Heather MacDougall, the top executive responsible for workplace health and safety at Amazon.com, will leave next month, according to a memo written by John Felton, the company’s head of operations. Ms. MacDougall joined Amazon in 2019 after serving in the Occupational Safety and Health Review Commission. “After building with us for over three years as an important member of our leadership team, Heather has decided to pursue other opportunities outside Amazon,” Mr. Felton wrote. “I want to thank her for her many contributions, and I wish her well on the next step in her journey.”