPherson
DuPont Crop Protection
PO Box 30
Newark, DE 19714
Dear Mr. McPherson:
Re:
Registration of a Major Change in Labeling for DuPont Matrix FNV Herbicide (EPA
Reg. No. 352-671) Containing the Active Ingredient Rimsulfuron (Active Ingredient
Code 129009)
The New York State Department of Environmental Conservation (Department) has evaluated your
application and supplemental materials received to date in support of the registration of the above-mentioned
pesticide product in New York State.
Rimsulfuron was initially registered by the Department on August 15, 1997 for use on potatoes and
field corn. As a condition of registration, aerial application was prohibited in New York State. The major
change in labeling application for DuPont Matrix FNV Herbicide proposes to add citrus fruit, stone fruit, tree
nuts, pome fruit, and grapes as labeled use sites in New York State. Subsequent to the original submission,
DuPont Crop Protection (DuPont) requested that the Department include non-crop uses such as roadsides,
industrial plant sites and utility substations as part of the pending review. DuPont Matrix FNV Herbicide
contains 25.0 % rimsulfuron as a dry flowable formulation. It is labeled for broadcast and banded application.
Aerial application of the subject product is prohibited. The maximum labeled use rates are the same per
application and per year (0.0625 pounds of active ingredient per acre).
The application was determined to be complete for purposes of technical review on July 29, 2008.
Pursuant to the review time frames set forth in Environmental Conservation Law §33-0704, a decision date of
December 26, 2008 was established. On December 23, 2008, Department staff indicated by email to DuPont
Crop Protection that the Department would not be supporting registration at such time due to concerns
regarding data deficiencies with regard to environmental fate characteristics of rimsulfuron and its degradates.
As a result, DuPont requested, and was granted, a waiver of the legislatively mandated decision. A formal
letter detailing the data deficiencies was sent to DuPont on February 2, 2009. On March 17, 2009, the
Department received DuPont’s response to the concerns expressed in the letter. This response included
additional information regarding environmental fate not previously submitted to the Department. The
additional information sufficiently mitigated the Department’s concerns regarding the additional proposed uses
on agricultural sites. However, the Department continues to have concerns regarding the proposed use on noncrop use sites including roadsides, highway medians, industrial plant sites, and utility substations. The
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following technical reviews were performed to evaluate the risk of the additional uses of rimsulfuron.
Human Health Risk Assessment:
New York State Department of Health (NYSDOH) staff previously reviewed rimsulfuron and the
formulated product DuPont Matrix FNV Herbicide for the registration of Matrix, Basis, and Basis Gold
Herbicides; DuPont Matrix FNV Herbicide is identical in formulation to the Matrix Herbicide product.
Neither rimsulfuron nor the formulated product was very toxic in acute oral, dermal or inhalation
exposure studies in laboratory animals. In addition, neither was a skin sensitizer nor very irritating to the
skin and eyes nor skin. Rimsulfuron caused some toxicity in subchronic and chronic animal feeding
studies, including liver, kidney, and testicular toxicity. However, this chemical did not cause any
developmental toxicity in offspring when administered to pregnant rats and rabbits during organogenesis.
In a multi-generation reproductive toxicity study, reproductive effects did not occur, but decreased body
weight and body weight gain in the F1 generation was reported. Rimsulfuron did not cause oncogenic
effects in rat or mouse chronic feeding studies and was negative in a number of genotoxicity studies.
Based on these studies, the U.S. Environmental Protection Agency (U.S. EPA) classified rimsulfuron as
“not likely to be a human carcinogen.” A current search of the toxicological literature did not find any
significant new information on the toxicity of rimsulfuron.
The U.S. EPA established tolerances for rimsulfuron residues in or on a number of crops (Federal
Register 72 (No. 147): 41,909–41,913; August 1, 2007). The U.S. EPA derived a chronic population
adjusted dose (cPAD) for rimsulfuron of 0.818 milligrams per kilogram body weight per day (mg/kg/day)
from the no-observed-effect-level (NOEL) of 81.8 mg/kg/day in a one year dog study (increased absolute
liver and kidney weights and testicular toxicity) and an uncertainty factor of 100. The U.S. EPA
estimated that the chronic dietary exposure from food and drinking water to rimsulfuron residues would
be less than 1 percent of the cPAD for the general population and all population subgroups. This chronic
exposure analysis is based on the conservative assumptions that 100 percent of the crops are treated and
that these treated crops contain tolerance level residues.
The U.S. EPA did not conduct an occupational risk assessment for exposure to rimsulfuron from
DuPont Matrix FNV Herbicide because no dermal or inhalation toxicological endpoints were identified in
the toxicity database for any exposure time period. No direct residential exposures are anticipated to occur
from the labeled use of DuPont Matrix FNV Herbicide.
There are no chemical specific federal or New York State drinking water/groundwater standards
for rimsulfuron. Based on its chemical structure, this chemical falls under the 50 microgram per liter
(µg/L) New York State drinking water standard for “unspecified organic contaminants” (10 NYCRR Part
5, Public Water Systems).
The available information on rimsulfuron and the formulated product DuPont Matrix FNV
Herbicide indicates that they are not very acutely toxic in laboratory animal studies, nor were they
irritating or sensitizers. While rimsulfuron caused some adverse effects in chronic animal feeding studies,
it did not cause oncogenic, teratogenic or reproductive effects. The expected direct exposure from the
labeled use of the formulated product is rather low and should not pose a significant risk to the general
public or to workers. Given the above, NYSDOH does not object to the registration of DuPont Matrix
FNV Herbicide in the State. However, as NYSDOH staff noted in our previous review, rimsulfuron may
pose a risk of groundwater/drinking water contamination and the Bureau of Pesticides Management
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should consider whether mitigative measures (e.g., prohibiting its use in vulnerable areas of the State) are
necessary before making a final decision on registration of this product in New York State.
Ecological Effects Risk Assessment:
Chemical Description:
Matrix FNV Herbicide is a sulfonylurea herbicide with the active ingredient rimsulfuron that was
originally registered for use on corn and potatoes. The Bureau of Habitat completed the original review
of rimsulfuron in June 1997.
The active ingredient rimsulfuron is applied at a single and maximum application rate of 0.0625
lbs AI/year (28.4 g/year). This is twice the maximum seasonal application of 0.031 lbs AI/acre previously
reviewed. Matrix FNV is applied as a single, broadcast, pre-emergence application to the bare ground of
orchard floors where it permeates the soil and is absorbed by growing target broadleaf weeds and grasses.
It can also be applied early post-emergence if the target weeds are small and actively growing. Instead of
broadcast applications, Matrix FNV can also be applied directly around the base of trees in band
applications. In this manner, Matrix can be applied twice annually, but the maximum application rate
cannot exceed 0.0625 lbs rimsulfuron per acre per year.
Rimsulfuron is highly soluble in water, and has a very low n-octanol water partition coefficient
(KOW), indicating that it is likely to be very mobile in soil and not bind strongly to organic carbon in the
soil when applied, and is not likely to bioaccumulate in fish or other aquatic organisms. However, the
disassociation constant pKa of 4.0 suggests that it would be anionic in soils with a pH of over 4.0, and
bind weakly to soil particles, most of which are negatively charged.
Toxicity:
The rimsulfuron mode of action is to inhibit acetolactate synthase (also known as
acetohydroxyacid synthase, AHAS), a key enzyme in biosynthesis of certain amino acids in plants. As
this enzyme occurs in plants, rimsulfuron has little toxic impact on mammals, birds, fish, or aquatic
invertebrates. Non-target plants, including aquatic plants potentially exposed through runoff or spray
drift, are highly susceptible to rimsulfuron toxicity. The most sensitive aquatic plant tested was duckweed
(Lemna gibba), with a 14 day EC50 of 0.0116 mg/L and a corresponding no effects concentration
(NOEC) of 0.0009 mg/L.
Exposure:
Rimsulfuron breaks down rapidly when applied to soil. Four terrestrial field dissipation studies
showed half-lives to range from T1/2 = 5 - 18 days with a geometric mean of 9 days. The primary route of
degradation appears to be aerobic metabolism. In water, the primary route of degradation appears to be
hydrolysis, with the rate being somewhat dependent upon pH:
T1/2 = 4.5 to 4.7 days @ 25°C,
pH 5
T1/2 = 7.1 to 7.3 days @ 25°C,
pH 7
T1/2 = 4.2 to 10.9 hours @ 25°C, pH 9
One of the major degradation products of rimsulfuron is IN-70942 (N-((3-Ethylsulfonyl)-2pyridinyl)-4,6-dimethoxy-2-pyrimidineamine). This degradation product is persistent, showing no decline
in a one year aerobic soil metabolism study. In a study of rimsulfuron degradation in mixed
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sediment/water systems, IN-70942 reached a maximum concentration of 98% then declined to 65% by the
end of the six month study. Although this was an aerobic metabolism study, it is possible that the
biodegradation of IN-70942 was enhanced by photolysis. There is no indication that IN-70942 exhibits
any toxicological properties, but the U.S. EPA has required aquatic fish early life stage (ELS) and
invertebrate life cycle studies of this metabolite.
Risk Assessment Modeling:
Rimsulfuron clearly poses no risks to birds, mammals, fish, or aquatic invertebrates. The mode of
toxicity is applicable only to plant physiology, the residue values are all well below toxicity thresholds,
and rimsulfuron is generally applied to bare ground to prevent weeds (pre-emergence), and not to foliage
that birds, mammals, and other varieties of organisms would feed upon.
PONDTOX modeling was conducted to evaluate the risks to aquatic plants via runoff. Because of
the low KOW of rimsulfuron, the model selected runoff rates of 1%, 3%, and 5% to evaluate. No
allowance was made for foliar application, as rimsulfuron is applied to bare ground. At the highest runoff
rate evaluated, 5%, the risk quotient (i.e., concentration ÷ risk threshold ) for the no observed effects
concentration (NOEC) was exceeded. RQ Values were 69.7 for a one foot deep pond, 33.3 for a 3 foot
deep pond, and 18.7 for a 3 foot deep pond. At the lowest runoff rate of 1%, the RQs diminish to 13.9,
6.7, and 3.7 in one, three, and six foot deep ponds, respectively. EC50s were not exceeded at either
runoff rate. The next most sensitive representative aquatic plant green algae (Selenastrum capricornutum)
was not affected by rimsulfuron.
Risk Analysis:
Risk assessment modeling of rimsulfuron suggests that this active has the potential to be harmful
to aquatic macrophytes. However, the macrophyte test was a 14 day exposure. At neutral pH,
rimsulfuron degrades via hydrolysis with a half life of about 7 days. At higher or lower pH values,
hydrolysis is even faster. The effect of rimsulfuron evaluated in the aquatic macrophyte test was growth,
not survival. Thus, it is possible that some sensitive aquatic plants might experience a short period of
reduction in growth from a sizeable runoff event, but such an impact is not likely to cause significant
harm to aquatic macrophytes.
Other Ecotoxicology Issues:
The Bureau of Habitat is becoming increasingly concerned about the application of persistent
materials and the evolution of persistent degradates to the landscape, even if they do not appear to be
toxic. The long term effect of these extremely persistent molecules to ecological resources is unknown.
Rimsulfuron degrades into one such persistent degradate, IN-70942. The U.S. EPA has required
additional toxicity testing for this material. The Bureau of Habitat would like to receive copies of these
studies as soon as they are submitted to the U.S. EPA so as to be aware of any potential problems that
could result from the use of rimsulfuron.
Mr. Tim McPherson
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Environmental Fate Risk Assessment:
Solubility:
The solubility of rimsulfuron is 7.3 ppm.
Hydrolysis:
MRID 41356333 In a study that the U.S. EPA found acceptable, the average calculated half-lives
in pH 5, 7, and 9 buffer solutions were 4.6 days, 7.2 days and 7.6 hours, respectively.
Aqueous Photolysis:
MRID 41931608 In a study that the U.S. EPA found acceptable, the half-lives in pH 5, 7, and 9
buffer solutions for the pyridine label were 1.1 days, 12.4 days and 12 hours, respectively. In the
pyrimidine labeled ring half-lives in pH 5, 7, and 9 buffer solutions for the pyridine label were 1.1 days,
11.0 days and 10.2 hours, respectively.
Soil Photolysis:
MRID 41931609 In a study that the U.S. EPA found acceptable, in a sandy loam soil (pH 6.7,
1.1% OM), the half-lives ranged from 11-12 days. No major transformation products were found.
Aerobic Aquatic Metabolism:
MRID 41356334 In a study that the U.S. EPA found acceptable, in a sandy loam soil (pH 6.7,
1.1% OM), the observed and calculated half-lives were 10 and 21.3 days, respectively. Major
transformation product IN-70941 was found at 41.3% and IN-E9260 was found at 15.6% of applied.
Anaerobic Soil Metabolism:
MRID 41356335 In a study that the U.S. EPA found supplemental, the calculated half-lives were
18.1 and 17.9 days in the pyridine and pyrimidine labels, respectively. Major transformation product IN70941 was found at 23.1% and 33.9% in pyridine and pyrimidine labels, respectively.
Anaerobic Aquatic Metabolism:
MRID 43288502 In a study that the U.S. EPA found ancillary, half-lives were less than 2 days and
1 day, respectively, in the non-sterile and sterile samples.
Aerobic Soil Metabolism:
According to the March 14, 2007 U.S. EPA Environmental Fate and Effects Division (EFED)
Section 3 Registration memo, the half-lives range from 19-21 days for one soil, and 5-18 days in another
study under field conditions. However, the U.S. EPA requested that the registrant submit another aerobic
metabolism study for this active ingredient. DuPont indicated that they will be submitting this study to
the U.S. EPA, and indicated that the study had half-life values ranging from 5-40 days.
DuPont referenced another study entitled “Aerobic Soil metabolism of [Pyridine-2-14C]DPXE9636 and [Pyrimidine-2-14C]DPX-E9636” dated September 13, 1989 (Naidu, M. V.). That study
indicated that the half-life of the parent is 10 days, and that IN-70942 was found at a maximum of 20%,
IN-70941 was found at a maximum of 54%, and E9260 was found at a maximum of 16%.
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Aerobic Soil Metabolism Degradates:
Soil Type
Sandy loam
Sandy loam
Clay soil
Sandy loam
Loamy sand
Sandy loam
Silt loam
%OM
2.0
2.7
1.9
1.4
0.5
4.3
1.8
pH
5.4
7.9
5.8
8.0
5.5
6.7
6.1
T½
IN-J0290
T½
IN-70941
359
38
615
T½
IN-70942
214
101
116
T½
E9623
744
252
696
19
18
3
13
Adsorption/Desorption:
MRID 41356336. In a study which DuPont indicated that the U.S. EPA accepted (via memo dated May
19, 1992 from A. Abramovitch to R. Taylor/V. Walters):
Freundlich adsorption
Soil Type
%OM
pH
Kd
Sandy loam
2.1
6.5
0.23
Sandy loam
1.1
6.3
0.32
Clay loam
4.3
7.7
1.36
Silt loam
4.3
4.3
1.57
According to the March 14, 2007 EFED Section 3 Registration memo, the Kocs range from
19-74.
Adsorption/Desorption Degradates:
Soil Type
Sandy loam
Sandy loam
Clay soil
Sandy loam
Loamy sand
Loamy sand
Silt loam
Sandy loam
Silt loam
%OM
2.0
2.7
1.9
0.9
3.6
0.8
5.3
1.2
2.0
pH
5.4
7.9
5.8
6.3
6.4
5.2
5.5
7.8
5.8
Koc INJ0290
Koc
IN-70941
39
116
34
54
Koc
IN-70942
223
195
145
214
Koc
E9623
23
86
16
34
96
952
6849
245
391
Column Leaching:
MRID 41356337 In a study that provides additional information:
Soil Type
Mobility
%OM
Sandy loam
Mobile
2.1
Sandy loam
Very mobile
1.1
Clay loam
Medium mobility
4.3
Silt loam
Medium mobility
4.3
pH
6.5
6.3
7.7
4.3
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Terestrial Field Dissipation:
MRID 41931606. No review conclusions could be made from a study that the U.S. EPA
determined had multiple deficiencies. DuPont provided a copy of their response to the U.S. EPA.
MRID 41931610. From a study that the U.S. EPA found unacceptable, the registrant indicated
that half-lives were 5.4 days and 5.9 days in a silt loam soil (pH 6.0, 1.4% OM) in the pyridine and
pyrimidine labels, respectively. In DuPont’s response to the U.S. EPA, they indicated that the half-life in
a clay loam soil (pH 7.0, %OM 1.3) was 7.9-9.6 days, in a silty clay loam soil (pH 7.7, %OM 1.2) was
8.0-8.2 days, in a clay soil soil (pH 17.4, %OM 4.5) was 5.9-17.7 days, and in a sandy loam soil (pH 6.7,
%OM 1.1) was 5.4-5.9 days.
Lysimeter Study:
According to DuPont, the U.S. EPA did not review the lysimeter study submitted in 1997. The
soil was a silt loam (pH 5.9-6.7, 0.7-1.8% OM). The study indicates that rimsulfuron was not observed in
the leachate from any lysimeter at any time during the study. Transformation products were not part of
the analyses.
Computer Modeling:
Name
Rimsulfuron
Rimsulfuron
Rimsulfuron
Rimsulfuron
IN-70941
IN-70942
E9260
Koc
19
19
19
74
39
223
23
T½
5
10
40
10
359
214
744
Application rate
0.0625
0.0625
0.0625
0.0625
0.0338 (54%)
0.0125 (20%)
0.01 (16%)
Leaching
Peaks to 0.38
Peaks to 1.1
Peaks to 0.21
Peaks to 0.006
Cyclic peaks 3 to 7 ppb
Accumulation up to 0.015
Cyclic peaks 2.5 to ~3.5
Environmental Fate Summary:
This active ingredient is currently registered for use on potatoes, tomatoes and field corn. Given
the large acreage of field corn in New York State, the use of this product as a selective broadleaf herbicide
on pome and stone fruit, grapes and tree nuts will probably not have a significant negative impact on
groundwater. However, the additional non-crop uses are a concern; the model projected that degradate
IN-70941 will leach consistently into groundwater and the non-crop sites tend to have more bare ground
than the pome and stone fruit, grapes and tree nut sites. Therefore, Engineering Geology staff have no
objection from a groundwater perspective to the addition of pome and stone fruit, grapes and tree
nuts, but object to the addition of non-crop sites.
Summary:
The environmental fate technical review indicated a concern regarding the leaching characteristics
of the major degradate IN-70941. As such, the Department objected to the non-crop application sites due
to the fact that these sites tend to have lower interception rates than agricultural sites. The Department’s
position regarding the use of Matrix FNV Herbicide on non-crop sites was communicated to DuPont on
May 8, 2009. To facilitate registration of the agricultural uses, DuPont requested that the application for
non-crop use be withdrawn. Therefore, the Department has registered DuPont Matrix FNV
Herbicide (EPA Reg. No. 352-671) for the additional use sites of citrus fruit, stone fruit, pome fruit,
Mr. Tim McPherson
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grape, and tree nuts. In addition, DuPont’s written request to withdraw the application for
non-crop uses of Matrix FNV Herbicide has been granted.
Any future application for non-crop uses of rimsulfuron, or any other application containing
rimsulfuron that is likely to increase the potential for significant impact on humans, non-target organisms,
or the environment, would constitute a major change in labeled use pattern. Such an application must be
accompanied by a new fee and meet the application requirements specified in 6 NYCRR Part 326.17.
Please contact Shaun Peterson, of my staff, at (518) 402-8768 if you have any questions regarding
this letter.
Sincerely,
Maureen P. Serafini
Maureen P. Serafini
Director
Bureau of Pesticides Management