SUBJECT: Drinking Water Assessment to Support First Fenazaquin (4-tert-butylphenethyl 

quinazolin-4-yl ether) Use on Food Crops PC Code: 044501; DP Barcode: 

394030 ; DECl ~ r 0 N: 444 :ZOO 

TO: 

FROM: 

EXECUTIVE SUMMARY 

The registrant (Gowen) is seeking registration of the first food uses of fenazaquin [GWN-1708F) 

for control of mites and white flies on crops. The food crops include alfalfa, avocado, beans dry, beans succulent, berry crop group, citrus crop group, field and sweet com, cotton, cucurbits, 

fruiting vegetables, grapes, hops, mint, pome fruit crop group, stonefruit crop group, 

strawberries, and tree nut crop group. The proposed new use requests ground, aerial, or 

chemigation spray applications of fenazaquin at a single maximum seasonal application rate of 

0.45 lb ail A. 

The drinking water assessment was conducted using the total toxic residue (TTR) approach. The residues considered in this assessment include fenazaquin (parent),4-(2-(4-(1,1-

imethylethyl)phenyl)ethoxy)quinazolone (Metabolite 1), and 2-Methyl-2-( 4-{ 2-[ (2-oxo-1,2-

dihydroquinazolin-4-yl)oxy]ethyl }phenyl) propanoic acid (Metabolite 2) (HED ROCKS, 

2/23/12). 
average. Tier I ground water modeling indicates the fenazaquin residue concentrations are not expected to exceed 0.0704 J.tg/L for peak and long-term average concentrations. No monitoring 

. data are available to assess fenazaquin concentrations in ground and surface waters. 

PROBLEM FORMULATION 

Fenazaquin is an insecticide with a mitochondrial electron transport (METI) mode of action. The chemical structure of fenazaquin and its degradation products are provided in Figures 1 and 2. Chemical identification and physical chemical properties of fenazaquin are provided in Table 1. 

Figure 1. Chemical Structure of Fenazaquin 

Structure of Metabolite 1 

Structure of Metabolite 2 

Figure 2. Chemical Structure of Fenazaquin Degradation Products 

2 
€h«tmical nam:e 

l!ro~l\b, -

Chemical Abstract Service number 120928-09-8 

Empirical Formula C2oH22N20 

Molecular weight 306.41 glmol Aqueous Solubility 0.102 mg!L 

Vapor Pressure (25°C) 7.2E-7 torr 

Octanol-water partition coefficient (log Kow) 5.7 

Use Characterization 

The registrant (Gowen) is seeking registration for f~od uses of fenazaquin [GWN-1708F] for control of mites and white fly on alfalfa, avocado, beans dry, beans succulent, berry crop group, citrus crop group, field and sweet com, cotton, cucurbits, fruiting vegetables, grapes, hops, mint, pome fruit crop group, stonefruit crop group, strawberries, and tree nut crop group. The proposed new use requests ground, aerial, or chemigation spray applications of fenazaquin at a single maximum seasonal application rate of 0.45 lb ail A. Table 2 provides a summary of the proposed new uses of fenazaquin. 

3 
Crop/Site 

alfalfa, avocado, beans 

dry, beans succulent, 

berry crop group, 

citrus crop group, field 

and sweet com, 

cotton, cucurbits, 

fruiting vegetables, 

grapes, hops, mint, 

pome fruit crop group, 

stonefruit crop group, 

strawberries, and tree 

nut crop group 

Type! Method 

Ground/ AeriaV 

Chemigation 

Environmental Fate Assessment 

Range 

(lba.iJA) 

0.45 

Per Season 

(lba.iJA) 

0.45 

pp

Number 

Fenazaquin is persistent and immobile in terrestrial and aquatic environments. Major routes of 

dissipation include acid catalyzed hydrolysis, microbial-mediated degradation, erosion, and spray 

drift. The half-life for fenazaquin ranged from 51 to 123.8 days in aerobic soil and 58.7 to 

133.3 days in aerobic aquatic environments. The half-life of fenazaquin total toxic residues 

ranged from 73 to 197 days in aerobic soil metabolism studies, and 65 to 291 days in aerobic 

aquatic environments. Degradation products of fenazaquin can be classified according to their 

formation by cleavage of the ether (ethoxy) linkage. This cleavage generates products with only 

the ter-butylphenyl group or the quinazoline group. The quinazoline products form mostly 4-

quinazolinol and 2,4-quinazoline-diol. Linkage intact products are reactions involving the 

quinazoline part of the molecule. Major degradation products(> 10% of applied radioactivity) of 

fenazaquin are 4-(2-(4-(1,1-imethylethyl)phenyl)ethoxy)quinazolone (Metabolite 1), and 2-

Methyl-2-(4-{2-[(2-oxo-1,2-dihydroquinazolin-4-yl)oxy]ethyl}phenyl) propanoic acid 

(Metabolite 2). Organic carbon sorption coefficients of fenazaquin range from 15,800 in sand 

and sandy loam soils to 101,083 in clay loam soil. Because fenazaquin has a low vapor pressure 

(7.2E-7 torr), volatilization is not expected to be a route of dissipation for fenazaquin. Field 

dissipation studies conducted on soils in Germany and Italy showed half-lives from 11-44 days. 

Although degradation products were not identified in the field studies, the route of dissipation 

appeared to be associated with degradation, due to lack of leaching of fenazaquin. The 

bioaccumulation factor for fenazaquin ranged from 390 to 1400, depending on the exposure time 

and exposure concentration. Although fenazaquin has the potential to bioaccumulate, depuration 

of fenazaquin was rapid. 

4 
of residue-bound sediment. Because fenazaquin is moderately persistent in soil with a high soil sorption coefficient, it is not expected to significantly leach into ground water. An illustration highlighting possible environmental dissipation routes is shown in Figure 3. 

Figure 3. Routes of Pesticide Dissipation in the Environment 

Analysis 

The modeling for fenazaquin and its degradation products was conducted using a total residue approach. Tier I groundwater estimated drinking water concentrations (EDWCs) were calculated using SCI-GROW (~creening Concentration in Groundwater, version 2.3, August 8, 2003. Tier II surface water EDWCs were calculated using PRZM ~esticide Root Zone Model, version 3.12.3, June 2006) and EXAMS (EXposure Analysis Modeling ~ystem, version 2.98.04.06, April2005) models in the PES shell. All Tier II surface water modeling was corrected for default percent cropped area (PCA) of 0.87. For additional details on the modeling, refer to http://www.epa.gov/pesticides/science/models pg.htm#aquatic. 

5 
before the maturation date for each PRZM scenario. Pesticide application conditions (i.e., 

method, rate, application interval) were taken from Table 2. The chemical input parameters for 

fenazaquin and its degradation product are shown in Table 4. Tier I FIRST PCA corrected 

EDWCs are shown in Table 5. Tier II PRZM/EXAMS PCA corrected EDWCs are shown in 

Tables 6 and 7. 

T a bl e 3 R t f PRZMJEXAMS Sta d d S p dC 0 0 epresen a 1ve n ar cenanos or ro_p_ose ropso 

Crop Type/Crop Grouping Representative Crop Scenarios 

Alfalfa CA alfalfa, MN alfalfa 

Avocado CA avocado, FL avocado 

Bean MI bean, OR bean 

Berry Group OR berries, 

Corn IL corn, MN corn, OH corn, MS corn, ND corn, KS corn, lA corn, IN corn 

Cotton CA cotton, NC cotton, MS cotton 

Fruiting Vegetables PA veg NMC, CA fruit 

Grapes CA grapes, NY grapes 

Hops OR hops 

Citrus FL citrus, CA citrus 

Mint OR mint 

PomeFruit PA apples, OR apples, NC apples 

Stone Fruit MI cherries, GA peach 

Strawberries CA strawberries, FL strawberries, 

Tree Nut GA Pecans, CA almonds 

6 
Input Parameter -':' Value .J Source ' 

Molecular Weight 306.41 g/mole (parent) Calculated 

Water Solubility 0.1 m giL (parent) Product Chemistry 

Vapor Pressure 7.2 x 10"7 Torr (parent) Product Chemistry 

Hydrolysis 130 days (parent) MRID 47168704 

Aqueous Photolysis 31 days (parent) MRID 47097610 

Aerobic Soil Metabolism 151.7 days\ MRID 47168705 

(mean t112 + (t90 x s)/n112) MRID 48167601 

Aerobic Aquatic Metabolism 249.5 days\ 

(mean t112 + (t90 x s)/n112) 

MRID 48167601 

Anaerobic Aquatic Metabolism Stable MRID 45854821 

Mobility 815 mUg Koc KOCWIN v2.001 

(Metabolite 2) 

1-Because Metabolite 2 has a carboxyhc actd funcuonal group, tt will be toruzed m most envlTOnrnental medta and, therefore, more mobile than fenazaquin. Therefore, the Koc for Metabolite 2 was estimated using KOCWINv2.00. 

Table S: Tier I FIRST PCA 1 corrected Estimated Drinking Concentrations for Fenazaquin and Its D e2ra d' ation Pd ro ucts m 'Sf: ur ace S ource W ater 

Application Method Acute Chronic 

~ 

Ground 17.74 3.11 

Aerial 18.24 3.33 

1 PCA=0.87 

7 
1 in 10 year Concentration 30 year Annual 

Scenario (p:VL> Average 

Peak Annual Average (pgiL) 

CA alfalfa 7.21 3.82 3.05 

MN alfalfa 10.27 3.55 2.83 

CA avocado 5.14 1.11 1.03 

FLavocado 2.75 0.64 0.50 

Mlbean 8.50 2.16 1.64 

OR bean 5.22 1.66 1.33 

OR berries 3.13 1.13 0.89 

ILcorn 14.06 2.77 1.91 

MNcorn 6.77 1.81 1.31 

OHcorn 13.04 2.85 1.82 

MS corn 15.37 3.09 1.85 

NDcorn 4.96 1.54 1.26 

KS corn 18.09 3.48 2.36 

lA corn 12.57 2.16 1.36 

IN corn 10.36 1.86 1.44 

PA vegetables 9.57 2.48 1.67 

CA fruit 4.16 0.91 0.71 

CAgrapes 6.08 1.58 0.95 

NY grapes 5.99 1.66 1.14 

OR hops 6.91 1.80 1.24 

FLcitrus 8.94 1.72 1.08 

CAcitrus 2.83 0.85 0.66 

OR mint 2.81 0.91 0.71 

PAapples 5.20 1.30 0.97 

OR apples 3.18 0.90 0.82 

NC apples 7.75 1.37 0.88 

Mlcherries 5.74 2.09 1.33 

GA peach 4.81 0.92 0.61 

CA strawberries 4.51 1.35 0.97 

FL strawberries 9.99 1.57 0.99 

GApecan 8.54 1.25 0.91 

CAalmond 3.88 1.16 0.97 

MS Cotton 15.71 2.56 1.73 

NC Cotton 11.10 2.59 2.01 

1 PCA=0.87 

8 
y

30 year Annual Scenario (PIVL) Average Peak Annual Average (pg/L) CA alfalfa 5.95 2.73 2.22 

MN alfalfa 8.86 2.52 1.86 

CA avocado 3.92 

0.83 

0.74 

FLavocado 1.31 

0.38 

0.25 

MI bean 8.52 1.99 1.46 

OR bean 4.83 1.42 1.07 OR berries 2.82 

0.88 0.64 

ILcom 13.97 2.70 1.75 

MNcom 5.94 1.64 1.12 

OHcom 12.73 2.72 1.65 

MScom 15.67 3.06 1.77 

NDcorn 4.86 1.30 1.00 

KScom 17.75 3.42 2.25 

!Acorn 12.11 1.98 1.15 

IN corn 10.63 2.14 1.30 PA vegetables 8.72 2.29 1.47 

CAfruit 2.64 0.60 0.38 CAgrapes 4.97 1.28 0.62 NY grapes 5.99 1.66 1.14 

OR hops 6.65 1.62 1.02 

FL citrus 8.93 1.63 0.97 

CA citrus 2.08 0.49 

0.33 

OR mint 2.08 0.67 0.44 PAapples 4.51 1.06 0.73 OR apples 2.34 0.65 0.57 

NC apples 6.89 1.17 

0.66 Mlcherries 5.34 1.85 1.05 

GApeach 3.71 

0.67 

0.35 CA strawberries 

4.62 1.18 0.79 FL strawberries 9.77 1.42 

0.80 GA pecan 8.05 1.13 0.72 

CAalmond 3.88 0.93 0.74 

MS Cotton 15.01 2.50 1.63 

NC Cotton 10.54 2.50 1.89 1PCA=0.87 

9 
2 and 5. The Tier 1 SCI-GROW EDWCs are shown in Table 8. 

Table 8: Tier I SCI-GROW Estimated Drinking Concentrations for Total Toxic Residues 

of Fenazaquin in Ground Source Water from Fenazaquin 

Residues Application Application EDWC 

Rate Number (ugiL) 

lbai/A 

Fenazaquin Residues 1 0.45 1 0.0704 

1- Parent, Metabolite 1, and Metabolite 2 

Monitoring Data 

There are no water monitoring data for fenazaquin in USGS National Water-Quality Assessment 

Program (NA WQA), USEP A/USGS Pilot Reservoir Monitoring Program, USDA Pesticide Data 

Program (PDP), and California Department of Pesticide Regulation (CDPR). 

10