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ees3040HW3solns

# ees3040HW3solns - EES 3040 Homework 3 Solutions EES 3040...

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EES 3040 Homework 3 Solutions 1 EES 3040 Homework 3 Solutions Risk Assessment Reading Assignment: D&M1 Chapter 5, pp. 170-186; D&M2 Chapter 6, pp. 222-238 Problems: 1. a.) (4 pts.) Problem 5-1/6-1 Lifetime CDI for occupational exposure to Cr(VI) Given: Conc. = 0.05 mg/m 3 , exposure = 8 hr/d for age 18 to 65, 5 d/wk, 50 wk/yr Exposure = (65-18) = 47 years (0.5 pts.) From Table 6-8, Inhalation rate = ( 15.2 m 3 /d) / (24 hr) = 0.633 m 3 /hr (0.5 pts.) Using the inhalation form of the equation in Table 5-8/6-7: (0.05 mg/m 3 )( 0.633 m 3 /h)(8 h/d)(5 d/wk)(50 wk/y)(47 y) CDI = ---------------------------------------------------------------------- = 1.39 x 10 -3 mg/kg·d ( 78 kg)( 75 y)(365 d) (3 pts.) *For D&M1 Problem 5-1, IR=20m 3 /d, BW=70kg, AT=70yr. So then CDI= 2.2 x 10 -3 mg/kg·d b.) (3 pts.) Problem 5-7/6-8 Hexavalent chromium risk based on Problem 5-1 The slope factor (SF) for Cr(VI) from Table 5-5 is 42 kg · d/mg (1 pt.) From Problem 5-1, CDI = 2.2 x 10 -3 mg/ kg · d. Calculate risk: Risk = (CDI) (SF) (1 pt.) = (1.39 x 10 -3 mg/kg·d)(42 kg·d/mg) = 5.84 x 10 -2 (for D&M1 risk= 9.24 x 10 -2 ) (1 pt.) 2. (8.5 pts.) Problem 5-6/6-7 Estimating chronic daily intake Given: Child consumes water, bathes 10 min/d, and ignore swimming exposure. 1,1,1-trichloroethane in city water. Avg age = 8 years. Exposure time = 5 years. Assume exposure time = averaging time. Use Table 6-8 (from D&M2). Routes/pathways of exposure are: a. Ingestion of drinking water; b. Dermal contact with water during bath; c. Inhalation during bath (ignore); d. Ingestion while swimming (ignore); e. Dermal contact while swimming

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