THE Department of Defence announced on Thursday the completion of an environmental investigation into chemical contamination in and around RAAF Base East Sale, and reiterated its advice that there is "currently no consistent evidence that exposure causes adverse human health effects".
However, the precautionary advice remains about limiting consumption of fish and ducks from known sources of per- and poly-fluoroalkyl contamination, including Heart Morass wetlands and the Lower Latrobe River, due to fears of "bioaccumulation" in animals.
A report by independent research group Senserva found that the higher concentrations of PFAS contamination were found in non-residential areas on the East Sale RAAF Base, but that there had already been some migration of chemicals off-base via surface water drainage features, and, to a lesser extent, groundwater.
As part of the Defence management plan, land and waterways in and around the base, such as Heart Morass wetlands and some farming properties, will continue to be monitored to assess the PFAS impacts "as a precautionary measure".
Defence will also look at ways to "block" or divert the migration pathway of the contamination from within the Defence site to areas outside the site.
In May 2016, Defence began the detailed environmental investigation to identify the nature and extent of PFAS on and near the East Sale base, as a result of the historical use of legacy firefighting foams at the base.
As already widely reported, the PFAS has been found in detectable concentrations in soil samples collected across the site, however most concentrations were below adopted screening criteria for protection of human health in a residential setting.
In addition, soil samples collected within "more sensitive" areas of the site (including the child care centre, kindergarten, and areas used for residential or accommodation purposes), were many times below the residential human health screening criteria.
However, the chemicals were found in elevated levels in some non-residential areas of the site, including in stockpiled demolition waste in the south-west of the site, and are believed to have the potential to leach "should the material not be managed appropriately".
The findings revealed:
- Low concentrations of PFAS detected in soil on the RAAF base, many times lower than the adopted human health screening criteria for a residential setting.
- Elevated concentrations of PFAS in on-base shallow groundwater and drainage line surface waters, but lower concentrations in groundwater and surface water off-base.
- The main pathway for off-base migration of PFAS is via surface water drainage features, and, to a lesser extent, groundwater.
The management of the contamination will include ongoing testing and continuing public awareness of the potential dangers of consuming contaminated animals.
The East Sale site is considered sensitive to PFAS contamination, given it is an area used for agriculture.
All surrounding land is farm zoned and used principally for dairy farming and associated pasture irrigation, as well as cattle grazing and associated rural residential uses.
PFAS are a group of synthetic compounds that have been widely used around the world since the 1950s to make products that resist heat, stains, grease and water. These include hydraulic fluid, stain resistant applications for furniture and carpets, packaged food containers, waterproof clothing, personal care products and cleaning products.
Because of their effectiveness in extinguishing liquid fuel fires, the substances were also an ingredient in widely used fire fighting foams.
It is thought that most people living in developed nations will have some level of PFAS in their body because of their widespread use.