Human Health Risk Assessment - Raytheon

non-carcinogenic effects (µg/L)
Risk = Theoretical excess cancer risk (1 x 10 -6 )
BW = Body weight (kg)
ATc = Averaging time for carcinogenic effects (days)
CF = Conversion factor (1000 µg/mg)
IRo = Irrigation water ingestion rate (L/day)
EF = Exposure frequency (days/year)
ED = Exposure duration (years)
CSF = Cancer Slope Factor (Risk per mg/kg-day)
HQ = Hazard Quotient (1.0)
ATn = Averaging time for non-carcinogenic effects (days)
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Human Health Risk Assessment
Exposure factors are summarized in Table 6; toxicity values are presented in Table 8; and
calculated RBSLs are provided in Table 9.
DRAFT
Dermal Contact with Irrigation Water. For residents involved in home gardening activities, it
is assumed that a resident is exposed to irrigation water on average for 1 hour per day, 1 day
per week (50 days per year) for 30 years. During those two hours, it is assumed that the
resident’s head, hands, feet, forearms and lower legs could be exposed to irrigation water. The
RBSL to protect against potential exposures from dermal contact with irrigation water is
calculated according to equation (4-28) for carcinogenic effects and (4-29) for non-carcinogenic
effects.
where:
and
RBSL
RBSL
Derm
Derm
F
Risk ⋅ BW ⋅ ATc
⋅ CF
, c =
(4-28)
F ⋅ EV ⋅ SA ⋅ EF ⋅ ED ⋅CSF
HQ ⋅ BW ⋅ ATn
⋅ CF ⋅ RfD
, n =
(4-29)
F ⋅ EV ⋅ SA ⋅ EF ⋅ ED
=
6 ⋅τ
event ⋅ tevent
π
2 ⋅ FA ⋅ K p
if tevent ≤ t * (4-30)
( ) ⎥ ⎥ ⎡
2
t
⎛
⎞⎤
event 1 + 3B
+ 3B
= FA ⋅ K ⎢ + 2
⎜
⎟ 2
⎢⎣
1 + B ⎝ 1 + B ⎠⎦
F p τ event
if tevent > t * (4-31)
RBSLDerm,c = Risk-Based Screening Level for dermal contact with irrigation
water, carcinogenic effects (µg/L)