UNITEDSTATES ENVIRONMENTAL PROTECTIONAGENCY WASHINGTON D.C., 20460 OFFICE OF PREVENTION, PESTICIDESAND TOXIC SUBSTANCES PC Code 097805 DP Barcode D335 136 

### MEMORANDUM DATE: 

### April 24, 2007 SUBJECT: 

### Tier I Estimated Drinking Water Concentrations of Deltamethrin for the Use in the Human Health Risk Assessment: 1R-4TolerancePetition for the Use of Deltamethrin on Flax TO: 

### Shaja Brothers, Risk Manager Reviewer Barbara Madden, Team Leader Dan Rosenblatt, Chief Risk Integration Minor Use and Emergency Response Branch Registration Division (7505P) AND: 

### Christina Schwartz, Chief Registration Action Branch I1 Health Effects Division (7509P)

.-. + 

# ,%& ,YLd& 

## )?&&&& FROM: 

### Jose Luis Melendez, Chemist 

# d Environmental Risk Branch V 

### Environmental Fate and Effects Division (7507P) 

## +/

# 25/07 THROUGH: 

### Mah T. Shamim, Ph.D., Chief Environmental Risk Branch V 

### Environmental Fate and Effects Division (7507P) This memo presents the Tier 

### 1Estimated Surface Drinking Water Concentrations and Estimated Ground Drinking Water Concentrations (EDWCs) for deltamethrin, calculated using the Tier I 

### aquatic models FIRST and SCIGROW,respectively, for use in the human health risk assessment. The Estimated Drinking Water Concentrations (EDWCs) for deltarnethrin were calculated based on a maximum application rate of 0.45 lb a.i./A/season. The acute drinking water concentration in surface water is 200ppt of deltamethrin,based on applications of

### the chemical to sweet corn. The cancerlchronic drinking water concentration is 77.1 ppt (based on applications to sweet corn, with the highest applicationrate). The SCIGROW generated EDWC is 200 ppt of deltamethrin, which isrecommended for use, both for acute and chronic exposures. Both, the acute surface

### drinking water concentration, and the ground drinking water concentration were limited by the solubility of deltamethrin. Should there be a need for additional refinements, the EFED can perform a Tier I1 aquatic assessment, for surface waters. Data gaps: All data requirements for terrestrial food uses are satisfied. However, theregistrant submitted a 

### supplemental aerobic aquatic metabolism studythat yielded two very different half lives. The uncertainty lead to a more conservative input in the FIRST model. EXECUTIVE SUMMARY 

### Deltamethrin, CAS Name: 

### (8-cyano(3-phenoxypheny1)methyl (1R,3R)-3-(2,2-dibromoetheny1)- 

### 2,2-dimethylcyclopropanecarboxylate, IUPAC Name: 

### (8-a-cyano-3-phenoxybenzyl (1

### R,3R)-3- 

### (2,2-dibromovinyl)-2,2-dimethylcyclopropanecarboxylate or 

### (8-a-cyano-3-phenoxybenzyl (1



### R)- cis-3-(2,2-dibromovinyl)-2,2-dimethylcyclopropanecarboxylate; CAS No. 52918-63-5, and PC Code 097805, is a syntheticpyrethroid insecticide. Its structurehas three rings, two phenyl rings attached to each other by an oxygen, and a cyclopropyl ring. Thechemistry of deltamethrin may be dictated by its ester moiety. Themolecule has some chiral centers that results in stereoisomers. Chemically, it is the [lR,cis;

### alpha S]-isomer of 8 

### stereoisomeric esters ofthe dibromo analogue of chrysanthemic acid, 

### 2,2-dimethyl-3-(2,2-dibromovinyl)cyclopropanecarboxylic acid (Br2CA)with alpha-cyano-3-phenoxybenzyl alcohol. Deltamethrin is a neural toxic insecticide acting through direct contact and ingestion, having a slight repellent effect. Theprimary biological effects of deltamethrin and other pyrethroids on insects and vertebrates reflect an inhibition ofthe correct firing ofneurotransmitter deliver signals from one cell to another via nerve membrane inhibition ofthe voltage-gated ca2' channels (calcium ion channels) coupled with a stimulatory effect on the voltage-gated ~a' channels (sodiumion channels). All pyrethroids act as axonicpoisons, affecting both the peripheral and central nervous systems, and share similar modes of action. Pyrethroids, including deltamethn, stimulaterepetitive action in the nervous system by binding to voltagegated sodium channels, prolonging the sodium ion permeability during the excitatoryphase of the action potential. This action leads to spontaneousdepolarizations, augmented neurotransmitter secretion rate and neuromuscular block, which ultimately results in paralysis of the insect. In 1997 survey, deltamethrin was used essentially only in the South (Texas) and Southeast, in the cottonbelt. All the use ofthe chemical was due to cotton. Today, various crops are registered for use ofthis chemical. Deltamethrin may be used on corn, sweet corn, sorghum, soybean,pome fruits, and fruiting vegetables among others. Theproposed use under consideration is an IR-4 tolerance petition for the use of deltamethrin on flax. It should be applied at 0.02 lb a.i./A/ application, with a maximum oftwo applications at the maximum label rate, and a 7-day interval. The PHI is 2 1 days. Deltamethrin may be applied by aerial or ground equipment. There are two products that contain deltamethrinn involved in this action: DECISB 0.2 EC Insecticide and DECISB 1.5ECInsecticide. Themodels used in this screening level drinking waters assessment were FIRST v. 1.1.0 and SCIGROW v.2.3, for surface and ground waters, respectively. It was found that, despite the fact that the PCA was only 0.46 for sweet corn (assumed to be the same than for field corn), 2

### compared to the national default of 0.87, it was the worst case scenario, with 16 

### applications, at 0.028 lb a.i.lA1application at 1 

### day interval. Even though some degradates were observed in the laboratory (3-PBA, 3-PBaldehyde, tetramethrinic acid), it was found that they were the result oftherupture of the ester bond ofthe parent molecule. It is believed that the resulting molecules arenot as toxic as theparent because they presumably have lost their mode of action. These transformation products were not modeled. The acute drinking water concentration in surface water is 200 ppt ofdeltamethrin, based on applications of the chemical to sweet corn. The cancerlchronic drinking water concentration is 77.1 

### ppt (based on applications of sweet corn, with the highest application rate). The SCIGROW generated EDWC is200 ppt ofdeltamethrin,which isrecommended for use, both for acute and chronic exposures. All 

### datarequirements for terrestrial food uses are satisfied. However, the registrant submitted a supplemental aerobic aquatic metabolism study that yielded two very different half lives. This caused the input in the model FIRST to be very high and uncertain. A 

### summarytable ofTier 

### I modeled drinking water concentrations is provided in Table 1. 

### Additional refinements ofthe assessment can be developed with higher tier analysis, ifrequested by 

### HED.

PROBLEM FORMULATION

Table 

### 1. Maximum Tier 

### I Estimated DrinkingWater Concentrations (EDWCs) for drinking water assessment based on aerial application ofdeltamethrin.

This 

### is 

### a Tier I 

### drinking water assessment that uses modeling and monitoring data, ifavailable, to estimate the 

### ground water and surface water concentrations of pesticides in 

### drinking water source water (pre-treatment) resulting from pesticide use on sites that are highly vulnerable. This 

### initial tier screens out chemicals wi th 

### 1 

### ow potential risk 

### and provides estimated exposure concentrations for the 

### human health dietary risk 

### assessment.

DRINKING WATER SOURCE (MODEL USED) Groundwater (SCIGROW) Surface water (FIRST) USE (rate modeled) Sweet Corn (0.45 Ib a.i./A) Sweet Corn (0.45 Ib a.i./A) Sweet Corn (0.45 lb a.i.iA) MAXIMUM ESTIMATED DRINKING WATER CONCENTRATION (EDWC) (ppt) Acute and Chronic Acute Chronic 200 200 77.1

### ANALYSIS Use Characterization A 

### summary

### table 

### of all use 

### patterns, 

### highlighting Tier 

### I modeled 

### uses, is 

### illustrated below 

### (Table 2). The new 

### uses arebolded.



### Table 2. Summary use information for deltamethrin, based on DECIS@0.2EC Insecticide (EPA Reg. No. 264-1007) and DECISO 1.5EC Insecticide (EPA Reg. No. 264-1011) USE

('otton ('om. field and POP Corn, sweet Sorghum Soybeans Sunflowers (except Califolnia) Bulb vegetables crop group 3 (garlic.leeks. onion, shallots) Cucurbit crop group 9 cantaloupe, chayote, Chinese waxgourd. citron melon, cucumber, gherkin, gowds, Momordica species, muskmelon, pumpkin, squash, watermelon F~uiting vegetables crop group X (eggplant. ground-cheny, pepinos, peppers. tomatillo. tomato) APP. XETHOD

Aerial or Ground Spray Aerial or Ground Spray Aerial or Ground SP~Y Aerial or Ground Spray Aerial or Ground Spray Aerial or Ground Spray Aerial or Ground Spray
Aerial or Ground SP~Y

Aerial or Ground Spray PreHarvest Interval

(days)

2 1 2 1 1 14 21 21
I

3

1 

### labels. SINGLE APP

## . RATE

(lb a. i

### ./A)

0.030 0.022 0.028 0.022 0.022 0.018
0.028

0.028

0.028 mER OF APPS.

10 5 16 2 -4.5 -2.5

4

6

h SEASONAL APP. RATE (lb a.i./A)
0.3 0.095 0.45 0.045

0.1 0.045
0.112

0.168

0.168 INTERVAL BETWEEN

ApPS. (days)
5 21 I Not Specified Not specified Not specified
5

3

5

### Table 2. Summaryuse information for deltamethrin, based on DECISQ O.2EC Insecticide (EPA Reg. No. 264-1007) andDECISQ 1.5EC Insecticide (EPA Reg. No.For these labels, thepotential application methods are ground and aerial spray (no 

### ULV). Both products have the same offormulation (emulsifiableconcentrate, 

### EC). Thelabels impose certain restrictions (buffer zones) to protect adjacent bodies ofwater, accordingly: 25 

### ft for ground applications, 150

### ft for aerial applications.



### Table 2. Summaryuse information for deltamethrin, based on DECISB 0.2EC Insecticide (EPA Reg. No. 264-1007) andDECISO 1.5EC Insecticide (EPA Reg. No. 264-1011) labels.

Theuse patterns selected for drinking water modeling were sweet corn (highest application rate with smallest application interval) and cucurbit (next highest application rate, and highest PCA with smallest interval between applications). Even though cotton had ahigh application rate, its PCA of 0.20 would cause the surfacewaters to be too low compared to the other two crops. It was suspected that sweet corn would yield higher EDWCs than cucurbits. Themodeling confirmed that sweet corn yielded higher EDWCs. 

### Fate and Transport Characterization A detailed summary ofphysicallchemical and environmental fate1transport properties of deltamethrin, including measured parameters, values, data sources, and comments, is included in Table 3. APP. lrlETHOD

Aerial or Ground Spray

Aerial or Ground Spray USE

I'otne fruits crop group I I (apple. crabapple, loquat. mayhaw. pcar, oriental pear. quince Flax preHarvest Interval

(days)

2 1

I 21 mER OF APPS.

-1.9

2 SINGLE APP 

### . RATE

(lb a.i./A)

0.022

0.02



### '~able 

### 3. SummaryofphysicaVchemica1and environmental fate and transport properties of deltamethrin. SEASO= APP. RATE (lb a.i./A)

0.042

0.04 INTERVAL BETWEEN

APPS

### . (days)

7

7

PARAWETER Chemlcal Name

Molecular We~ght Solublllty (20 C) Vapor Pressure (25 C) SOURCE Deltamethrln

data sheet (web)

LaskOwskl' 2002 Laskowskl, 2002 Laskowskl 2002 VALUE(S) (units) (S) -cyan0(3- phenoxypheny1)methyl (1R. 3R)-3- (2.2- dlbromoetheny1)-2,2-dlmethylcyclopropanecarboxylate 505 2 0 000200 mg/L or

2 00x10 * ppm 9 32 x 10' mmHq COMMENT I -$ hnwh >A A ~L,OL + prc _ues a+ -U c 2/20/07
Laskowskl, 2002 Rev Envlron Contam Toxlcol 174 49-170 Laskowskl, 2002 Rev Envlron Contam Toxlcol 174 49-170 Laskowsk~, 2002 Rev Envlron Contam Toxlcol 174 49-170

### Table3. Summary of properties of deltamethrin. PARAMETER Henry's Law constant pKa I20 C) Octanol-Water Partition Coefficient

K, at 20 C) Hydrolysis Half-life (pH 5, 7, 9; (25 'C)) Aqueous Photolysis Half-life (pH 5) Soil Photolysis HalfI ife

Aerobic Soil Metabolism Half-life

Anaerobic Soil Metabolism Half-life Anaerobic Aquatic Metabolism

Half-life Aerobic Aquatic Metabolism Half -life Organic Carbon Partition, DELTAMETHRIN

Coefficient (K:.) Soil Partition Coefficient, DELTAMETHRIN (K,, ) Organic Carbon Partition, m-phenoxybenzoic Acid

Coefficient (KO,.) Soil Partition Coefficient, m-phenoxybenzoic Acid (Kd) Organic Carbon Partit ion, Br?CA

Coefficient (KC,,) Soil Partition Coefficient, Br-CA (Kn) 

### environmental fate
SOURCE Laskowski, 2002 N A Laskowski, 2002 MRID 41651038

MRID 42114818

MRID 42114819

MRID 41677404, 41677407 MRID 42114821
N/A

MRID 44977005

MRID 41651039, 42475908, 42976501

MRID 41651039, 42475908, 42976501 MRID 44977006

MRID 44977006

MRID 42475908

MRID 42475908 

### physicaYchernica1and VALUE(S) (units) 3.1 x 10~' Atm-m3/mol
N A 4.53
Stable at pH 5 and 7. Half-life of 2.5 days at pH 9. 64 and 84 days for benzyl and gem labels,

respectively The half life was 9 days, but, at the end of the 30 day study, both the irradiated and dark control samples had around the same amount of parent material. Dubbs fine SL and Memphis SiL, half-lives 11-19 days; alkaline Arizona SL half-life 22 and 26 days

Alkaline SL half-lives 32-36 days.
N

A
System I: 25.9 days System 11: 120 days 392000, 577000, 204000, 460000 mL/gp, 3000, 4750. 960, 3790 (Sic11 mL/g
288, 190, 105, 50.7 mL/ g,~
0.668, 1.54, 2.68, 1.34 mL/g 38.2, 46.8, 43.7, 23.0, 10.1 mL/g-,- 0'09' O.ll' 0'36' 0.59' 0.27 mLig 

### and transport
COMraENT Estimated from vapor

pressure and water solubility.

- Laskowski, 2002 Rev. Environ. Contam. Toxicol. 174:49-170

Relatively stable.

Considered stable to photodegradation on soil.

Systems from the Netherlands

Two silt loam soils, a sandy loam, and a silt clay

m-PBA

m-PBA
Decamethrinic acid, RU 23441
Decamethrinic acid, RU 23441When applied to the field, deltamethrin is likely to partition to the soil and organic matter inthe crops; deltarnethrin appears to bind strongly to soil and organic matter, though binding is not instantaneous (~c~~lOO,OOO; immobile). It is not expectedto leach into subsurfaces. It may reach aquatic environments via spray drift or in runoff events accompaniedby erosion. Deltamethn appears to bemoderately to highly persistent in terrestrial environments (aerobic soil metabolism 11-26days; terrestrial field dissipation 14-23 1days). It has the potential to persist in aquatic environments, where it may partition with the sediment andhas thepotential to affect benthic and epibenthic organisms (aerobicaquatic metabolism 26-120 days; anaerobic soil metabolism 32-36 days). Due to its low Henry's Law Constant (3.1 

### x atm-m3/mol), deltamethrin is unlikely to volatilize substantially. - 

### Table 3. 

### Summary ofphysicaYchernica1and environmental fate and transport properties of deltamethrin.

Deltamethrin is relatively stable at pH 5 and 7. However,it rapidly degraded (half-life of2.5 days) at an alkaline pH of 9 to form 

### (1R-cis)-3(2,2-dibromoethyl)-2,2-dimethylcyclopropanecarboxylic acid (Br2CA,<0.15 ug/L) and 3-phenoxybenzaldehyde (3-PBaldehyde,3.42 uglL). It does not appear to photodegrade substantiallyin aqueous solutions (half-lives 64, 84days). Although the soil photolysis study gave a half-life of9 days, considerable degradation was occurring in the dark controls as well. Based on acceptable aerobic soil metabolism data, deltamethrin in Dubbs fine sandy loam and Memphis silt loam soil degraded rapidly (half-life 11-19days) to form DBVA or Br2CA(40%) and C02. Over the 128day incubation period, 62-77% and 52-60%ofthe 14c-cyano-and the I4cphenoxy-labelled parent evolved as I4c02. Theproposed routes of degradation are ester hydrolysis and microbial-mediated mineralization to C02.An additional aerobic soil metabolism studywas submitted for an alkaline Arizona sandy loam (pH 8.1)' which yielded half-lives of22 and 26 days. For the gem label study, Br2CAwas formed, which peaked at 23-26% on day 30 and 14, respectively. It is noted that despite the fact that the pH ofthe latter study was higher, thehalf-lives were higher as well, which was contrary to what was expected from the hydrolysis study. P-TER Terrestrial Field Dissipation

Half-life

Biaccumulation in Fish (BCF)

In an anaerobic soil metabolism study, deltarnethrin degraded in an Arizona sandy loam (pH 8.1) with a half-life of 32-36 days for thebenzyl and gem labels, respectively. For the gem label experiment, only 1 metabolite, Br2CAor decamethrinic acid, was found at 49% ofthe applied 8 SOURCE MRID 42137505, 42773903, 42114822

MRID 43072701, 43072702, 41651040 VALUE(S) (units) Louisiana cotton 231 days, long half-life observed, both for the

bareground and the cropped plot. California cotton 37 d for bareground plot, and

40 d for cropped plot. Minnesota corn 69 d for bareground plot, and 14

days for the cropped plot. 698X whole body, 189X edible portion, depuration was moderately slow (50% between 3-7 days, and 70-758 after 2 weeks COMMENT

One separate study (41651040)provides data on depuration.

### radioactivity by day 30 and remained at about this level on days 59 (52%) and 90 (48%). For the benzyl label, the only metabolite identified was mPBAcid, which was only detected in a day 30 sample, accounting for only 3%ofthe applied radioactivity. In aerobic aquatic metabolism study, consisting of a loam or a sandy loam test systems fi-omthe Netherlands, the half lives forthe whole systems were 26 and 120days, respectively. Themajor transformation product was the a-R-isomer of deltamethrin, at up to 24% in the SL. An anaerobic aquatic metabolism studywould provide additional information on the test system completely anaerobic. In batch equilibrium studies, deltamethrin was found to be immobile (Ko(~>lOO,OOO, FA0 classification) and had Freundlich &'s of 3,790 for a Mississippi SiClL, 3000 for an Arkansas SiL, 4750 for a Georgia SiL, and 960 for a Texas SL. IC,'s ranged from 204000 to 577000. Although deltamethrin istightly bound, adsorptionis not immediate, because equilibrium times were 4-24 hours. In three terrestrial field dissipation studies parent appearednot to bemobile in soil and degraded in 1-2months, except the Louisiana study, where the half-life was almost 8 months. The longer halflife could fall within therange ofnormal field variabilityand the Louisiana soil was the lowest in organicmatter, which would result in the lowest amount of soil binding and soil microbial degradation. No clear pattern ofdegradate formation and decline was seen, possibly because the low application rate and 6" sampling intervals resulted in soil dilution, so degradates were not detected. In fish bioconcentration study, deltamethrinhad bioconcentration factors of 189xand 3630x in edible and visceral fish tissues, respectively. Thewhole body BCF of 698x was calculated from edible and visceral fish tissue results. Themajority ofthe radioactive residue found in fish was parent, accounting for 78 and 83%ofthe total radioactive residue in edible and visceral fish tissues, respectively. No depuration study was done; however, the depuration rate (about 50%between days 3-7 and 70-75% after 2 

### weeks' depuration) from a previous study submitted was considered (MRID#4165 10-40, similar BCF's). Table 4 provides a summary of the various degradation products formed by each process in the studies reviewed. 

### Table 4. 

### Summary ofdegradateformation fromdegradation ofdeltamethrin. STUDY TYPE
Hydrolysis Aqueous Photolysis Soil Photolysis Aerobic Soil Metabolism SOURCE

MRID 41651038

MRID 42114818 MRID 42114819
MRID 41677404, 41677407 DEGRADATE and MAXIMUM CONCENTRATION Br,CA (% applied) ~0.15 ug/L
cis-Br-CAat day 21 trans-Br,CA 53.9% at 30 days 23-268 at 14-30 days mPBA (% applied)

-
11% at day 21

-

- mPBaldehyde (% applied) 3.37 ug/L at 30 days (app. rate 10.0 ug/L)
- a-R-deltamethrin

-

### It appears that m-PBA and m-PBaldehyde arenot verypersistent in the environment. However Br2CAappearsto persist much more than the formercompounds. It was observed in laboratory studies and in the field. These degradates are theresult of the ester rupture in the parent molecule. Another transformationproduct that was observed in various ofthe studies(soil photolysis and aerobic aquatic metabolism)was 

### the a-R-deltarnethrin,an isomer ofdeltamethn. Table4. Summary ofdegradate formation from degradationofdeltamethrin.

Based on batch equilibrium data, a majordegradate, Br2CAor decamethrinic acid, appeared to be mobile (Freundlich &S 

### 4, and IG~~'s=10.1-46.8, FA0classification) in 5 soils. In addition, forthe degradatemPBA, 

### &'s were in the range of0.7-2.7 while the Koc's were in the range of 5

### 1-288 (mobileto moderately mobile, FA0classification). Of these degradates, Br2CAhas the potential to leach to subsurfaces,or to reach adjacent bodies of water via runoff events, most likely dissolvedin the water. DrinkingWater Exposure Modeling SOURCE

MRID 42114821

MRID 44977005

MRID 42137505, 42773903, 42114822 STUDY TYPE

Anaerobic Soil Metabolism

Aerobic Aquatic Metabolism

Terrestrial Field Dissipation



### Models 

### (Ref:1) SCIGROW (v2.3, 8/5/03) (Screening Concentrationin Ground Water) is a regression model used as a screening tool to estimate pesticide concentrations found in ground water used as drinking water. SCIGROW was developedby fitting a linear model to groundwater concentrations with the Relative Index ofLeaching Potential (RILP) as the independent variable. Groundwater concentrations were taken from 90-day average high concentrations from Prospective Ground Water studies; the RILP is a hnction of aerobic soil metabolism and the soil-water partition coefficient. The output of SCIGROW represents the concentrations that might be expected in shallow unconfined aquifers under sandy soils, which is representative ofthe ground water most vulnerableto pesticide contamination likely to serve as a drinking water source. (Ref.2) DEGRADATE and MAXIMUU CONCENTRATION



### FIRST (v 1.1

### .O, 1211

### 8/07) (FQPA Index Reservoir Screening Tool) is a metarnodel of PRZM and EXAMS used as a screening tool to estimate pesticide concentrations found in surface water used as drinking water. FIRST was developedby making multiple runs ofPRZM using varying sorption coefficients and determining the concentration in the EXAMS index reservoir scenario after a two-inch single storm event. (The Index Reservoir is a standard water body used by the Office of Pesticide Programs to assess drinking water exposure mPBaldehyde (% applied)

-
a-R-isomer of deltamethrin 24% at day 14
- Br2CA (% applied)

498 by day 30, and remained at that level through day 90

-
0.5 ppb at 4 days mPBA (% applied)

-

-

-

### (Officeof Pesticide Programs, 2002). It isbased on a real reservoir (albeit not currently in active use as a drinking water supply), Shipman City Lake in Illinois, that isknown to be vulnerable to pesticide contamination.) The singlerunoff event moves a maximum of 8% 

### of the applied pesticide into the reservoir. This amount can be reduced by degradation or effects ofbinding to soil in the field. Additionally, FIRST can account for spray drift and adjusts for the area within a watershed that isplanted with the modeled crop (Percent Cropped Area). Spray drift (modeled as direct deposition of thepesticide into the reservoir) is assumed to be 16%

### ofthe applied active ingredient for aerial application, 6.3% 

### for orchard air blast application, and 6.4% 

### for other ground spray application. Despite being a single event model, FIRST can account for spray drift from multiple applications. The default agricultural Percent Cropped Area (PCA) is 87%. 

### The PRZM scenario used for FIRST development was among the most vulnerable, and thus resulting surface water concentrations represent the upper bound values on the concentrations that might be found in drinking water from the use of a pesticide. (Ref.3 and 4) 

### For volatile and semi-volatile compounds, Tier I modeling will tend to over-estimate surface water EDWCsbecause there are no parameters in FIRST that explicitly take into account volatility (i.e., no vapor pressure or Henry's Law Constant inputs). Therefore, in reality, more ofthe compound will be volatilizingthan Tier 

### I can account for. If drinking water levels of concern are exceeded for over-estimated Tier I surfacewater EDWCs, Tier I1 modeling will be ableto refine these EDWCs by includingvolatility, Henry's Law, diffusion in air, and enthalpy considerations. Since SCIGROW is a regression model developed from actual pesticide data with a range of volatilities, systematic conclusions cannot be drawn about over orunderestimation of groundwater EDWCs at Tier I. Modeling Approach and Input Parameters 

### Tables 5 

### and 6 

### present modeling parameter input values for SCIGROW and FIRST, respectively, based on the current input parameter guidance 

### (Re$ 5). 

### For SCIGROW, the median organic carbon partition coefficient (Koc, 

### of four values), and the mean (offour values) aerobic soil metabolism half-life were used. In FIRST, theparameters selected were as follows: the lowest non-sand organic carbonpartition coefficient was utilized (it was the lowest of all the values). The 

### Koc model was utilized as per SAP recommendation. For the aerobic soil metabolism and the aerobic aquatic metabolism, the 9oth percentile ofthe upper confidence bound on the mean of four and two, respectively, were utilized. Thehydrolysis at pH 7 

### was stablewhile for the aqueousphotolysis, the maximum value was used. Two PCAs were used because modeling of sweet corn and cucurbits were performed. These were the crops suspected to be the ones with the highest EDWCs. The only transformation product included in the modeling isthe a-R-deltamethrin in the aerobic aquatic metabolism. Thehalf-lives derived in the studyincluded the transformation product because it is only an isomer ofdeltamethrin. Other degradates were not included.

## able 6. 

### FIRST (v.1.1.0)input parameter values for deltarnethrinuse on sweet corn1. Table 5. 

### SCI-GROW (v.2.3) input parameter values for deltamethrin use on sweet corn'. PARAMETER (units) Maximum Application Rate (lb a. i
. /A) Number of Applications per Year Organic Carbon Partition Coefficient (K. ; mL/g) Aerobic Soil Metabolism Halflife (days)

PARAMETER (units ) 1 Parameters are selected as per Guidance for Selecting Input Parameters in Modeling the Environmental Fate and Transport of Pesticides; Version 11, February 28, 2002. SOURCE Proposed label Proposed label MRID 41651039, 42475908, 42976501 MRID 41677407 VALve(S)

0.028

16 426000

19.5

Application Rate (lb a.i./A) 0.028 COMMENT
- Represents the worst case scenario for sweet corn. Represents the median value of four values ranging from 204000 to 577000 mL/g for the parent compound. Represents the average value of four

available for the parent compound, ranging from 11 to 26 days.

I I I

VALUE (S) SOURCE Proposed label Number of Applications 16, 6 COMMENT

I I I Proposed label Sweet corn, cucurbit Interval between Applications (days I I I Percent Cropped Area (decimal ) I 1, 3

Soil Partition Coefficient iK,; irnL/g) or KO, (mL/go,) )

Wetted in? 

### I No 

### 1 Proposed label 

### I 0.46, 0.87

Aerobic Soil Metabolism Halflife (days) Proposed label

204000

Method of Application 

# I Asyriay 

# 1 Proposed label 

# I Sweet corn, cucurblt Proposed label

24.7

Depth of Incorporation ( inches Sweet corn, cucurblt MRID 41651039, 42475908, 42976501

Aerobic Aquatlc Metabolism Half-life (days) Represents the lowest non-sand K-, value among four values ranglng from 204000 to 577000 mL/g. The Kc model was utilized as per SAP MRID 41677404, 41677407

0

Solubility in Water @ 20 kc, unbuffered (mg/L or ppm)

Hydrolysis Half-life @ pH 7 (days ) Aquatic Photolysis Half-life

@ pH 7 (days) recommendation. Represents the 90"' percentile of the upper confidence bound on the mean of

four half-life values, mean = 19.5 days; standard deviation = 6.35 days

-

upper confidence bound on the mean of

two half-life values, mean = 73.0; MRID 41651038 Stable. Proposed label

0.0000200 mg/L or 2.00~10-" -

-
I

MRID 42114818

Laskowski, 2002

Maximum value. Laskowski, 2002 Rev. Environ. Contam. Toxicol. 174:49-170The PCAs used were 0.46 for sweet corn (correspondsto corn), and 0.87 for cucurbits. Two values were used because two crops were suspected to yield the highest EDWCs. Options for Tier 1are national scale cotton, wheat, corn, soybeans, or default; regional PCAs are a 

### Tier I1 tool intended for refined assessment. 

### (Ref: 6) 

### Table 6. FIRST (v.1.1.0)inputparameter values for deltamethrin use on sweet corn'.

Modeling Results PARAlaeTER (unit 8)

Table 7 is a summary ofthe modeling results for all model runs. I Parameters are selected as per Guidance for Selecting Input Parameters in Modeling the Environmental Fate and Transport of Pesticides; Version 11, February 28,2002 VALUE (S)



### SCIGROW concentration (ppb)represents the groundwater concentration that might be expected in shallow unconfined aquifers under sandy soils. Output is used,forboth acute and chronic endpoints. SOURCE 

# I COMMENT



### Table 7. 

### Maximum Tier 

### I Estimated DrinkingWater Concentrations (EDWCs)for drinking water risk assessment based on aerial application of deltamethrin.

FIRST concentrations (ppb)represent untreated su~face water concentrations. The one-in-10-yearpeak day concentration is used,foracute endpoints and the one-in-10- year annual average concentration is used,forchronic endpoints. The estimated concentrationsprovided in this assessment are conservative estimates of' concentrations in drinking water. Ifdietary risks require refinement, higher tiered cropspecificand location-specificmodels and modeling scenarios can be used. DRINKING WATER SOURCE (MODEL USED) Groundwater (SCIGROW) Surface water (FIRST)



### Monitoring Data USE (rate modeled) Sweet Corn (0.45 lb a.i./A) Sweet Corn (0.45 lb a.i . /A) Sweet Corn (0.45 lb a.i 

### . /A) MAXIMUM ESTIMATED DRINKING WATER CONCENTRATION (EDWC) (ppt)



### Monitoring data provide different kinds of information than modeling estimates. For 

### example, monitoring data consist of actual information from the 

### field, reflecting current use pattern and usually underestimating frequency of occurrence. Moni toring data does not always include peak values, and inputs for monitoring cannot be 

### adjusted as modeled ones can. In 

### addition, monitoring is 

### often conducted for purposes other than characterizing exposure from a particular pesticide, and as a Acute and Chronic Acute Chronic 200
200 77.1

### consequence is used to complement modeling rather than to refine 

### i t . 

### In general, 

### a useful interpretation of moni toring values requires in-depth assessment of the data, which is beyond the scope of a Tier I 

### assessment. TheNAWQA database was searched and no data were observed. DrinkingWater Treatment 

### It is likely that primary treatment may reduce the levels ofdeltamethn dueto its tendency to bind. However, there is no information available at this time to determine the levels of reduction. Furthermore, the softening of drinking water will generally result in an increase in pH. Deltamethrin is more susceptibleto hydrolysis under alkaline conditions; therefore, softeningmay result in increased dissipation from hydrolysis. (Ref: 8) 

### CONCLUSIONS 

### The acute drinking water concentration in surfacewater is 200 ppt ofdeltamethrin, based on applications ofthe chemical to sweet corn. The cancedchronic drinking water concentration is 77.1 

### ppt (based on applications of sweet corn, with the highest application rate). The SCIGROW 

### generated EDWC is 200 ppt of deltamethrin,which isrecommended for use, both for acute and chronic exposure. No degradates were assessed (except for the transformation product a-R-deltamethrin). It was assumed that deltamethrin was applied to sweet corn at the maximum application rate for 26 consecutive days (theminimum interval between applications). It appearsthat this scenario is unlikely. Thepeak surface water drinking water concentration and the ground drinking water concentration were limited by the solubilitylimit ofdeltamethrin. Theenvironmental fate data base for deltamethrin was complete and consisted of a number of studies,makingthis assessment strong. Theweakness ofthe data base isthe aerobic aquatic metabolism study, which yielded two very different half lives. This study was considered supplemental, with various deficiencies. In addition, it was noted that one terrestrial field dissipation studyyielded also a very different half-life (around 8 

### months vs. around 12months for all the other studies). Despite the weaknesses in the data, the assessment is conservative. Theinput parameter for the aerobic aquatic metabolism was a high value, and made the assessment more conservative. A 

### more definitive assessment can bemade if a Tier I1 

### surface waters assessment isperformed.

### APPENDIX Nomenclature: 

### Deltamethrin = 

### CAS name = 

### (S)-cyano(3-phenoxyphenyl)methy1(1R,3R)-3-(2,2- 

### dibromoethenyl)-2,2-dimethylcyclopropanecarboxylate IUPAC names = 

### (9-a-cyano-3-phenoxybenzyl 

### (lR,3R)-3-(2,2-dibromoviny1)-2,2- dimethylcyclopropanecarboxylate 

### or 

### (5')-a-cyano-3-phenoxybenzyl(1 R)-cis-3-(2,2- 

### dibromovinyl)-2,2-dimethylcyclopropanecarboxylate a-R-isomer of deltamethrin = [l

### R-[I 

### -a-(R*),3-a-]]-3-(2,2-Dibromovinyl)-2,2-dimethylcyclopropanecarboxylic acid, cyano (3-phenoxypheny1)methylester 3-PBA = 

### 3-phenoxybenzoic acid
RU 53605 = [1 

### R-[ 1

### -a-(S*),3-a-]I-3-(2,2-Dibromoviny1)-2 dimethyl-cyclopropanecarboxylic 

### acid, 

### cyano[3-(4-hydroxyphenoxy) phenyll-methyl ester Transformation Product ofhydrolysis, 

### (1R-cis)-3(2,2-dibromoethy1)-2,2-dimethylcyclopropanecarboxylic acid (oneform ofBrzCA) Transformation Product of aerobic soil metabolism, DBVA =

### (3-(2,2-dibromoviny1)-2,2- dimethylcyclopropanecarboxylic 

### acid (one form ofBr2CA)

### Deltamethrin, CAS No. 52918-63-5 Br 

### (S)-alcohol 

### (1~) -cs-ac

### id 

### !,' Br-C 

### 0

m-PBA, m-phenoxybenzoic acid, CAS No. 3739-38-6 0



### m-PBaldehyde, m-phenoxybenzaldehyde, CAS No. 39515-51-0 0

H



### Decamethrinic acid, Br2CA,CAS No. 53179-78-5FIRST 

### and SCIGROW model output files:

RUN No. 1 FOR Deltamethrin ON Sweet Corn * INPUT VALUES *

....................................................................

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

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

.................................................................... .028( .366) 16 1 204000.0 200.0 AERIAL(16.0) 46.0 .O FIELD AND RESERVOIR HALFLIFE VALUES (DAYS)

.................................................................... METABOLIC DAYS UNTIL HYDROLYSIS PHOTOLYSIS METABOLIC COMBINED (FIELD) RAIN/RUNOFF (RESERVOIR) (RES.-EFF) (RESER.) (RESER.)

.................................................................... 24.70 2 N/ A 84.00-10416.00 217.70 213.24 UNTREATED WATER CONC (NANOGRAMS/LITER (PPTr))Ver 1.1.0 DEC 12, 2005

.................................................................... PEAK DAY (ACUTE ) ANNUAL AVERAGE (CHRONIC) CONCENTRATION CONCENTRATION

.................................................................... 200.000 77.120

RUN No. 2 FOR Deltamethrin ON Cucurbit * INPUT VALUES *

....................................................................

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

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

.................................................................... .028( .138) 6 3 204000.0 200.0 AERIAL(16.0) 87.0 .O FIELD AND RESERVOIR HALFLIFE VALUES (DAYS)

.................................................................... METABOLIC DAYS UNTIL HYDROLYSIS PHOTOLYSIS METABOLIC COMBINED (FIELD) RAIN/RUNOFF (RESERVOIR) (RES.-EFF) (RESER.) (RESER.)

.................................................................... 24.70 2 N/ A 84.00-10416.00 217.70 213.24 UNTREATED WATER CONC (NANOGRAMS/LITER (PPTr)) Ver 1.1.0 DEC 12, 2005

.................................................................... PEAK DAY (ACUTE) ANNUAL AVERAGE (CHRONIC) CONCENTRATION CONCENTRATION

.................................................................... 200.000 54.779SCIGROW VERSION 2.3 ENVIRONMENTAL FATE AND EFFECTS DIVISION OFFICE OF PESTICIDE PROGRAMS U.S. ENVIRONMENTAL PROTECTION AGENCY SCREENING MODEL FOR AQUATIC PESTICIDE EXPOSURE SciGrow version 2.3 chemica1:Deltamethrin time is 2/21/2007 12: 9:17

Application Number of Total Use Koc Soil Aerobic rate (lb/acre) applications (lb/acre/yr) (ml/g) metabolism (days) groundwater screening cond (ppb) = 2.69E-03* "Estimated concentrations of chemicals with Koc values greater than 9995 ml/g are beyond the scope of the regression data used in SCI-GROW development. If there are concerns for such chemicals, a higher tier groundwater exposure assessment should be considered, regardless of the concentration returned by SCI-GROW.

........................................................................

References: 1. Policy Establishing Current Versions of Exposure Models and ~esponsibilityfor Model Maintenance (11/06/2002) 2. SCIGROW: Users Manual (11/01/2001, revised 08/23/2002) 3. FIRST Users Manual (08/01/2001) 4. FIRST: A Screening Model to Estimate Pesticide Concentrations in Drinking Water (05/01/2001) 5. Guidance for Selecting Input Parameters in Modeling the ~nvironmental Fate and Transport of Pesticides, Version I1 (02/28/2002) 6. Use of the Index Reservoir and Percent Crop Area in EFED Drinking Water Assessments (12/01/1999) 7. Golf Course Adjustment Factors for Simulated Aquatic Exposure Concentrations (06/01/2005) 8. The Incorporation of Water Treatment Effects on Pesticide Removal and Transformations in Food Quality Protection Act (FQPA) Drinking Water Assessments (10/25/2001) 9. Food and Agriculture Organization of the United Nations. FA0 PESTICIDE DISPOSAL SERIES 8. Assessing Soil Contamination: A Reference Manual. Appendix 2. Parameters of pesticides that influence processes in the soil. Editorial Group, FA0 Information Division: Rome, 2000. ~ttp:www.tac).org DOCPEP 00, ir5 /LIE A25 7OEI)L .nrn

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