Detection of degradation products of chemical warfare agents in Halabja soil: In vitro genotoxicity and effects in exposed humans.

The town of Halabja in Iraqi Kurdistan remains a symbol of the devastating impact of chemical weapons. Almost four decades after the attack, inhabitants continue to suffer from increased cancer rates and severe respiratory, neurological, and psychiatric disorders. While the acute effects of chemical warfare agents have been widely studied, their long-term environmental persistence and associated health impacts remain poorly understood. Here, we investigated the presence of chemical warfare agent residues in the environment and assessed their potential genotoxic effects. Soil and water samples collected in Halabja in 2021 were analyzed for chemical warfare agents, including sulfur mustard, sarin, and their degradation products using gas chromatography-mass spectrometry with dual flame photometric detection and liquid chromatography-mass spectrometry, selected for their sensitivity toward sulfur- and phosphorus-containing compounds. In soil samples, we detected thiodiglycolic acid and methylphosphonic acid, degradation products of sulfur mustard and organophosphorus nerve agents, respectively. To evaluate biological relevance, soil-derived extracts were tested in vitro using Western blotting to assess markers of DNA damage and inflammation, revealing elevated levels of both endpoints. Because some soil samples also contained the persistent organic pollutant p,p'-DDE, the observed genotoxic effects were interpreted as potentially reflecting contributions from both CWA-related degradation products and other environmental contaminants. To complement these findings, plasma and peripheral blood mononuclear cells from individuals exposed in 1988 were analyzed in 2025, by flow cytometry and ELISA, demonstrating increased levels of the same markers compared with controls. Together, these findings indicate long-term environmental persistence of chemical warfare agent degradation products and their genotoxic potential, while also highlighting that other environmental contaminants may contribute to the biological effects observed in complex soil extracts, alongside sustained biological effects in exposed individuals.