UNITED STATES ENVIRONMENTAL PROTECTION AGENCY

WASHINGTON, D.C. 20460

OFFICE OF PREVENTION, PESTICIDES AND

TOXIC SUBSTANCES

 							   

PC Code No.: 110003

DP Barcode:  357854

Date: June 30, 2009

	

MEMORANDUM 

SUBJECT:	Drinking Water Assessment for the Use of Spinosad on Dates and
Pomegranate under the IR4 Petition

TO:	Laura Nollen 

Registration Division

FROM:	Larry Liu, Environmental Scientist

Environmental Risk Branch 5

Environmental Fate and Effects Division 

THROUGH:	Mah T. Shamim, Chief

Environmental Risk Branch 5

Environmental Fate and Effects Division 

The petitioner, IR4, requested the use of spinosad on dates and
pomegranate.  Table 1 lists the maximum single application rate, number
of application, seasonal maximum application and application intervals
for these crops.        

Table 1.  Uses and application rates for spinosad

Label/Crop	Single

Application Rate

(lb a.i./A)	Maximum  Number of

Applications per Season	Minimum. Application Interval (days)	Maximum
Application rate per Season

(lb a.i./A/Season)

Entrust

Pomegranate	0.06-0.12

	3	10-14

	0.4



Entrust

Dates  	0.12	3 	unspecified	0.4



Since the maximum single application rate and the maximum seasonal rate
of spinosad in this IR4 petition are lower than those for the other crop
which was evaluated previously, EFED is recommending to use the
Estimated Environmental Concentrations (EEC) for turf that were
developed proviously.  For spinosad, the surface water acute (peak)
value is 34.5 ppb and the chronic (average 56-day) value is 10.5 ppb
based on applications representative of turf. The groundwater screening
concentration is 1.1 ppb based on applications representative of turf.
These values represent upper-bound estimates of the concentrations that
might be found in surface water and groundwater due to the use of
spinosad on the representative crop. The single application rate used in
the turf assessment was 0.4 pounds per acre with four applications at a
seven day spacing. See Appendix A attached to this memo.

Appendix A

UNITED STATES ENVIRONMENTAL PROTECTION AGENCY

	WASHINGTON, D.C.  20460

			

		

OFFICE OF   

PREVENTION, PESTICIDES

AND TOXIC SUBSTANCES 

									

	

DP Barcode: 331271

									PC code: 110003

									July 28, 2006

MEMORANDUM                                                              
                    

											

SUBJECT:	Human Health Water Assessment for Spinosad (Naturalyte GF-1592
and GF-1593)  Mosquito Larvicide Use

TO:	George Larocca, Team Leader

Marion Johnson, Branch Chief 

Insecticide Branch

		Registration Division (7505P)

		Felicia Fort, Branch Chief 

		Tom Bloem, Toxicologist

		Health Effects Division (7509P)

FROM:	Ronald Parker, Senior Environmental Engineer

	Larry Liu, Chemist

		Environmental Risk Branch 5

		Environmental Fate and Effects Division (7507P)

THROUGH:	Mah T. Shamim, Chief

Environmental Risk Branch 5

		Environmental Fate and Effects Division (7507P)

Executive Summary. This is a revised human health exposure assessment
for drinking water and other water-related routes of exposure for a new
use of Spinosad as a mosquito larvicide. Since the use is for direct
application to water, OPP will not only re-evaluate drinking water for
human consumption but also evaluate potential human exposure via the
consumption of fish exposed to treated water, the use of treated water
for irrigation purposes, and the consumption of treated water by
livestock. Recalculation of the drinking water exposure concentrations
and re-estimation of concentrations for the other routes of exposure are
estimated by different methods as described below.

OPP has also re-reviewed environmental fate studies submitted previously
using a total residue method and developed what is believed to be a more
accurate interpretation of the results. This new interpretation of the
environmental fate data and new modeling results indicate that spinosad
residues can be expected to dissipate very slowly in the environment.
This is due to the fact that the main ring structures in the identified
transformation products remain substantially unchanged from that of the
parent compound. In the new modeling, EFED assumed spinosad and its
transformation products are stable under the aqueous photolysis,
hydrolysis, aerobic soil metabolism, and anaerobic aquatic metabolism
conditions. 

The range of application sites listed on the label indicates that the
larvicide use is not likely to cause exposure through drinking water
that would exceed other crops already assessed. The drinking water
portion of this assessment is therefore based on application to turf,
adjusting it for the changes in interpretation of the environmental fate
data. The turf use previously produced the highest (or equal to the
highest) concentration of all crops assessed. For spinosad, the surface
water acute (peak) value is 34.5 ppb and the chronic (average annual)
value is 10.5 ppb based on applications representative of turf. The
groundwater screening concentration is 1.1 ppb based on applications
representative of turf. These values represent upper-bound estimates of
the concentrations that might be found in surface water and groundwater
due to the use of spinosad on the representative crop. The application
rate used in the turf assessment was 0.4 pounds per acre with four
applications at seven-day spacing. 

For the other water uses, the surface water acute (peak) value is 489
ppb, the chronic non-cancer value is 472 ppb and the chronic cancer
value is 259 ppb based on applications to a ten-centimeter deep static,
dormant rice field. These exposure concentrations were calculated using
the EPA/ORD linked PRZM3.12 and EXAMS 2.98.04 models assuming 20
applications (every seven days) The assessment is conservative in that
it assumes no degradation in the water, uses the maximum number of
applications and the maximum application rate (0.1 lbs/ac) permitted by
the label, and does not consider either flow through the field or
dilution from rainfall. Exposure results are summarized in Table 1.

Table 1. Summary of EDWC’s and EECs for Spinosad Mosquito Larvicide
Use

EDWCs and EECs for Spinosad Mosquito Larvicide Use



	

Application 

Rate 

(lb a.i./ac)	

Number of Applications (Interval)	1/10 Year

Acute 

Conc

(ppb)	1/10 Year

Annual

Conc

(ppb)	Average 

Annual

Conc

(ppb)

Surface Water Drinking Water Turf-GENEEC2	0.4	4 (7days)	34.5	10.5	10.5

Groundwater Drinking Water Turf-SCIGROW	0.4	4	1.1	1.1	1.1

Other Water (Larvicide)

(Consumption of fish exposed to treated water; use of treated water for
irrigation; and consumption of treated water by livestock)	0.033-0.1
20(7days)	489	472	259



Previous drinking water assessments are attached as Appendices C and D
below.

Measures of Aquatic Exposure 

Drinking Water and Other Human Health Aquatic Exposure Modeling 

Since this larvicide use calls for direct application to water, OPP will
not only re-evaluate drinking water for human consumption but also
evaluate potential human exposure via the consumption of fish exposed to
treated water, the use of treated water for irrigation purposes, and the
consumption of treated water by livestock. Recalculation of the drinking
water exposure concentrations and re-estimation of concentrations for
the other routes of exposure are estimated by different methods as
follows. 

EDWCs for this drinking water assessment are based on an updating of the
FIRST and SCIGROW computer simulation modeling of spinosad application
to turf which was completed for previous drinking water assessments. See
Appendices C and D attached to this assessment. The assessment based on
turf is used again since the larvicide direct application to static
water is not applicable to drinking water sources. See descriptions of
the FIRST and SCIGROW models in Appendix A.

Potential human exposure via the consumption of fish exposed to treated
water, the use of treated water for irrigation purposes, and the
consumption of treated water by livestock was estimated using a
PRZM/EXAMS dormant rice paddy scenario assuming direct application to 10
centimeters of standing water. Both acute and chronic column water
concentrations were estimated for these three routes of exposure. The
acute exposure concentration value selected is the 1-in-10 year peak EEC
value from the 30-year assessment. The chronic values are the 1-in-10
year annual value for the chronic non-cancer endpoint and the long-term
average value for the chronic cancer value respectively. The longer term
values are used to determine the implication of the new interpretation
of the degradation data. See descriptions of the PRZM and EXAMS models
in Appendix B.

Environmental Fate of Spinosad

Summary

Environmental fate data and modeling results indicate that spinosad
residues can be expected to dissipate very slowly in the environment. A
total residue method was used in estimating the water concentrations in
the eco risk assessment. This is because the main ring structures in the
transformation products which were tentatively identified or
characterized in the fate studies remain unchanged (almost the same as
the parent compound).  In the modeling, EFED assumed spinosad and its
transformation products are stable under the aqueous photolysis, aerobic
soil metabolism, and anaerobic aquatic metabolism conditions. In
conclusion, spinosad residues are expected to be very stable in the
aquatic environment. Below are the general fate properties for spinosad
Factor A and Factor D. 

Spinosad Factors A and D converted in an aerobic soil metabolism study
to transformation products very similar to the parent with half-lives of
approximately 9-17 days. Similar transformation products are formed
under photolytic conditions with a half-life of less than one day at pH
7 in sterile water and about 10 days in soil. The photodegradation
half-life is assumed to be stable because the study was not conducted
long enough to provide formation and decline information on the
transformation productsSpinosad Factor A has a low to moderate water
solubility and a low to slight mobility in sandy soils, and is immobile
in silt loam and clay loam soils. Although no mobility data are
available for Spinosad Factor D, it is 180x less soluble than Factor A
and therefore would be expected to be less likely to leach in the soil. 
In terrestrial field dissipation studies with Spinosad Factor A on
bareground plots, the half-life was <1 day, no leaching was observed,
and 3.1% of the applied was recovered in runoff.

Spinosad has a high affinity for sediment and moves rapidly from the
water to the sediment phases where it is highly persistent.  In
anaerobic aquatic metabolism studies, spinosad had a half-life of
161-250 days.  In an aquatic microcosm dissipation outdoor study,
spinosad residues in the sediment peaked at 8 days and had an observed
half-life of >>25 days. Spinosad has a relatively low bio-concentration
factor (BCF’s of the parent 7.5X, 28.8X, and 21.1X for muscle,
viscera, and whole fish, respectively), and a relatively rapid rate of
depuration (half-life of about one day).  These factors generally would
prevent substantial bio-concentration of the material in the food web. 

Degradation and Metabolism

Spinosad Factors A and D were relatively stable in pH 5, 7, and 9
sterile aqueous buffer solutions that were incubated in the dark at
25°C.  

In sterile buffered (pH 7) solutions, Spinosad Factors A and D
phototransformed with half-lives of 0.8-0.9 days.  The β-isomers of the
13,14-dihydro of the pseudoaglycone of Factor A and of Factor D were
detected at a maximum of 20.2-24.9% of the applied at 48 hours (study
termination).  In alkaline (pH 9.2) pond water, Factors A and D
phototransformed rapidly with half-lives of 0.54-0.55 days. On soil,
Factors A and D had photodegradation half-life of 8.68-9.71 days. The
only transformation present at >5 % of the applied was Factor B
(N–demethylated Factor A), which reached 14.8% of the applied at 18
days post-treatment. These studies were not long enough to determined
the fate of the transformation products

In aerobic silt loam soil, Spinosad Factors A and D converted to
transformation products with initial half-lives of 17.3 and 14.5 days,
respectively. Factor A converted to transformation products with a
half-life of 9.4 days in sandy loam soil incubated under similar
conditions. Approximately 75-90% of the applied spinosad converted to
transformation products by 28 days. The major degradate of Factor A was
Factor B (N-demethylated Factor A), which accumulated to a maximum
51-61% of the applied at 14-28 days post-treatment, then decreased to
12.27-21.72% at 9 months and 2.77-5.96% at 1 year.  The major
transformation product of Factor D was N-demethylated Factor D (the
Factor D analogue of Factor B), which accumulated to a maximum 68% of
the applied at 28 days post-treatment and approximately 50% at 6 months.
Several minor transformation products, each <10% of the applied, were
isolated but not conclusively identified.

In anaerobic flooded clay sediment, Factors A and D converted to
transformation products with half-lives of 161 and 250 days. By 7 days
post-treatment, >90% of the applied radioactivity was associated with
the sediment fraction.  Three major transformation products of Factor A,
each present at a maximum 8-12% of the applied, were identified: Factor
B (N-demethylated Factor A), reversepseudoaglycone (806643), and
ketoreversepseudoaglycone (814426).  One major transformation products
of Factor D, N-demethylated Factor D (the Factor D analogue of Factor
B), was present at a maximum 6.5% of the applied. 

The fate of spinosad under the aerobic aquatic environment is unknown. 
This is because the submitted study (MRID 46642701) is classified as
unacceptable and is scientifically invalid because significant
variability in the results between sampling intervals and between
systems at the same sampling interval prevents any confident
interpretation of the study results.  Because of poor results in the
initial experiment, the data presented in this MRID are a compilation of
analyses of selected test systems from four separate experimental sets
for each test substance and system.  In addition, transformation
products comprising (10% of the applied may have been present and not
identified.

Soil sorption and mobility

The mobility of Factor A, at nominal concentrations of 0.04-5.0 µg/mL,
was investigated in sand, loamy sand, sandy loam, silt loam, and clay
loam soils.  Koc values were 2,862, 831, 4,237, 134,583, and 21,938,
respectively.  Freundlich Kdes values for both desorption phases for the
sand, loamy sand, sandy loam, and silt loam soils were 8.4-9.2, 6.6-8.2,
27-30, 288-357 and 292-296, respectively; corresponding 1/n values
ranged from 0.826-0.921.  The reviewer-calculated coefficients of
determination (r2) for the relationships Kads vs. organic matter, Kads
vs. pH and Kads vs. clay content were 0.0647, 0.0498, and 0.8114,
respectively.

The mobility of Factor B, the major degradate of Factor A, was
investigated at 0.05-5.0 µg/mL in sand, loamy sand, sandy loam, and
silt loam soils.  Koc values were 2,138, 662, 2,881, and 74,583,
respectively.  Freundlich Kdes values for both desorption phases for the
sand, loamy sand, sandy loam, and silt loam soils were 6.3-6.5, 5.3-6.3,
19-20, and 171-179, respectively; corresponding 1/n values ranged from
0.775-0.880.  The reviewer-calculated coefficients of determination (r2)
for the relationships Kads vs. organic matter, Kads vs. pH and Kads vs.
clay content were 0.425, 0.235 and 0.957, respectively.

Factors A and D are not volatile; vapor pressures (25°C) are 2.0 to 3.0
x 10-11 kPa.  CO2 was the only volatile compound detected in metabolism
studies.

Field dissipation

Factor A, formulated as an emulsifiable concentrate, degraded with
half-lives of 0.5 days in bareground plots of silt loam soil in
Mississippi and 0.3 days in loam soil in California.  Approximately 2-3%
remained after 3-5 days.  No degradates were identified.  Spinosad
Factor A and its degradates were not detected below the 6-inch soil
depth.  Unextracted [14C]residues increased to a maximum of 34-58% by
38-40 days.  At the Mississippi site, total radioactivity in the runoff
accounted for 3.1% of the applied radioactivity. 

Pond water (pH 7.6, ca. surface area 2.2 m2, depth 47.5-50 cm) and clay
loam sediment (ca. depth 5.5-6 cm) maintained in outdoor tanks were
treated once with a broadcast-spray application of the suspension
concentrate at 100 g/ha to the water surface.  Spinosad (Factors A + D)
dissipated rapidly from the water with a calculated half-life of 1.5
days, and total spinosad residues dissipated from the water with a
calculated half-life of 4 days.  In the water, the degradates Factors B
and B of D were detected at maximums of 2.3 ppb (8 hours) and 3.6 ppb (0
hour), respectively, and were <0.5 ppb at 15 days.  In the sediment,
Factor A was detected at a maximum average 14.9 ppb at 4 days and was
14.3 ppb at 35 days.  Factor B was detected at a maximum average 11.1 at
15 days and was ≤9.4 ppb at 35 days.  Factors D was ≤4.2 ppb and B
of D was not detected (LOD 11.3 ppb) at any interval in the sediment.
Total spinosad residues in the water had an observed half-life of <1
days.  Total spinosad residues in the sediment reached a maximum
concentration at 8 days post-treatment and had decreased by
approximately 25% by 35 days. These field studies need to be
re-evaluated because the half-lives may reflect the transformation of
the parent to other transformation products similar to the parent. Also
the dissipation half-lives reflect the movement of the parent and
transformation products from one media to another and do not show
degradation of the product.

Accumulation

[14C]Factors A and D accumulated in rainbow trout held under laboratory
flow-through conditions for up to 28 days.  In the high concentration
experiments (19.0 ng/L for Factor A and 33.0 ng/L for Factor D), maximum
BCFs for Factor A were 28.8 mL/g (at Day 28) for the nonedible tissue,
7.5 mL/g (at Day 25) for the edible tissue, and 21.1 mL/g (at Day 7) for
the whole fish tissue; and for Factor D were 42 mL/g (at Day 11) for the
nonedible tissue, 20.5 mL/g (at Day 11) for the edible tissue, and 41.9
mL/g (at Day 7) for the whole fish tissue.  Registrant-calculated BCFs
for total [14C]residues were 103-152, 16-47, and 84-115 mL/g for the
nonedible, edible, and whole fish tissues, respectively. 

In fish exposed to Factor A, parent accounted for 68.34% of the HPLC
distribution in whole fish extracts on exposure day 1, and ≤29.74% at
later sampling intervals.  Spinosad Factor J was present at 125 ng/g in
day 25 nonedible extracts and day 28 whole fish extracts; all other
degradates were each <50 ng/g.  In fish exposed to Factor D, parent
accounted for 83.43% of the HPLC distribution in whole fish tissue on
exposure day 1, 48.80% on day 7, 42.19% on day 14, and 35.44% on day 28.
 In the whole fish tissues, 15-Pk4 and 20-Pk4 [N-monomethylated,
O-demethylated Spinosad Factor D] was a maximum of 134 ng/g; 15-Pk6 and
20-Pk6 [N-monomethylated, O-demethylated Spinosad Factor D]  was a
maximum of 230 ng/g; Spinosad Factor L was a maximum of 229 ng/g;
Spinosad Factor O was a maximum of 173 ng/g; and Spinosad Factor B of D
was a maximum of 544 ng/g.  All other metabolites were <50 ng/g.

Modeling Inputs 

This environmental fate data plus the proposed label application rates
and timings were used in calculating the inputs for the models. See:
Water Models; Guidance for Selecting Input Parameters

 (http://www.epa.gov/oppefed1/models/water/input_guidance2_28_02.htm)
for EFED policy on selection of modeling inputs. Spinosad inputs are
summarized in Table 2. 

Table 2.  Spinosad Environmental Fate Input Parameters for GENEEC2 and
PRZM/EXAMS Models

Parameter	Spinosad A Value	Source



PC Code	110003	N/A

Water Solubility 

(20 C, distilled water)	89.4 mg/L



	Molecular Weight	732 g/mole

	Hydrolysis Half-Life (pH 5,7,9)	Stable	MRID 43507301

Aerobic Soil Metabolism (days)	Stable 	MRID 43507305



Anaerobic Aquatic Metabolism (days)	Stable 	MRID 43507304



Aqueous Photolysis Half-Life (days)	Stable 	MRID 43507302



Soil Water Partition Coefficient (Lowest non-sand Koc)	4237

	MRID 43507306



Vapor Pressure (torr)	2.4e-10

	

Use Characterization (Proposed Larvacide Use)

Application Information

Application rates, numbers of applications and intervals between
applications are taken directly from the pesticide labels. Application
rates and timings are summarized in Table 3.

Table 3. Application Information

Crop	Label Rate (lbs/ac)	Input Rate (lbs a.i./ac)	Max App /

Year	Max (lbs a.i. / season)	MinFreq (Days)	Application Method

Mosquito Larvacide

(Typical)	0.018-0.033	0.033	20	0.66 	7	Aerial or ground

Mosquito Larvacide

(Maximum)	0.10 (when lower rate ineffective)	0.10	20	2.0	7	Aerial or
ground

Turf	0.4	0.4	4	1.6	7	Aerial or ground



GF-1592 and GF-1593 are Naturalyte insect products for control of
mosquito and midge larvae.  The product’s active ingredient is
biologically derived from the fermentation of a naturally occurring soil
organism. Both products may be applied by suitable ground or aerial
application equipment.

Aquatic Exposure Characterization

The magnitude of the concentration values in this assessment for routes
of exposure other than drinking water is related to the static
conditions of the assessment water body (dormant rice paddy) and the
assumption of no degradation of the toxic portion of the Spinosad
molecule. The assessment assumes that new chemical is applied every
year, but none is removed through degradation or advection. In applying
the chemical directly to a 10 centimeter flooded rice field, the
concentrations have a maximum of about 27 ppb the first year and then
increases by roughly 16-17 ppb each year for the whole 30 years of the
assessment period. This buildup leads to a concentration of 525 ppb the
final year.

The conservative assumptions in the assessment lead to very conservative
estimated concentration values. If other routes of dissipation such as
more rapid degradation than that measured in the laboratory, dilution by
rainfall, removal by overflow, or leaching through the bottom of the
paddy were to occur, concentration values would be reduced below these
modeled values. 

Appendix A. Revised FIRST and SCIGROW Output Files for Spinosad on Turf 

   RUN No.   1 FOR Spinosad         ON   Turf          * INPUT VALUES * 

   --------------------------------------------------------------------

    RATE (#/AC)   No.APPS &   SOIL  SOLUBIL  APPL TYPE  %CROPPED INCORP

     ONE(MULT)    INTERVAL    Koc   (PPM )   (%DRIFT)     AREA    (IN)

   --------------------------------------------------------------------

   .400(  1.600)   4   7    4237.0   89.4   GROUND( 6.4)  87.0    .0

   FIELD AND RESERVOIR HALFLIFE VALUES (DAYS) 

   --------------------------------------------------------------------

   METABOLIC  DAYS UNTIL  HYDROLYSIS   PHOTOLYSIS   METABOLIC  COMBINED

    (FIELD)  RAIN/RUNOFF  (RESERVOIR)  (RES.-EFF)   (RESER.)   (RESER.) 

   --------------------------------------------------------------------

       .00        2          N/A       .00-     .00      .00       .00

   UNTREATED WATER CONC (MICROGRAMS/LITER (PPB)) Ver 1.1.0 DEC 12, 2005

   --------------------------------------------------------------------

        PEAK DAY  (ACUTE)      ANNUAL AVERAGE (CHRONIC)      

          CONCENTRATION             CONCENTRATION            

   --------------------------------------------------------------------

             34.456                     10.500

                           

SCIGROW              

                VERSION 2.2: NOVEMBER 1, 2001                

   RUN No.   1 FOR Spinosad            ** INPUT VALUES **       

   --------------------------------------------------------  

    APP RATE   APPS/   TOTAL/     SOIL   AEROBIC SOIL METAB  

    (LBS/AC)   YEAR    SEASON     KOC     HALFLIFE (DAYS)    

   --------------------------------------------------------   

       .400      4     1.600     831.0      1000000.00

   GROUND-WATER SCREENING CONCENTRATION (IN UG/L - PPB)  

   --------------------------------------------------------  

                           1.122606

   --------------------------------------------------------   

 

Background Information on FIRST:

	FIRST is a new screening model designed to estimate the pesticide
concentrations found in water for use in drinking water assessments.  It
provides high-end values on the concentrations that might be found in a
small drinking water reservoir due to the use of pesticide.  Like
GENEEC, the model previously used for Tier I screening level, FIRST is a
single-event model (one run-off event), but can account for spray drift
from multiple applications.  FIRST uses a Drinking Water Reservoir
instead of a pond as the standard scenario.  The FIRST scenario includes
a 427 acres field immediately adjacent to a 13 acres reservoir,  9 feet
deep, with continuous flow (two turnovers per year).  The pond receives
a spray drift event from each application plus one runoff event.  The
runoff event moves a maximum of 8% of the applied pesticide into the
pond.  This amount can be reduced due to degradation on field and the
effect of binding to soil.  Spray drift is equal to 6.4% of the applied
concentration from the ground spray application and 16% for aerial
applications.

	FIRST also makes adjustments for the percent crop area. While FIRST
assumes that the entire watershed would not be treated, the use of a PCA
is still a screen because it represents the highest percentage of crop
cover of any large watershed in the US, and it assumes that the entire
crop is being treated.  Various other conservative assumptions of FIRST
include the use of a small drinking water reservoir surrounded by a
runoff-prone watershed, the use of the maximum use rate, no buffer zone,
and a single large rainfall.

Background Information on SCI-GROW:

	SCI-GROW provides a groundwater screening exposure value to be used in
determining the potential risk to human health from drinking water
contaminated with the pesticide.  Since the SCI-GROW concentrations are
likely to be approached in only a very small percentage of drinking
water sources, i.e., highly vulnerable aquifers, it is not appropriate
to use SCI-GROW for national or regional exposure estimates.  SCI-GROW
estimates likely groundwater concentrations if the pesticide is used at
the maximum allowable rate in areas where groundwater is exceptionally
vulnerable to contamination.  In most cases, a large majority of the use
area will have groundwater that is less vulnerable to contamination than
the areas used to derive the SCI-GROW estimate.

Appendix B. PRZM/EXAMS Output File for Direct Application to Dormant
Rice Paddy

stored as LAMosqSP.out

Chemical: Spinosad

PRZM environment: LAsugarcaneC.txt	modified Satday, 12 October 2002 at
16:02:46

EXAMS environment: pond298.exv	modified Thuday, 29 August 2002 at
16:33:30

Metfile: w13970.dvf	modified Wedday, 3 July 2002 at 09:05:36

Water segment concentrations (ppb)

Year	Peak	96Hr	21Day	60Day	90Day Yearly

1961	27.16	25.55	23.71	21.72	20.54	9.776

1962	44.34	42.73	40.89	38.9	37.72	26.96

1963	61.52	59.92	58.07	56.08	54.9	44.14

1964	78.7	77.1	75.25	73.26	72.08	61.29

1965	95.88	94.28	92.43	90.44	89.26	78.5

1966	113	111	110	108	106	95.68

1967	130	129	127	125	124	113

1968	147	146	144	142	141	130

1969	165	163	161	159	158	147

1970	182	180	178	176	175	164

1971	199	197	196	194	192	182

1972	216	215	213	211	210	199

1973	233	232	230	228	227	216

1974	251	249	247	245	244	233

1975	268	266	264	262	261	250

1976	285	283	281	279	278	267

1977	302	300	299	297	295	285

1978	319	318	316	314	313	302

1979	336	335	333	331	330	319

1980	354	352	350	348	347	336

1981	371	369	367	365	364	353

1982	388	386	384	383	381	371

1983	405	404	402	400	399	388

1984	422	421	419	417	416	405

1985	439	438	436	434	433	422

1986	457	455	453	451	450	439

1987	474	472	470	468	467	456

1988	491	489	488	486	484	474

1989	508	507	505	503	502	491

1990	525	524	522	520	519	508

Sorted results

Prob.	Peak	96 hr	21 Day	60 Day	90 Day	Yearly

0.032258064516129	525	524	522	520	519	508

0.0645161290322581	508	507	505	503	502	491

0.0967741935483871	491	489	488	486	484	474

0.129032258064516	474	472	470	468	467	456

0.161290322580645	457	455	453	451	450	439

0.193548387096774	439	438	436	434	433	422

0.225806451612903	422	421	419	417	416	405

0.258064516129032	405	404	402	400	399	388

0.290322580645161	388	386	384	383	381	371

0.32258064516129	371	369	367	365	364	353

0.354838709677419	354	352	350	348	347	336

0.387096774193548	336	335	333	331	330	319

0.419354838709677	319	318	316	314	313	302

0.451612903225806	302	300	299	297	295	285

0.483870967741936	285	283	281	279	278	267

0.516129032258065	268	266	264	262	261	250

0.548387096774194	251	249	247	245	244	233

0.580645161290323	233	232	230	228	227	216

0.612903225806452	216	215	213	211	210	199

0.645161290322581	199	197	196	194	192	182

0.67741935483871	182	180	178	176	175	164

0.709677419354839	165	163	161	159	158	147

0.741935483870968	147	146	144	142	141	130

0.774193548387097	130	129	127	125	124	113

0.806451612903226	113	111	110	108	106	95.68

0.838709677419355	95.88	94.28	92.43	90.44	89.26	78.5

0.870967741935484	78.7	77.1	75.25	73.26	72.08	61.29

0.903225806451613	61.52	59.92	58.07	56.08	54.9	44.14

0.935483870967742	44.34	42.73	40.89	38.9	37.72	26.96

0.967741935483871	27.16	25.55	23.71	21.72	20.54	9.776

0.1	489.3	487.3	486.2	484.2	482.3	472.2

					Average of yearly averages:	258.8782

Inputs generated by pe4.pl - 8-August-2003

Data used for this run:

Output File: LAMosqSP

Metfile:	w13970.dvf

PRZM scenario:	LAsugarcaneC.txt

EXAMS environment file:	pond298.exv

Chemical Name:	Spinosad

Description	Variable Name	Value	Units	Comments

Molecular weight	mwt	732	g/mol

Henry's Law Const.	henry		atm-m^3/mol

Vapor Pressure	vapr	2.4e-10	torr

Solubility	sol	235	mg/L

Kd	Kd		mg/L

Koc	Koc	4237	mg/L

Photolysis half-life	kdp	0.0	days	Half-life

Aerobic Aquatic Metabolism	kbacw	0.0	days	Halfife

Anaerobic Aquatic Metabolism	kbacs	0.0	days	Halfife

Aerobic Soil Metabolism	asm	1000000	days	Halfife

Hydrolysis:	pH 5	0	days	Half-life

Hydrolysis:	pH 7	0	days	Half-life

Hydrolysis:	pH 9	0	days	Half-life

Method:	CAM	2	integer	See PRZM manual

Incorporation Depth:	DEPI		cm

Application Rate:	TAPP	0.1123	kg/ha

Application Efficiency:	APPEFF	0.0	fraction

Spray Drift	DRFT	1.0	fraction of application rate applied to pond

Application Date	Date	01-06	dd/mm or dd/mmm or dd-mm or dd-mmm

Interval 1	interval	7	days	Set to 0 or delete line for single app.

Interval 2	interval	7	days	Set to 0 or delete line for single app.

Interval 3	interval	7	days	Set to 0 or delete line for single app.

Interval 4	interval	7	days	Set to 0 or delete line for single app.

Interval 5	interval	7	days	Set to 0 or delete line for single app.

Interval 6	interval	7	days	Set to 0 or delete line for single app.

Interval 7	interval	7	days	Set to 0 or delete line for single app.

Interval 8	interval	7	days	Set to 0 or delete line for single app.

Interval 9	interval	7	days	Set to 0 or delete line for single app.

Interval 10	interval	7	days	Set to 0 or delete line for single app.

Interval 11	interval	7	days	Set to 0 or delete line for single app.

Interval 12	interval	7	days	Set to 0 or delete line for single app.

Interval 13	interval	7	days	Set to 0 or delete line for single app.

Interval 14	interval	7	days	Set to 0 or delete line for single app.

Interval 15	interval	7	days	Set to 0 or delete line for single app.

Interval 16	interval	7	days	Set to 0 or delete line for single app.

Interval 17	interval	7	days	Set to 0 or delete line for single app.

Interval 18	interval	7	days	Set to 0 or delete line for single app.

Interval 19	interval	7	days	Set to 0 or delete line for single app.

Record 17:	FILTRA	

	IPSCND	1

	UPTKF	

Record 18:	PLVKRT	

	PLDKRT	

	FEXTRC	0.5

Flag for Index Res. Run	IR	Pond

Flag for runoff calc.	RUNOFF	none	none, monthly or total(average of
entire run)

Background Information on Linked PRZM/EXAMS Models

The linked EPA PRZM-EXAMS models estimate aquatic concentrations in a
one hectare pond that is two meters deep next to a ten hectare plot. The
pond receives simulated drift, runoff and eroded soil from the adjacent
field.  PRZM models terrestrial pesticide fate and transport and EXAMS
models the aquatic portion.

The Pesticide Root Zone Model (PRZM) is a one-dimensional, dynamic,
compartmental model that can be used to simulate chemical movement in
unsaturated soil systems within and immediately below the plant root
zone.  It has two major components: hydrology (and hydraulics) and
chemical transport. The hydrologic component for calculating runoff and
erosion is based on the Soil Conservation Service curve number technique
and the Universal Soil Loss Equation. Evapotranspiration is estimated
either directly from pan evaporation data, or based on an empirical
formula. Evapotranspiration is divided among evaporation from crop
interception, evaporation from soil, and transpiration by the crop.
Water movement is simulated by the use of generalized soil parameters,
including field capacity, wilting point, and saturation water content.  

Exposure Analysis Modeling System (EXAMS) is a model that can receive
progressive PRZM runoff concentration output to further predict aquatic
pesticide concentrations in a simulated pond.  The predicted
concentrations over the period of time (usually 30 years) can be
averaged over time to produce peak and time averaged concentrations that
take into account aquatic degradation.

Appendix C. Drinking Water Assessment for the Use of Spinosad on Bulb
Vegetables; Mint; Legume Forage, Hay and Alfalfa Seed; and Grass
Forages, Grass Grown for Seed, Pastures and Rangeland under the IR4
Tolerance Petition

	UNITED STATES ENVIRONMENTAL PROTECTION AGENCY

	WASHINGTON, D.C.  20460

			

OFFICE OF   

PREVENTION, PESTICIDES

AND TOXIC SUBSTANCES 

									

	

DP Barcodes: D314102,  D314863,                    D313314,  D310860

									PC code: 110003

									September 14, 2005

MEMORANDUM                                                              
                    

											

SUBJECT:	Drinking Water Assessment for the Use of Spinosad on Bulb
Vegetables (Green Onions); Mint; Legume Forage, Hay and Alfalfa Seed;
and Grass Forages, Grass Grown for Seed, Pastures and Rangeland under
the IR4 Tolerance Petition

TO:	George Larocca 

		Registration Division (7505C)

FROM:	Ronald Rarker, Environmental Engineer

		Environmental Risk Branch 5

		Environmental Fate and Effects Division (7507C)

THROUGH:	Mah T. Shamim, Chief

Environmental Risk Branch 5

		Environmental Fate and Effects Division (7507C)

The petitioner, IR4, requested the establishment of tolerances for the
residues of the spinosad, in or on bulb vegetables (green onions); mint;
legume forage, hay and alfalfa seed; and grass forages, grass grown for
seed, pastures and rangeland  Table 1 lists the maximum single
application rate, number of application, seasonal maximum application
and application intervals for these crops.            

Table 1. Application Information for Use of Spinosad

Crop	Label Rate (lbs/ac)	PRZM Input     Rate (lbs/ac)	Max Apps	Max a.i.
/ season	Min Freq.

Legume Forage Hay and Alfalfa Seed 	0.031-0.062	0.031	6 / season	0.186	7
days

Grass Foraages, Grass Grown for Seed, Pastures and Rangeland	0.031-0.062
0.031	6 / season	0.186	7 days

Mint	0.062-0.156	0.150	3 / calendar year	0.450	5 days

Bulb Vegetables (Green Onions)	0.047-0.094	0.090	5 / calendar year	0.450
5 days



Since the maximum single application rate and the maximum seasonal rate
of spinosad in this IR4 petition are much lower than those for the other
crop which was evaluated previously, EFED is recommending to use the
Estimated Environmental Concentrations (EEC) for turf that were
developed proviously. For spinosad, the surface water acute (peak) value
is 25.227 ppb and the chronic (average 56-day) value is 2.313 ppb based
on applications representative of turf. The groundwater screening
concentration is 0.037 ppb based on applications representative of turf.
These values represent upper-bound estimates of the concentrations that
might be found in surface water and groundwater due to the use of
spinosad on the representative crop. The application rate used in the
turf assessment was 0.4 pounds per acre with four applications at a
seven day spacing. See Appendix A attached to this memo.

Tier I Estimated Environmental Concentrations of Spinosad, for Use in
Human Health Risk Assessment (PC Code 110003).  Completed on 8/12/02.  

The above document can be found at: F:\user\share\document tracking and
storage\files\110003sn\DWA\7-3-02 Final water turf spinosad.wpd

  TC \l1 "	UNITED STATES ENVIRONMENTAL PROTECTION AGENCY

	WASHINGTON, D.C.  20460

			

OFFICE OF   

PREVENTION, PESTICIDES

AND TOXIC SUBSTANCES 

									

	

DP Barcodes: D314102,  D314863,                       D313314,  D310860

								PC code: 110003

								September 14, 2005

MEMORANDUM                                                              
                    

											

SUBJECT:	Drinking Water Assessment for the Use of Spinosad on Bulb
Vegetables (Green Onions); Mint; Legume Forage, Hay and Alfalfa Seed;
and Grass Forages, Grass Grown for Seed, Pastures and Rangeland under
the IR4 Tolerance Petition

TO:		George Larocca 

		Registration Division (7505C)

FROM:	Ronald Rarker, Environmental Engineer

		Environmental Risk Branch 5

		Environmental Fate and Effects Division (7507C)

THROUGH:	Mah T. Shamim, Chief

Environmental Risk Branch 5

		Environmental Fate and Effects Division (7507C)

The petitioner, IR4, requested the establishment of tolerances for the
residues of the spinosad, in or on bulb vegetables (green onions); mint;
legume forage, hay and alfalfa seed; and grass forages, grass grown for
seed, pastures and rangeland  Table 1 lists the maximum single
application rate, number of application, seasonal maximum application
and application intervals for these crops.            

	

Table 1. Application Information for Use of Spinosad

Crop	Label Rate (lbs/ac)	PRZM Input     Rate (lbs/ac)	Max Apps	Max a.i.
/ season	Min Freq.

Legume Forage Hay and Alfalfa Seed 	0.031-0.062	0.031	6 / season	0.186	7
days

Grass Foraages, Grass Grown for Seed, Pastures and Rangeland	0.031-0.062
0.031	6 / season	0.186	7 days

Mint	0.062-0.156	0.150	3 / calendar year	0.450	5 days

Bulb Vegetables (Green Onions)	0.047-0.094	0.090	5 / calendar year	0.450
5 days



Since the maximum single application rate and the maximum seasonal rate
of spinosad in this IR4 petition are much lower than those for the other
crop which was evaluated previously, EFED is recommending to use the
Estimated Environmental Concentrations (EEC) for turf that were
developed proviously. For spinosad, the surface water acute (peak) value
is 25.227 ppb and the chronic (average 56-day) value is 2.313 ppb based
on applications representative of turf. The groundwater screening
concentration is 0.037 ppb based on applications representative of turf.
These values represent upper-bound estimates of the concentrations that
might be found in surface water and groundwater due to the use of
spinosad on the representative crop. The application rate used in the
turf assessment was 0.4 pounds per acre with four applications at a
seven day spacing. See Appendix A attached to this memo.

Tier I Estimated Environmental Concentrations of Spinosad, for Use in
Human Health Risk Assessment (PC Code 110003).  Completed on 8/12/02.  

The above document can be found at: F:\user\share\document tracking and
storage\files\110003sn\DWA\7-3-02 Final water turf spinosad.wpd

 Should the results of this assessment indicate a need for further
refinement, please, contact us as soon as possible so that we may
schedule a Tier II assessment.

Appendix A (Of Appendix C)

	U. S. ENVIRONMENTAL PROTECTION AGENCY

	WASHINGTON, DC 20460

.	OFFICE OF             

	PREVENTION, PESTICIDES

	AND TOXIC SUBSTANCES 

										August 12, 2002

MEMORANDUM 	

SUBJECT:	Tier I Estimated Environmental Concentrations of Spinosad, for
Use in Human Health Risk Assessment (PC Code Spinosad 110003)

FROM:	Larry Liu, Ph.D., Environmental Scientist

		Environmental Risk Branch V  

		Environmental Fate and Effects Division (7507C)

THROUGH:	Mah T. Shamim, Ph.D., Chief

		Environmental Risk Branch V

		Environmental Fate and Effects Division (7507C)

TO:	Shaja Brothers

		Registration Division (7508C)

	This memo presents the Tier I Estimated Environmental Concentrations
(EECs) for  spinosad, calculated using FIRST (surface water) and
SCI-GROW (ground water), for use in the human health risk assessment.

	For spinosad, the surface water acute (peak) value is 25.227 ppb and
the chronic (average 56-day) value is 2.313 ppb based on applications
representative of turf. The groundwater screening concentration is 0.037
ppb based on applications representative of turf. These values represent
upper-bound estimates of the concentrations that might be found in
surface water and groundwater due to the use of spinosad on the
representative crop.  Details of the application scenarios that were
evaluated are presented in Table 3.

	Should the results of this assessment indicate a need for further
refinement, please, contact us as soon as possible so that we may
schedule a Tier II assessment.

Background Information on FIRST:

	FIRST is a new screening model designed to estimate the pesticide
concentrations found in water for use in drinking water assessments.  It
provides high-end values on the concentrations that might be found in a
small drinking water reservoir due to the use of pesticide.  Like
GENEEC, the model previously used for Tier I screening level, FIRST is a
single-event model (one run-off event), but can account for spray drift
from multiple applications.  FIRST uses a Drinking Water Reservoir
instead of a pond as the standard scenario.  The FIRST scenario includes
a 427 acres field immediately adjacent to a 13 acres reservoir,  9 feet
deep, with continuous flow (two turnovers per year).  The pond receives
a spray drift event from each application plus one runoff event.  The
runoff event moves a maximum of 8% of the applied pesticide into the
pond.  This amount can be reduced due to degradation on field and the
effect of binding to soil.  Spray drift is equal to 6.4% of the applied
concentration from the ground spray application and 16% for aerial
applications.

	FIRST also makes adjustments for the percent crop area. While FIRST
assumes that the entire watershed would not be treated, the use of a PCA
is still a screen because it represents the highest percentage of crop
cover of any large watershed in the US, and it assumes that the entire
crop is being treated.  Various other conservative assumptions of FIRST
include the use of a small drinking water reservoir surrounded by a
runoff-prone watershed, the use of the maximum use rate, no buffer zone,
and a single large rainfall.

Background Information on SCI-GROW:

	SCI-GROW provides a groundwater screening exposure value to be used in
determining the potential risk to human health from drinking water
contaminated with the pesticide.  Since the SCI-GROW concentrations are
likely to be approached in only a very small percentage of drinking
water sources, i.e., highly vulnerable aquifers, it is not appropriate
to use SCI-GROW for national or regional exposure estimates.  SCI-GROW
estimates likely groundwater concentrations if the pesticide is used at
the maximum allowable rate in areas where groundwater is exceptionally
vulnerable to contamination.  In most cases, a large majority of the use
area will have groundwater that is less vulnerable to contamination than
the areas used to derive the SCI-GROW estimate.

Modeling Inputs and Results:

	Table 1 and Table 2 summarize the input values used in the model runs
for FIRST 1.0 and SCI-GROW, respectively.  Fate parameters were obtained
from studies submitted by the registrant and modified, if necessary,
according to the Guidance for Selecting Input Parameters in Modeling the
Environmental Fate and Transport of Pesticides, Version II (February 28,
2002; USEPA Water Quality Tech Team).  Note that the parameters that
were used are for Spinosad A and that application assumed 100% as
Spinosad A.   The lowest Koc for a nonsand soil was used in FIRST. 
Since the variation between the lowest and highest Koc was greater than
three-fold, the lowest Koc was used in SCI-GROW.  The mean aerobic soil
metabolism half-life for spinosad A plus [(t90, n-1 x σ ) / n1/2] was
used for FIRST.  The median aerobic soil metabolism half-life for
spinosad A was used for SCI-GROW.   Twice the aerobic soil metabolism
value used in the model was used in lieu of the aerobic aquatic
metabolism for FIRST, as per current EFED guidelines.  The modeling
results associated with maximum allowable rate per year for
representative crops are presented in Table 3.  Attached to this memo
are copies of the original printouts generated from FIRST and SCI-GROW
runs.

cc: HED

Table 1.  Environmental Fate Input Parameters for FIRST.

Parameter	Spinosad A Value	Source

PC Code	110003	N/A

Water Solubility (20̊C, distilled water)	89.4 mg/L

	Hydrolysis Half-Life (pH 7)	Stable	MRID 43507301

Aerobic Soil Metabolism t½

(mean value plus t90, n-1 x σ ) / n1/2)	25.54 days	MRID 43507304

Aerobic Aquatic Metab. t½, (2X the Aerob. Soil Metab.)	51.08 days	MRID
43507304

Aqueous Photolysis Half-Life (at pH 7)	0.9 days	MRID 43507302

Soil Water Partition Coefficient (Lowest non sand Koc)	4237	MRID
43507306

Pesticide is Wetted-In	No	Product Label

PCA	0.87	Default Value

Depth of Incorporation (Aerial)	0.0	Product Label



Table 2.  Environmental Fate Input Parameters for SCI-GROW.

Parameter	Spinosad A Value	Source

Organic Carbon Partition Coefficient (Lowest KOC)	831	MRID 43507306

Aerobic Soil Metabolism Half-Life	13.35 days	MRID 43507304



Table 3. Application Information and Modeling Results for Use of
Spinosad on Turf.

Parameter	Spinosad value	Source

Crop	Turf

	Application Method	Ground spray

	Application Rate	0.4 lbs a.i/acre

	Application Frequency	4 /year

	Incorporation Depth	0 inches

	Application Interval (days)	7 days

	FIRST 1.0 Peak Untreated Water Concentration	25.227 ppb	FIRST Output

FIRST 1.0 Annual Average Untreated Water  Concentration00	2.313 ppb
FIRST Output

SCIGROW Ground Water Concentration	0.037 ppb	SCI-GROW Output



FIRST Output File for For Turf:

   RUN No.   1 FOR spinosad         ON   turf    * INPUT VALUES * 

  
------------------------------------------------------------------------
-------------------------------------------------------

    RATE (#/AC)   No.APPS &       SOIL    SOLUBIL   APPL TYPE     
%CROPPED INCORP

    ONE(MULT)    INTERVAL      Koc      (PPM )         (%DRIFT)        
AREA           (IN)

  
------------------------------------------------------------------------
--------------------------------------------------------

   .4000( 1.231)        4   7                4237.0   89.4            
GROUND(6.4)      87.0                .0

   FIELD AND RESERVOIR HALFLIFE VALUES (DAYS) 

  
------------------------------------------------------------------------
--------------------------------------------------------

   METABOLIC     DAYS UNTIL    HYDROLYSIS   PHOTOLYSIS   METABOLIC 
COMBINED

    (FIELD)             RAIN/RUNOFF  (RESERVOIR)   (RES.-EFF)       
(RESER.)          (RESER.) 

  
------------------------------------------------------------------------
--------------------------------------------------------

     25.54                 2                          N/A               
     .90-  111.60           51.08                  35.04

   UNTREATED WATER CONC (MICROGRAMS/LITER (PPB))   Ver 1.0 AUG 1, 2001

  
------------------------------------------------------------------------
--------------------------------------------------------

        PEAK DAY  (ACUTE)      ANNUAL AVERAGE (CHRONIC)      

          CONCENTRATION             CONCENTRATION            

  
------------------------------------------------------------------------
--------------------------------------------------------

                    25.227                                          
2.313

SCIGROW  Output File Turf:

   RUN No.   1 FOR spinosad a          ** INPUT VALUES **     

  
------------------------------------------------------------------------
-------------------------------------------------------  

    APP RATE   APPS/   TOTAL/      SOIL     AEROBIC SOIL METAB  

    (LBS/AC)     YEAR   SEASON     KOC     HALFLIFE (DAYS)    

  
------------------------------------------------------------------------
-------------------------------------------------------   

       .400            4           1.600           831.0              
13.4

	

   GROUND-WATER SCREENING CONCENTRATION (IN PPB)

  
------------------------------------------------------------------------
-------------------------------------------------------  

                                             .037075

  
------------------------------------------------------------------------
-------------------------------------------------------  

  A=     8.350  B=   836.000  C=      .922  D=     2.922  RILP=     
.993

  F=    -1.635  G=      .023  URATE=     1.600  GWSC=         .037075

  
------------------------------------------------------------------------
-------------------------------------------------------  

Appendix D. Tier I Estimated Environmental Concentrations of Spinosad,
for Use in Human Health Risk Assessment (August 12, 2002; This document
can be found at: F:\user\share\document tracking and
storage\files\110003sn\DWA\7-3-02 Final water turf spinosad.wpd)

	U. S. ENVIRONMENTAL PROTECTION AGENCY

	WASHINGTON, DC 20460

.	OFFICE OF             

	PREVENTION, PESTICIDES

	AND TOXIC SUBSTANCES 

										August 12, 2002

MEMORANDUM 	

SUBJECT:	Tier I Estimated Environmental Concentrations of Spinosad, for
Use in Human Health Risk Assessment (PC Code Spinosad 110003)

FROM:	Larry Liu, Ph.D., Environmental Scientist

		Environmental Risk Branch V  

		Environmental Fate and Effects Division (7507C)

THROUGH:	Mah T. Shamim, Ph.D., Chief

		Environmental Risk Branch V

		Environmental Fate and Effects Division (7507C)

TO:		Shaja Brothers

		Registration Division (7508C)

	This memo presents the Tier I Estimated Environmental Concentrations
(EECs) for  spinosad, calculated using FIRST (surface water) and
SCI-GROW (ground water), for use in the human health risk assessment.

	For spinosad, the surface water acute (peak) value is 25.227 ppb and
the chronic (average 56-day) value is 2.313 ppb based on applications
representative of turf. The groundwater screening concentration is 0.037
ppb based on applications representative of turf. These values represent
upper-bound estimates of the concentrations that might be found in
surface water and groundwater due to the use of spinosad on the
representative crop.  Details of the application scenarios that were
evaluated are presented in Table 3.

	Should the results of this assessment indicate a need for further
refinement, please, contact us as soon as possible so that we may
schedule a Tier II assessment.

Background Information on FIRST:

	FIRST is a new screening model designed to estimate the pesticide
concentrations found in water for use in drinking water assessments.  It
provides high-end values on the concentrations that might be found in a
small drinking water reservoir due to the use of pesticide.  Like
GENEEC, the model previously used for Tier I screening level, FIRST is a
single-event model (one run-off event), but can account for spray drift
from multiple applications.  FIRST uses a Drinking Water Reservoir
instead of a pond as the standard scenario.  The FIRST scenario includes
a 427 acres field immediately adjacent to a 13 acres reservoir, 9 feet
deep, with continuous flow (two turnovers per year).  The pond receives
a spray drift event from each application plus one runoff event.  The
runoff event moves a maximum of 8% of the applied pesticide into the
pond.  This amount can be reduced due to degradation on field and the
effect of binding to soil.  Spray drift is equal to 6.4% of the applied
concentration from the ground spray application and 16% for aerial
applications.

	FIRST also makes adjustments for the percent crop area. While FIRST
assumes that the entire watershed would not be treated, the use of a PCA
is still a screen because it represents the highest percentage of crop
cover of any large watershed in the US, and it assumes that the entire
crop is being treated.  Various other conservative assumptions of FIRST
include the use of a small drinking water reservoir surrounded by a
runoff-prone watershed, the use of the maximum use rate, no buffer zone,
and a single large rainfall.

Background Information on SCI-GROW:

	SCI-GROW provides a groundwater screening exposure value to be used in
determining the potential risk to human health from drinking water
contaminated with the pesticide.  Since the SCI-GROW concentrations are
likely to be approached in only a very small percentage of drinking
water sources, i.e., highly vulnerable aquifers, it is not appropriate
to use SCI-GROW for national or regional exposure estimates.  SCI-GROW
estimates likely groundwater concentrations if the pesticide is used at
the maximum allowable rate in areas where groundwater is exceptionally
vulnerable to contamination.  In most cases, a large majority of the use
area will have groundwater that is less vulnerable to contamination than
the areas used to derive the SCI-GROW estimate.

Modeling Inputs and Results:

 x σ ) / n1/2] was used for FIRST.  The median aerobic soil metabolism
half-life for spinosad A was used for SCI-GROW.   Twice the aerobic soil
metabolism value used in the model was used in lieu of the aerobic
aquatic metabolism for FIRST, as per current EFED guidelines.  The
modeling results associated with maximum allowable rate per year for
representative crops are presented in Table 3.  Attached to this memo
are copies of the original printouts generated from FIRST and SCI-GROW
runs.

cc: HED

Table 1.  Environmental Fate Input Parameters for FIRST.

Water Solubility (20̊C, distilled water)	89.4 mg/L

	Hydrolysis Half-Life (pH 7)	Stable	MRID 43507301

Aerobic Soil Metabolism t½

(mean value plus t90, n-1 x σ ) / n1/2)	25.54 days	MRID 43507304

Aerobic Aquatic Metab. t½, (2X the Aerob. Soil Metab.)	51.08 days	MRID
43507304

Aqueous Photolysis Half-Life (at pH 7)	0.9 days	MRID 43507302

Soil Water Partition Coefficient (Lowest non sand Koc)	4237	MRID
43507306

Pesticide is Wetted-In	No	Product Label

PCA	0.87	Default Value

Depth of Incorporation (Aerial)	0.0	Product Label



Table 2.  Environmental Fate Input Parameters for SCI-GROW.

Parameter	Spinosad A Value	Source

Organic Carbon Partition Coefficient (Lowest KOC)	831	MRID 43507306

Aerobic Soil Metabolism Half-Life	13.35 days	MRID 43507304



Table 3. Application Information and Modeling Results for Use of
Spinosad on Turf.

Parameter	Spinosad value	Source

Crop	Turf

	Application Method	Ground spray

	Application Rate	0.4 lbs a.i/acre

	Application Frequency	4 /year

	Incorporation Depth	0 inches

	Application Interval (days)	7 days

	FIRST 1.0 Peak Untreated Water Concentration	25.227 ppb	FIRST Output

FIRST 1.0 Annual Average Untreated Water  Concentration00	2.313 ppb
FIRST Output

SCIGROW Ground Water Concentration	0.037 ppb	SCI-GROW Output



FIRST Output File for Turf:

   RUN No.   1 FOR Spinosad         ON   Turf    * INPUT VALUES * 

  
------------------------------------------------------------------------
-------------------------------------------------------

h 

h 

h 

h 

.

/

0

b

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Ё㨃㈀ۖȁ̋x혲ĆЂ㨃㈀ۖ̂̋x혲ȆЃ㨃㐀ۖĀ̊e砃昀Ĵ瑹櫜
s਀--------------------------------------------------------------------
---------------------------------

   .4000( 1.231)        4     7              4237.0     89.4        
GROUND(6.4)        87.0                 0.0

   FIELD AND RESERVOIR HALFLIFE VALUES (DAYS) 

  
------------------------------------------------------------------------
--------------------------------------------------------

   METABOLIC     DAYS UNTIL    HYDROLYSIS   PHOTOLYSIS   METABOLIC 
COMBINED

    (FIELD)             RAIN/RUNOFF  (RESERVOIR)   (RES.-EFF)       
(RESER.)          (RESER.) 

  
------------------------------------------------------------------------
--------------------------------------------------------

     25.54                           2                       N/A        
       0.90-  111.60          51.08                 35.04

   UNTREATED WATER CONC (MICROGRAMS/LITER (PPB))   Ver 1.0 AUG 1, 2001

  
------------------------------------------------------------------------
--------------------------------------------------------

        PEAK DAY  (ACUTE)      ANNUAL AVERAGE (CHRONIC)      

          CONCENTRATION             CONCENTRATION            

  
------------------------------------------------------------------------
--------------------------------------------------------

             25.227                                                  
2.313

SCIGROW  Output File for Turf:

   RUN No.   1 FOR spinosad a          ** INPUT VALUES **     

  
------------------------------------------------------------------------
-------------------------------------------------------  

    APP RATE   APPS/   TOTAL/      SOIL     AEROBIC SOIL METAB  

    (LBS/AC)     YEAR   SEASON     KOC     HALFLIFE (DAYS)    

  
------------------------------------------------------------------------
-------------------------------------------------------   

       .400               4           1.600           831.0             
13.4

	

   GROUND-WATER SCREENING CONCENTRATION (IN PPB)

  
------------------------------------------------------------------------
-------------------------------------------------------  

                                                     .037075

  
------------------------------------------------------------------------
-------------------------------------------------------  

  A=     8.350  B=   836.000  C=      .922  D=     2.922  RILP=     
.993

  F=    -1.635  G=      .023  URATE=     1.600  GWSC=         .037075

  
------------------------------------------------------------------------
-------------------------------------------------------  

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