PFAS has again been in the news this week after it emerged that it had been found in fire-fighting foams still used and stored at Nelson Airport. But what exactly are PFAS…
PFAS are a large group of man-made chemical compounds that have both industrial and consumer uses. PFOS (Perfluoroocane sulfonate) and PFOA (perfluorooctanoic acid) are two compounds in the PFAS family that are of particular interest.
PFAS have been used around the world since the 1950s in the production of a wide range of products that resist heat, and in particular have been widely used around the world in the production of fire-fighting foams for quelling flammable liquid fires. For this reason, PFAS containing fire-fighting foams have been commonly used at airports, fire-fighter training facilities, Department of Defence facilities, and large industrial / manufacturing facilities.
PFOS and PFOA compounds have also been used in the production of commercially available products such as: oil and water-resistant coatings on textiles and upholstery (carpets, leather, paints and inks), hydraulic fluids in some medical devices, Teflon products, colour printer / photo-copier parts, and some insecticides.
When PFAS compounds were first developed and used in the 1950’s, they were considered relatively inert and non-hazardous. However, as more data has become available, our understanding of PFAS has improved. It is now understood that PFAS compounds (particularly PFOS and PFOA) are persistent in the environment (generally resistant to natural degradation processes), and bioaccumulate in the tissues of living organisms (including humans).
Due to such common use of PFAS containing products around the world, we are exposed to small amounts of some PFAS in everyday life, through food, dust, air and contact with products containing these compounds (including food wrappers and containers, clothing and electronics). Most people have small amounts of PFAS compounds in their systems, and at small levels is not known to cause a health risk.
Given the concern around PFAS is still relatively recent (e.g. the use of PFAS based fire-fighting foams has only been illegal in New Zealand since 2006), there remains a lack of certainty over the long-term risks to human health from significant exposure to PFAS.
In general, PFAS products have not been used as extensively in New Zealand as they have in other parts of the world. For instance, at a typical Defence site in Australia, it is estimated that 74,000 litres of PFOS/PFOA fire-fighting foam was used per year for 30-years (prior to being banned); in the same period, a typical Defence site in New Zealand is estimated to be approximately 1,000 litres per year.
Notwithstanding, PFAS compounds are considered to be a potential risk that should be considered alongside other more common contaminants of concern when developing conceptual site models at both preliminary site investigations (PSI), and details site investigations (DSI).
Given the prevalence of PFAS compounds in our everyday lives, and the relatively low thresholds at which accumulation in the environment triggers further assessment, additional protocols need to be implemented during the design and execution of site investigation / sampling activities to limit the potential for cross-contamination of samples and occurrence of ‘false positives’. Similarly, as PFAS compounds are very soluble, no detection of PFAS in soil samples at a Site is not necessarily an indication that groundwater has not been impacted by PFAS at the same site.
In the absence of specifically developed New Zealand guidance on PFAS investigation and assessment, practitioners have typically defaulted to the Western Australia Department of Environmental Regulation (WA DER) Interim Guideline on the Assessment and Management of Perfluoroalkyl and Polyfluoroalkyl Substances (PFAS), February 2016 in accordance with the requirements of the Ministry for the Environment (MfE) Contaminated Land Management Guidelines No. 2 – Hierarchy and Application in New Zealand of Environmental Guideline Values, October 2011 (CLMG No.2).
However, in January 2018 the Heads of the Environment Protection Agencies of Australia and New Zealand (HEPA) released the PFAS National Environment Management Plan (PFAS NEMP). While this guidance has only, as yet been endorsed for use in Australia; given this document supersedes the WA DER guidance, this document will now likely become the primary reference for PFAS assessment in New Zealand.
As a rapidly developing field, our understanding of PFAS is constantly evolving as new research and guidelines from regulatory authorities around the world are published. Since circa-2013 PFAS have been considered to be an emerging contaminant of concern; but with recent research suggesting persistence in the environment, and as yet fully understood potential risks to human health; it can be concluded that PFAS has emerged as a contaminant of concern.
4Sight remain committed to providing the most efficient investigation strategies in relation to PFAS, taking advantage of innovative cutting-edge technologies to provide the best project outcomes. 4Sight staff have conducted PFAS investigations at Site in both New Zealand and Australia, and are well versed in the intricate sampling protocols required for sampling potentially PFAS affected sites.