For Razi Khan, a debt of almost $900 has condemned him and his family to years of work in a brick factory in an eastern Afghan city, with little or no hope of ever paying it off.

Khan has eight children. Six of them, including a 4-year-old, toil at the brick factory to pay off a crushing debt that has followed him for the past six years. With a salary of just $6 a day to feed his children and sick wife, it is unlikely he can pay off the debt.

"My heart wants to accomplish more things, such as to educate my children and to make them equal with other people, but unfortunately, I can't do this," Khan said.

When he turned 18, Khan went to work in Iran before returning to Peshawar, a Pakistani city across the border, where he wed in a marriage arranged by his family. He was working in a brick factory in Peshawar when his wife became ill. So he borrowed money from the factory to pay for treatments and feed his growing family.