Bendigo and other parts of Victoria were centres of large goldmining activity in the 1800s and early 1900s. A byproduct of these operations were mine wastes such as calcined sand and grey sands.

Mining wastes can contain arsenic, lead and other contaminants that can be harmful to your health.  However, just because arsenic is in the environment, does not mean people will be exposed at harmful levels.

The Victorian Government funded EPA to investigate the ‘ambient’ or background level of arsenic in the region. We have also investigated the  bioavailability of arsenic in mine waste.

Arsenic bioavailability represents how much of a chemical is available to be absorbed by a person if they ingest it. The more bioavailable a chemical is, the more it can be absorbed into the body and cause harm. A chemical’s bioavailability is found by measuring its bioaccessibility. This indicates how much arsenic could be absorbed by our gut.

We wanted to find a regional bioavailability factor for mine wastes in the Goldfields region. This would help to develop health investigation levels (HILs) specific to the region. It would also support contaminated land practitioners, developers and other decision makers. 

HILs are screening levels for different land use types. These include:

• residential with home grown produce (HIL A)
• residential with limited soil access (HIL B)
• public open space (HIL C)
• commercial industrial (HIL D). 

What we measured

We took samples of different mine wastes at sites across Bendigo to:

• see if we could categorise mine waste types by their colour and other physical characteristics
• analyse arsenic and other metal concentrations in mine waste
• assess trends and drivers for bioaccessibility of arsenic in mine waste
• identify the mineral species present in the mine waste.

What we found

• We could not identify a regional bioavailability factor for mine wastes as the results were highly variable. However, the tests provided information to aid contaminated site assessments in the region.
• Key factors driving bioavailability were the waste type, waste particle size and mineral speciation (related to waste type).
• Calcined sands consistently showed high arsenic concentrations and high bioavailability. Steps must be taken to prevent or limit exposure.
• Grey sands showed variable bioavailability in the following instances:  
  • Average bioaccessible concentrations were above the HIL A residential criteria of 100 mg/kg or 250 mg/kg for a hotspot. There are circumstances where grey sands at a site pose a low risk.  
  • Average bioaccessible concentrations were below the HIL B residential criteria of 500 mg/kg. They were only marginally above public open space criteria.  

What this means

Whether arsenic in mine waste poses a risk to human health depends on:

• how much waste is present and where it is located at the site
• how easy it is to expose
• the concentrations of arsenic in the mine waste
• the bioavailability of the arsenic in the mine waste.

The concentrations of arsenic in calcine sand and grey sands mine wastes are often high. It is likely that these wastes will need management to prevent risks to human health.

Bioavailability in grey sands can be variable. Site-specific assessment would be beneficial in finding if there is a risk requiring management.

Where to find more information?

This study is one of several pieces of information available.

• Investigating soil arsenic concentrations in Bendigo
• Living in an area with mine tailings 
• Understanding the types of historic mining waste in the Goldfields region 
• Excavating in the Goldfields region 
• Understanding your contaminated land duties

 
This scientific information should not replace medical advice or guidance. If you are concerned about the health impacts, contact your GP.