Apple, Dell, HP, Huawei, Lenovo, LG, Microsoft, Samsung, Sony, and Vodafone all have connections to child labor in the Democratic Republic of Congo by virtue of their acquisition of cobalt, an element found in lithium-ion batteries, according to a new report.

Artisanal mining for cobalt ore can include children, and working in this business comes with health hazards — exacerbated by poor working conditions, such as a lack of face masks to prevent exposure to dust containing cobalt — according to a report (PDF) today from nonprofit organizations Amnesty International and Afrewatch. Children interviewed during research for the report indicated they were paid the equivalent of $1-2 per day.

One company involved with this type of production of cobalt ore is Congo Dongfang International Mining (CDM), a subsidiary of Huayou Cobalt. Technology companies such as those listed above have an indirect relationship with these entities:

Operating in the DRC since 2006, CDM buys cobalt from traders, who buy directly from the miners. CDM then smelts the ore at its plant in the DRC before exporting it to China. There, Huayou Cobalt further smelts and sells the processed cobalt to battery component manufacturers in China and South Korea. In turn, these companies sell to battery manufacturers, which then sell on to well-known consumer brands.

In the past several years, discussion about developing conflict-free supply chains of metals has focused on four materials: gold, tantalum, tin, and tungsten. With the publication of this report, which focuses on the connections between cobalt mining and big companies that make consumer devices, cobalt will likely have a higher profile in the future.

The organizations behind the report are calling for companies involved in the supply chain to do due diligence on their use of cobalt, and to release information on their use of certain smelters.

Companies named in the report have offered up different responses. For example, here is the one from Apple:

We are currently evaluating dozens of different materials, including cobalt, in order to identify labor and environmental risks as well as opportunities for Apple to bring about effective, scalable and sustainable change. As we gain a better understanding of the challenges associated with cobalt we believe our work in the African Great Lakes region and Indonesia will serve as important guides for creating lasting solutions.

And here is Microsoft’s statement:

Tracing metals such as cobalt up through multiple layers of our supply chain is extremely complex. … Tracking the origin of the cobalt metal in [the different compounds used in Microsoft products] to the precise mining area is extremely challenging. Due to our supply chain complexity and the in-region co-mingling of materials, we are unable to say with absolute assurance that any or none of our cobalt sources can be traced to ore mined in the Katanga region. To create such a tracing mechanism would require a large degree of vertical and cross-industry collaboration.

See the full report for much more detail.