As it turned out, growing up in Waukegan, Ill., on the shores of Lake Michigan, provided great health risks for Nancy Nichols and her sister Sue.

"Every chemical known dangerous to human health was in one of three toxic sites there," Nancy A. Nichols said.

Her book, "Lake Effect: Two Sisters and a Town's Toxic Legacy," provides considerable evidence that environmental pollution played a role in the ovarian cancer that killed her sister and a rare form of pancreatic cancer that afflicted her.

Island Press published her book in August.

Ms. Nichols will be keynote speaker Sept. 25 at the Heinz Endowments' conference, "Women's Health & the Environment: New Science, New Solutions." The conference at the David L. Lawrence Convention Center already is sold out, but people will be able to see conference speeches on podcasts on www.womenshealthpittsburgh.org.

Publication of Ms. Nichols' book fulfilled a deathbed wish of her sister to investigate whether her ovarian cancer could be linked to industrial pollutions in Waukegan and Lake Michigan. That posed a sizable challenge given the difficulty of tracking a precise cause of cancer, be it genes, lifestyle, environmental exposure, or a combination of the three.

Ms. Nichols said she was aware of such difficulties. Yet she presents convincing proof that Waukegan and Lake Michigan are prime suspects in the sisters' cancers.

"I have no courtroom proof, but I have no doubt either," said Ms. Nichols, now of Boston. "In the book I don't say this caused my cancer. I show the huge amount of evidence, then let readers make their own conclusions."

She said the nation's medical system is not set up to ask why cancers occur and receives no encouragement or support to track down the causes.

For that reason, Ms. Nichols said, her story is universal. Many people live near polluted water, landfills and toxic waste sites. Suspicions about cancer and its causes should compel people to raise questions and do research whether environmental exposures might be a cause.

It's a story "played out time and time again in this country," she said.

"Lots of people are asking questions about asthma, autism and learning disabilities and the environment," Ms. Nichols said. "I wanted to use my story to try to help people think about these issues."

Waukegan has numerous Superfund sites, which the Environmental Protection Agency has earmarked for cleanup. Lake Michigan also is polluted with contaminants including PCBs -- polychlorinated biphenyls that now are banned industrial chemicals that cause cancer, birth defects and illnesses.

"I don't have a legislative agenda, but I think the Great Lakes should be cleaned up because it represents 20 percent of Earth's fresh water supply," Ms. Nichols said

She was diagnosed with a rare form of pancreatic cancer, but after surgery and chemotherapy she said she thinks she is cured. She has not needed further treatment.

People magazine said her book represents "a chilling indictment of how government and big business prize profits over health." It describes "Lake Effect" as "a moving tale of one woman's struggle to understand why."