NORTHPORT, Wash. — Rose Kalamarides was in her early 20s when she was diagnosed with ulcerative colitis. Her older brother also got the debilitating disease. So did one of her childhood friends, her third-grade teacher and a former classmate at her elementary school.

At the kitchen table of her mother’s home in Northport, Wash., Kalamarides noted a common thread in each diagnosis: People who got sick were from families living downwind and downstream from a smelter in Trail, British Columbia, that funneled pollution through the narrow canyon of the Columbia River.

“When we were kids walking to school, we could smell it in the air,” said Kalamarides, now 56, who grew up about 15 miles from the smelter’s stacks.

The disease cluster in this tiny border town of 296 people has caught the attention of a Harvard Medical School researcher, who thinks it could provide clues for solving a medical mystery.

About 1.4 million people nationwide have ulcerative colitis or Crohn’s disease, a similar inflammatory bowel condition. The illnesses affect about one in every 200 people. Both diseases are believed to have environmental triggers, but despite extensive research the causes have never been identified.

Last year, 119 current and former Northport residents took part in a health survey designed by Dr. Josh Korzenik. Seventeen had confirmed cases of either ulcerative colitis or Crohn’s disease.

“That’s about 10 to 15 times what we’d expect to see in a population the size of Northport,” said Korzenik, director of the Crohn’s and Colitis Center at Brigham and Women’s Hospital, one of Harvard Medical School’s teaching hospitals. “I’m not aware of any other cluster like it.”

Environmental toxins

Researchers have long suspected that environmental toxins play a role in Crohn’s disease and colitis, which have symptoms including abdominal pain and diarrhea. Both illnesses emerged after the Industrial Revolution, when exposure to pollution from coal-fired factories and vehicle emissions became a part of many people’s daily lives.

Northport might help provide some answers.

Korzenik has ruled out a genetic influence in the town’s cluster: Few of the individuals were related. Seven of the 17 cases were people who lived along Mitchell Road, where sulfur dioxide emissions from the smelter killed farmers’ crops in the 1920s and 1930s, leading to an international lawsuit.

For a century, the smelter now owned by the Canadian mining company Teck Resources also dumped millions of tons of waste laden with heavy metals into the Columbia River.

Korzenik plans to expand the health survey to gather information from other communities near Northport. He’s also interested in pursuing funding to explore possible pollution exposures, including looking into whether the smelter’s emissions may have played a role in disease rates. An earlier study he worked on in England showed a mild correlation between rates of inflammatory bowel disease in young adults and certain types of air pollution.

“It’s important for the people of Northport to understand why this is happening — if there’s a particular exposure that’s leading to this extent of the disease in their community. It’s also important for the larger community,” Korzenik said. “Does this hold an important clue? … Then it may hold answers for many other people out there.”

David Godlewski, vice president for Teck American, the U.S. subsidiary of the Canadian company that owns the smelter, declined to comment for this story.