Scenario:
Your older sister is six weeks pregnant with her first child. She and her husband have just returned from a fishing trip on Lake Michigan. While on the trip, they cooked and ate a rainbow trout and a chinook salmon, each about a foot long. They can't remember exactly how many yellow perch they ate. They have brought home a 36" chinook salmon, a couple of dozen small yellow perch, an 18" rainbow trout, and a 27" lake trout.
Your family normally does not eat fish, and your parents have heard that Lake Michigan fish is not safe to eat. They are very concerned about your sister and their first grandchild. Your sister is not concerned because she read that the chemicals which were once a big problem for Lake Michigan fish have been banned. She says it is obvious that the lake is clean because the fishing is so good. Besides, she argues, "If the lake water is safe enough for us to drink, it is safe enough for fish to swim in."
Your parents are still worried. They are clueless about computers. They have asked you to find information so that you can help them advise their daughter whether or not she and her husband should eat the fish.