Updated 09/08/2017

It is estimated by the Global Slavery Index  that 45.8 million people were living in some form of slavery in 2016, of which there may be around 11,700 in the UK. While slavery is illegal throughout the world it still exists in the form of forced labour of children and adults; bonded labour (work in order to repay a debt); sexual exploitation; and forced marriage. While drugs can be sold once, human beings can be sold again and again.
In the developed world most people end up in slavery through human trafficking.