Slave labour
According to advocacy groups, there are an estimated 27 million humans in forcible uncompensated labour worldwide, not counting prison labour.
Further, the ILO estimates 250 million children who work every day, many in unsafe conditions such as in mines. Many of these children are effectively slaves insofar as parents authorize their use even in dangerous workplaces. See child labour for a separate analysis of this.
The use of slave labour is banned in all countries by UN Universal Declaration of Human Rights in article 4