Under the Securities and Exchange Commission’s conflict minerals rule, public companies are required to track the source of tantalum, tin, gold, and tungsten in their supply chains, an effort to strike against mining operations that finance violent militia groups in the Democratic Republic of the Congo. A push is on to require similar measures for cobalt.

The call for additional supply chain due diligence is made in a new report by Amnesty International that cites a prevalence of child labor in cobalt mining.

“Companies must not simply discontinue a trading relationship with a supplier or embargo DRC cobalt once human rights risks have been identified in the supply chain. They must take remedial action on the harm suffered by people whose human rights were abused,” said Mark Dummett, a business and human rights researcher at Amnesty International.

Cobalt is used as a blue pigment in many paints and is widely used as a component of lithium ion batteries. Its strength and durability has also made it a preferred metal in tool construction, notably drill bits, and for artificial joints and limbs. The Democratic Republic of Congo, targeted by the conflict minerals rule, is also the largest producer of the world's cobalt supply. The Enough Project estimates that 60 percent of that production comes from illegal mines. Unsafe working conditions and child labor have also been cited by the human rights watchdog.

The Amnesty International report charges that major electronics brands “are failing to do basic checks to ensure that cobalt mined by child laborers has not been used in their products.” It documents how traders buy cobalt from areas where child labour is rife and sell it to Congo Dongfang Mining (CDM), a wholly-owned subsidiary of Chinese mineral giant Zhejiang Huayou Cobalt Ltd (Huayou Cobalt). Using investor documents, it makes the claim that the cobalt is then sold to battery makers who claim to supply technology and car companies, including Apple, Microsoft, Samsung, Sony, Daimler, and Volkswagen.

Amnesty International contacted 16 multinational consumer brands listed as direct or indirect customers of the three battery component manufacturers. None said they had traced where the cobalt in their products had come from.

“Many of these multinationals say they have a zero tolerance policy for child labour. But this promise is not worth the paper it is written when the companies are not investigating their suppliers. Their claim is simply not credible,” Dummett says.

Amnesty International also cites worker health and safety concerns, claiming that least 80 artisanal miners died underground in the southern DRC between September 2014 and December 2015 alone. The true figure, it says, is unknown as many accidents go unrecorded and bodies are left buried in the rubble. Children told Amnesty International they worked for up to 12 hours a day in the mines. In 2014 approximately 40,000 children worked in mines across southern DRC, many of them mining cobalt, according to UNICEF.

Citing the conflict minerals rule, the report concludes that “governments must put an end to this lack of transparency,” adding that “without laws that require companies to check and publicly disclose information about where they source minerals and their suppliers, companies can continue to benefit from human rights abuses.”