On her deathbed, Sue asked her sister for one thing: to write about the connection between the industrial pollution in their hometown and the rare cancer that was killing her. Fulfilling that promise has been Nancy Nichols' mission for more than a decade. Lake Effect is the story of her investigation. It reaches back to their childhood in Waukegan, Illinois, an industrial town on Lake Michigan once known for good factory jobs and great fishing. Now Waukegan is famous for its Superfund sites: as one resident put it, asbestos to the north, PCBs to the south.   Drawing on her experience as a journalist, Nichols interviewed dozens of scientists, doctors, and environmentalists to determine if these pollutants could have played a role in her sister's death. While researching Sue's cancer, she discovered her own: a vicious though treatable form of pancreatic cancer. Doctors and even family urged her to forget causes and concentrate on cures, but Nichols knew that it was relentless questioning that had led to her diagnosis. And that it is questioning-by government as well as individuals-that could save other lives.   Lake Effect challenges us to ask why. It is the fulfillment of a sister's promise. And it is a call to stop the pollution that is endangering the health of all our families.