Per- and poly-fluoroalkyl substances (PFAS) have been commonly used to improve the ability of fire-fighting foam to smother fire. In such ‘aqueous film-forming foams’, or AFFFs, these chemicals have been used on fires at many thousands of emergency and training sites worldwide over the past half-century. They are also widely used to treat fabrics and leather, and in paper products, non-stick cookware, food packing and insecticides.
PFAS can be dangerous to human health. In particular PFOS (perfluorooctanesulfonate) and PFOA (perfluorooctanoic acid) are two commonly used PFAS that are known to enter ecosystems and move up food chains, accumulating in animal and human tissue, including the liver and blood. PFAS have been linked to bladder and liver cancer, endocrine disruption, and developmental and reproductive toxicity, including neonatal mortality,1 and are potentially lethal to animals.
The Stockholm Convention on Persistent Organic Pollutants has listed PFAS as chemicals of concern to human health.2 PFOS is listed under Annex B (restriction) of the Convention and PFOA was proposed for listing in 2016. In 2016 the US EPA issued new, more stringent drinking water health advisory levels of 0.07 parts per billion (ppb) for both PFOS and PFOA.3 PFAS-contaminated animal food chains in the US have had PFOS levels as high as 59,500 ppb.4
PFOS and PFOA are increasingly being phased out of modern foams. Concentrations in human blood appear to be decreasing in the US, although they are still rising in China.5 Today they remain significant residual contaminants at many sites globally, for example, at many of the world’s 49,000 airports (including 450 civilian and military airports in Australia).
Foams are also deployed on fires at traffic, truck and railway accidents and even building fires. As at airports, the chemicals can escape into the surrounding urban or rural environment and contaminate water supplies.
Australia does not yet have the infrastructure to ensure the quality and comparability (across different laboratories) of PFOS/PFOA measurements. To address this gap, two CRC CARE Participants – the National Measurement Institute and Environment Protection Authority Victoria – are collaborating in a CRC CARE-funded project to develop and demonstrate PFOS/PFOA ‘proficiency testing’, which assesses the performance of different labs and analytical methods by comparing their results for a single sample. Participation in proficiency tests helps provide end-user confidence in overall data quality and the reliability of results. The project will support Australian environmental policy and improve PFOS/PFOA analysis in Australia. For more information about the project please contact Cheryl Lim (email@example.com).
Cleaning up with clay
Aware of the high adsorption properties of clay-based materials, scientists at CRC CARE identified one clay type that was especially effective in trapping the contaminant PFAS. By tailoring its mineral constituents, researchers were able to fine-tune the clay’s adsorption properties to achieve full recovery of the PFAS.
In further laboratory trials this modified clay, named matCARETM, remediated both water and soil, removing PFOS, PFOA and other fluorinated surfactants to below detection limits.
Based on this research, CRC CARE has established remediation facilities at Royal Australian Air Force sites in Edinburgh (SA), Pearce (WA) and Townsville (Qld), where years of foam use, mainly in fire-fighter training, had caused substantial PFAS contamination. Treatment has so far resulted in the clean up of over 1 million litres of water to less than the reporting level of 5 ppb.
To further improve the clean up of PFAS, CRC CARE has developed an anionic surfactant test kit (astkCARE™), which can be used to detect AFFFs.
As research reveals more about the long-term effects of PFAS on people and animals, it is likely that governments and communities will demand increasing restrictions on their use, as well as lower levels of environmental contamination. This new technology from CRC CARE is ready to play a key role in the response.