They've been called "blood phones."

It's a reference to the fact that some metals used to make smartphones and other electronic gadgets are sourced from war-torn areas of the Democratic Republic of the Congo.

Experts say these "conflict minerals" help fuel one of the world's deadliest conflicts. An estimated 5.4 million people have died there from war-related causes, including disease and malnutrition, since 1998, according to the International Rescue Committee.

But according to a report released Thursday by the Enough Project, an advocacy group, metals from the Congo are getting less bloody.

That's thanks in part to the fact that tech companies like Intel, HP, Dell, Microsoft and Apple have made efforts to trace the source of metals used in their devices. An auditing system for smelters, the industrial facilities that process raw metals, also has been put in place. A certification system is in the works that would allow companies to certify some metals from Congo as "conflict free."