In her essay “Inventing Sex Work” (which appears in the anthology Whores and Other Feminists edited by Jill Nagle), Carol Leigh aka Scarlot Harlot wrote that, in 1979 or 1980, she attended a conference in San Francisco by Women Against Violence in Pornography and Media. She had intended to be “a sort of ambassador to this group, educating feminists about prostitution.” However, she discovered that the workshop on prostitution included the phrase “Sex Use Industry.”
“The words stuck out and embarrassed me.” She wrote. “How could I sit amid other women as a political equal when I was being objectified like that, described only as something used, obscuring my role as actor and agent in the transaction?”
Leigh suggested that the title be changed to “Sex Work Industry” as that prioritised the work of the provider rather than the customer. The term stuck and Leigh used it in her one-woman play The Adventures of Scarlot Harlot, which she began performing in 1980.
According to BAYSWAN, the NSWP member group Leigh cofounded, the earliest documented use (printed in mainstream media) of the term "sex worker" as it is currently used was found in an article from the Associated Press Newswire from 1984 about the use of this term in her theatrical production.
“Sex work” came into more common use with the 1987 publication of Sex Work: Writings by Women in the Industry (edited by Frédérique Delacoste and Priscilla Alexander). Since then it has been adopted by health agencies and advocacy organisations around the world, and its use is increasingly used by the mainstream media.
“The usage of the term “sex work” marks the beginning of a movement.” Carol Leigh wrote in her essay. “It acknowledges the work we do rather than defines us by our status.”
Sources: Inventing Sex Work by Carol Leigh; www.bayswan.org