A Washington Post investigation last year detailed abuses in Congo’s artisanal cobalt supply chain, showing how miners — including children — labored in hazardous, even deadly, conditions. Amnesty International and other human rights groups also have alleged problems. Earlier this week, British broadcaster Sky News published an investigation that alleged continued problems in the cobalt supply chain.

The Post connected this troubling trade to Zhejiang Huayou Cobalt Company, a Chinese firm that is the largest buyer of artisanal cobalt in Congo and whose minerals are used in Apple products.

Last year, Apple pledged to clean up its cobalt supply chain, but the technology giant said it wanted to avoid hurting the Congolese miners by cutting them off. Mining provides vital income for hundreds of thousands of people in what is one of the world’s poorest countries.

Now, Apple says it has stopped — for now — buying cobalt from artisanal mines.