Leaked documents seen by the Guardian suggest a source of drinking water close to a $1bn (£800m) mining project owned by the Indonesia-based Harita Group on remote Obi Island, was contaminated with unsafe levels of hexavalent chromium (Cr6), the cancer-causing chemical more widely known for its role in the Erin Brockovich story and film.

Cr6 can cause liver damage, reproductive problems and developmental harm when ingested or inhaled. Long-term exposure through drinking water has also been linked to stomach cancer. Evidence has shown that Cr6 in drinking water can be a result of industrial processes.