A new study has established that individuals whose drinking water was supplied by newer groundwater were at a greater risk of getting Parkinson disease as compared to those individuals whose drinking water was supplied by older ground water.
- The study does not prove that newer groundwater causes Parkinson’s; it only shows an association.
- Older groundwater would usually have less contaminants since it is mostly deeper and well covered.
- It was discovered by the researchers that drinking water that was derived in carbonate aquifers was related to the 24 percent greater risk of Parkinson disease as compared to other varieties of aquifers.
- It was also linked to increased 62 percent risks than when one uses water in glacial aquifers.
- It has also been reported that newer ground water, less than 75 years, in carbonate systems was linked to increased risk of Parkinson by 11 per cent than older than 12,000 years of ice age ground water.
People whose drinking water was supplied by more recent groundwater were at a greater risk of developing Parkinson’s disease compared to those whose drinking water was served by older groundwater as per a preliminary study published March 2, 2026, and will be presented at the 78th Annual Meeting of the American Academy of Neurology to be held April 18-22, 2026, in Chicago and online. The research does not demonstrate that newer groundwater is a cause of Parkinson disease but just indicates that there is a correlation.
The paper examined the age of ground water. It also examined aquifers which were the sources where groundwater was extracted. An aquifer refers to a layer of porous rock, sand or silt in the ground that contain and moves the ground water.
This study was carried out by a study author who at the time of conducting the research was a member of the American Academy of Neurology in Phoenix, Arizona, a researcher named Brittany Krzyzanowski, PhD at the Atria Research Institute in New York City, and is considered to have conducted the research in one way or the other as she was studying our exposure to modern pollution through drinking water. More pollutants have been exposed to newer groundwater, which is formed by precipitation that has fallen during the last 70 to 75 years. The aged groundwater tends to have fewer contaminants due to the fact that most of them tend to be deep and have a better protection against surface contaminants. Our research established that the groundwater age and groundwater location is a possible environmental risk factor of Parkinson disease.
The researchers used 12,370 individuals with Parkinson’s disease and over 1.2 million individuals without the disease to derive the results after matching the individuals based on variables such as age, sex and race and ethnicity. All the participants were within 3 miles of 1,279 groundwater sampling locations in 21 large aquifers in the U.S.
The researchers sought to examine age of groundwater, type and source of drinking water (either municipal groundwater systems or personal wells) to be used as a possible indicator of exposure to neurotoxic contaminants.
The most common aquifer in the United States is carbonate aquifers which are mainly composed of limestone and the water is trapped in the fissures and cracks. They are usually quite vulnerable to the contamination of the surface water by groundwater flowing through fractures very fast.
The composition of glacial aquifers is made up of sand and gravel containing water in the cracks and they are formed when the glaciers had moved forward and back over 12, 000 years ago. Such aquifers are more likely to facilitate a more diffuse flow and natural filtration.
Carbonate aquifers are prevalent in U.S. in portions of Midwest, South and Florida whereas glacial aquifers are prevalent in Upper Midwest and Northeast.
Of all individuals with Parkinson 3,463 received their drinking water as a product of carbonate aquifers, 515 received it as a product of glacial aquifers and 8,392 received it as a product of other aquifers. Of non-Parkinson 300 264 obtained their drinking water through carbonate aquifers, 62 917 glacial aquifers, and 860 993 other aquifers.
It was found that when factors like age, sex, income, and air pollution were taken into consideration, individuals that received their drinking water in municipal ground water system or in private wells that worked off carbonate aquifers were at a greater risk of developing Parkinson disease by 24% compared to everyone who received their drinking water in all other aquifers. Their risk was also 62 times and compared to individuals who had glacial water aquifers.
The safety of older groundwater was discovered under the condition when water was obtained in carbonate aquifers. The risk of Parkinson disease decreased by about 6.5 per one-standard-deviation of groundwater age. It was also discovered that newer ground water (less than 75 years old) of carbonate systems had 11% more likelihood of causing Parkinson disease than ground water older than 12,000 years old of ice age.
Carbonate systems
Krzyzanowski postulated that the data on the apparent protective effect of older groundwater is observed predominantly in carbonate systems due to their ability to present a more distinct contrast between newer and older water. Newly recharged groundwater in such aquifers is more susceptible to surface contamination, whereas older groundwater can also be cleaner in case it is segregated by a confining layer.
According to Krzyzanowski, on the contrary, groundwater flow in glacial aquifers is slower, and contaminants are filtered in their natural course by groundwater as it flows through the ground. Consequently, the amount of contamination between new and old groundwater in these aquifers might not vary greatly and thus might be difficult to detect.
Krzyzanowski observed that the origin of the drinking water of individuals can typically be determined through the local water utility or, in the case of a personal well, through state or county groundwater sources.
According to Krzyzanowski, this study emphasized the fact that the origin of our water, groundwater age, and the nature of water source, may influence the long-term neurological health. Although further studies are required, the integration of knowledge on groundwater and brain health can be beneficial to enable communities to evaluate and mitigate environmental risks.
One of the weaknesses of the study was that, it assumed that all people within a 3-mile area around a point of sampling had the same aquifer characteristics and age of the groundwater at the point of sampling.
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