Per- and poly-fluoroalkyl substances (PFAS) are extremely stable chemical compounds. Their stability gives them very useful properties for multiple industrial uses, including in firefighting foams (known as ‘aqueous film-forming foams’, or AFFFs), nonstick cookware, food packaging, insecticides, and waterproof and fire-resistant fabric. But this same property also means that they don’t break down easily and therefore accumulate in the environment. They are now so widespread that almost every person on Earth has been exposed to PFAS and has them in their blood.
PFAS can enter ecosystems and move up food chains, accumulating in animal and human tissue, including the liver and blood. They have been linked to bladder and liver cancer, endocrine disruption and developmental and reproductive toxicity (including neonatal mortality).
Some firefighting foams contain two PFAS – perfluorooctanesulfonic acid (PFOS) and perfluorooctanoic acid (PFOA) – that improve the ability of the foam to smother fire (PFOS is listed under the Stockholm Convention on persistent organic pollutants, and PFOA was last year proposed for listing). The manufacture of AFFFs containing these chemicals is now prohibited, but it is legal to use existing stockpiles in Australia. In 2017, Queensland and South Australia banned the use of AFFFs containing PFOS and PFOA.
AFFFs have been used on fires at many thousands of emergency and training sites worldwide over the past half-century (e.g. airports, air force bases and other military sites, and metro and country fire service training sites). The foam can seep into soil and groundwater, eventually moving beyond the source site and potentially into residential areas.
At some of these sites PFOS and PFOA have been found at elevated levels in surface water and groundwater in residential areas outside the facility boundaries. Some residents have elevated levels of PFOS and/or PFOA In their blood and property prices in the affected areas have in some cases fallen dramatically. Investigations are ongoing at all the above sites as well as a number of others.
CRC CARE commenced its PFAS activities in 2005 at the invitation of the Department of Defence (one of our inaugural CRC Participants), well before PFAS were recognised as priority contaminants. Remediation facilities established by CRC CARE at four sites (including RAAF Bases Edinburgh, Pearce and Townsville) have so far remediated over 1 million litres of contaminated groundwater, with annual costs substantially reduced. Our technology for remediating PFCs, matCARE, has been a finalist in three national awards (the Australian Innovation Challenge 2014 and 2015, and the Banksia Sustainability Awards 2013).
matCARE is a modified clay sorbent that irreversibly immobilises PFAS, including PFOS and PFOA, in both soil and water. This technology remediates PFOS and PFOA in AFFF-contaminated wastewater to < 0.002 μg/L, which is well below the US EPA’s 2016 drinking water health advisory levels of 0.07 parts per billion.
pfasCARE is a new technology developed by the CRC. It uses electricity to generate extremely strong oxidising agents (including free radicals) that strip the PFAS molecules of electrons and thus break them down into smaller – and safe – components. Previously, this approach has been prohibitively costly, requiring expensive materials, such as diamonds, to be effective. pfasCARE uses lead peroxide (a common, inexpensive industrial material) to dramatically cut the cost of production.
CRC CARE’s astkCARE (anionic surfactant test kit) has been developed to provide a safe, sensitive and reliable method to detect and measure the concentration of highly toxic surfactants, including PFAS, in the environment. Available for use with a smartphone app or colour indicator, it is simple and quick to use, does not require highly skilled operators, and can easily be used in the field.
In 2017 CRC CARE published national guidance on the best-practice assessment, management and remediation of PFOS and PFOA. The guidance is designed to help regulators and practitioners assess PFAS contamination, as well as to make decisions about if and how to remediate and/or manage PFAS-contaminated sites.
If you'd like to know more about PFAS and the best ways to deal with it, contact Dr Sreeni Chadalavada at email@example.com or on +61 (2) 4921 5201.