A pandemic is not inevitable, scientists say. But the outbreak has passed worrisome milestones in recent weeks, including cattle that may have been reinfected.
Levels of PFAS in sewage sludge used as fertilizer can pose risks that sometimes exceed safety thresholds βby several orders of magnitude,β the agency said.
Tiny genetic alterations could help the bird flu virus enter cells in the upper respiratory tract, the C.D.C. said. But there is no sign that mutations are widespread in nature.