Some work underground, others pick over tailings; all are running huge risks. But in the town of Huanani, the mines are the only way to support a family

Most nights, under cover of darkness, Sandra* ventures underground into the Huanuni tin mine, about 40 miles (60km) south of the city of Oruro, in Bolivia. She walks for around nine hours collecting about 35kg of rocks containing the mineral before heading back the way she came, hiding from anyone who might be patrolling the tunnels.

She sells what she collects through unofficial channels and typically makes 1,800 to 3,000 Bolivianos (£200 to £330) a week.