1

OFFICE OF

CHEMICAL SAFETY AND 

POLLUTION PREVENTION

UNITED STATES ENVIRONMENTAL PROTECTION AGENCY

WASHINGTON, D.C. 20460

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)

1 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, 
2

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 (PRZMGW) 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 μg/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 

(μg/L)

Bait Scattered on Surfaces

0.082 lbs a.i./A, 24x, 3 day interval, 

ground

Cranberries3

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 μg/L, respectively. 

Previously estimated groundwater concentrations were 0.04 μg/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 
3

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 Act1. Additionally, human health advisories and drinking water 

standards2have not been developed for acetamiprid. Human health benchmarks for Pesticides3(HHBP) 

have been established for acetamiprid, as follows:

 Acute or One-day HHBP = 1000 μg/L (Children)

 Chronic or Lifetime HHBP (Noncancer) = 497 μg/L (General Population)

2 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 upto-date models (PRZM-GW and the Provisional Cranberry Model). Additionally, new aerobic aquatic 

metabolism data (MRID 49034201) were available and used in modeling.

3 ANALYSIS

3.1 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.

 

1 http://iaspub.epa.gov/waters10/attains_nation_cy.control?p_report_type=T#causes_303d

2 http://water.epa.gov/drink/standards/hascience.cfm

3 http://iaspub.epa.gov/apex/pesticides/f?p=HHBP:home:16658387747054:::::
4

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)

4 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 

25oC, but does undergo aqueous photolysis (half-life = 34 days). Based on the low log octanol-water 

partition coefficient (log Kow = 0.08 at 25oC), 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

-cyanoN

1

-methylacetamidine MRID 44651803 None

Molecular Weight 222.68 MRID 44651803 None
5

Parameter Value Source Comments

Water Solubility 4250 mg/L (25°C) MRID 44651811 None

Vapor Pressure

<1 x 10-8 Torr at 25oC MRID: 46235701 Nonvolatile from dry 

non-adsorbing surfaces 

(USEPA, 2010a) 7.50 x 10-10 Torr at 25oC

1 X 10-4 mPa at 25oC

(AERU, 2009)

Henry’s Law 

constant

5.2 x 10-14 atm-m

3

/mol at 25oC

(estimated)

(Estimated from vapor 

pressure

and water solubility at 

pH 7 and 20oC)

Calculated with vapor 

pressure reported by 

AERU (2009).

Dissociation 

Constant (pKa) 0.7 at 25oC (USEPA, 2002) None

Log KOW 0.8 at 25oC MRID 44651883

Not likely to 

bioconcentrate 

(USEPA, 2010a)

1All 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 acetamiprid5

Parameter

Value(s)

Parent (Value for acetamiprid 

plus unextracted residues)

Source Comments

Hydrolysis Halflife3 (days)

Stable (pH 5, 7, 9 at 25oC)

50.8 (pH 9 at 35oC)

12.8 (pH 9 at 45oC)

MRID 

44651876 None

Atmospheric 

Degradation Halflife (days)0.140 (estimated)

(USEPA, 

2009a)

NA

Estimated Hydroxyl Radical Reaction Half-life 

for a 12-hour day; 1.5x106 OH molecules/cm3

Using EPIWeb Version 4.0 

Aqueous Photolysis 

Half-life (days) 342 (pH 7, 25oC) MRID 44988509 None

Soil Photolysis Halflife No half-lives available MRID 

48563501

The study provides evidence on degradation 

products that may be observed with irradiation.

Aerobic Soil 

Metabolism Halflife (days)

20oC:

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.

20oC:

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

20oC:

1.4 (2.0), loamy sand

MRID 

44699101

Foreign soils. Unextracted residues ranged 

from 2 to 17% of applied radioactivity. 
6

Parameter

Value(s)

Parent (Value for acetamiprid 

plus unextracted residues)

Source Comments

25oC:

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 Halflife (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 Halflife or DT50 (days)

25oC:

25 (74), loamy sand sediment

MRID 

44988513 Maximum of 38% unextracted residues. 

20oC:

23 (59, IORE), loam sediment

32 (38, IORE), clay loam sediment 

MRID 

49034201 Maximum of 43% unextracted residues. 

Anaerobic Aquatic 

Metabolism Halflife (days)

25oC:

325 (568), loamy sand sediment

MRID 

44988512 Data available for only one sediment.

Solid-water 

distribution 

coefficient (Kd) in 

L/kg

20oC:

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 solidwater distribution 

coefficient (KF) in 

L/kg

20oC:

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

20oC:

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. 
7

Parameter

Value(s)

Parent (Value for acetamiprid 

plus unextracted residues)

Source Comments

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 μg/kg-soil

Acetamiprid, IM 1-2, IC-0, 1M-1-4

LOQ = 10 μg/kg-soil

HPLC-UV for parent, IC-0, IM 1-4, 

IM 1-2 in water

MRID 

44988536

LOD = 0.033 μg/L

LOQ=0.1 μg/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 40oN 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. 

5 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).4 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). 

 

4

If unextracted residues formed along with loss of the parent compound it is possible that the unextracted residues 

are the parent compound; however, if the parent degraded significantly in the beginning of the study and unextracted 

residues did not form until the end of the study, the unextracted residues are unlikely to be the parent compound.
8

6 DRINKING WATER EXPOSURE MODELING

6.1 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 
9

(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 cranberries5and 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:

  w sed sed b d

ai

w

d d K

m

C

 

3

2

0

10

10 '



 



where,

Cw0 = initial water concentration [μg/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/m3

 

5 Other models may be used to calculate EDWC for use on cranberries (e.g., the Surface Water Concentration 

Calculator and the Pesticides in Flood Agriculture Model). The Provisional Cranberry Model was used because it is 

expected to result in the highest EDWC for this use pattern.
10

This simplifies to:

And, if appropriate:

Kd = 0.01Koc

where: 

Cw=water concentration in μg/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.

6.2 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 
11

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 90th 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 25oC.

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 25oC

Aerobic Aquatic 

Metabolism Half-life 

(days)

Parent: 24

Parent+ Unextracted 

Residues: 99

MRID 44988513, 

49034201

The 90th percentile upper confidence 

bound on the mean of 3 values. Two

values were adjusted to 25oC.

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 25oC.
12

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 90th percentile upper 

confidence bound on the mean of 

3 values. Two values were 

adjusted to 25oC.

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 9. Tier I PRZM-GW input parameters

Parameter (units) Residues Input Value Data Source Comments

Hydrolysis Halflife (days) Parent Stable (0) MRID 

44651876 Hydrolysis half-life at pH 7 and 25oC.

Soil Metabolism 

Half-life at 25oC 

(days)

Parent 2.4 at 25oC MRIDs 

46867004, 

44746001, 

46386605

The 90 percent upper confidence 

bound on the mean of 8 half-life 

values. Values were adjusted to 25oC.

Parent + 

unextracted 

residues

39 at 25oC

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%).

6.3 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 μg/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.
13

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 water1

Use Site Application 

Scenario

EDWC in μg/L 

SCIGROW 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.

7 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.

8 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 
14

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).

9 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.

10 REFERENCES

10.1 Literature Cited

AERU. 2009. The FOOTPRINT Pesticide Properties Database. Agriculture & Environment Research 

Unit (AERU). Available at http://sitem.herts.ac.uk/aeru/footprint/ (Accessed July 9, 2009).

Badriyha, B. N., Ravindran, V., Den, W., & Pirbazari, M. 2003. Bioadsorber efficiency, design, and 

performance forecasting for alachlor removal. Water Research, 37. 

Burns, L. A. 2000. Exposure Analysis Modeling System (EXAMS): User Manual and System 

Documentation. Revision G. EPA/600/R-00/81-023. September 2000. Ecosystems Research 
15

Division. National Exposure Research Laboratory. United States Environmental Protection 

Agency. 

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.

USEPA. 2009a. Estimation Program Interface (EPI) Suite: United States Environmental Protection 

Agency. Available at http://www.epa.gov/oppt/exposure/pubs/episuite.htm (Accessed July 9, 

2009).

USEPA. 2009b. Guidance for Selecting Input Parameters in Modeling the Environmental Fate and 

Transport of Pesticides, Version 2.1. Environmental Fate and Effects Division. Office of 

Pesticide Programs. U.S. Environmental Protection Agency. Available at 

http://www.epa.gov/oppefed1/models/water/input_parameter_guidance.htm (Accessed June 22, 

2014).

USEPA. 2010a. Guidance for Reporting on the Environmental Fate and Transport of the Stressors of 

Concern in the Problem Formulation for Registration Review, Registration Review Risk 

Assessments, Listed Species Litigation Assessments, New Chemical Risk Assessments, and Other 

Relevant Risk Assessments, January 25, 2010. 

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_9sep201

0.html (Accessed March 13, 2015).

USEPA. 2010c. Guidance on Development and Use of the Index Reservoir in Drinking Water Exposure 

Assessments. September 14, 2010. Environmental Fate and Effects Division. Office of Pesticide 

Programs. U.S. Environmental Protection Agency. Available at 

http://www.epa.gov/oppefed1/models/water/index_reservoir_dwa.pdf (Accessed December 9, 

2010).

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_te

am/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 
16

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_Syst

em.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_te

ch_team/Unextracted_Residues_in_Lab_Studies.htm (Accessed March 13, 2015).

USEPA, & Health Canada. 2013. Guidance for Selecting Input Parameters for Modeling Pesticide 

Concentrations in Groundwater Using the Pesticide Root Zone Model. Version 1. October 15, 

2012. Environmental Fate and Effects Division. Office of Pesticide Programs. U.S. 
17

Environmental Protection Agency. Available at 

http://www.epa.gov/oppefed1/models/water/przm_gw/wqtt_przm_gw_input_guidance.htm

(Accessed February 28, 2013).

USNLM. 2009. TOXNET Toxicology Data Network. United States National Library of Medicine 

(USNLM). Available at http://toxnet.nlm.nih.gov/ (Accessed July 9, 2009).

Zhao, X., Hickey, R. F., & Voice, T. C. 1999. Long-term evaluation of adsorption capacity in a 

biological activated carbon fluidized bed reactor system. Water Research, 33(13). 

10.2 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. 
18

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: EC96-351. 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 
19

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 
20

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.
21

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 * 

 --------------------------------------------------------------------
22

 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..
23

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 

0.092
24

cm

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
25

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 

************************************************************************