The source of the Lead is not officially known ... BUT ... some rural ladies may have solved the mystery. Coal seam gas mining gives off increased amounts of Radon gas which drops as lead after radioactive decay.
The cover up was exposed by use of the US Freedom Of Information Act (FOIA) ... while mainstream media and political parties keep it covered, showing themselves to be agencies captive to medical/vaccine industry influences.
Surviving official records indicate that the activities of the Queensland Native (mounted) Police killed at least 40 000 Originals in 40 years. This is calculated from historical records, researched over many years, by various people. Prof Raymond Evans conservatively extrapolated from officially recorded killings to arrive at over fourty thousand killed.