1. Out of 300 workers in a plant manufacturing Gen-X, 23 developed liver cancer. A controlgroup consisting of individuals with smoking histories similar to the plant workers, andwho were unlikely to have encountered Gen-X, had 35 with liver cancers and 510 whodid not develop liver cancer. What is relative risk, attributable risk, and odd ratio?2The

Step 1: Step 2: Step 3: Step 4:

Answered: 1. Out of 300 workers in a plant…

Structural Analysis

6th Edition

ISBN:9781337630931

Author:KASSIMALI, Aslam.

Publisher:KASSIMALI, Aslam.

Chapter2: Loads On Structures

Section: Chapter Questions

Problem 1P

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You are asked to complete an investigation into the efficiency of removal of your toilet. The bowl hold 5 liters of water. When you flush almost all flows out, but some does remain. You inject dye into the bowl at a concentration of 1g/L. The dye that remains (with the water) then dilutes evenly into the water that fills up the bowl after the flush. The concentration after five flushes is 0.313 ug/L (micrograms per liter). How much water (volume) remains in the toilet after each flush?
Determine the individual Hazard Quotients and the overall Hazard Index associated with a 70 kg adult eating 15 g fish every day that contains 9.8 μg/ kg of Arochlor 1254 and 1 mg/kg of Methylmercury? Arochlor 1254 can exhibit noncarcinogenic effects in humans. Methylmercury has been shown to cause developmental neuropsychological impairment in human beings. The RfD for methylmercury is 1x10-4 mg/kg-day and the RfD for Arochlor 1254 is 2 x 10-5. Also, comment on the risk involved, based on the individual Hazard Quotients.
Mainstream smoke inhaled by a 70-kg smoker contains roughly 0.03 mg per cigarette of the class B2 carcinogen, benzo(a) pyrene. For an individual who smokes 20 cigarettes per day for 40 years, estimate the lifetime risk of cancer caused by that benzo(a)pyrene (there are other carcinogens in cigarettes as well).
A house in State College, PA consists of the following: 12 single pane windows (each 10 ft by 1 ft with an R value of 1.86). Calculate the total number of Btus lost for one season through these 12 windows. HDD for State College are 6,000
A student is concerned with the amount of air pollution students are exposed to in the school’s parking lot after school. The student conducts an investigation to compare the quantity of particulate matter released from the diesel-powered buses, natural gas-powered buses, and the large and small cars as they idle waiting to pick up students. To make measurements, a small piece of white fabric is used to collect particulate matter from the tailpipe of each vehicle as it idles for five minutes. Each piece of fabric is then analyzed to measure the amount of particulate matter it collected. (j) The student wants to ensure that the results are reliable. Explain how the student could modify the experimental design to make results of the investigation more reliable.
BOD is 196 mg/I
The Hazard Index criterion is often used for potential health risk associated with a chemical exposure incident. If the MTBE exposure intake is 0.00378 mg/(kg*d) and the oral RfD for MTBE is 0.005 mg/(kg*d), find the HI for an oral exposure in the drinking water system.
A step-dose tracer test was conducted on the clear well of a water treatment plant. A constant fluoride dosage of 2.0 mg/l was added at the inlet starting at time zero, and the fluoride concentrations in the outflow were measured and recorded every 5 or 10 min as listed in the following table. Calculate the C/C0 values, plot C/C0 versus t, and determine t10. (Answer t10 = 22 min) HINT: For 7-59, after you plot C/Co vs. time with Co = 2.0 mg/L, to find t10 you look for the value C/Co = 0.1 and this determines t10 on the graph. t10 is the length of time for 10% of the water entering the tank to discharge from the tank. This time is determined by tracer studies.
The residential drinking water in a small town with a population of 50,000 has been detected to contains 0.5 ppb tetrachloroethylene. There is also a waste incineration plant in the town that emits 0.001 ppb dioxin. Long-term health monitoring of the town yielded the following data: With Disease Without Disease Exposed 72 185 Not exposed 34 560 Show how to calculate the CDI values for the 2 contaminants: (CDI_TCE = 5.86x10-6 mg/kg/d, CDI_Dioxin = 1.17x10-8 mg/kg/d) Show how to calculate the number of cancers caused: 0.01 cases caused by TCE and 91 cases caused by Dioxin
3. Particulate matter (PM) from vehicle exhaust is entering a gym through an open window and mixing with air discharged from the air conditioning system. The air conditioning system discharges 15 m³/s of air with a low PM concentration of only 0.20 mg/m³. The PM concentration in the air entering through the window is 4.50 mg/m³. If the mixed air exiting the gym has a PM concentration of 0.75 mg/m², what is the estimated flow rate of the air entering the window of the gym?
Consider a sample of water contaminated with organic pollution represented by an equivalent sugar concentration of 52 mg/L. Estimate the Theoretical Oxygen Demand
Problem 2. The consumption of nitrates in drinking water is a particular concern for young children. Nitrates are a problem in agricultural areas of the Midwest due to fertilizer runoff. Compare the CDI over a one-year period for a 1-year-old child and an adult female consuming drinking water with a nitrate concentration of 10 mg/1. Use the EPA recommended values shown in Table 3-8.

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