A study conducted by researchers from the Faculty of Medicine of the University of Buenos Aires (UBA) revealed that well water can contain elevated levels of nitrates, capable of altering the function and structure of the thyroid gland.
The finding, published in the journal Environmental Science and Pollution Research, warns of a danger that often goes unnoticed in communities that rely on this resource for drinking, cooking, and irrigation.
Evidence in animal models
The team led by Dr. Osvaldo Juan Ponzo, along with researchers María Fernanda Modarelli and Rodrigo Miguel Bilbao, used larvae of the African frog Xenopus laevis, an amphibian sensitive to hormonal changes.
The results were conclusive:
- 62.3% of the frogs exposed to well water never completed their metamorphosis.
- Only 37.7% managed to complete the vital process, showing visible damage to the thyroid.
- Histological and molecular alterations were detected in the gland, linked to the presence of nitrates.
The study also showed that the expression of the NIS transporter, responsible for capturing iodine in the thyroid cell, increased at the beginning of metamorphosis but then decreased drastically, reaching almost undetectable levels in some individuals.
Nitrates and human health
Nitrates enter the water mainly through the use of agricultural fertilizers and waste from cattle feedlots. These compounds interfere with the absorption of iodine, essential for metabolism and growth.
Excess nitrates have already been associated with:
- Problems in child development.
- Alterations in pregnant women.
- Risks of cancer.
In well samples from the Buenos Aires Conurbation, values of up to 83 mg/liter were detected, more than double the limit recommended by the WHO for human consumption.
Epidemiological background
The same authors had previously conducted a population study that showed that those who consume well water have between 5 and 10 times more prevalence of goiter and subclinical hypothyroidism than usual.
This new work reinforces the hypothesis that chronic exposure to nitrates in groundwater can be an endocrine disruptor with cumulative effects on health.
Recommendations and warnings
The researchers suggest:
- Strengthening the analysis of well water before use.
- Updating the valid nitrate limits according to the detected risks.
- Implementing monitoring systems and removal strategies when levels exceed the recommended ones.
Dr. Alejandro Oliva, director of the Environment and Health Program (PROMAS) of the National University of Rosario, warned in dialogue with Infobae that although the results come from an animal model, there are international studies that also link nitrates with thyroid alterations in humans.
Oliva highlighted the need to monitor drinking water in agricultural and rural areas, given that the nitrate content is highly variable depending on the source and time of year. He also proposed evaluating levels both in the water and in urine samples from inhabitants in areas with epidemiological warning signs.
Well water, considered safe in many rural communities, may hide invisible health risks. Scientific evidence shows that nitrates affect thyroid function and the development of sensitive organisms and could be behind the increase in cases of hypothyroidism and goiter in exposed populations.
The research reinforces the urgency to monitor and control the quality of groundwater, especially in agricultural regions, to protect people’s health and ensure safe consumption.
