Document ID: EPA-HQ-OPP-2014-0740-0010
Agency: epa
Document Type: Supporting & Related Material
Title: 
Posted Date: 2015-11-06T05:00Z

UNITED STATES ENVIRONMENTAL PROTECTION AGENCY
	WASHINGTON, D.C. 20460

                                   OFFICE OF
                   CHEMICAL SAFETY AND POLLUTION PREVENTION
                                   OFFICE OF
                   CHEMICAL SAFETY AND POLLUTION PREVENTION

	
                                                                PC Code: 099050
	DP Barcode: D423299
                                                           Date: March 25, 2015
MEMORANDUM					
SUBJECT:	Tier I Drinking Water Exposure Assessment for Acetamiprid in Regards to a Proposed Reduction in the Preharvest Interval for Clover and Hay

TO:	Sidney Jackson, Risk Manager
Barbara Madden, Minor Use Team Leader
Minor Use and Emergency Response Branch
Registration Division (7505P)

Jacquelyn Marchese, Risk Manager
Venus Eagle, Product Manager
            Meredith Laws, Branch Chief
Invertebrate-Vertebrate Branch 3
Registration Division (7505P)

Elizabeth Holman, Physical Scientist  
Christina Swartz, Branch Chief
Risk Assessment Branch 2
Health Effects Division (7509P)
	
FROM:	Katrina White, Ph.D., Environmental Scientist
		Environmental Risk Branch IV
		Environmental Fate and Effects Division (7507P)

REVIEWED	Cheryl Sutton, Ph.D., Environmental Scientist
BY:		Environmental Risk Branch IV
		Environmental Fate and Effects Division (7507P)

APPROVED	Jean Holmes, D.V.M., M.P.H., Branch Chief
BY:		Environmental Risk Branch IV
		Environmental Fate and Effects Division (7507P)

		
EXECUTIVE SUMMARY

A screening-level drinking water assessment (DWA) for acetamiprid (PC Code 099050, (E)-N1-[(6-chloro-3-pyridyl)methyl]-N2-cyano-N1-methylacetamidine; CAS No. 135410-20-7) was conducted in support of the proposed reduction of preharvest intervals (PHI) for the use of acetamiprid for control of a variety of insects on clover and hay.  The new proposed PHI is 30 days.  A drinking water assessment was requested in support of this action because new models (Pesticide Root Zone Model GroundWater, PRZM-GW) and new data (an aerobic aquatic metabolism study, MRID 49034201) have become available since the last drinking water assessment was completed.  Additionally, cranberries is modeled with the Provisional Cranberry Model.

The Food Quality Protection Act Index Reservoir Screening Tool (FIRST) and the Provisional Cranberry Model were used to generate surface water Estimated Drinking Water Concentrations (EDWCs) for use in the human health dietary risk assessment, while the Pesticide Root Zone Model for Groundwater (PRZM-GW) and Screening Concentration in GroundWater (SCI-GROW) models were used to generate groundwater EDWCs.  Consistent with previous drinking water assessments, the residues of concern (ROC) for acetamiprid were the parent compound and unextracted residues (USEPA, 2001, 2011, D394234, D394479). 

For surface water sources of drinking water, the peak and annual average EDWCs associated with acetamiprid are 81.5 and 32.2 μg/L, respectively.  For groundwater sources of drinking water, the peak and annual average EDWCs associated with acetamiprid are 49.7 and 45 μg/L, respectively.  Selected modeling results files are provided in Appendix A.

Maximum EDWCs for acetamiprid residues in surface water and groundwater are presented in Table 1.  The maximum EDWC values recommended for use in the human health dietary risk assessment are 81.5 ug/L for acute EDWC and 45 ug/L for chronic and cancer EDWCs.  The acute value was generated for surface water sources of drinking water using FIRST and the chronic value was generated for ground water sources of drinking water using PRZM-GW.  Complete modeling results are presented in Table 10 and 11. 

Table 1.  Tier I EDWCs for drinking water exposure assessment based on acetamiprid and unextracted residues use as a bait scattered on surfaces and on cranberries[1,2]
Source of Drinking Water (Model)
  Acetamiprid and unextracted residue concentration in drinking water (ug/L)

                          Bait Scattered on Surfaces
                 0.082 lbs a.i./A, 24x, 3 day interval, ground
                                Cranberries[3]
                  0.13 lbs a.i./A, 2x, 7-day interval, aerial
Surface water 
(FIRST and Provisional Cranberry Model)
                                  Acute: 81.5
                             Annual average: 14.6
                                  Acute: 88.3
                             Annual average: 32.2
Groundwater
(PRZM-GW)
                               Daily peak:  49.7
                          Post breakthrough ave:  45
                                      --
[1] The highest EDWCs for the proposed and previously evaluated use scenarios are shown in purple.
[2] Previously estimated acute and annual average surface water concentrations were 95.2 and 26.6 ug/L, respectively.  Previously estimated groundwater concentrations were 0.04 ug/L and were estimated using SCIGROW.
3 EDWCs were calculated using the Provisional Cranberry Model.  

This assessment is based on available environmental fate data.  There were a number of uncertainties associated with this drinking water exposure assessment.  The major uncertainty is the maximum number of applications for the scatter bait use.  A maximum of 24 applications was assumed because there was not a specified number of maximum applications on the label.  Another source of uncertainty in the assessment is the inclusion of unidentified, unextracted residues in the calculation of aerobic soil metabolism half-lives.  For the scenarios resulting in the highest EDWCs in surface water, inclusion of unextracted residues in half-life calculations resulted in EDWCs that are 14 to 43 times EDWCs based on parent alone.  Therefore, the identity of the unextracted residues results in a significant uncertainty in the risk assessment.  Finally, all models used were screening-level models.   

Acetamiprid has not been identified as a cause of impairment for any water bodies listed as impaired under section 303(d) of the Clean Water Act.  Additionally, human health advisories and drinking water standards have not been developed for acetamiprid.  Human health benchmarks for Pesticides (HHBP) have been established for acetamiprid, as follows:

   * Acute or One-day HHBP = 1000 ug/L (Children)
   * Chronic or Lifetime HHBP (Noncancer) = 497 ug/L (General Population)

PROBLEM FORMULATION

This is a screening-level drinking water assessment (DWA) that uses modeling to estimate surface water and groundwater concentrations of pesticides in drinking water source water (pre-treatment), resulting from pesticide use on sites that are expected to be vulnerable to runoff and/or leaching.  Screening-level DWAs are designed to eliminate the need for further scrutiny of chemicals with low potential for posing drinking water concerns.  The current proposed action is to reduce the preharvest interval for clover and hay.  This is not expected to alter the EDWCs for acetamiprid; however, new models were available since the last drinking water assessment was completed.  Therefore, modeling was updated using the most up-to-date models (PRZM-GW and the Provisional Cranberry Model).  Additionally, new aerobic aquatic metabolism data (MRID 49034201) were available and used in modeling.
      
ANALYSIS

Use Characterization

Acetamiprid use patterns were summarized based on the Registration Review Problem Formulation (USEPA, 2012, DP Barcode 401171) and the most recently completed drinking water assessment (USEPA, 2011, D394234, D394479).  Acetamiprid is a neonicotinoid insecticide used to control a variety of insects on agriculture, residential, commercial, industrial, and nursery use sites.  Formulations include water dispersible granules (WDG), emulsifiable concentrates (EC), soluble concentrates (SC), liquids, water soluble packets (WSP), impregnated stickers, impregnated bait stations, gels, and an attract-and-kill device.  Water dispersible granules, EC, SC, and WSP are applied as ground or aerial sprays and may result in spray drift. Gels are used as spot treatments, beads, and thin films to control ants and cockroaches.  Water dispersible granules are all applied as a liquid.  There are also seed treatment uses on potatoes, canola, and mustard.  Some liquid formulations are injected into trees.  Termiticides may be applied as a liquid or foam.  They may be applied on soil surfaces as a perimeter treatment, crack and crevice treatment, or brush and spray.  They may also be applied into soil using trenching, rodding, sub slab injection, and soil excavation techniques.  Some termiticide products are applied to subsurfaces into piping, injections, and reticulation delivery systems.  The impregnated materials are generally stickers used to control flies.  The attract-and-kill device is a pheromone mixed with acetamiprid that is hung in trees.  Table 2 summarizes the use patterns modeled in this drinking water assessment.  The use patterns modeled were chosen because they are expected to result in maximum EDWCs based on previous drinking water assessments and/or the availability of new models used in estimating exposure. 

Table 2. Summary of use patterns modeled in this drinking water assessment
Use
                                  Max. Single
                                   App Rate
                                  lbs a.i./A
                                 (kg a.i./ha)
                             Max. Annual App. Rate
                                  lbs a.i./A
                                 (kg a.i./ha)
                          Max Number of Applications
                      Minimum Retreatment Interval (days)
                                  Application
                                     Type
Scatter Bait
                                     0.082
                                    (0.092)
                                     1.97
                                    (2.20)
                                      24
                                       3
                                  Ground boom
Tree Nuts
                                     0.18
                                    (0.20)
                                     0.72
                                    (0.80)
                                       4
                                      14
                                    Aerial
Cranberries
                                     0.13
                                    (0.15)
                                     0.26
                                    (0.29)
                                       2
                                       7
                                    Aerial
Source:  Previous Drinking Water Assessment (USEPA, 2011, D394234, D394479)

ENVIRONMENTAL FATE AND TRANSPORT CHARACTERIZATION

Acetamiprid may be transported to surface water and ground water via runoff, leaching, and spray drift.  Acetamiprid is classified as moderately mobile using the Food and Agriculture Organization (FAO) classification system (KOCs = 157 to 298 L/kg OC).  The primary route of degradation is aerobic soil metabolism.  Unextracted residues made up a significant amount of radioactivity and the identity of the residues is unknown in metabolism studies.  Therefore, degradation rates were estimated both for the parent alone and assuming that unextracted residues were the parent.  Aerobic soil metabolism rates for the parent ranged from <1 day to six days for the parent and two to 99 days for the parent plus unextracted residues in nine soils (USEPA, 2011, D390070).  Aerobic aquatic metabolism rates were slower at 23 to 32 days for the parent alone and 38 to 74 days for parent plus unextracted residues in three sediments (MRIDs 44988513 and 49034201).  Anaerobic aquatic metabolism was much slower, with a half-life of 325 days in a loamy sand sediment (MRID 44988512).  Acetamiprid is stable to hydrolysis at 25[o]C, but does undergo aqueous photolysis (half-life = 34 days).  Based on the low log octanol-water partition coefficient (log Kow = 0.08 at 25[o]C), acetamiprid is not expected to bioconcentrate.  

Table 3 summarizes the identity information and physical-chemical properties of acetamiprid.  Table 4 summarizes other environmental fate data for the parent and provides half-lives for the parent and unextracted residues.

Table 3.  Summary of physical-chemical properties of acetamiprid
Parameter
                                     Value
                                    Source
                                   Comments
PC Code
                                    099050
                                     None
                                     None
CAS Number
                                  135410-20-7
                                 (USNLM, 2009)
                                     None
Structure
 
 

                                     None
Chemical Name
      N[1]-[(6-chloro-3-pyridyl)methyl]-N[2]-cyano-N[1]-methylacetamidine
                                 MRID 44651803
                                     None
Molecular Weight
                                    222.68
                                 MRID 44651803
                                     None
Water Solubility
                               4250 mg/L (25°C)
                                 MRID 44651811
                                     None
Vapor Pressure
                         <1 x 10[-8] Torr at 25[o]C
                                MRID: 46235701
          Nonvolatile from dry non-adsorbing surfaces (USEPA, 2010a)
 
                         7.50 x 10[-10] Torr at 25[o]C
                           1 X 10[-4] mPa at 25[o]C
                                 (AERU, 2009)
                                       
Henry's Law constant
                     5.2 x 10[-14] atm-m[3]/mol at 25[o]C
                                  (estimated)
                        (Estimated from vapor pressure
                   and water solubility at pH 7 and 20[o]C)
            Calculated with vapor pressure reported by AERU (2009).
Dissociation Constant (pKa)
                                 0.7 at 25[o]C
                                 (USEPA, 2002)
                                     None
Log KOW
                                 0.8 at 25[o]C
                                 MRID 44651883
                  Not likely to bioconcentrate (USEPA, 2010a)
[1]All estimated values were estimated according to "Guidance for Reporting on the Environmental Fate and Transport of the Stressors of Concern in Problem Formulations for Registration Review, Registration Review Risk Assessments, Listed Species Litigation Assessments, New Chemical Risk Assessments, and Other Relevant Risk Assessments" (USEPA, 2010a).

Table 4.  Summary of environmental fate and transport properties of acetamiprid[5]
Parameter
                                   Value(s)
           Parent (Value for acetamiprid plus unextracted residues)
                                    Source
                                   Comments
Hydrolysis Half-life3 (days)
Stable (pH 5, 7, 9 at 25[o]C)
50.8 (pH 9 at 35[o]C)
12.8 (pH 9 at 45[o]C)
                                 MRID 44651876

                                     None
Atmospheric Degradation Half-life (days)
0.140 (estimated)
                                (USEPA, 2009a)
                                      NA
Estimated Hydroxyl Radical Reaction Half-life for a 12-hour day; 1.5x10[6] OH molecules/cm[3] Using EPIWeb Version 4.0 
Aqueous Photolysis Half-life (days)
342 (pH 7, 25[o]C)
                                 MRID 44988509
                                     None
Soil Photolysis Half-life
No half-lives available
                                 MRID 48563501
The study provides evidence on degradation products that may be observed with irradiation.
Aerobic Soil Metabolism Half-life (days)
20[o]C:
1.1 (76), sandy loam
1.2 (75), clay loam
1.0 (99), clay loam
                                 MRID 46255603
Only one replicate.  Unextracted residues made up <1 to 31 % of applied radioactivity.
 
20[o]C:
2.8, sandy loam
0.90, silty clay loam
6 (10), clay loam
                                 MRID 44651881
Foreign soils.  Unextracted residues made up approximately 20-40% at the end of the study (182 days); however, unextracted residues were not observed until most of the parent had degraded in the silty clay loam and sandy loam suggesting that the unextracted residues were not the parent compound.[4]
 
20[o]C:
1.4 (2.0), loamy sand
                                 MRID 44699101
Foreign soils.  Unextracted residues ranged from 2 to 17% of applied radioactivity. 
 
25[o]C:
3.5 (6.4), loamy sand
                                 MRID 44651879
Biphasic degradation was observed with an initial 3.6 day half-life followed by a 75 day half-life.  Unextracted residues were up to 20%.
Anaerobic Soil Metabolism Half-life (days)
No half-lives available
                                 MRID 48554501
Dissolved oxygen concentrations ranged from 1.87-1.94 mg/L, indicating system was not fully anaerobic.  Data on degradates can be used as the environment is expected to occur in natural systems.  
Aerobic Aquatic Metabolism Half-life or DT50 (days)
25[o]C:
25 (74),  loamy sand sediment
                                 MRID 44988513
                     Maximum of 38% unextracted residues. 

20[o]C:
23 (59, IORE), loam sediment
32 (38, IORE), clay loam sediment 
                                 MRID 49034201
                     Maximum of 43% unextracted residues. 
Anaerobic Aquatic Metabolism Half-life (days)
25[o]C:
325 (568),  loamy sand sediment
                                 MRID 44988512
                     Data available for only one sediment.
Solid-water distribution coefficient (Kd) in L/kg
20[o]C:
0.39, loamy sand, pH 4.4
3.9, loamy sand II, pH 6.2
1.1,  silt loam, pH 6.6
3.5, clay, pH 7.5
4.1,  sandy loam sediment, pH 5.6
Mean = 2.60
                                 MRID 44651883
                       Coefficient of variation is 66%.
Freundlich solid-water distribution coefficient (KF) in L/kg
20[o]C:
0.33, loamy sand, pH 4.4
3.0, loamy sand II, pH 6.2
1.0,  silt loam, pH 6.6
3.2, clay, pH 7.5
3.2,  sandy loam sediment, pH 5.6
                                 MRID 44651883
            Sorption was dependent on concentration in some soils.
Organic-carbon normalized distribution coefficient (Koc) in L/kgorganic carbon
20[o]C:
157, loamy sand, pH 4.4
266, loamy sand II, pH 6.2
251,  silt loam, pH 6.6
298, clay, pH 7.5
164,  sandy loam sediment, pH 5.6
Mean = 227
                                 MRID 44651883
Coefficient of variation is 28%.  The coefficient of variation is less than that for Kd values indicating that Koc values will be better at predicting sorption across soils than Kd values.  Moderately mobile according to FAO classification.
Terrestrial Field Dissipation Half-life (days)
2.8, CA, Gilman loamy fine, Vinca rosea
14.1, FL, Astatula fine, tree ferns
4.2, NJ, Penn silt loam, garden mums
                                 MRID 44988514
Wettable powder 70% ai (EXP80667A 70WP).  Degradate IM 1-2 converted to IM 1-4 in storage stability study and IM 1-4 was not stable.  Broadcast at 0.15 lbs ai/A with four applications.  Parent was not detected below 15 cm.  
 
3, WA, Timerman coarse sandy loam, apples
6, FL, Candler sand soil, oranges
13, NY, Oakville loamy fine sand, cabbage
6, CA, Romona loam soil, cotton
                                 MRID 44988515
Wettable powder 70% ai (EXP80667A 70WP).  Degradate IM 1-2 converted to IM 1-4 in storage stability study and IM 1-4 was not stable.  Broadcast at 0.15 lbs ai/acre with four applications.  Parent was not detected below 15 cm.  Conditions not favorable to leaching.  Subset of data used to estimate half-life for FL and WA site. 
 
10.1, Prince Edward Island, Alberry sandy loam
5.2, Ontario, London loam
17.8, Manitoba, Ryerson clay loam
                                 MRID 44988625
Wettable powder 70% ai (EXP61486A). Storage stability data were not submitted for the test site soils.  Acetamiprid was applied four times at 168 g ai/ha with a 7 day interval to bare plots in Canada.  Parent not detected below 15 cm depth. 
Environmental Chemistry Methods and Independent laboratory Validation
LC/MS/MS for detection of acetamiprid, IM 1-2, IC-0 in soil
                                MRID 44988516/
                                   44988517
                           Acetamiprid, IC-0, IM 1-4
                            LOD = 3.33 ug/kg-soil
                       Acetamiprid, IM 1-2, IC-0, 1M-1-4
                             LOQ = 10 ug/kg-soil

HPLC-UV for parent, IC-0, IM 1-4, IM 1-2 in water
                                 MRID 44988536
                               LOD = 0.033 ug/L
                                 LOQ=0.1 ug/L
ai=active ingredient
[1] Degradation kinetics were calculated using the single first order decay equation unless otherwise specified.  Two aerobic aquatic metabolism studies used the Indeterminate Order Rate Equation (IORE) to calculate the time to 50% decline of residues (DT50).	
[2] Value corrected to represent natural sunlight at 40[º]N latitude. 
[3] MRID 44651877 is supplemental.  A material balance was not conducted in the study; however, the results suggest that degradates IM-1-4 and IC-0 are stable.
[4] This indicates that the unextracted residues were not the parent compound.  Unextracted residues in the clay loam appeared as the parent was lost the identity of unextracted residues is unknown.
[5] This table shows half-lives for the parent and parent plus unidentified unextracted residues which may or may not be the parent.  These values are relevant in understanding the uncertainty in data due to unextracted residues.  

RESIDUES OF CONCERN

The Metabolism Assessment Review Committee (MARC) reported that the residue of concern for acetamiprid is the parent only (USEPA, 2001).  The 2011 "Tier I Drinking Water Exposure Assessment for the Section 3 New Use of Acetamiprid on Various Agricultural Crops and as a Scatter Bait to Control Insects" was conducted for acetamiprid and unextracted residues as residues of concern (USEPA, 2011, D394234, D394479).  Therefore, this assessment will also be conducted on acetamiprid and unextracted residues.  Unextracted residues were observed in aerobic soil and aerobic aquatic metabolism studies and in some studies it was uncertain whether the unextracted residues were parent compound (MRIDs 46255603, 44651881, 44699101, 44651879, 44988513, and 44988512).  Additionally, the extraction techniques were not exhaustive and it is likely that if different extraction techniques were used a higher percentage would be extracted.  Therefore, when it was uncertain, half-lives were estimated assuming the unextracted residues were the parent compound.  When the parent was shown to degrade at the beginning of the study and unextracted residues did not appear until the end of the study, it was assumed that the unextracted residues were not the parent compound.  This approach is consistent with Guidance for Addressing Unextracted Residues in Laboratory Studies (USEPA, 2014c).  

DRINKING WATER EXPOSURE MODELING

Models

EDWCs were generated using EFED's standard suite of models.  The FQPA Index Reservoir Screening Tool (FIRST version 1.1.1, March 25, 2008) is a surface water model that is used to estimate both acute and chronic pesticide concentrations in untreated drinking water.  EDWCs from FIRST represent concentrations which might occur from a single 1-in-10-year storm event following the last application of pesticide at a location more vulnerable than most locations in the United States to runoff, regardless of the crop being produced. The model considers reductions in dissolved concentration 1) due to the percentage of the watershed which is cropped (percent cropped area - PCA), 2) due to sorption of pesticide to field soil and to reservoir bottom sediment, 3) due to incorporation of the pesticide at the time of application, 4) due to degradation in soil before runoff to the reservoir, and 5) due to degradation of the pesticide within the water body.  Reservoir water concentrations may be increased due to deposition of spray drift into the feeding stream or directly into the reservoir itself.  FIRST is designed to mimic a more complex simulation using the linked PRZM3 (Carsel et al., 1997) and EXAMS 2.97.7 (Burns, 2000) models, but requires less time and effort to complete.  A more detailed description of the index reservoir watershed can be found in USEPA, 2010 (USEPA, 2010c).  The FIRST model and users manuals may be downloaded from the U.S. Environmental Protection Agency (EPA) Water Models web-page (http://www.epa.gov/oppefed1/models/water/#first).  Percent Cropped Areas (PCA) that account for the maximum area within a watershed that may be planted with the modeled crop are applied to concentrations predicted by FIRST (USEPA, 2010b, 2014a).  If a chemical has uses in a variety of land cover classes that include residential areas, a PCA is not applied because the land-class was not included in the development of PCAs (USEPA, 2010b).  Acetamiprid may be used on a variety of landcover classes and a PCA was not applied to the EDWC.  The FIRST model assumes spray drift fractions (as shown in Table 5) that are more conservative than the spray drift fraction currently recommended for use in risk assessment (USEPA, 2013b).  The currently recommended spray drift fraction is calculated using the same methodology as that used when FIRST was designed, but uses the most current AgDRIFT model.  The new AgDRIFT model results in a slightly different spray drift fraction from that used in the FIRST model.  

Table 5.  Comparison of FIRST and updated spray drift estimates
Application Type
                             Spray Drift Fraction

                                     FIRST
                                Updated Values
Aerial Spray
                                     0.16
                                     0.125
Ground Spray
                                     0.064
                                     0.062
Airblast
                                     0.063
                                     0.042
Granular
                                       0
                                      0.0

Groundwater EDWCs for were derived using the PRZM-GW model (Pesticide Root Zone Model for GroundWater, version 1.07, Nov., 2014), with the GW-GUI (Graphical User Interface, version 1.0, August 31, 2012).  PRZM-GW is a one-dimensional leaching model that estimates the concentrations of pesticides in groundwater.  It accounts for pesticide fate in the crop root zone by simulating pesticide transport and degradation through the soil profile after a pesticide is applied to an agricultural field.  PRZM-GW permits the assessment of multiple years of pesticide application (up to 100 years) on a single site.  Six standard scenarios, each representing a different region known to be vulnerable to groundwater contamination, are available for use with PRZM-GW for risk assessment purposes.  In PRZM-GW simulations, each of these standard scenarios was used and the highest EDWCs across scenarios is shown in the modeling results section.  PRZM-GW output represents pesticide concentrations in vulnerable groundwater located directly beneath an agricultural field, following many years of pesticide application (USEPA 2012a, 2012b).

EDWCs in groundwater were also estimated using EFED's groundwater model SCI-GROW (Screening Concentration in Ground Water, version 2.3; 8/8/2003).  SCI-GROW is a regression model used as a screening tool to estimate potential pesticide concentrations in vulnerable groundwater that might be used as drinking water.  SCI-GROW was developed by fitting a linear model to groundwater concentrations with the Relative Index of Leaching Potential (RILP) as the independent variable.  Groundwater concentrations were taken from 90-day average high concentrations from Prospective Ground Water monitoring studies; the RILP is a function of aerobic soil metabolism and the soil-water partition coefficient.  The output of SCI-GROW represents concentrations that might be expected to occur in shallow unconfined aquifers under sandy soils, which is representative of the groundwater most vulnerable to pesticide contamination likely to serve as a drinking water source (USEPA 2002).  

The surface water EDWC for cranberries were determined using the Provisional Cranberry Model, this is the Tier 1 Rice Model (v1.0, May 8, 2007) with a modified depth for cranberries and some modifications made to allow for degradation and multiple applications.  Some cranberries are grown in bogs, where the field is temporarily flooded to control pests, prevent freezing, and to facilitate harvest.  After flooding, water may be held in a holding system, recirculated to other cranberry growing areas, or released to adjacent waterbodies (rivers, streams, lakes, or bays).  Introduction of acetamiprid to surface water via flooding of the bog and release of water is evaluated using the Provisional Cranberry Model.  The Provisional Cranberry Model will estimate residues in water that is introduced to the field and not mixed with any additional water.  The Provisional Cranberry Model will overestimate exposure to pesticides in drinking water to the extent that drinking source water is not drawn from cranberry bogs.  Dilution and microbially-mediated degradation are expected to reduce concentrations in water prior to their movement to the vicinities of drinking water treatment plant intakes.  The extent of this reduction in concentrations depends on 1) the length of time the compound is in the water, 2) the distance the water will travel before the drinking water intake, 3) the amount of dilution and 4) whether the water it is mixed with also carries residues of acetamiprid.  

The Tier 1 Rice model estimates concentrations in a water body holding a 10 cm water depth.  When a pesticide is applied to the water, the model employs the assumption that the pesticide instantaneously partitions between water and sediment, as determined by the chemical's sorption coefficient, according to:
           		
                                       
      where,
      	Cw0 = initial water concentration [ug/L]
      mai' = mass applied per unit area [kg/ha]
      Kd = water-sediment partitioning coefficient [L/kg]
      dw = water column depth = 0.10 m
      dsed = sediment depth = 0.01 m
      θsed = porosity of sediment = 0.509
      ρb = bulk density of sediment = 1300 kg/m[3]
 
 
       This simplifies to:
          
       And, if appropriate:
 
       Kd = 0.01Koc
 
       where: 
 		Cw=water concentration in ug/L
 		mai'=mass applied per unit area in kg/ha
       Koc=organic-carbon normalized soil-water distribution coefficient (L/kg-oc)
 
 This model was used for this assessment with a modification to the depth of the water body, to reflect concentrations in the water of a cranberry bog rather than that of a rice paddy (Cape Cod Cranberry Growers Association, 2001).  Specifically, in the first equation above, the value of dw (water column depth) was changed to 0.305 m (1 foot), from the usual 0.10 m depth that is assumed for rice paddies.  This modification has been used in a previous assessment, to estimate aquatic exposure concentrations for the chemical fenpyroximate (USEPA, 2012, D391431, 2012, D405064).
 
The concentration in water over time for the Provsional Cranberry Model was based on the following equation:

      Cw, t = Cw, 0 e[(-][kt][)]

      Where
      Cw, t 	= the concentration in water at time, t
      Cw, 0 	= the concentration in water at application or time of zero
      e 	= base of natural logarithm
      k 	= first-order rate constant of degradation or dissipation (1/days)
      t 	= time after application (days)

When two applications were modeled, the initial concentration in the water after each application was estimated using the Provsional Cranberry Model.  Daily concentrations (after the application day) were then determined from the initial concentration by using the aerobic aquatic metabolism rate and the above equation.  This was completed for each application.  Concentrations in water from the first and second applications were added to determine the total concentration in water over time for each day.  Acute concentrations were reported at the maximum concentration for the given scenario.  Chronic concentrations were taken as the average daily concentration over 365 days.

Input Parameters 

Input parameters used in modeling are presented in Tables 6, 7, and 8.  Input parameters were selected in accordance with EFED's guidance documents (USEPA, 2009b, 2010d, 2012, 2013a, 2013b, 2014b, 2014c; USEPA and Health Canada, 2013).

The uses on agricultural crops allow for ground, aerial, and airblast applications of a flowable material.  The scatter bait is applied as a dry material on surfaces or placed in a bait station and no spray drift is expected with this use.  The scatter bait use is evaluated as a granule formulation.  For the agricultural crop uses, EDWC for broadcast aerial spray applications were estimated, as these almost always result in higher concentrations than a ground or airblast application.  In the previous DWA, only one aerobic aquatic metabolism half-life value was available (25 for parent only and 74 days for parent and unextracted residues in a loamy sand; MRID 44988513).  These values were multiplied by three to obtain the model input values of 75 and 222 days for FIRST.  With the additional submitted aerobic aquatic metabolism study available, the new input was based on the 90[th] percentile upper confidence bound on the mean of three values, resulting in an input of 24 days for acetamiprid alone and 99 days for acetamiprid plus unextracted residues.  

Table 6.  FIRST (v1.1.0) input parameter values for acetamiprid 
Parameter
                                     Value
                                    Source
                                    Comment
Organic carbon partitioning coefficient (KOC; mL/g OC)
                                      227
                                 MRID 44651884
Mean of five KOC values.  Coefficients of variation (CV) were lower for KOC (CV=28%) as compared to Kd (CV=66%).
Aerobic Soil Metabolism Half-life (days)
                               Parent Only:  2.4
                       Parent+Unextracted Residues:  39
                                MRIDs 44655603,
                         44651881, 44699101, 44651879
The 90 percent upper confidence bound on the mean of 8 half-life values.  Values were adjusted to 25[o]C.
Wetted in?
                                      No
                        (USEPA, 2011, D394234, D394479)
                                      --
Depth of Incorporation (inches)
                                       0
                                       
                                      --
Application Parameters
                               See Results Table
                                       
                                      --
Percent Cropped Area (PCA)
                                      1.0
                          PCA Guidance (USEPA, 2014b)
      There are currently registered residential and rights-of-way uses.
Solubility in Water (mg/L)
                                     4250 
                                 MRID 44651811
                              Measured at 25[o]C
Aerobic Aquatic Metabolism Half-life (days)
                                  Parent: 24
                       Parent+ Unextracted Residues: 99
                            MRID 44988513, 49034201
The 90[th] percentile upper confidence bound on the mean of 3 values.  Two values were adjusted to 25[o]C.
Hydrolysis Half-life at pH 7 (days)
                                  Stable (0) 
                                 MRID 44651876
                                      --
Aquatic Photolysis Half-life at pH 7 (days)
                                      34
                                 MRID 44988509
Corrected for continuous irradiation as well as for latitude/season to reflect photolysis in summer sunlight at 40o N latitude.

Table 7.  SCI-GROW (v2.3) input parameter values for acetamiprid 
Parameter
                                     Value
                                    Source
                                   Comments
Koc (mL/g)
                                      251
                                 MRID 44651884
Median of five values.  Coefficients of variation (CV) were lower for KOC (CV=28%) as compared to Kd (CV=66%).
Aerobic soil metabolism t (1/2) (days)

                              Parent Only:  0.92
                       Parent+Unextracted Residues:  6.7
                                MRIDs 44655603,
                         44651881, 44699101, 44651879
      The median of 8 half-life values.  Values were adjusted to 25[o]C.

Table 8.  Provisional Cranberry Model input parameters values for acetamiprid
Input Parameter
                                     Value
                                    Source
                                   Comments
Application Rate
(lbs a.i./A)
                                     0.13
                        (USEPA, 2011, D394234, D394479)
                           Maximum application rate
Aerobic Aquatic Metabolism Half-life (days)
                                  Parent: 24
                       Parent+ Unextracted Residues: 99
                           MRIDs 44988513, 49034201
The 90[th] percentile upper confidence bound on the mean of 3 values.  Two values were adjusted to 25[o]C.
Organic carbon normalized distribution coefficient (KOC; mL/g OC)
                                      227
                                 MRID 44651884
Mean of five KOC values.  Coefficients of variation (CV) were lower for KOC (CV=28%) as compared to Kd (CV=66%).

Table 13.  Tier I PRZM-GW input parameters
 Parameter (units)
                                    Residues
                                  Input Value
                                  Data Source
                                    Comments
 Hydrolysis Half-life (days)
                                    Parent
                                  Stable (0) 
                                 MRID 44651876
 Hydrolysis half-life at pH 7 and 25[o]C.
 Soil Metabolism Half-life at 25[o]C (days)
                                    Parent
                                 2.4 at 25[o]C
                      MRIDs 46867004, 44746001, 46386605
The 90 percent upper confidence bound on the mean of 8 half-life values.  Values were adjusted to 25[o]C.
 
                         Parent + unextracted residues
                                 39 at 25[o]C
                                       
                                       
 Koc (L/kg-OC)
                                    Parent
                                      227
                                 MRID 44651884
Mean of five KOC values.  Coefficients of variation (CV) were lower for KOC (CV=28%) as compared to Kd (CV=66%).

      
Modeling Results

Surface water modeling results for acetamiprid plus unextracted residues are presented in Table 10, with maximum values given in bold.  Groundwater modeling results are presented in Table 11.  Output files from the model run associated with the maximum EDWCs for each model are provided in Appendix B.  Output concentrations for surface water were not adjusted using a PCA adjustment factor because acetamiprid is registered for use on a variety of landcover classes including residential, commercial, and agricultural areas and is applied to more than one crop.  The national default PCA adjustment factor is 1.0.  Model output concentrations for groundwater are not adjusted using a PCA, since PCAs represent watershed-scale dilution effects that cannot be presumed to apply to groundwater.  

Table 10.  Estimated concentrations of acetamiprid and unextracted residues in surface water source drinking water
Use Pattern (Model)
                             Application Scenario
                                  EDWC ug/L

                                       
                                     Peak
                                Annual Average
Bait (FIRST)
       0.082 lbs a.i./A (0.092 kg a.i./ha), 24x, 3 day interval, ground
                                     81.5
                                     5.88*
                                     14.6
                                    0.339*
Tree Nuts (FIRST)
          0.18 lbs a.i./A (0.20 kg a.i./ha), 4x, 14 day interval, air
                                     38.8
                                     7.11
Cranberries (Provisional Cranberry Model)
          0.13 lbs a.i./A (0.15 kg a.i./ha), 2x, 7 day interval, air
                                     88.3
                                     79.2*
                                     32.2
                                     7.88*
*Residues of Acetamiprid alone, calculated for the scenarios that resulted in a highest EDWCs for surface water. 
1 EDWCs are shown for residues of acetamiprid plus unextracted residues, assuming an aerobic soil metabolism input of 39 days and an aerobic aquatic metabolism half-life of 99 days, unless otherwise indicated with an asterisk. Values with an asterisk are results for residues of acetamiprid alone, assuming an aerobic soil metabolism half-life of 2.4 days and an aerobic aquatic metabolism half-life of 24 days.

Table 11.  Estimated concentrations of acetamiprid and unextracted residues in groundwater source drinking water[1]
Use Site
                             Application Scenario
                                EDWC in ug/L 

                                       
                                   SCI-GROW
                                    PRZM-GW

                                       
                                     Peak
                                   Scenario
                                  Daily Peak
                           Post Breakthrough Average
                       Average Breakthrough Time (Days)
                                     Bait
       0.082 lbs a.i./A (0.092 kg a.i./ha), 24x, 3 day interval, ground
                                     0.019
                                      WI
                                     49.7
                                     0.03*
                                      45
                                     0.01*
                                     5411
                                   Tree Nut
          0.18 lbs a.i./A (0.20 kg a.i./ha), 4x, 14 day interval, air
                                     0.013
                                      WI
                                     18.8
                                     16.8
                                     5411
Abbreviations: WI=Wisconsin Corn
Bold values show the highest EDWC from groundwater source drinking water.  
*Residues of Acetamiprid alone
[1] EDWCs are shown for residues of acetamiprid plus unextracted residues, assuming an aerobic soil metabolism input of 39 days, unless otherwise indicated with an asterisk. Values with an asterisk are results for residues of acetamiprid alone, assuming an aerobic soil metabolism half-life of 2.4 days.  The Wisconsin sands scenario resulted in the highest EDWCs across PRZM-GW scenarios.

MONITORING DATA

The following databases and sources were searched for monitoring information on acetamiprid:

   * Water Quality Portal (http://www.waterqualitydata.us/portal.jsp)
   * California Environmental Data Exchange Network (http://ceden.waterboards.ca.gov/AdvancedQueryTool)

No monitoring information was found.

DRINKING WATER TREATMENT EFFECTS
	
There is no available information on the effects of drinking water treatment on acetamiprid.  The EDWCs in this assessment are representative of concentrations in drinking water source water (pre-treatment).  For surface water, the conceptual model assumes that a pesticide reaches surface water via spray drift or surface runoff and it is instantaneously mixed and concentrations are observed in the water body.  Acetamiprid is stable to hydrolysis.  Therefore, acetamiprid will not degrade by hydrolysis during the time that elapses from drinking water intake through distribution to the first tap.    Photolysis is a relatively unimportant degradation pathway.  Therefore, if ultraviolet light were used as a means of disinfection, degradation of acetamiprid would not be expected to be significant.  Acetamiprid does degrade via aerobic metabolism in soil and sediment and some may degrade in an aerobic digester where aerobic metabolism occurs.  However, the half-life is much longer than the residence time of the water within a typical treatment plant.  The most successful drinking water treatment process for removal of pesticides from drinking water is thought to be treatment with granular activated carbon (GAC) which is only used in larger drinking water treatment facilities.  The ability of GAC to remove pesticides will vary with the properties of the chemical and whether the sorption sites on GAC have reached capacity (Badriyha et al., 2003; Zhao et al., 1999).  Data on the sorption of acetamiprid to GAC are not available; however, a high percentage of sorption and thus removal of acetamiprid to GAC is likely to occur, as acetochlor (reported KOC of 156 L/kg) was removed from river water treated with GAC (AERU, 2009; Badriyha et al., 2003).

UNCERTAINTIES AND DATA GAPS

The estimated concentrations provided in this assessment were generated from Tier 1 models and are conservative estimates of acetamiprid concentrations in untreated drinking water.  There were a number of uncertainties associated with this drinking water exposure assessment.  The major uncertainty what the maximum number of applications would be for the scatter bait use.  Another source of uncertainty in the assessment is the inclusion of unidentified, unextracted residues in the calculation of aerobic soil and aerobic aquatic metabolism half-lives.  For the scenarios resulting in the highest surface water EDWCs, inclusion of unextracted residues in half-life calculations resulted in EDWCs that are 14 to 43 times EDWCs based on parent alone.  Therefore, the identity of the unextracted residues results in a significant uncertainty in the risk assessment.  

The drinking water assessment is a screening-level assessment based upon standard models and assumptions.  The modeling assessment relies on a maximum use pattern (maximum label application rates) to reflect surface water and groundwater concentrations, and a national PCA of 1.0 to reflect potential surface water concentrations.  To the extent that actual use patterns involve application of less a.i. than the permissible on the label, and location-specific crop acreages represent lower land coverage percentages than the national maximum PCA used in this assessment, aquatic concentrations (particularly the acute) in some locations will be lower than EDWCs reported herein.  

There is also uncertainty associated with modeling with FIRST, SCI-GROW, PRZM-GW, and the Provisional Cranberry Model.  They are all Tier I models or were run with Tier I assumptions and therefore could potentially overestimate chemical concentrations.  If dietary risks require refinement, higher tiered models and modeling scenarios can be utilized upon request.  It is noted that as a groundwater screening tool, PRZM-GW in general works to simulate concentrations greater than those that are likely to be present in the vast majority of drinking water supplies.  PRZM-GW does not consider erosion or runoff of a pesticide, which may make a compound less available for leaching to groundwater.  The Provisional Cranberry Model, estimates concentrations in the cranberry bog, assuming the bog is flooded for the entire year.  Cranberry bogs are not flooded the entire year, and it is understood that dilution of water would occur before it would move to where drinking water intakes were located.  Therefore, the Provisional Cranberry Model will likely overestimate EDWCs.
      
REFERENCES

Literature Cited

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Cape Cod Cranberry Growers Association. 2001. Conservation District Grant Program of the Commonwealth of Massachusetts Executive Office of Environmental Affairs. Cranberry Water Use.  An Information Fact Sheet.  June 2001. Available at http://www.cranberries.org/pdf/wateruse.pdf (Accessed October 25, 2012).
Carsel, R. F., Imhoff, J. C., Hummel, P. R., Cheplick, J. M., & Donigian Jr., J. S. 1997. PRZM-3, A Model for Predicting Pesticide and Nitrogen Fate in Crop Root and Unsaturated Soil Zones: Users Manual for Release 3.0. Memorandum From to  Environmental Research Laboratory.  Office of Research and Development.  United States Environmental Protection Agency.   
USEPA. 2001. Acetamiprid.  Results of the HED Metabolism Assessment Review Committee. D278652. Memorandum From H. Bietlot, M. Doherty & P. Hurley to Y. Donovan.  Office of Prevention, Pesticides, ans Toxic Substances.  United States Environmental Protection Agency.   
CFR. Part 2002. Acetamiprid Pesticide Fact Sheet. Government Printing Office.  Washington, D.C.
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USEPA. 2010b. Guidance on Development and Use of Percent Cropped Area Adjustment Factors in Drinking Water Exposure Assessments.  September 9, 2010. Environmental Fate and Effects Division, Office of Pesticide Programs, U.S. Environmental Protection Agency. Available at http://www.epa.gov/pesticides/science/efed/models/water/archives/pca_adjustment_dwa_9sep2010.html (Accessed March 13, 2015).
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USEPA. 2010d. WQTT Advisory Note Number 9:  Temperature Adjustments for Aquatic Metabolism Inputs to EXAMs and PE5. Memorandum From D. F. Young to Water Quality Tech Team.  September 21, 2010. Environmental Fate and Effects Division.  Office of Chemical Safety and Pollution Prevention.  U.S. Environmental Protection Agency.  Available at http://www.epa.gov/pesticides/science/efed/policy_guidance/team_authors/water_quality_tech_team/wqtt_temp_adjust_exams_pe5.htm (Accessed March 13, 2015).
USEPA. 2011.D390070.  Tier I Drinking Water Exposure Assessment for the Section 3 New Use of Acetamiprid on Soybeans to Control a Variety of Insect  Pests. D390070. Memorandum From K. White to M. Doherty, C. Swartz & J. Urbanski.  July 21, 2011. Environmental Fate and Effects Division.  Office of Chemical Safety and Pollution Prevention.  United States Environmental Protection Agency.  
USEPA. 2011.D394234, D394479.  Tier I Drinking Water Exposure Assessment for the Section 3 New Use of Acetamiprid on Various Agricultural Crops and as a Scatter Bait to Control Insects.  D394234 & D394479. October 11, 2011. Environmental Fate and Effects Division.  Office of Pesticide Programs.  United States Environmental Protection Agency. 
USEPA. 2012.D391431.  Fenpyroximate: Drinking Water Exposure Assessment for Proposed New Uses on Snap Beans and Tropical Fruits including Avocado and a Proposed Outdoor Use on Cucumbers. D391431. Memorandum From G. Orrick to G. Kramer & S. Jackson.  Environmental Fate and Effects Division.  Office of Pesticide Programs. United States Environmental Protection Agency.   
USEPA. 2012.DP Barcode 401171.  Registration Review- Preliminary Problem Formulation for Ecological Risk and Environmental Fate, Endangered Species, and Drinking Water Assessments for Acetamiprid.  D401171. Environmental Fate and Effects Division.  Office of Pesticide Programs.  United States Environmental Protection Agency. 
USEPA. 2012. Standard Operating Procedure for Using the NAFTA Guidance to Calculate Representative Half-life Values and Characterizing Pesticide Degradation.  November 30, 2012. Environmental Fate and Effects Division.  Office of Pesticide Programs.  U.S. Environmental Protection Agency. Available at http://www.epa.gov/oppefed1/ecorisk_ders/degradation_kinetics/NAFTA_Degradation_Kinetics.htm (Accessed December 16, 2013).
USEPA. 2012.D405064.  Tier I Drinking Water Exposure Assessment for the Section 3 New Use of Boscalid on Various Agricultural Crops Including Cranberries. D405064. Memorandum From K. White to S. Funk, B. O'Keefe, A. Ertman & B. Madden.  November 27, 2012. Environmental Fate and Effects Division.  Office of Pesticide Programs. Office of Chemical Safety and Pollution Prevention.  U.S. Environmental Protection Agency.   
USEPA. 2013a. Guidance for Using PRZM-GW in Drinking Water Exposure Assessments.  December 11, 2012. Environmental Fate and Effects Division.  Office of Pesticide Programs. U.S. Environmental Protection Agency. Available at http://www.epa.gov/oppefed1/models/water/przm_gw/wqtt_przm_gw_guidance.htm (Accessed January 22, 2013).
USEPA. 2013b. Guidance on Modeling Offsite Deposition of Pesticides Via Spray Drift for Ecological and Drinking Water Assessment.  Environmental Fate and Effects Division.  Office of Pesticide Programs.  Office of Chemical Safety and Pollution Prevention. U.S. Environmental Protection Agency. Available at http://www.regulations.gov/#!docketDetail;D=EPA-HQ-OPP-2013-0676 (Accessed April 11, 2014).
USEPA. 2014a. Development of Community Water System Drinking Water Intake Percent Cropped Area Adjustment Factors for use in Drinking Water Exposure Assessments: 2014 Update.  September 9, 2104. Environmental Fate and Effects Division.  Office of Pesticide Programs.  U.S. Environmental Protection Agency. Available at http://www.epa.gov/oppefed1/models/water/ (Accessed March 9, 2015).
USEPA. 2014b. Development of Community Water System Drinking Water Intake Percent Cropped Area Adjustment Factors for use in Drinking Water Exposure Assessments:  2014 Update.  9/9/14. Environmental Fate and Effects Division.  Office of Chemical Safety and Pollution Prevention.  U.S. Environmental Protection Agency. Available at http://www.epa.gov/oppefed1/models/water/Development_and_Use_of_Community_Water_System.pdf (Accessed February 9, 2014).
USEPA. 2014c. Guidance for Addressing Unextracted Residues in Laboratory Studies. Memorandum From to E. F. a. E. Division.  September 12, 2014. Environmental Fate and Effects Division.  Office of Pesticide Programs.  Office of Chemical Safety and Pollution Prevention.   Available at http://www.epa.gov/pesticides/science/efed/policy_guidance/team_authors/environmental_fate_tech_team/Unextracted_Residues_in_Lab_Studies.htm (Accessed March 13, 2015).
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Submitted Studies

Solubility
44651810
Gomyo, T.; Kobayashi, S. (1997) NI-25--Solubility in Organic Solvents: Amended Final Report: Lab Project Number: NISSO 2-83: EC-376-3: 2-83. Unpublished study prepared by Nisso Chemical Analysis Service Co., Ltd. 32 p. 
44651811
Gomyo, T.; Kobayashi, S. (1997) NI-25--Solubility in Water: Amended Final Report: Lab Project Number: NISSO 2-81: EC-377-3: 2-81. Unpublished study prepared by Nisso Chemical Analysis Service Co., Ltd. 37 p. 
Vapor Pressure
44651812
Gomyo, T.; Kobayashi, S. (1997) NI-25--Vapor Pressure: Amended Final Report: Lab Project Number: NISSO 2-79: EC-372-2: 2-79. Unpublished study prepared by Nisso Chemical Analysis Service Co., Ltd. 43 p. 

Dissociation Constant
44651813
Gomyo, T.; Kobayashi, S. (1997) NI-25--Dissociation Constant in Water (pKa): Amended Final Report: Lab Project Number: NISSO 2-88: EC-371-2: 2-88. Unpublished study prepared by Nisso Chemical Analysis Service Co., Ltd. 30 p. 

Oct/Water partition Coef.
44651814
Gomyo, T.; Kobayashi, S. (1997) NI-25--Octanol/Water Partition Coefficient: Amended Final Report: Lab Project Number: NISSO 2-84: EC-378-2: 2-84. Unpublished study prepared by Nisso Chemical Analysis Service Co., Ltd. 34 p. 

Hydrolysis
44651876
Gomyo, T.; Kobayashi, S. (1997) NI-25--Hydrolysis: Amended Final Report: Lab Project Number: NISSO 2-89: EC-375-2: 2-89. Unpublished study prepared by Nisso Chemical Analysis Service Co., Ltd. 126 p. 
44651877
Class, T. (1997) Hydrolysis of IM-1-4 and IC-0 (Two Degradates of Acetamiprid) as a Function of pH: Lab Project Number: P 225 G: B 225 G: 97-32. Unpublished study prepared by PTRL Europe. 24 p. 

Photodegradation-water
44988509
Hausmann, S.; Class, T. (1998) Aqueous Photodegradation of (carbon-14)-Acetamiprid at pH 7 and Determination of Quantum Yield: Lab Project Number: P196G: B196G: 96-82. Unpublished study prepared by PTRL, West PTRL, Europe. 124 p. 
44988510
Emeric, G. (1998) Acetamiprid--Verification of the Identity of the Photolyte Obtained at pH 7--Study: Lab Project Number: 98-47. Unpublished study prepared by Rhone-Poulenc Agro. 36 p. 
44988511
Mamouni, A. (1997) Aqueous Photolysis of (carbon-14)-IM-1-4 Under Laboratory Conditions: Lab Project Number: 671332: 97-166. Unpublished study prepared by RCC Umweltchemie. 64 p. 

Photodegradation-soil
44988508
Mislankar, S. (1998) Acetamiprid (NI-25) Soil Photolysis: Lab Project Number: EC-97-359: F97125-806: EC-97-359-HP. Unpublished study prepared by Rhone-Poulenc Ag Company. 149 p. 

Aerobic soil metabolism
44651879
Feung, C. (1998) Acetamiprid (NI-25): Aerobic Soil Metabolism: Lab Project Number: EC-96-351. Unpublished study prepared by Rhone-Poulenc Ag Company. 122 p. 
44651880
Feung, C. (1998) Acetamiprid (NI-25): Metabolism in Collombey Soil: Lab Project Number: EC-97-406. Unpublished study prepared by Rhone-Poulenc Ag Company. 78 p. 
44651881
Burr, C. (1997) (Carbon 14)-NI-25: Rate of Aerobic Degradation in Three Soil Types at 20 (degrees Centigrade) and One Soil Type at 10 (degrees Centigrade): Lab Project Number: 11256: 201445. Unpublished study prepared by Rhone-Poulenc Agriculture Limited. 213 p. 
44651882
Lowden, P.; Oddy, A.; Jones, M. (1997) NI-25: Rate of Degradation of the Acid Metabolite, (carbon 14)-IC-O in Three Soils: Lab Project Number: 11257: 20147. Unpublished study prepared by Rhone-Poulenc Agriculture Limited. 153 p. 
44699101
Morgenroth, U. (1997) (Carbon 14)-NI-25: Metabolism in One Soil Incubated Under Aerobic Conditions: Lab Project Number: 373994. Unpublished study prepared by RCC Umweltchemie AG. 125 p. 

Anaerobic aquatic metab.
44988512
Feung, C. (1999) Acetamiprid (NI-25): Anaerobic Aquatic Metabolism: Lab Project Number: EC-97-404. Unpublished study prepared by Rhone-Poulenc Ag Co. 128 p. 

Aerobic aquatic metab.
44988513
Andrawes, N. (1999) Acetamiprid (NI-25): Aerobic Aquatic Metabolism: Lab Project Number: EC-96-352. Unpublished study prepared by Rhone-Poulenc Ag Co. 143 p. 

49034201
Degradation in Two Water/Sediment Systems. Unpublished study performed and sponsored by Rhone-Poulenc Agriculture Limited, Essex, UK, and submitted by Nippon Soda Co., Ltd, Tokyo, Japan. Laboratory Project ID.: 11263. Experiment started June 28, 1996, and terminated March 14, 1997 (p. 49). Final report issued June 20, 1997.

Leach/adsorp/desorption
44651883
Liu, A. (1997) Acetamiprid (NI-25): Soil Adsorption/Desorption Study: Lab Project Number: EC-97-381: F97525-001: RP397ACL. Unpublished study prepared by Rhone-Poulenc Ag Company. 180 p. 
44651884
Liu, A. (1997) 6-Chloronicotinic Acid (Acetamiprid Metabolite): Soil Adsorption/Desorption Study: Lab Project Number: EC-97-370: F97525-001: RP397ACL. Unpublished study prepared by Rhone-Poulenc Ag Company. 195 p. 
44651885
Liu, A. (1998) (Carbon 14)-N-methyl-(6-chloro-3-pyridyl)- methylamine IM-1-4 (Acetamiprid Metabolite): Soil Adsorption/Desorption Study: Lab Project Number: EC-97-382: F97525-001: RP397ACL. Unpublished study prepared by Rhone-Poulenc Ag Company. 168 p. 
44651886
Morgenroth, U. (1997) (Carbon 14)-NI-25: Leaching Characteristics of Aged Residues in One Soil: Lab Project Number: 374005. Unpublished study prepared by RCC Umweltchemie Ag. 95 p. 
46255604
Simmonds, M. (2003) (Carbon 14) - Acetamiprid: Aged Residue Column Leaching Study in Two Calcareous Soils. Project Number: CX/02/018, CX02018. Unpublished study prepared by Battelle Agrifood, Ltd. 159 p.

Terrestrial field dissipation
44988514
Norris, F. (1999) Acetamiprid: Terrestrial Soil Dissipation of Acetamiprid Following Applications of EXP 80667A 70WP to Ornamental Crops: Lab Project Number: 45752: 97512637. Unpublished study prepared by Rhone-Poulenc Ag Co. and Agvise, Inc. 798 p. 
44988515
Norris, F. (1999) Acetamiprid: Terrestrial Soil Dissipation of Acetamiprid (EXP 80667A) Under Agricultural Field Conditions Crops: Lab Project Number: 45753: 975126643: 12643-06. Unpublished study prepared by Rhone-Poulenc Ag Co. and ACDS Research, Inc. 788 p. 
44988516
Yang, J. (1999) Method Validation Report for Acetamiprid (NI-25): Performance Summary of Methods of Analysis for NI-25 and its Metabolites IC-0, IM-1-4, and IM-1-2 in US Soil Using LC/MS/MS: Lab Project Number: 45841: 45453: 9752643. Unpublished study prepared by Rhone-Poulenc Ag Co. 572 p. OPPTS 850.7100
44988517
Zheng, S. (1999) Independent Laboratory Validation of Analytical Methods NI-25: Method of Analysis and its Metabolite, IC-0, Using LC/MS/MS; NI-25: Methods of Analysis for IM-1-2 a Metabolite of NI-25 in Soil Using LC/MS/MS; and NI-25: Method of Analysis for IM-1-4, a Metabolite of NI-25, in Soil Using LC/MS/MS: Lab Project Number: 019-016: 98P-019-016: EC-98-447. Unpublished study prepared by Centre Analytical Labs., Inc. 152 p. OPPTS 850.7100 
44988625
Cosgrove, D. (1999) A Terrestrial Field Dissipation Study with Acetamiprid, Canada, 1999: Final Study Report: Lab Project Number: 99086DC: 99001: 99002. Unpublished study prepared by Enviro-Test Lab., Inc. 388 p. 

Dissociation constants in water
46255602
Takashima, K. (2002) Dissociation Constant of IM-1-5. Project Number: NCAS/02/132. Unpublished study prepared by Nisso Chemical Analysis Service Co., Ltd. 18 p.

Photodegradation of parent and degradates in soil
48563501
Sugiyama, K. (2011) Photodegradation of [(Carbon 14)] Acetamiprid on Soil by Artificial Sunlight. Project Number: 2126W. Unpublished study prepared by PTRL West, Inc. 235p.

Aerobic soil metabolism
46255603
Simmonds, M. (2002) (Carbon 14)-Acetamiprid: Rate of Degradation in Three Calcareous Soils at 20 (Degrees) C. Project Number: CX/01/013. Unpublished study prepared by Battelle Agrifood, Ltd. 198 p.

Anaerobic soil metabolism
48554501
Hiler, T. (2011) (Acetamiprid Technical): Anaerobic Soil Metabolism of Carbon 14 Acetamiprid on Two Soil Types. Project Number: 2105W, 2111W. Unpublished study prepared by PTRL West, Inc. 170p.

                                       
                                       
                                       
                                       
                                       

Appendix A.  Selected Modeling Output Files

SELECTED SURFACE WATER MODELING OUTPUT FILES

FIRST

Residues of Acetamiprid Plus Unextracted Residues

RUN No.   1 FOR acetamiprid      ON   bait          * INPUT VALUES * 
   --------------------------------------------------------------------
    RATE (#/AC)   No.APPS &   SOIL  SOLUBIL  APPL TYPE  %CROPPED INCORP
     ONE(MULT)    INTERVAL    Koc   (PPM )   (%DRIFT)     AREA    (IN)
   --------------------------------------------------------------------
  0.082(  1.140)  24   3     227.0 4250.0   GRANUL( 0.0) 100.0   0.0

   FIELD AND RESERVOIR HALFLIFE VALUES (DAYS) 
   --------------------------------------------------------------------
   METABOLIC  DAYS UNTIL  HYDROLYSIS   PHOTOLYSIS   METABOLIC  COMBINED
    (FIELD)  RAIN/RUNOFF  (RESERVOIR)  (RES.-EFF)   (RESER.)   (RESER.) 
   --------------------------------------------------------------------
     39.00        2           0.00   34.00- 4216.00   99.00      96.73

   UNTREATED WATER CONC (MICROGRAMS/LITER (PPB)) Ver 1.1.1  MAR 26, 2008
   --------------------------------------------------------------------
        PEAK DAY  (ACUTE)      ANNUAL AVERAGE (CHRONIC)      
          CONCENTRATION             CONCENTRATION            
   --------------------------------------------------------------------
             81.484                     14.633

   RUN No.   2 FOR acetamiprid      ON   treenuts      * INPUT VALUES * 
   --------------------------------------------------------------------
    RATE (#/AC)   No.APPS &   SOIL  SOLUBIL  APPL TYPE  %CROPPED INCORP
     ONE(MULT)    INTERVAL    Koc   (PPM )   (%DRIFT)     AREA    (IN)
   --------------------------------------------------------------------
  0.180(  0.515)   4  14     227.0 4250.0   AERIAL(16.0) 100.0   0.0

   FIELD AND RESERVOIR HALFLIFE VALUES (DAYS) 
   --------------------------------------------------------------------
   METABOLIC  DAYS UNTIL  HYDROLYSIS   PHOTOLYSIS   METABOLIC  COMBINED
    (FIELD)  RAIN/RUNOFF  (RESERVOIR)  (RES.-EFF)   (RESER.)   (RESER.) 
   --------------------------------------------------------------------
     39.00        2          N/A     34.00- 4216.00    99.00     96.73

   UNTREATED WATER CONC (MICROGRAMS/LITER (PPB)) Ver 1.1.1  MAR 26, 2008
   --------------------------------------------------------------------
        PEAK DAY  (ACUTE)      ANNUAL AVERAGE (CHRONIC)      
          CONCENTRATION             CONCENTRATION            
   --------------------------------------------------------------------
             38.782                      7.107
Residues of Acetamiprid Alone

RUN No.   3 FOR acetamiprid ON   bait    * INPUT VALUES * 
   --------------------------------------------------------------------
    RATE (#/AC)   No.APPS &   SOIL  SOLUBIL  APPL TYPE  %CROPPED INCORP
     ONE(MULT)    INTERVAL    Koc   (PPM )   (%DRIFT)     AREA    (IN)
   --------------------------------------------------------------------
  0.082(  0.141)  24   3     227.0 4250.0   GRANUL( 0.0) 100.0   0.0

   FIELD AND RESERVOIR HALFLIFE VALUES (DAYS) 
   --------------------------------------------------------------------
   METABOLIC  DAYS UNTIL  HYDROLYSIS   PHOTOLYSIS   METABOLIC  COMBINED
    (FIELD)  RAIN/RUNOFF  (RESERVOIR)  (RES.-EFF)   (RESER.)   (RESER.) 
   --------------------------------------------------------------------
      2.40        2          N/A     34.00- 4216.00    24.00     23.86

   UNTREATED WATER CONC (MICROGRAMS/LITER (PPB)) Ver 1.1.1  MAR 26, 2008
   --------------------------------------------------------------------
        PEAK DAY  (ACUTE)      ANNUAL AVERAGE (CHRONIC)      
          CONCENTRATION             CONCENTRATION            
   --------------------------------------------------------------------
              5.881                      0.339.458

                                       
                                       
                       GROUNDWATER MODELING OUTPUT FILES
                          
  
PRZM-GW Output  -  Acetamiprid Plus Unextracted Residues

Groundwater Analysis for Acetamiprid Plus Unextracted Residues and the Wisconsin Corn - WI Central Sands Scenario
Groundwater Analysis for acetamiprid plus unextracted residues for a scatter bait use using the Wisconsin Corn - WI Central Sands Scenario
Estimated groundwater concentrations and breakthrough times for acetamiprid scatter bait use are presented in Table 1 for the Wisconsin Corn - WI Central Sands groundwater scenario. A graphical presentation of the daily concentrations in the aquifer is presented in Figure 1. These values were generated with the PRZM-GW (Version 1.07). Critical input values for the model are summarized in Tables 2 and 3.

Table 1. Groundwater Results for Acetamiprid plus unextracted residues or descriptive information. and the Wisconsin Corn - WI Central Sands Scenario.
Peak Concentration (ppb)
    49.7
Post-Breakthrough Mean Concentration (ppb)
      45
Entire Simulation Mean Concentration (ppb)
    25.8
Average Breakthrough Time (days)
5411.183
Throughputs
2.025435

Table 2. Chemical Properties for Groundwater Modeling of Acetamiprid plus unextracted residues or descriptive information..
Koc (ml/g)
227
Surface Soil Half Life (days)
39
Hydrolysis Half Life (days)
0
Diffusion Coefficint Air (cm2/day)
0.0
Henry's Constant
0.0
Enthalpy (kcal/mol)
0.0

Table 3. Pesticide application scheme used for Acetamiprid plus unextracted residues or descriptive information..  This application scheme was applied every year of the simulation.
Application Days Relative to Emergence Date (05/01)
Application Method
Application Rate
(kg/ha)
0
Ground application with mass distribution increasing proportionally with depth to 4 cm
0.092
3
Ground application with mass distribution increasing proportionally with depth to 4 cm
0.092
6
Ground application with mass distribution increasing proportionally with depth to 4 cm
0.092
9
Ground application with mass distribution increasing proportionally with depth to 4 cm
0.092
12
Ground application with mass distribution increasing proportionally with depth to 4 cm
0.092
15
Ground application with mass distribution increasing proportionally with depth to 4 cm
0.092
18
Ground application with mass distribution increasing proportionally with depth to 4 cm
0.092
21
Ground application with mass distribution increasing proportionally with depth to 4 cm
0.092
24
Ground application with mass distribution increasing proportionally with depth to 4 cm
0.092
27
Ground application with mass distribution increasing proportionally with depth to 4 cm
0.092
30
Ground application with mass distribution increasing proportionally with depth to 4 cm
0.092
33
Ground application with mass distribution increasing proportionally with depth to 4 cm
0.092
36
Ground application with mass distribution increasing proportionally with depth to 4 cm
0.092
39
Ground application with mass distribution increasing proportionally with depth to 4 cm
0.092
42
Ground application with mass distribution increasing proportionally with depth to 4 cm
0.092
45
Ground application with mass distribution increasing proportionally with depth to 4 cm
0.092
48
Ground application with mass distribution increasing proportionally with depth to 4 cm
0.092
51
Ground application with mass distribution increasing proportionally with depth to 4 cm
0.092
54
Ground application with mass distribution increasing proportionally with depth to 4 cm
0.092
57
Ground application with mass distribution increasing proportionally with depth to 4 cm
0.092
60
Ground application with mass distribution increasing proportionally with depth to 4 cm
0.092
63
Ground application with mass distribution increasing proportionally with depth to 4 cm
0.092
66
Ground application with mass distribution increasing proportionally with depth to 4 cm
0.092
69
Ground application with mass distribution increasing proportionally with depth to 4 cm
0.092

Figure 1. Aquifer Breakthrough Curve for Acetamiprid plus unextracted residues or descriptive information. and the Wisconsin Corn - WI Central Sands Scenario

SciGrow version 2.3

Bait Use

SciGrow version 2.3
chemical: acetamiprid
 time is  3/13/2015  13:56:26
 ------------------------------------------------------------------------
  Application      Number of       Total Use    Koc      Soil Aerobic
  rate (lb/acre)  applications   (lb/acre/yr)  (ml/g)   metabolism (days)
 ------------------------------------------------------------------------
      0.082          24.0           1.968      2.51E+02        6.7
 ------------------------------------------------------------------------
 groundwater screening cond (ppb) =   1.89E-02 
 ************************************************************************