Words by Stefano Marconetto
“As many of the main sources of PFAS are investigated, we expect attention to shift to secondary sites — and increasingly to brownfield sites in urban areas”
Per- and polyfluoroalkyl substances (PFAS) are a group of several thousand manmade chemicals that have been widely used in consumer products, construction materials and industrial processes for more than 50 years. They are also the latest in a long line of “wonder materials” that have been discovered to have negative consequences for human and environmental health. To date, the focus has been on assessing and in some cases removing the most harmful chemicals from industrial sites such as military bases, airports, landfills and manufacturing facilities, and from water supplies. But as many of the main sources are investigated, we expect attention to shift to secondary sites where PFAS have been used — and increasingly to brownfield sites in urban areas. With growing awareness and ever-tighter restrictions, the need for more effective management solutions including sustainable remediation could become a pressing concern for governments, city authorities and developers everywhere.
PFAS are often referred to as “forever chemicals”. Their resistance to oil, heat and water — the properties that have made them incredibly useful for everything from construction materials and firefighting foam to non-stick cookware, waterproof clothing and cosmetics — also mean that many of them do not degrade naturally. We now know that they are dispersed over long distances via water, wind or sediment, and that they accumulate in the environment, in the water supply and in our bodies. Studies around the world have found that almost everyone has chemicals from the PFAS family in their blood. Research has so far linked some PFAS to health issues including cancer, thyroid hormone disruption, damage to the liver and low birth weights, but the toxicological studies are still evolving.
For regulators, PFAS present a particularly challenging puzzle. Each compound has its own unique chemical and physical properties, which affect its distribution, half-life and toxicity, and most are still unregulated. Around the world, current environmental standards target only a small number of specific compounds and are generally limited to soil and drinking water. Two of the most studied variants — PFOS and PFOA — have been phased out in many countries, though these have often been substituted with newer, unregulated PFAS and biomonitoring has found levels of these newer compounds rising in the population.
Work is ongoing in certain jurisdictions to develop standards that are more holistic, covering a broader range of compounds and exposure pathways. For example, earlier this year, the Canadian federal government issued a notice of intent to address PFAS as a class, based on scientific evidence suggesting that several of these substances may affect people and the environment. Meanwhile, other places such as the US states of Michigan and California are responding to the PFAS crisis by setting ultra-low permitted levels — even down to single digit parts per trillion or parts per quadrillion, equivalent to a few drops of water in 20 or more Olympic-size swimming pools.
With ever-tighter restrictions, managing PFAS effectively and sustainably could become a pressing concern for governments, city authorities and developers everywhere
This may catch many sites where PFAS use was only marginal, or even sites that have no obvious direct connection to PFAS at all. Given the prevalence of PFAS in the environment, there is a tangible risk that almost every site tested will be found to exceed some of the acceptable limits. This is already an additional cost of development in some jurisdictions where soil that is moved off site during construction must also be tested for PFAS, and treated or disposed of accordingly. Many products containing PFAS — and there are very many — eventually end up in landfills, and the resulting leachate must be treated to prevent them from entering water supplies.
Municipalities will be among the organizations most affected by the PFAS crisis since they may have to deal with them in water supplies, landfills and wastewater treatment plants — both in terms of having to treat the wastewater and also managing the resulting biosolids, which often have elevated concentrations of PFAS. In some cases, municipalities may also have to deal with large volumes of PFAS-impacted soil or water during water or sewer replacement or the construction of roads, bridges and tunnels.
But because of municipalities’ central role, they also have a great opportunity to work with regulators and industry to set reasonable PFAS standards and promulgate legislation that protects human and environmental health without imposing insurmountable barriers to development. In this, they will be supported by continuing scientific developments. Environmental risk assessment can be a very useful tool to identify risks posed by PFAS by looking at the specific characteristics of a site, along with its current and future use. Concentrations that could be an issue for certain land uses may not be an issue in other circumstances. Risk assessment allows us to determine these differences and develop measures to safely address the risks.
In some cases, remediation or treatment of PFAS may be required — and this is where innovations in the industrial sector could help during construction and redevelopment projects. Today, most treatment methods do not destroy PFAS, but merely transfer them elsewhere or reduce their mobility. Current destructive technologies involve high-temperature incinerators, which are expensive to operate, particularly given the volume of materials that may contain PFAS. But strong interest from several industries is driving the development of more sustainable technologies that break the molecules down into inert substances, effectively and affordably, and we are now starting to see significant progress.
At Golder, we’ve been exploring the potential of ball-milling — borrowed from the mining sector — to break down PFAS molecules in soil. This shows promise but still requires some optimization. Other solutions are ready to be adopted: we have been successful in applying electro-oxidation to destroy PFAS in groundwater and wastewater in the laboratory and are now moving to field implementation. This technology destroys PFAS in less than an hour, requires only electricity to operate and does not produce sludge or spent materials that must be disposed of. Using long-lasting electrodes, it can operate for over 10 years with minimal maintenance. These new destructive solutions will enable soil to be reused safely, save precious landfill space and keep PFAS away from wastewater treatment plants and water supplies.
PFAS present a daunting challenge, but by working together we are starting to see evidence that it isn’t insurmountable — and that we may finally be able to use sustainable solutions to bring the long story of forever chemicals to an end.
Stefano Marconetto is a senior principal environmental engineer and global leader of the PFAS practice at Golder, member of WSP, based in Ottawa