In April, a Hengdong court agreed to hear the case again. Still, Ms. Mao said she worried that the outcome would be the same.

“Sometimes I lose hope and feel this will never end,” she said. “Nobody wants to take responsibility for what has happened to our children.”

In Dapu, the local government has tried to restore a sense of calm. Officials acknowledge that some children, but no more than 100, showed signs of serious lead poisoning but insist they have all been treated. Tan Zhenli, a propaganda official in Hengdong County, said that all the children were now healthy and that the polluted land had been cleaned.

“It’s old news,” Ms. Tan said. “The factory has been closed. Everything is improving here.”

But Ms. Tan would not allow people in Dapu to speak with reporters unless she was present. Several said the authorities had ordered them not to accept interviews and warned they could be imprisoned for continuing to speak out.

Meilun has relocated to a nearby town, and its old factory in Dapu sits abandoned. Yifei plays nearby, splashing in puddles and pushing a yellow racecar down the sidewalk.

On Tuesdays, he goes to the hospital to check the level of lead in his blood, which was once nine times international standards and remains dangerously high. His condition is mostly unchanged, his parents said, but his memory shows signs of weakening.

“We’re powerless to change our situation,” his father said. “There’s nothing we can do to win.”