WASHINGTON — The Senate on Sept. 16 confirmed Elizabeth Hagen as Undersecretary for Food Safety, making her the top food safety official at the U.S. Department of Agriculture. Prior to her new post Dr. Hagen was the U.S.D.A.’s chief medical officer and a senior executive at the department’s Food Safety and Inspection Service. The Senate also confirmed Catherine Woteki as Undersecretary for Research, Education and Economics. Dr. Woteki, who served as the first Undersecretary for Food Safety from 1997-2001, most recently was global director of scientific affairs at Mars, Inc.