Sip at your own risk.
A new study suggests that where you get your drinking water could increase your odds of being diagnosed with Parkinson’s disease, a devastating movement disorder with no cure.
Even more concerning, the source linked to the highest risk is used widely across the country, especially in the southeastern and central US.
Researchers focused on aquifers — underground layers of rock, gravel, sand or silt where rain and snowmelt collect after seeping through the soil.
These natural reservoirs filter and store groundwater until humans bring it to the surface through wells for drinking, irrigation and industrial uses.
It’s not a foolproof system. Aquifers can be contaminated by leaking tanks, septic systems, fertilizers, pesticides and other chemicals that make their way into the soil, sometimes causing short- and long-term health problems.
Curious whether this could affect Parkinson’s risk, the team examined 12,370 people with the disease and more than 1.2 million people without it.
All participants lived within 3 miles of 1,279 groundwater sampling sites across 21 major US aquifers.
Researchers looked at the age of their groundwater, the type of aquifer and whether they got their water from municipal systems or private wells.
“Our study found that groundwater age and location is a potential environmental risk factor of Parkinson’s disease,” Dr. Brittany Krzyzanowski, senior author of the study, said in a press release.
Among people with Parkinson’s, 3,463 got their water from carbonate aquifers, 515 from glacial aquifers and 8,392 from other types.
Of those without the disease, 300,264 drank from carbonate aquifers, 62,917 from glacial aquifers and 860,993 from other aquifers.
Carbonate aquifers, the most common type in the US, are mostly made of limestone with water stored in cracks.
Glacial aquifers, created when glaciers advanced and retreated more than 12,000 years ago, are primarily made of sand and gravel, with water held in the spaces between the sediments.
After adjusting for factors like age, sex, income and air pollution, people drinking from municipal or private wells in carbonate aquifers had a 24% higher risk of developing Parkinson’s compared to other aquifers.
They had a 62% higher risk compared to glacial aquifers.
Researchers also found that newer groundwater, from the past 75 years, in carbonate systems was associated with an 11% higher risk of Parkinson’s compared to groundwater older than 12,000 years.
“We speculate that the apparent protective effect of older groundwater is seen mainly in carbonate aquifers because these systems can show a clearer contrast between newer and older water,” Krzyzanowski said.
“In these aquifers, newly recharged groundwater is more vulnerable to surface contamination, while older groundwater can remain cleaner if it is separated from recent inputs by a confining layer,” she explained.
“In contrast, glacial aquifers tend to slow groundwater movement and naturally filter contaminants as water travels underground,” she continued. “As a result, differences in contamination between newer and older groundwater in these aquifers may be smaller and therefore harder to detect.”
The study did have some limitations.
For example, it assumed that all people within a 3-mile radius of a sampling site shared the same aquifer characteristics and groundwater age.
Even so, Krzyzanowski says the research provides valuable insights.
“This study highlights that where our water comes from, including the age of groundwater and the type of water source, could shape long-term neurological health,” she said.
“While additional research is needed, bringing together knowledge about groundwater and brain health may help communities better assess and reduce environmental risks.”
Across the country, carbonate aquifers are common in parts of the Midwest, the South and Florida, while glacial aquifers are found mostly in the Upper Midwest and Northeast.
Krzyzanowski said that people can usually check their water source through their local utility provider or, for private wells, through state or county groundwater resources.
The findings come as the number of Americans with Parkinson’s is on the rise, with nearly 90,000 new cases diagnosed each year in the US.
The chronic disease is caused by the loss of dopamine-producing neurons in the brain, which affects balance, movement and motor control.
Common symptoms include tremors, stiffness, slow movement and trouble with posture — all of which worsen over time. While there’s no cure, medications and other treatments can help improve quality of life.
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