MANILA, July 7 — A new study has identified a mechanism through which a common environmental pollutant may contribute to Alzheimer’s disease, raising fresh concerns for communities across Asia where rapid industrialisation has introduced novel chemicals into daily life. The research, published in the journal Environmental Health Perspectives in January 2024, examined a compound called 6PPD-Q. This chemical is a transformation product of 6PPD, a substance widely used as an antioxidant in rubber tires to prevent cracking.
When tires wear down on roads, 6PPD reacts with ozone to form 6PPD-Q, which can then wash into waterways and soil. Scientists found that 6PPD-Q interferes with the function of a protein called TDP-43, or TAR DNA-binding protein 43.
Under normal conditions, TDP-43 resides in the cell nucleus, where it regulates gene expression and processes RNA. In Alzheimer’s disease, and in other neurodegenerative conditions such as amyotrophic lateral sclerosis (ALS), this protein becomes mislocalised — it moves from the nucleus into the cytoplasm and forms toxic clumps. The study showed that exposure to 6PPD-Q in laboratory cell cultures caused TDP-43 to clump and malfunction, directly mimicking a hallmark of Alzheimer’s pathology.
This disruption can lead to neuronal death and cognitive decline. The research was conducted using human brain cell models.
The findings suggest that environmental toxins like 6PPD-Q may trigger or accelerate protein misfolding, a key process in Alzheimer’s disease.
What this means for communities
For families across the Philippines and the wider region, the implications are significant. Many Asian cities have some of the highest traffic densities in the world. In Metro Manila alone, millions of vehicles traverse roads daily, shedding tire particles that contain 6PPD and its transformed product.
These particles do not simply disappear — they accumulate in roadside dust, drain into rivers, and can be inhaled or ingested. The study adds to a growing body of evidence linking environmental pollutants to neurodegenerative diseases.
Alzheimer’s is already a mounting public health challenge in Asia. According to the World Health Organization, the number of people living with dementia in the Western Pacific region — which includes the Philippines — is projected to rise sharply as populations age. Closer to home, this research offers a potential new target for understanding why some individuals develop Alzheimer’s while others do not, even when genetic risk factors are similar.
It points to the possibility that environmental exposures, combined with genetic susceptibility, may drive disease onset. The researchers emphasised that further studies are needed to confirm this mechanism in living animals and humans.
The current findings are based on cell cultures, not whole organisms. However, the consistency of the effect — a clear disruption of TDP-43 function — provides a strong foundation for future work.
A growing list of concerns
6PPD-Q first gained widespread attention in 2020, when researchers in the United States identified it as the chemical responsible for killing coho salmon in urban streams. Rainwater runoff from roads was found to contain lethal concentrations of the compound. Since then, scientists have been racing to understand its effects on other species, including humans.
The new study represents a significant step forward. It is among the first to demonstrate a direct molecular link between 6PPD-Q and a protein central to neurodegeneration.
For communities across Asia, where rapid urbanisation often outpaces environmental regulation, the findings underscore the importance of monitoring emerging pollutants. The chemical is not currently regulated in most countries, and its presence in the environment is largely unmeasured outside of research studies. The researchers called for expanded monitoring of 6PPD-Q in air, water, and soil, as well as further investigation into its potential role in human disease. Consult your doctor for medical advice.
