They can invade your home, making you sick and forcing you out. They can stalk you on vacation, turning a dream trip into a nightmare. They are the silent killers – medical and environmental problems that strike without warning, causing serious – and even fatal - illnesses. 48 Hours looks at four of these killers through the eyes of some of their victims. Toxic Mold: Remember Erin Brockovich, the antipollution crusader whose story became an Oscar-winner for Julia Roberts? She has another cause: Her home was invaded by the toxic mold called stachybotrys, which Brockovich says gave her 10-year-old daughter and her husband a variety of ailments. Fatal Flights: On Jan.. 9, 1999, Karen Perkins flew to Belize – a flight of more than nine hours. The next day, Karen, an avid SCUBA diver, went on her first dive. It lasted only minutes, but when she surfaced, she complained of pain and fatigue. As soon as she was back on the boat, and before the crew could help her take off her gear, she was dead. Did she die of blood clots, related to the long flights she took? Death Boats: For Ken and Bambi Lynn Dixey and their four boys, summer vacation has always meant houseboating. But on the night of August 2, 2000, the Dixey's youngest boys, Dillon, 11, and Logan, 8, went for a last swim before bed off the back of the boat. Five minutes later, they were both dead from carbon monoxide poisoning. Danger In The Attic From 1963 to 1990, in the town of Libby, Mon., the W.R. Grace Company mined tons of an ore called vermiculite. It turns out vermiculite contains a contaminant called tremolite, which is a form of asbestos. Now the town must face the consequences.