5 The drinking water at Jims industrial workplace contains 0

5) The drinking water at Jim’s industrial workplace contains 0.07 mg/L arsenic and 0.56 mg/L methylene chloride. Based on his exposure at work, what is his hazard index for non-carcinogenic effects? [Answer: 3.5]

a) If the water at Jim’s home contains 0.05 mg/L arsenic and 0.02 mg/L methylene chloride, what would be the hazard index for Jim’s combined exposure at work and at home? [sum his exposure at work and at home, then compare to RfD, then sum hazard index]

Solution

Harard index (HI) = Chronic daily index (CDI)/ Reference Dose (RfD)

For workplace only:

HI_arsenic = 0.07/(3 x 10^-4) = 0.0233 x 10⁴ = 233

HI_{methylene chloride} = 0.56/(6 x 10^-3) = 0.0933 x 10³ = 93.3

Combined exposure:

HI_arsenic= (0.07 + 0.05)/(3 x 10^-4) = 0.04 x 10^-4 = 400

HI_{methylene chloride} = (0.56 + 0.02)/(6 x 10^-3) = 0.0966 x 10³ = 96.6