REPORTS on any associated health risks and how PFAS contamination at the Gingin satellite airfield will be managed are expected to be available before the end of the year, according to the Department of Defence.
On Friday, November 16 the department held an information session for Shire of Gingin residents to update residents on its investigations into per- and poly- fluoroalkyl substances (PFAS) at Gingin satellite airfield and nearby areas but the reports were unavailable and only information sheets were made available for those seeking an update.
Gingin PFAS risk to Gnangara Mound, Yanchep News Online, August 5 said a report presented to Gingin residents on July 25 recommended a human health risk assessment (HHRA) to further assess risks identified during the detailed site investigation (DSI) carried out by Jacobs Group for the department.
The report said the HHRA should focus specifically on the use of groundwater from abstraction bore 2 by site personnel and should additionally consider the risk to the Gnangara underground water pollution control area from off-site migration of PFAS in groundwater.
As well as found in firefighting foams once used by the Department of Defence PFAS are found in a wide range of consumer products that people use daily such as cookware, pizza boxes and stain repellants so most people have been exposed to PFAS.
According to the United States Environmental Protection Authority certain PFAS can accumulate and stay in the human body for long periods of time.
According to the United States Environmental Protection Authority website there is evidence that exposure to PFAS can lead to adverse health outcomes in humans.
“The most-studied PFAS chemicals are PFOA and PFOS,’’ the US website says. “Studies indicate that PFOA and PFOS can cause reproductive and developmental, liver and kidney, and immunological effects in laboratory animals – both chemicals have caused tumors in animals.
“The most consistent findings are increased cholesterol levels among exposed populations, with more limited findings related to low infant birth weights, effects on the immune system, cancer (for PFOA) and thyroid hormone disruption (for PFOS).
In contrast in Australia the Environmental Health Standing Committee (enHealth) guidance statements on per- and poly-fluoroalkyl substances, released in June 2016, say there is currently no consistent evidence that exposure to PFAS causes adverse human health effects.
But the federal Department of Health website recommends as a precaution that human exposure to PFAS be minimised as the chemicals remain in humans and the environment for many years.
“People can be exposed to PFAS in their workplace if they are involved in the manufacture or use of PFAS, ’’ the website says.
“Outside of the workplace, exposure to PFAS can occur from food, water (ground and surface water) and various consumer products.
“Dermal (skin) contact with PFAS is not considered a significant exposure pathway.’’
According to the information sheets released by the department the environmental investigation on Friday, November 16 the aim of the HHRA was to better understand the potential for PFAS exposure to people within the investigation area and involved detailed analysis of the samples taken during the preliminary site investigation (PSI) and the DSI.
“This assessment also included additional sampling, specifically, groundwater samples were collected from additional off-site groundwater wells, including from two Water Corporation abstraction bores used for public water supply – these bores are located 7.5km from the base,’’ the information sheet said.
According to the Department of Water and Environmental Regulation the Gnangara groundwater areas consist of three main aquifers – the unconfined Superficial aquifer (commonly known as the Gnangara Mound), the deep, partly confined Leederville aquifer and the deep, mostly confined Yarragadee aquifer.
Minor aquifers include the Mirrabooka and Fractured Rock.
The Gnangara Mound includes part of the Gingin Brook and the Moore River in the Shire of Gingin and part of the Ellen Brook in the City of Swan.
A graphic for the DSI report shows the Gingin satellite airfield as sitting in the Gnangara underground water pollution control area.
The information sheets said the investigation findings had determined an ecological risk assessment (ERA) was not required because no significant exposure risks to the local ecology (plants and animals) have been identified.
“For individuals that currently use the base, the potential exposure risks associated with contact with bore or groundwater (for example, through showering) were found to be low.
“The base currently uses bottled water for drinking because the bore is not drinking quality.
“The HHRA determined that bottled water should continue to be used for drinking because, in addition to the previously known quality concerns, the level of PFAS in the bores is above the drinking water guidance value.
“Bottled water will continue to be provided at the base.’’
The information sheet said the HHRA also assessed the risk of exposure to PFAS in groundwater off-site and found this risk to be low.
“This assessment including reviewing the potential for PFAS in groundwater to migrate towards the Water Corporation abstraction bores located 7.5km away.
“The risk of PFAS migrating from the base to the two off-site abstraction bores and therefore the public water supply, was found to be low.’’
The information sheet said PFAS had not been detected in the Water Corporation abstraction bores.
“PFAS was also not detected in a nearby monitoring well located half way between the boundary of the base and the Water Corporation abstraction bores.’’
“Extensive analysis of the groundwater system was undertaken to better understand the potential for PFAS to travel towards (and reach) the abstraction bores 7.5km away.
“The potential for this to occur is very low.’’
The department said it would perform ongoing sampling and evaluate the assessment if necessary.
