The entire staff of the lead poisoning office at the Centers for Disease Control and Prevention was included in layoffs at the agency last week. And in recent weeks, state water officials have complained that funding for replacing lead pipes had been frozen or delayed. These actions have alarmed public health experts, who worry that decades of progress in eliminating a persistent and preventable threat could be jeopardized. More than 20 employees from the CDC’s Lead Poisoning Prevention and Surveillance Branch were let go as part of a sweeping staff reduction across the Department of Health and Human Services, where more than 10,000 employees were put on administrative leave. The division played a key role in addressing lead contamination in applesauce pouches and in helping communities across the country curb the threat of lead in schools.