Sethoxydim Risk Assessment

Worksheet F06: Consumption of contaminated water by a small mammal, acute exposure scenario for runoff or 
percolation into a stream. [DWAcStrmERA01]. 
Verbal Description: An small mammal consumes stream water contaminated by runoff and/or percolation.  The 
peak levels in water are estimated from modeling or monitoring data and thus dissipation, degradation and 
other environmental processes are implicitly considered.  The calculations involve multiplying the application 
rate by the water contamination rate to get the concentration in ambient water.  This product is in turn 
multiplied by the amount of water consumed per day and then divided by the body weight to get the estimate of 
the absorbed dose. 
Parameters/Assumptions 
Value 
Units 
Source/Reference 
Application Rates (R) 
Central 
0.3 
lb/acre 
APPL.Typ 
Lower 
0.09375 
APPL.Low 
Upper 
0.375 
APPL.Hi 
Peak Water Contamination Rate (rr): 
Central 
0.2 
mg/L per 
AMBWAT.AWPT 
lb/acre
Lower 
0.02 
AMBWAT.AWPL
applied 
Upper 
0.5 
AMBWAT.AWPU 
Body weight (W) 
0.02 
kg 
Allometric coefficients for water consumption in L based on body weight in kg 
a 
0.099 
All mammals. U.S. 
EPA/ORD 1993, Eq. 3-17, p.
b 
0.9 
3-10. 
Water consumed per day (A): a×W
 b 
0.002928 
L 
Concentration in Water (C): R × rr 
Central 
0.06 
mg/L 
These values are used in 
Worksheet G03 for
Lower 
1.88e-03 
characterizing acute risks to 
Upper 
0.1875 
aquatic species. 
Dose estimates (D): C × A ÷ W 
Central 
0.00878 
mg/kg bw/day 
Lower 
0.00027 
Upper 
0.02745 
WS-51  

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Worksheet F07: Consumption of contaminated water by a small mammal, chronic exposure scenario 
[DWChERA01]. 
Verbal Description: A small mammal consumes contaminated ambient water for an extended period of time. 
The levels in water are estimated from modeling or monitoring data and thus dissipation, degradation and other 
environmental processes are implicitly considered.  The calculations involve multiplying the application rate by 
the water contamination rate to get the concentration in ambient water.  This product is in turn multiplied by 
the amount of water consumed per day and then divided by the body weight to get the estimate of the absorbed 
dose. 
Parameters/Assumptions 
Value 
Units 
Source/Reference 
Application Rates (R) 
Central 
0.3 
lb/acre 
APPL.Typ 
Lower 
0.09375 
APPL.Low 
Upper 
0.375 
APPL.Hi 
Water Contamination Rate (rr): 
Central 
0.0008 
mg/L per 
AMBWAT.AWT 
Lower 
0.000020 
lb/acre 
applied 
AMBWAT.AWL 
Upper 
0.0012 
AMBWAT.AWU 
Body weight (W) 
0.02 
kg 
Allometric coefficients for water consumption in L based on body weight in kg 
a 
0.099 
All mammals. U.S. 
b 
0.9 
EPA/ORD 1993, Eq. 3-17, p. 
3-10. 
Water consumed per day (A): a×W
 b 
0.002928 
L 
Concentration in Water (C): R × rr 
Central 
2.40e-04 
mg/L 
Lower 
1.88e-06 
Upper 
4.50e-04 
Dose estimates (D): C × A ÷ W 
Central 
3.51e-05 
mg/kg/day 
Lower 
2.74e-07 
Upper 
6.59e-05 
WS-52  

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Worksheet F08: Consumption of contaminated fish by predatory bird, acute exposure scenario after accidental 
spill. [FishBirdAcute] 
Verbal Description: A predatory bird consumes fish taken from contaminated water after an accidental spill of 
200 gallons of a field solution into a pond that has an average depth of 1 m and a surface area of 1000 m
2
 or 
about one-quarter acre .  No dissipation or degradation is considered.  The assumption is made that 
bioconcentration will reach equilibrium.  This probably will overestimate exposure and subsequent risk. 
Parameters/Assumptions 
Value 
Units 
Source/Reference 
Surface area of pond (SA) 
1000 
m
2 
N/A 
Average depth (DPTH) 
1 
m 
N/A 
Volume of pond in cubic meters (VM) 
1000 
m
3 
N/A 
Volume of pond in Liters (VL) 
1000000 
L 
1 m
3
 = 1,000 L 
Volume of spill (VS) 
200 
gallons 
N/A 
VS
L 
757 
liters 
1 gallon = 3.785 liters 
Concentrations in field solution (FC) 
Central 
3600 
mg/L 
APPL.TypDR×1000 
Lower 
560 
APPL.LowDR×1000 
Upper 
9000 
APPL.Hi_DR×1000 
Concentrations in ambient water (WC): FC × VS
L
 /VL 
Central 
2.7252 
mg/L 
Lower 
0.42392 
Upper 
6.813 
Bioconcentration factor (BCF) 
3.6 
L/kg fish 
CHEM.BCFWA 
Concentrations in fish (C
Fish
): WC × BCF 
Central 
9.81072 
mg/kg fish 
Lower 
1.526112 
Upper 
24.5268 
Fish consumed as a proportion of body weight (P
F
) 
Central 
0.1 
g fish/g bw 
Various species based on 
values  from U.S.
Lower 
0.05 
EPA/ORD (1993). 
Upper 
0.15 
Dose estimates (D) (C
Fish
 × P
F
) 
Central 
9.81e-01 
mg/kg bw/day 
Lower 
7.63e-02 
Upper 
3.68e+00 
WS-53  

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