When residents living near a chemical plant in Thornton-Cleveleys, Lancashire, recently had their blood analysed, many were found to contain high levels of Pfas (so-called “forever chemicals”). So what does this mean for their health?
I have worked on that question for more than a decade, as more and more contaminated sites have been discovered around the world. The levels reported in Thornton-Cleveleys are higher than those usually found in the general population, but they are in the same range as those seen in some other Pfas-exposed communities. However, they are far from the worst I have seen in Sweden and elsewhere.
A blood test can show that a person has been exposed to Pfas. The pattern of different Pfas can sometimes also give clues about the main source of exposure, and the measured levels can be compared with those in other populations. What the test cannot tell is whether that particular person will become ill.
For several of the best-studied Pfas, we now have plenty of studies tracking their effects in humans. The clearest links include changes in blood fats such as cholesterol, a weaker immune response to vaccines in children, lower birth weight and, particularly for PFOA (the type of Pfas found in Thornton-Cleveleys), an increased risk of kidney and testicular cancer.
At exposure levels such as those now reported from the UK, the changes in risk for many of these outcomes are small for an individual person. They become visible mainly when larger groups with different exposure levels are compared.
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Lessons from a Swedish town
One population I know particularly well is Ronneby in southern Sweden. In 2013, very high levels of Pfas were discovered in drinking water contaminated by firefighting foam from a military airfield. Thousands of people had consumed the water for many years. Blood testing later confirmed high exposure. The discovery also led to a long compensation case that eventually reached the Swedish Supreme Court.
Ronneby has given us an unusual opportunity to follow both exposure and health over time. We can measure how Pfas levels decline after the contaminated water source is removed. We can also study a large variety of health outcomes in the exposed population. But there is a limit to what such studies can tell us.
It is much harder to determine exactly what a given exposure has meant for the health of one particular person. Despite these difficulties, the Swedish Supreme Court concluded that markedly elevated Pfas levels in blood, in combination with the observed health effects, constituted personal injury.
Time matters as well. For persistent Pfas, the level measured today reflects exposure that may have started many years ago and may still be continuing. That has led researchers to ask whether Pfas can be removed from the body more quickly.
In a small study of the people in Ronneby who had been exposed to a lot of Pfas, a type of cholesterol medicine helped their bodies get rid of some of these chemicals faster.
The finding is interesting, but remains experimental. It is not a treatment that would routinely be recommended for the more moderate exposure levels reported in Thornton-Cleveleys. For now, the first step is still to reduce or stop the exposure.
Pfas are difficult pollutants to deal with because they do not break down in the environment. Several are also highly mobile in water, meaning they can move easily through soil into groundwater and spread over large distances in aquatic systems. Once they have reached soil, groundwater and surface water, they will remain there for a very long time.
Cleaning them up can also be extraordinarily expensive. The European Commission has estimated that treating Pfas-contaminated water in Europe alone could cost more than €1 trillion by 2050.
The problem is no longer just a few well-known Pfas. As some of the older ones have been banned or restricted, companies have switched to similar chemicals instead. Many of these replacements also last a very long time in the environment, but we know far less about how harmful they are or how they spread. That’s one reason Europe is now considering restricting Pfas as a whole group, rather than one chemical at a time.
Persistence changes the problem. If emissions continue while we wait for complete evidence, the pollution does not wait with us. It may still be present decades later, when the science is much clearer.
That is the difficult lesson from communities such as Ronneby, and now perhaps Thornton-Cleveleys as well. We should be careful not to turn a Pfas blood test into a prediction of disease. But being unsure what a blood test means for one person’s health does not make us unsure that continued exposure should be stopped and those responsible held accountable.
Mattias Öberg receives research funding from the Swedish research council for sustainable development (Formas) and the Bank of Sweden Tercentenary Foundation.