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.