The water supply of a city is contaminated with PCB at a concentration of 0.2X103mg/L. The oral ingestion Potency Factor for PCB is 7.7(KGMGDAY)1. The exposure factors for residential ingestion of potable water are: IR (intake rate) =2L/ day; ET (exposure time )=30 years; BW (body weight )=70kg; AT (average lifetime) =70 years. (a) What is the CDI? (b) What is the individual lifetime cancer risk for an adult residential consumer? (c) In a city of 1 million people, use this risk assessment to estimate the number of extra cancers per year caused by the PCB in the water supply. (d) Assume the average cancer death rate in the US is 193 per year per 100,000 people. How many cancer deaths would be expected in a city of 1 million people? Do you think the incremental cancers caused by the PCB in the drinking water would be detectable