New ExpoSignalz Paper Explores the Impact of Pollutants on Our Brains
In a new paper by ExpoSignalz, researchers investigated the impact of long-lasting persistent organic pollutants (POPs) on people’s brains. Although POPs are known to be damaging to our brain health, this study found no clear links – which suggests more research may be needed.
Whilst some of the non-genetic causes of Alzheimer’s disease are well-recognised – such as levels of education, cardiometabolic health, and lifestyle habits – the contribution of chemical exposures is still unclear. This is particularly true for people who aren’t exposed to a large amount of pollutants through their work, only general everyday exposures.
By their nature, POPs stay in the environment for a long time. They are used in agricultural and industrial settings – for example, as pesticides, electrical insulators and flame retardants. Despite a wave of international bans, they are still regularly found in human bodies and food chains. Crucially, POPs have also been found in both babies and adults’ brains.
In fact, one EU Commissioner, Jessika Roswall, even had her blood tested for PFAS recently. PFAS are a sub-category of POPs. The test came back positive for six different PFAS compounds, demonstrating how widespread pollutants can be in our environment.
What did the study do?
In this ExpoSignalz study, researchers examined POPs in the blood of older adults from the general population, using samples collected in 1999 and 2000. These were from 515 individuals in the French Three-City (3C) Bordeaux cohort. They investigated three different aspects of brain ageing: the incidence of dementia and cognitive decline in the 17 years following blood collection, as well as the atrophy of specific regions in the brain (established as a marker of Alzheimer’s disease).
The participants underwent eight repeated assessments of cognitive function and dementia over 17 years, alongside three neuroimaging examinations spread over 10 years. They also had their blood analysed to create an overall POP level ‘score’ for each participant.
What did they find out?
The study found no clear link between the levels of POPs in someone’s blood and incidences of dementia, cognitive decline or brain atrophy. Whilst some signals did seem to link to specific types of POPs, they weren’t clear enough to be conclusive. More specifically, the few signals found were not consistent across the three aspects of brain ageing, meaning they may be false positives (where some results seem to suggest a link, but there isn’t one consistently).
They did find a higher concentration of POPs in the French cohort than in similar studies in the United States or Canada, which could be because of the extensive use of some industrial POPs in Europe for a longer period of time.
What happens now?
The study has identified several areas that might need more research. One crucial area is to examine the effects of interactions between different chemical exposures on brain ageing. Whilst this analysis didn’t find a link between POPs and an increased risk of dementia, new insights may be gained from using alternative measuring techniques and incorporating new methods. An important aspect is also statistical power: a sample size of 515 individuals may not be large enough to conclude significant associations; we may need to study larger samples. This is just the start of ExpoSignalz’s research into understanding the impact of environmental pollutants on Alzheimer’s disease.
Paper
Sophie Lefèvre-Arbogast, Pierre Scala, Aurore Zorilla, Catherine Helmer, Jade Chaker, Arthur David, Fabien Mercier, Cécilia Samieri. Associations of plasma persistent organic pollutants with brain atrophy, cognitive decline and risk of dementia in older adults. Environment International (2025).