Reference no: EM132449783
1. Identify four possible risk agents in each:
(a) Seafood
(b) Urban air
(c) Drinking water
List their permissible limits, carcinogenic and/or non-carcinogenic effects with proper citation.
2. Tabulate (a) sources (b) cancer slope factors for different pathways; (b) RfD and/or RfC values (if available); and (c) Human health effects from benzene, cadmium, arsenic, dioxin, carbon tetrachloride, and nickel.
3. A health insurance company believes that people can be divided into two classes: those that are affected by some chronic diseases and those that are not. Their statistics show that the chronic diseases person will have a chronic disease at some time within a fixed 1-year period with probability 0.4, whereas this probability decreases to 0.2 for a non-chronic diseases person. If we assume that 30 percent of the populations have chronic diseases, what is the probability that a new policy holder will have a chronic disease within a year of purchasing a policy?
4. Consider the system shown in the following figure which consists of three valves, a pump, a pipeline, and a tank to collect water pumped from the pond. Construct a fault tree corresponding to the top event: "no flow of water into the tank"
3. An industrial complex is located near two towns: town A with 50,000 populations and town B with 35,000 populations. The wind rose diagram based on long-term meteorological records shows that 24% of the time, the wind direction from the industrial complex is towards town A and the remaining time it is towards town B. The statistical data on the chemical release shows that 20% of the time the emission from the industrial complex reaching to the town A is of concern to human health with 40% chances to aggravate respiratory problems. On the other hand, 35% of the time, the emission from the industrial complex reaching to the town B is of concern to human health with 12% chances to aggravate respiratory problems. Draw an event tree diagram with probability number on the nodes. List assumptions are made in your estimate, if any.
4. Water samples collected in a stream on monthly basis were tested for COD for a year shows skewness in the data. The concentration levels in mg/l are as follows: 55, 43, 38, 62, 101, 78, 125, 85, 72, 91, 68, and 31. If log-normal distribution is used, determine the probability if (a) COD level exceeds 70 mg/l; (b) COD level is between 75 mg/l and 85 mg/l; and (c) COD is less than 90 mg/l.