A twenty-year study just published in JAMA shows that reducing exposure to arsenic in drinking water reduces mortality from chronic diseases by up to 54%. Researchers followed 11.746 adults in Bangladesh from 2000 to 2022, comparing those who changed their water source with those who remained exposed. Results: less arsenic equals fewer deaths from cancer, heart disease, and cardiovascular disease. Even those who had been exposed for years benefited from the switch to clean water.
The study's numbers: -54% deaths with clean water
The team led by Fen Wu of NYU and from Joseph Graziano Columbia University has monitored over 10.000 wells in the Araihazar district of Bangladesh. Interventions began in 2000: water testing, labeling of contaminated wells (red for those above limits, green for those safe), health education, and drilling of deeper wells. In twenty years, the average concentration of arsenic in wells dropped from 102 to 32 micrograms per liter, and the participants' urine levels dropped from 283 to 132 micrograms per gram of creatinine.
The study recorded 1.401 deaths from chronic diseases: 730 cardiovascular, 256 tumors. For every reduction of 197 micrograms/g of urinary arsenic, Total mortality decreased by 22%, oncological mortality by 20%, and cardiovascular mortality by 23%. Who has gone from high levels to low levels had mortality rates identical to those who had never been exposed. Those who remained at the contaminated wells saw no reduction in risk.
WHO has declared arsenic crisis in Bangladesh “the largest mass poisoning in history”Approximately 50 million people in the country drink water with levels above 10 µg/L (the recommended limit). Analyses confirm that the benefit is not dependent on socioeconomic factors: it is only clean water that saves lives.
How much arsenic do we drink in water in Italy, Europe, and the USA?
The legal limit is the same everywhere: 10 micrograms per liter (µg/L or ppb). It was set by the WHO in 1993 and adopted by the European Union (Directive 98/83/EC) and the United States (EPA, 2001). It's a bit like saying: this is the threshold that balances costs and safety. However, the WHO itself suggests aiming for values below 5 µg/L, ideally close to zero.
In ItalyThe critical areas are those of volcanic origin: Lazio (Viterbo, Latina), Tuscany (Livorno, Siena, Pisa), Campania, Lombardy, Trentino-Alto Adige. Until 2012 Some municipalities obtained exemptions that allowed levels up to 50 µg/L, five times the limit. In 2021 The European Commission has referred Italy to the Court of Justice over the municipalities of Bagnoregio, Civitella d'Agliano, Fabrica di Roma, Farnese, Ronciglione e Tuscania, where arsenic and fluoride still exceeded safety thresholds.
In United StatesThe EPA lowered the limit from 50 to 10 ppb only in 2001, with compliance only becoming mandatory in 2006. The most affected areas are the Western states (Nevada, Arizona, New Mexico), where artesian aquifers draw from rocks rich in arsenic minerals. Over 100 million Americans they get their supplies from private wells, often unmonitored.
Reducing arsenic in water is always a good idea, even at "legal" levels.
The most interesting fact of the study? Reducing arsenic brings benefits even starting from moderate levels, below 200 µg/L. Previous studies in Taiwan and Chile had demonstrated the effect only with extreme contamination (over 600 µg/L). This means that even in areas where water meets legal limits, lowering levels further could save lives.
Analyses show a linear dose-response relationship: the more you reduce, the more you gain in health. If all participants had switched from high to low exposure, up to a third of chronic deaths would have been preventable. Arsenic has no taste, no smell, and no visible signs. It can remain inside a body for decades without showing any signs. But in the end it comes with the bill: cancers of the bladder, lung, kidney, and liver; heart attacks, strokes, and chronic kidney disease.
In Bangladesh now exists NOLKUP, a free app developed by researchers with over 6 million well tests. Users can search for the nearest well, check arsenic levels and depth, and find safe sources nearby. A way to turn twenty years of data into concrete prevention.
The lesson is clear: investing in clean water works. There's no need to wait generations. Those who drink arsenic-laced water today and switch to a safe source tomorrow eliminate the risk within a few years. A new well, a dearsenification filter, a new aqueduct. Technical solutions that, as data from Bangladesh demonstrate, can cut mortality rates in half. Standing still, however, costs lives.
(Thanks to Dr. Giovanni Ghirga, ISDE Italia, for the very kind report Follow his Facebook page, that's interesting!)
