There are just over 5,000 people in Rye, New Hampshire. So when Mindi Messmer heard that four of them — all children — had developed an exceedingly rare cancer, she knew something was gravely wrong. Messmer, who had worked as an environmental consultant for 30 years, called Tom Sherman, who was her representative in the state legislature, to discuss what she feared was an environmental crisis.

The call was a first step in bringing the cancers — and, along with them, Messmer — into the public eye. That was in 2014. Within two years, the state Department of Health and Human Services acknowledged that the children’s illnesses constituted a rare official cancer cluster. Maggie Hassan, who was then governor of New Hampshire, set up a task force to investigate what became known as the Seacoast cluster and asked Messmer to join it. And in May 2016, less than a week before the filing deadline, Sherman, who had decided to run for state Senate, suggested that Messmer run for his seat in the state legislature.