Two Years After Türkiye’s Deadly Quakes, Drinking Water Still Carries a Hidden Arsenic Risk

When a pair of magnitude 7.8 and 7.6 earthquakes tore through Kahramanmaraş Province in southeastern Türkiye on 6 February 2023, they killed tens of thousands of people and reduced entire city blocks to rubble. The disaster also fractured something far less visible: the network of pipes, reservoirs, and aquifers that delivered drinking water to more than a million residents. Now, a new province-wide screening study suggests that the seismic fingerprints on the region’s water supply may linger far longer than anyone expected, with arsenic emerging as the dominant driver of cumulative health risk in several districts even two years after the ground stopped shaking.

The study, published in the journal Environmental Geochemistry and Health, was led by Serdar Çetinkaya and colleagues at the University of Health Sciences in Ankara, with additional participation from Lokman Hekim University. The team sampled municipal drinking water from all 11 districts of Kahramanmaraş Province at two time points: roughly 18 months after the earthquakes, in August 2024, and again at roughly 24 months, in February 2025. This two-timepoint design allowed the researchers to look not just at a single snapshot of contamination but at whether post-earthquake exposure patterns were persisting, shifting, or resolving over time.

The analytical backbone of the study was inductively coupled plasma mass spectrometry, or ICP-MS, a technique capable of detecting trace elements at concentrations down to parts per trillion. Water samples were analyzed in triplicate, and the team validated their measurements with matrix spike-recovery experiments, the raw data for which are included in the paper’s supplementary materials. The target analytes included the classic toxic metal(loid)s of environmental health concern: arsenic, lead, cadmium, chromium, and several others that can leach into groundwater from natural mineral deposits or from damaged and disturbed infrastructure.

The headline result is, on its face, reassuring. Every measured concentration of every trace element remained below the guideline values set by the World Health Organization and by Türkiye’s national drinking-water regulation, TS 266. When the researchers compressed their multi-element dataset into a Water Quality Index, a composite score that summarizes overall water quality on a scale where lower is better, the values ranged from just 3.1 to 13.4, well within the range considered excellent for drinking purposes. By conventional single-element standards, the tap water of Kahramanmaraş passed the test.

But the story becomes considerably more complicated when the team moved from individual contaminants to cumulative risk. Using both deterministic calculations and probabilistic Monte Carlo simulations, a statistical technique that runs thousands of hypothetical exposure scenarios by varying input parameters such as water consumption rates, body weight, and contaminant concentrations, the researchers estimated the aggregate non-carcinogenic and carcinogenic hazards facing adults and children in each district. The results revealed substantial spatial heterogeneity across the province, and they singled out one group as consistently the most vulnerable: children.

In up to four districts per sampling campaign, the cumulative hazard index for children exceeded the safety threshold of 1, the point at which estimated non-carcinogenic exposure crosses the level regulators consider acceptable. Arsenic was by far the largest contributor, accounting for approximately 76 percent of the total cumulative non-carcinogenic risk. This finding matters because arsenic is a well-established human carcinogen with a long list of additional toxic effects, and because children consume more water per unit of body weight than adults, amplifying their dose from any given concentration.

The carcinogenic risk calculations produced an even more striking pattern. Deterministic estimates of lifetime cancer risk exceeded the benchmark of 1 in 10,000, a widely used screening threshold, in 21 of the 44 district-period-population combinations analyzed. The exceedances clustered consistently in three districts: Afşin, Türkoğlu, and Elbistan. Notably, Afşin and Elbistan sit atop the Afşin-Elbistan lignite coal basin, a region whose coals are known from earlier geological studies to be enriched in trace elements, providing a plausible geological context for arsenic-rich groundwater in those areas.

Here the study delivers one of its most important and most easily misread findings. The apparent carcinogenic risk exceedances do not reflect a deterioration in the actual arsenic concentrations measured in the water, all of which remained below the WHO and Turkish guideline value of 10 micrograms per liter. Instead, they are driven largely by a regulatory change: in January 2025, the US Environmental Protection Agency’s Integrated Risk Information System, or IRIS, adopted a substantially higher oral cancer slope factor for inorganic arsenic, raising it from 1.5 to 32 per milligram per kilogram per day. That more-than-twentyfold increase in the toxicity parameter means that the same measured concentrations now translate into far higher estimated cancer risks than they would have under the old factor. The exceedances, in other words, are a product of updated toxicology meeting persistent low-level contamination, not of worsening water quality.

The Monte Carlo simulations, which account for uncertainty and variability in exposure parameters, identified the same three districts as recurring screening-level hotspots, lending statistical robustness to the spatial pattern. The authors are careful, however, about what their data can and cannot prove. Because the study lacks a pre-earthquake baseline and a comparable control area outside the earthquake zone, direct causal attribution to the seismic event is not possible. The findings are consistent with the hypothesis that major earthquakes can reshape drinking-water exposure patterns long after the immediate disaster period, a phenomenon documented in other seismic settings, including the 2016 Kumamoto earthquake in Japan and the Amatrice-Norcia sequence in central Italy, where hydrogeochemical changes in groundwater have been observed before and after major quakes. But consistency is not proof.

What the study does establish is methodological and practical. It is the first province-wide assessment of post-earthquake drinking-water quality and health risk following the 2023 Türkiye earthquakes, and it demonstrates why single-contaminant, single-timepoint compliance testing is insufficient in post-disaster settings. A water supply can meet every individual regulatory limit and still produce cumulative hazard indices above 1 for the most sensitive populations when multiple trace elements are considered together over years of consumption. The authors argue that post-disaster water management should incorporate cumulative, probabilistic, and long-term monitoring, with particular attention to districts like Afşin, Türkoğlu, and Elbistan where arsenic-driven risk persists. For the residents of Kahramanmaraş, the message is nuanced: their water is, by every conventional measure, safe to drink. Yet the invisible arithmetic of chronic, low-dose exposure, weighted by the newest and most conservative toxicological assessments, suggests that the true health legacy of the 2023 earthquakes may still be unfolding, quietly, one glass of water at a time.

Subject of Research: Post-earthquake drinking-water quality and health risk assessment in Kahramanmaraş Province, Türkiye

Article Title: Post-earthquake monitoring of drinking-water quality and health risk in Kahramanmaraş Province, Türkiye: a two-timepoint screening assessment

Article References: Çetinkaya, S., Aydin, H., Çetin, M., Macit, E., & Erdem, O. (2026). Post-earthquake monitoring of drinking-water quality and health risk in Kahramanmaraş Province, Türkiye: a two-timepoint screening assessment. Environmental Geochemistry and Health, 48(15), Article 621. https://doi.org/10.1007/s10653-026-03517-w

Image Credits: AI Generated

DOI: 10.1007/s10653-026-03517-w

Keywords: drinking water, arsenic, earthquake, Kahramanmaraş, health risk assessment, ICP-MS, Monte Carlo simulation, water quality index, trace elements, Türkiye, Environmental Geochemistry and Health, post-disaster monitoring