Per-and Polyfluorinated Alkyl Substances (PFAs)
Per-and polyfluorinated alkyl substances (PFAs) are currently an emerging contaminant, meaning that their impacts of human health and ecological health are uncertain. The two most well-known PFAS are perfluorooctane sulphonate (PFOS) and perfluorooctanoic acid (PFOA).
Per-and polyfluorinated alkyl substances are a group of synthetic chemicals that have been extensively used since the 1950’s. PFAs have been constituents in several household items and prevalent in firefighting foams. Due to their widespread use, high solubility and chemical stability, PFAS are likely to persist in the environment and be transported through surface water and groundwater. Moreover, their high bioaccumulation potential means they can move through the food chain through plants and animals. Some studies have shown that PFAS can cause health issues in laboratory animals. As such, it is recommended that human and environmental exposure to these substances are minimised as a precaution. As a signatory of the Stockholm Convention (2009), Australia is aiming to eliminate or reduce the release of PFOS and PFOA into the environment.
The main potential exposure pathway to humans is through ingestion of contaminated water and produce that uses this water. Humans are also typically exposed to small quantities of PFA mainly through food and water, as well as consumer products containing the chemicals such as carpet, and non-stick cookware.
Currently, guidance values used in site investigations in Australia are based on the Commonwealth Department of Health which has calculated drinking water quality and recreational water quality values. These values are based on the Food Standards Australia New Zealand (FSANZ) health based guidance values for PFOS and PFOA and indicate the amount of chemical in food or drinking water that a person can consume on a regular basis over a lifetime without significant risk to health.
The health based guidance values for use in site investigations in Australia are:
|Toxicity reference value||PFOS/PFHxS||PFOS/PFHxS||PFOA||PFOA|
|Tolerable daily intake (*ng* or *µg /kg bw/day*)||20||0.02||160||0.16|
|Drinking water quality value (*ng* or *µg /L*)||70||0.07||560||0.56|
|Recreational water quality value (*ng* or *µg /L*)||700||0.7||5,600||5.6|
*Note: bw = body weight, ng = nanograms, µg = micrograms. *Source: Department of Health, Australia
Since PFAs are highly soluble with high bioaccumulation potential, site assessments for PFAs require careful consideration of soil leachability, fauna and flora and water bodies. Moreover, due to their high leachability, the potential for contamination of off-site areas also needs to be addressed. The primary migration pathways of PFAS are surface water and groundwater.
The Environmental Protection Authority (EPA) is conducting investigations at NSW sites contaminated by PFAs to improve our understanding of the extent of use of PFAs and exposure pathways. Some examples of their work include sites at:
- Botany Bay area - PFAS have been detected on and offsite of the Botany Bay area. Potential sources of PFAS in the area include fire-fighting foams containing PFAS used for training as well as a range of other industrial operations. Initial sampling undertaken by Airservices Australia indicates that historical use of PFAS-containing firefighting foam is linked to detections in surface and groundwater within the airport precinct, and in some samples of fish and sediments.
- Kemps Creek Rural Fire Service (RFS) training site - NSW RFS is investigating potential PFAS contamination from the historical use of fire-fighting foams at its Kemps Creek site. PFAS were detected on and offsite in some of the groundwater, surface water and sediment samples. Future investigations will help determine the extent of the contamination and if there are any PFAS exposure pathways for local residents, such as the use of bore or dam water on their property.
- Deniliquin Fire and Rescue NSW - A preliminary investigation was conducted at the fire-fighting training facility in Deniliquin and indicated that concentrations of PFAS in soils and sediments were below the guidance values. However, the leachability data indicates that soils and sediments in some areas may act as sources of PFAS. Moreover, a sample from the groundwater monitoring wells on-site reported PFOS levels above the guidance values for drinking water. Concentrations of PFAS in four surface water samples from off-site locations contained concentrations of PFAS above the drinking water guidance values.
Further investigation will involve off-site sampling to determine the pathways for potential migration of PFAs from the site. Management plans to address PFAS present on site and minimize further migration include clearing of the drainage channels between dams to remove soils and sediments and removal of impacted soils around the fire training ground.
With over 40 years of combined management experience in Site Contamination Assessments, Getex is here to provide expertise and advice. Getex can assist you in assessing PFA levels in soil, groundwater and surface water and assessing the site for potential off-site transport mechanisms, pathways and receptors. Call us on (02) 9889 2488 or get in touch.