Sethoxydim Risk Assessment

Worksheet F11a (continued): Consumption of contaminated vegetation by a large mammal, chronic exposure 
scenario on-site. 
Initial Concentration on Vegetation (C
0
): R × rr × Drift 
Central 
25.5 
mg/kg veg. 
Lower 
7.96875 
Upper 
90 
Concentration on Vegetation at time T (C
T
): C
0
 e
-kT 
Central 
2.37e-08 
mg/kg veg. 
Lower 
7.42e-09 
Upper 
8.38e-08 
Time-weighted Average Concentration on Vegetation (C
TWA
): C
0
 (1 - e
-k T
) ÷ (k T) 
Central 
1.22629078 
mg/kg veg. 
Lower 
0.38321587 
Upper 
4.32808512 
Proportion of Diet Contaminated (Prop) 
Central 
0.3 
unitless 
Lower 
0.1 
Upper 
1.0 
Dose estimates (D): C
TWA
 × A × Prop ÷ W 
Central 
7.44e-02 
mg/kg bw/day 
Lower 
7.75e-03 
Upper 
8.76e-01 
WS-57  

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Worksheet F11b: Consumption of contaminated vegetation by a large mammal, chronic exposure scenario off-
site [VegChLrgMam02]. 
Verbal Description: A 70 kg herbivore, such as a deer, consumes range grass for a 90 day period after 
application of the chemical.  The contaminated vegetation accounts for 100% of the diet assuming that the 
animal would spends all of the grazing time near the application site.  Drift is estimated at distances of 25 to 
100 feet from the application site.  Residue estimates based on relationships for range grass.  Caloric 
requirements are used to estimate food consumption.  Dissipation is considered using the foliar halftime and 
taking time-weighted average concentration over the exposure period. 
Parameters/Assumptions 
Value 
Units 
Source/Reference 
Duration of exposure (D) 
90 
days 
N/A 
Body Weight (W) 
70 
kg 
Caloric requirement (KR) 
5226.28803 
kcal/day 
U.S. EPA/ORD (1993, p. 3­
6) 
above based on following equation: kcal/day = 1.518 × W(g)
0.73 
Caloric content of vegetation (dry weight, 
2.46 
kcal/g 
U.S. EPA/ORD (1993, p. 3­
KCD) 
5) 
Water content of vegetation (proportion, PW) 
0.85 
unitless 
U.S. EPA/ORD (1993, p. 4­
14) 
Caloric content of vegetation (wet weight, 
0.37 
kcal/g 
KCD × (1-PW) 
KCW) 
Food consumed per day (wet weight, A) 
14.16 
kg 
(KR ÷ KCW)/1000 g/kg 
Foliar halftimes (t
½
) 
Central 
3 
days 
Worksheet B03 
Lower 
3 
Upper 
3 
Application rates (R) 
Central 
0.3 
lb/acre 
APPL.Typ 
Lower 
0.09375 
APPL.Low 
Upper 
0.375 
APPL.Hi 
Residue rates (rr): 
Central 
85 
mg/kg veg per 
HK.SGT 
Lower 
85 
lb/acre 
HK.SGU 
Upper 
240 
HK.SGU 
Drift (Drift) 
50 feet 
0.0101 
unitless 
Estimated from AgDRIFT 
100 feet 
0.0058 
for low-boom applications. 
See Worksheet A06. 
25 feet 
0.0187 
Decay coefficient (k): ln(2)/t
50 
Central 
0.2310491 
day
-1 
Upper estimate of t
50
 used to 
Lower 
0.2310491 
calculate lower limit of k and 
lower estimate of t
50
 used to 
Upper 
0.2310491 
calculate upper limit of k. 
WS-58  

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Worksheet F11b (continued): Consumption of contaminated vegetation by a large mammal, chronic exposure 
scenario off-site. 
Initial Concentration on Vegetation (C
0
): R × rr × Drift 
Central 
0.25755 
mg/kg veg. 
Lower 
0.0462188 
Upper 
1.683 
Concentration on Vegetation at time T (C
T
): C
0
 e
-kT 
Central 
2.40e-10 
mg/kg veg. 
Lower 
4.30e-11 
Upper 
1.57e-09 
Time-weighted Average Concentration on Vegetation (C
TWA
): C
0
 (1 - e
-k T
) ÷ (k T) 
Central 
0.0123855 
mg/kg veg. 
Lower 
0.002223 
Upper 
0.0809352 
Proportion of Diet Contaminated (Prop) 
Central 
1 
unitless 
Lower 
1 
Upper 
1 
Dose estimates (D): C
TWA
 × A × Prop ÷ W 
Central 
2.51e-03 
mg/kg bw/day 
Lower 
4.50e-04 
Upper 
1.64e-02 
WS-59  

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Worksheet F12: Consumption of contaminated vegetation by a large bird, acute exposure scenario. [VGCLBA] 
Verbal Description: A 4 kg herbivorous bird, such as a Canada Goose, consumes grass shortly after application 
of the chemical - i.e. no dissipation or degradation is considered.  The contaminated vegetation accounts for 
100% of the diet.  Residue estimates based on relationships for short grass summarized in Worksheet A05. 
Parameters/Assumptions 
Value 
Units 
Source/Reference 
Body weight (W) 
4 
kg 
N/A 
Caloric requirement (KR) 
467.5185 
kcal/day 
U.S. EPA/ORD (1993, 
Eq. 3-35, p. 3-22) 
above based on following equation: kcal/day = 3.12 × W(g)
0.604 
Caloric content of vegetation (dry weight, KCD) 
2.46 
kcal/g 
U.S. EPA/ORD (1993, p. 
3-5) 
Water content of vegetation (proportion, PW) 
0.85 
unitless 
U.S. EPA/ORD (1993, p. 
4-14) 
Caloric content of vegetation (wet weight, KCW) 
0.369 
kcal/g 
KCD × (1-PW) 
Food consumed per day (wet weight, A) 
1.266988 
kg 
(KR ÷ KCW)/1000 g/kg 
Duration of exposure (T) 
1 
day 
N/A 
Application rates (R) 
Central 
0.3 
lb/acre 
APPL.Typ 
Lower 
0.09375 
APPL.Low 
Upper 
0.375 
APPL.Hi 
Residue rates (rr) 
Central 
85 
mg/kg 
HK.SGT 
Lower 
85 
vegetation per 
lb/acre applied 
HK.SGT 
Upper 
240 
HK.SGU 
Conc. in Vegetation (C): [R×rr] 
Central 
25.5 
mg/kg 
Note: lower value based 
Lower 
7.96875 
on typical rr and lower R. 
Upper 
90 
Drift (Drift) 
Central 
1 
unitless 
Direct spray on-site 
Lower 
1 
Upper 
1 
Proportion of Diet Contaminated (Prop) 
Central 
1 
unitless 
Assume feeding 
Lower 
1 
exclusively on-site. 
Upper 
1 
Dose estimates (D): Drift × Prop × C × A ÷ W 
Central 
8.08e+00 
mg/kg bw 
Lower 
2.52e+00 
Upper 
2.85e+01 
WS-60  

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