Question

A woman lives adjacent to a former manufactured gas plant site. She is at home for approximately 59 hours per week, 47 weeks per year, for 28 years. Vapors from coal tar in the subsurface under her home permeate into her basement and include benzo(a)pyrene at a concentration of 1 μg/m³. She weighs 117 kg, and breathes at a rate of 17 m³/d while at home.

Note: The slope factor for inhalation of benzo(a)pyrene is 6.1 kg·d /mg.

Assuming a target risk of 1 in 10,000, calculate the RBSL for inhalation of benzo(a)pyrene for this woman. Assume an averaging time for carcinogens of 75 years in your calculations:

Select one:

a. 26.7 µg/m^3

b. None of the other answers are correct.

c. 1.09e-4 µg/m^3

d. 0.955 µg/m^3

e. 0.00955 µg/m^3

Answer 1

Ans) We know,

TR = RBSL x IR x EF x ED x SF / [(BW x AT) x 365 days/year x 1000 gm/mg]

where, TR = Target Risk = 1/10000

RBSL= Risk based screening level gm/

IR = Inhalation rate = 17 m3/day

EF = 59 hr/week x 47 weeks/year / 24 hr/day = 115.54 days/year

ED = Exposure durtion in years = 28 years

SF = Slope factor = 6.1 kg d/mg

BW = Body weight = 117 kg

AT = Avearge time = 75 years

Putting all values,

=> = RBSL x 17 x 115.54 x 28 x 6.1 / (117 x 75 x 365 x 1000)

=> = RBSL x 1.047 x

=> RBSL = 0.955 gm/

​​​​​​​ Hence, option D is correct