Observations:

While the Democratic Republic of Congo (DRC) did not make the top 10, they are on the government list for Gold, Tin ore, Tungsten ore, Tantalum ore, Copper, Diamonds, and Cobalt ore. The Dodd-Frank act requires companies to report on 3TG (Gold, Tin, Tungsten, and Tantalum) sourced from the DRC. Further, there are calls for Cobalt (used in lithium ion batteries) to be added to the list.

Corporate social responsibility (CSR) is a corporate “self regulation” that monitors and ensures ethical standards. Companies are encouraged to do this for many ethical reasons, but ultimately, it will help protect their brand reputation. To help companies get started with a CSR program, the Electronics Industry Sourcing Initiative (EICC) has published guide lines for surveying suppliers and includes categories of labor, health&safety, environmental, ethics, and management systems.
A recent development:
In 2016, President Obama signed legislation closing a loophole on products tied to forced/slave labor. While enforcement is complicated, a business (competitor), agency or individual showing reasonable evidence that a product was made (in part) with slave labor, The Labor Department can launch an investigation. The Labor Department has a list of products produced by child/forced labor. Below are the top countries and products from that list that are suspected of using child/forced labor.