Amnesty International has accused Apple, Samsung, Sony and other companies of not ensuring their supply lines are free of minerals mined by children.
The human rights group said in a report about the mining of cobalt that children as young as seven are working in dangerous conditions in the Democratic Republic of Congo.
Cobalt is a key mineral used in the making of lithium-ion batteries used in electronic devices, and the DRC produces at least 50 percent of the world’s cobalt.
The tech firms have said they have a zero tolerance policy regarding child labor, but the Amnesty International report claimed miners faced potential long-term health issues and the risk of fatal accidents.
The report said at least 80 miners died underground in southern DRC between September 2014 and December 2015.
“The glamorous shop displays and marketing of state of the art technologies are a stark contrast to the children carrying bags of rocks, and miners in narrow manmade tunnels risking permanent lung damage,” said Mark Dummett, Business and Human Rights Researcher at Amnesty International.
“Millions of people enjoy the benefits of new technologies but rarely ask how they are made,” he added. “It is high time the big brands took some responsibility for the mining of the raw materials that make their lucrative products.”
While exact numbers are hard to come by, UNICEF recently estimated that around 40,000 children work in mines in the southern DRC.
The Amnesty report contains anecdotes from those identified as child miners.
Paul, a 14-year-old orphan, started mining at the age of 12,. He told researchers that cobalt mining left him constantly ill.
“I would spend 24 hours down in the tunnels,” Paul told Amnesty. “I arrived in the morning and would leave the following morning ... I had to relieve myself down in the tunnels … My foster mother planned to send me to school, but my foster father was against it, he exploited me by making me work in the mine.”
Apple said it was very proactively monitoring underage labor.
"Underage labor is never tolerated in our supply chain and we are proud to have led the industry in pioneering new safeguards," the company told the BBC, adding that it conducts rigorous audits of its supply chain.
Sony also told the BBC it was “working with the suppliers to address issues related to human rights and labor conditions at the production sites, as well as in the procurement of minerals and other raw materials."
“Many of these multinationals say they have a zero tolerance policy for child labor. 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,” said Amnesty's Dummett. “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. Governments must put an end to this lack of transparency, which allows companies to profit from misery.”