The Daileys’ suit, filed in St. Louis County, claims that the defendants have damaged the value of their property, which Robbin Dailey, 61, says they bought for $110,000 in 1999, and moved into with one son. The suit alleges that some samples of dust contained levels of thorium-230 — a radioactive decay product of uranium — that were 200 to 1,000 times greater than “background” levels that can be expected to occur naturally, along with traces of other radioactive elements.

The suit also lists costs of relocation and monitoring the couple’s future health among the damages it seeks to recover, even though they do not have any immediate health concerns they can attribute to the site.

“It’s scary. It’s like living in a state of you don’t know what’s going to happen with your health next,” Michael Dailey said. “How much have I been exposed?”

Representatives of Republic Services, the operator of the landfill and one of the defendants in the suit, maintained that the site and its surroundings are safe.