You probably never think about where your tap water starts its journey.
Most of us assume someone is checking the industrial site down the road. New research suggests that assumption deserves a second look.
People who lived within three miles of a facility that pollutes water were more likely to develop progressive supranuclear palsy.
The rare and incurable brain disease resembles Parkinson's.
Also read: Scientists discover why some cancers may be less common in type 1 diabetes
The finding comes from a UK study published on October 28, 2026, in Neurology, the medical journal of the American Academy of Neurology.
Researchers followed more than 500,000 adults for up to 25 years. In that time, 221 developed the disease, known as PSP.
About one in three of them lived within three miles of a polluting facility, compared with roughly one in four of those who stayed healthy.
What progressive supranuclear palsy actually is
PSP is an uncommon brain disorder that typically starts after age 65.
Also read: Scientists make breakthrough in fight against deadly childhood brain cancer
The first sign is often sudden loss of balance and unexplained falls, according to StatPearls at the National Library of Medicine.
Over time, people develop trouble with eye movements, speech and swallowing. There is no treatment that slows the disease, and most patients die within six to nine years of diagnosis.
PSP is rare overall. Earlier reviews put its prevalence at around 6 cases per 100,000 people worldwide, so even a sizable relative increase in risk still leaves the absolute chance of developing it low.
How much the risk rose by pollutant type
The signal was not the same for every pollutant. People living near a facility that released pesticides had a 66 percent higher risk of PSP.
Also read: Just 30 minutes of daily exercise could make a difference for your liver
Inorganic pollutants were tied to a 60 percent higher risk, organic pollutants to 52 percent, and heavy metals to 38 percent.
The facilities examined included wastewater treatment plants, chemical plants, intensive fish farms and thermal power stations.
There was also a distance pattern. The risk tapered off the farther people lived from the facility, dropping as the distance stretched to about six miles.
What the study cannot say
The research shows an association, not cause and effect. The authors could not tease apart the effect of one pollutant from another, because a single facility often releases several at once.
Also read: Wildfire smoke during pregnancy linked to 30% higher autism risk in children
Work-related exposure, such as handling the chemicals on the job, was not analyzed.
Lead author Charlie Weige Zhao, MD, of Harvard Medical School, said the overall risk of developing PSP was low, no matter where people lived. He spoke in the American Academy of Neurology press release.
More studies are needed before the findings translate into any health guidance.
Anyone with unexplained balance problems, repeated falls or new trouble with eye movements should raise it with a doctor.
Also read: med små bogstaver Taking thyroid and weight loss medicine? Timing could matter more than you think
This article is made and published by Ida-Marie Palm Varbæk, who may have used AI in the preparation.