Chromium-6: bushfire temperatures of up to 1,000 degrees can endanger human health long after the flames have gone out

"Fire-induced oxidation of Fe oxide-bound Cr(III) may represent a largely unexplored, yet globally-significant pathway for the natural formation of hazardous Cr(VI) in soil." [Burton E.D. el al, April 2019]

Echo NetDaily, 15 January 2020:

Scientists from Southern Cross University have made a startling discovery about the lethal threat of soils scorched by bushfires. 

The team, led by Professor Ed Burton, has found the naturally occurring metal chromium 3 can be converted by extreme bushfire heat into the highly toxic and cancerous chromium 6. 

Professor Ed Burton of Southern Cross Geoscience is looking at the levels of a toxic element in bushfire affected soil. 

Chromium 6 is the substance spotlighted by renowned American environmentalist Erin Brockovich, who blew the whistle on high concentrations in the water supply of her home town in southern California.

Professor Burton’s breakthrough research has confirmed bushfire temperatures of up to 1,000 degrees can endanger human health long after the flames have gone out. 

‘We’ve seen bushfires create conditions in the surface soil that transform the safe, naturally occurring chromium-3 into the toxic, cancer-causing chromium-6,’ Professor Burton said. 

‘Chromium-6 can cause lung cancer and leach into waterways.’ 

Professor Burton, an expert on the geochemistry and mineralogy of soils, sediments and groundwater systems, said frontline firefighters were immediately at risk but the contamination of water within catchment areas posed a wider threat. 

‘We know that firefighters have higher incidences of chromium in their urine and are more susceptible to cancer than other groups....

See the following peer-reviewed articles concerning the carcinogen Chromium-6:

Burton, E.D., Choppala, G., Karimian, N., Johnston, S.G. (2019) A new pathway for hexavalent chromium formation in soil: Fire-induced alterations of iron oxides. Environmental Pollution 247, 618-625; and 

Burton, E.D., Choppala, G., Vithana, C., Hockmann, K., Johnston, S.G. (2019) Chromium(VI) formation via heating of Cr(III)-Fe(III)-(oxy)hydroxides: A pathway for fire-induced soil pollution. Chemosphere 222, 440-444.

It should be noted that wildfires can also affect and possibly increase the mobility of other minerals naturally found in the soil. 

Initial research suggests that an example of this may be the carcinogen, arsenic. Additionally, past research suggests the potential of higher mercury content in freshwater fish after wildfire events.