Bloomberg has a lengthy piece illustrating just how great a challenge it is for Apple and other multinational companies to ensure the fair treatment of workers in complex supply chains.

When one of Apple’s suppliers like Flextronics wins a new contract, it needs to take on additional workers – lots of them, and fast. Those workers are recruited through employment brokers, which are required to adhere to Apple’s rules. But many of them are brought in from other countries, like Malaysia and Nepal.

Workers recruited from neighbouring countries can end up needing to pay several layers of agents and sub-agents for their jobs. Without the cash to do so, they take on loans – and are required to surrender their passports as security. The piece says that Apple’s attempts to deal with this are proving less successful over time.

One worker’s plight is used to illustrate just how badly things can go wrong. 27-year-old Bibek Dhong started work for Flextronics, testing iPhone cameras, already $1000 in debt to agents. When the company hit quality control problems, and was forced to shutdown production, Dhong and his fellow workers were left redundant, in debt and – with their passports held by local agents – no way to get home.

Even when he was eventually allowed home, around a third of his income is used to pay interest on loans for payments on a job he no longer has.

Apple says that it has led the industry in addressing such abuses, and has helped contract workers reclaim $16.4 million since 2008. Flextronics’s Bukit Raja facility is no longer in Apple’s supply chain.