I happened to catch some of Naomi Campbell's testimony at Charles Taylor's war crimes trial at the Hague about whether the supermodel received 'blood diamonds' from the former Liberian president, broadcast live on Sky News. It says a lot about Sky's news agenda that her entire testimony was live (or almost live, there was a court imposed time delay), and much about the great British public's infatuation with celebrity. When the trial moves on to more serious things like whether Taylor was indeed responsible for the murder of scores of civilians or kept young girls as sex slaves, Sky News and the public, will undoubtedly be long gone.

Anyway, the whole thing got me thinking about my iPhone and iPad. While most of us will, quite rightly, condemn Campbell for allegedly taking these diamonds from a known warlord who is, at the very least, of dubious moral character, we all have in our possession at least one, probably several, devices that potentially have as much blood on them as Campbell's diamonds. At least some of the most important materials used in your mobile, e-reader and computer—gold and the 'three Ts': tungsten, tin and tantalum—have possibly come from the wartorn eastern region of the Democratic Republic of Congo, mined by slave and/or child labour.

Briefly, the war in the DRC began in 1998 and has been the deadliest conflict ever in Africa, with 5.4 million dead. Despite a peace accord in 2003, fighting continues in the Eastern Congo, where the bulk of the country's gold and 'three Ts' mines are. These mines are controlled by paramilitary groups who force children into labour (the World Bank estimates that up to 40% of the mine workers are children under 16). The materials are smuggled out of Eastern Congo, eventually getting to smelting plants in Asia where they are incorporated with materials from other countries and are manufactured into electronic goods.

The Eastern Congo is not an insignificant player. The anti-conflict materials pressure group Enough estimates that 20% of global tantalum—the material manufacturers use to make your mobile vibrate—comes from Eastern Congo. At 6-8%, the area is the 6th largest producer of tin in the world, though a smaller player for tungsten (2-4%), and gold (1%).

Some electronics companies have anti-conflict material policies. Apple, for one, requires its suppliers to say they are not using materials mined illegally from the DRC. The problem is, because of the smuggling and smelting operations, it is difficult to track down where exactly materials come from. Steve Jobs admitted as much in an e-mail to Wired's Brian Cheng: "We require all of our suppliers to certify in writing that they use conflict free materials. But honestly there is no way for them to be sure. Until someone invents a way to chemically trace minerals from the source mine, it’s a very difficult problem."

Other major electronic manufacturers are not as assiduous as Apple, using the difficulty in tracking source materials as a mask to employ a sort of 'don't ask, don't tell' policy. And pressure groups like Enough have disputed that the tracking of materials is so difficult. But the bottom line is when you send a text or read an e-book, it is more likely than not partly courtesy of a child slave labourer, and helps to perpetuate murder and rape (the paramilitaries use the profits to buy more weapons, and control is maintained through killings and sexual violence against women—the DRC has been called by the UN’s special representative on sexual violence in conflict Margot Wallstrom as the 'rape capital of the world').

What can be done? Well, last month the US  government passed a law requiring companies to find out if source materials come from conflict regions. A similar law in the UK would be a start. But there is a role publishers need to play in this. For one, refuse to work with any device manufacturer who doesn't have a conflict material free policy. Or less prescriptive perhaps:  is there scope for a movement like the FSC certification on print books to let the consumer know that the device they are using is conflict-material free?