In Bangladesh, workers wade into muddy, parasite-infested waters near the Sundarban mangrove forests to catch baby shrimp that will later be processed for export. Elsewhere in rural South Asia, they toil in locked buildings, weaving luxury carpets on filthy, ramshackle looms.

These workers, many of them children, often work 14 or more hours a day. They are bonded laborers—essentially, slaves.

According to Siddharth Kara, six out of every 10 slaves in the world—between 18.5 and 22.5 million people—are bonded laborers. Kara, a fellow on forced labor at the FXB Center for Health and Human Rights at Harvard School of Public Health (HSPH) and a fellow on human trafficking at the Carr Center for Human Rights Policy at Harvard Kennedy School, says these slaves work in a wide range of industries: rice, tea, frozen fish and shrimp, carpets, cigarettes, fireworks, construction, brickmaking, minerals and stones, gems, and apparel.

An expert on contemporary slavery, Kara read from his new book,???Bonded Labor: Tackling the System of Slavery in South Asia, and answered questions at a reception celebrating the book’s publication, at HSPH on November 7, 2012. The new book is the second of three Kara is writing about modern slavery. The first, Sex Trafficking: Inside the Business of Modern Slavery, was named co-winner of the prestigious 2010 Frederick Douglass Award at Yale University for the best nonfiction book on slavery.