Sethoxydim Risk Assessment

Worksheet F09: Consumption of contaminated fish by predatory bird, chronic exposure scenario. 
[FishBirdChronic] 
Verbal Description: An predatory bird consumes fish taken from contaminated ambient water for a lifetime. 
The levels in water are estimated from monitoring and modeling data and dissipation, degradation and other 
environmental processes are considered. 
Parameters/Assumptions 
Value 
Application Rates (R) 
Central 
0.3 
Lower 
0.09375 
Upper 
0.375 
Water Contamination Rate (WCR) 
Central 
0.0008 
Lower 
0.00002 
Upper 
0.0012 
Concentration in Water (C): WCR × R 
Central 
0.00024 
Lower 
0.0000019 
Upper 
0.00045 
Bioconcentration factor (BCF) 
21 
Concentrations in fish (FC): C × BCF 
Central 
0.00504 
Lower 
0.000039 
Upper 
0.00945 
Fish consumed as a proportion of body weight (P
F
) 
Central 
0.1 
Lower 
0.05 
Upper 
0.15 
Dose estimates (D): FC × P
F 
Central 
5.04e-04 
Lower 
1.97e-06 
Upper 
1.42e-03 
Units 
lb/acre 
mg/L per 
lb/acre 
applied 
mg/L 
L/kg fish 
mg/kg fish 
g fish/g bw 
mg/kg bw/day 
Source/Reference 
APPL.Typ 
APPL.Low 
APPL.Hi 
AMBWAT.AWT 
AMBWAT.AWL 
AMBWAT.AWU 
These values are used in 
Worksheet G03 to 
characterize the longer-term 
risks to aquatic species. 
CHEM.BCFWhl 
Various species based on 
values  from U.S. EPA/ORD 
(1993). 
WS-54  

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Worksheet F10: Consumption of contaminated vegetation by a large mammal, acute exposure scenario on-site. 
[VGCLMA] 
Verbal Description: A 70 kg herbivore, such as a deer, consumes short grass shortly after application of the 
chemical - i.e. no dissipation or degradation is considered. Caloric requirements are used to estimate food 
consumption. 
Parameters/Assumptions 
Value 
Units 
Source/Reference 
Body weight (W) 
70 
kg 
N/A 
Caloric requirement (KR) 
5226.288 
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, KCD) 
2.46 
kcal/g 
U.S. EPA (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) 
0.37 
kcal/g 
KCD × (1-PW) 
Food consumed per day (wet weight, A) 
14.16338 
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 veg. per 
HK.SGT 
lb/acre applied
Lower 
85 
HK.SGT 
Upper 
240 
HK.SGU 
Conc. in Vegetation (C): R × rr 
Central 
25.5 
mg/kg 
Note: lower value based 
on typical rr and lower R.
Lower 
7.96875 
Upper 
90 
Drift (Drift) 
Central 
1 
unitless 
Direct spray on-site 
Lower 
1 
Upper 
1 
Proportion of Diet Contaminated (Prop) 
Central 
1 
unitless 
Assume grazing 
exclusively on-site.
Lower 
1 
Upper 
1 
Dose estimates (D): Drift × Prop × C × A ÷W 
Central 
5.16e+00 
mg/kg bw 
Lower 
1.61e+00 
Upper 
1.82e+01 
WS-55  

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Worksheet F11a: Consumption of contaminated vegetation by a large mammal, chronic exposure scenario on-
site [VegChLrgMam01]. 
Verbal Description: A 70 kg herbivore, such as a deer, consumes short grass for a 90 day period after 
application of the chemical.  The contaminated vegetation accounts for 10 to 100% of the diet assuming that 
the animal would spend 10 to 100% of the grazing time at the application site.  Because the animal is assumed 
to be on-site, drift is set to unity - i.e., direct spray.  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 (T) 
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, 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) 
14.1633822 
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 
HK.SGT 
Lower 
85 
per lb/acre 
HK.SGU 
Upper 
240 
HK.SGU 
Drift (Drift) 
Central 
1 
unitless 
On-site scenario assumes a 
Lower 
1 
function drift of 1 - i.e., 
direct spray 
Upper 
1 
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-56  

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