user's guide and background technical document for the nevada ...

Inhalation of Non-carcinogenic Contaminants
Eq.18
where:
mg/kg =
THQ AT
EF ED ET ( 1
) [(
RfC 1 1
) or (
PEF VF )]
THQ = Target hazard quotient of 1
AT = Averaging time (25 years x 365 days/year x 24 hours/day)
EF = Exposure frequency (225 days/year)
ED = Exposure duration (25 years)
ET = Exposure time (8 hours/day)
RfCi = Inhalation reference concentration in (chemical specific) (mg/m 3 )
PEF = Particulate emission factor used for dusts (1.2×10 9 m 3 /kg)
VF = Volatilization factor used for volatile organic chemicals (m 3 /kg)
Skin Contact with Carcinogenic Contaminants
Eq. 19
where:
mg/kg =
TR BW AT 365 days/year
EF ED 10 -6 kg/mg SA AF ABS
TR = Target risk of 10 -6
BW = Body weight of adult (70 kg)
AT = Averaging time of worker (25 years)
EF = Exposure frequency (225 days/year)
ED = Exposure duration of worker (25 years)
SFo = Oral cancer slope factor (chemical specific) (mg/kg-day) -1
SA = Surface area exposed for adult (3300 cm 2 /day)
AF = Adherence factor (0.2 mg/cm 2 )
ABS = Skin absorption (chemical specific)
Skin Contact with Non-carcinogenic Contaminants
Eq. 20
mg/kg =
where:
THQ = Target hazard quotient of 1
THQ BW AT 365 days/year
EF ED 1
10
RfD -6 kg/mg SA AF ABS
17