Deborah Leigh Blum (born October 19, 1954) is an American science journalist, and the director of the Knight Science Journalism program at the Massachusetts Institute of Technology. She is the author of several books, including The Poisoner's Handbook (2010) and The Poison Squad (2018), and has been a columnist for The New York Times and a blogger, via her blog titled Elemental, for Wired.

As a science writer for the Sacramento Bee, Blum wrote a series of articles examining the professional, ethical, and emotional conflicts between scientists who use animals in their research and animal rights activists who oppose that research. Titled "The Monkey Wars," the series won the 1992 Pulitzer Prize for Beat Reporting.

The eldest of four daughters, Blum was born in 1954 to Jewish parents in Urbana, Illinois. Her father was entomologist Murray S. Blum and her mother was Nancy Ann Blum, an educator and writer. Deborah grew up in Baton Rouge, Louisiana, Bristol, England, and Athens, Georgia. She graduated from the University of Georgia, where she majored in journalism and was chief editor of the student newspaper, The Red and Black.

Blum worked as a reporter covering police, fires, courts, and other general assignment beats for newspapers in Georgia, Florida and California before she turned to science writing. She was on the staffs of the Macon Telegraph, the St. Petersburg Times and the Fresno Bee, among other publications.

After earning a master's degree in environmental journalism from the University of Wisconsin–Madison, Blum returned to the Fresno Bee, where she became an award-winning environmental reporter. She was the first to report on the alarming incidence of severely deformed waterfowl at the Kesterson National Wildlife Refuge, where poor management of irrigation runoff had polluted the wetland with toxic levels of the element selenium. Her work for the Fresno Bee put the mid-sized paper ahead of much larger regional rivals, including the San Francisco Chronicle and the Los Angeles Times in covering that major environmental story.

In 1984, Blum joined the staff of the Fresno Bee's sister newspaper, the Sacramento Bee, where she broadened her range, covering science subjects. Her series "California: The Weapons Master" was awarded the 1987 Livingston Award for National Reporting. In 1992 the American Association for the Advancement of Science awarded her its AAAS-Westinghouse Award for Science Journalism, also for the "Monkey Wars" series.

Blum expanded the Pulitzer Prize-winning newspaper series into a book of the same title. Her second book, Sex on the Brain examines the biological differences between men and women. In Love at Goon Park, she explores the life and career of groundbreaking psychology researcher Harry Harlow, and in Ghost Hunters she follows a quest by 19th century psychologist-philosopher William James and colleagues to apply objective scientific methods to the study of paranormal phenomena. In The Poisoner's Handbook she explores the pioneering work of two unheralded scientists who paved the way for modern forensic detectives. This book was promoted on Point of Inquiry. She received the James T. Grady-James H. Stack Award for Interpreting Chemistry for the Public from the American Chemical Society in 2015 for this book.

Blum has written, most often about science and its interrelationship with American culture, for publications that have included The New York Times, The Wall Street Journal, The Boston Globe, Time, The Washington Post, the Los Angeles Times, Discover, Psychology Today, Rolling Stone, the Utne Reader, and Mother Jones. In 2013, she began writing "Poison Pen" which appears as a column in The New York Times and as a blog post in the newspaper's online edition. website. After becoming director of the Knight Science Journalism Program, she created and became publisher of a new on-line science magazine, Undark.