Overview
- A Ferromex freight train derailed during the night of July 25–26 near the ejido Cuauhtémoc in Naco, Sonora, releasing tens of thousands of liters of hydrosulfuro de sodio that spread over nearby soil and runoff.
- Residents reported headaches, dizziness, nausea and breathing problems and at least four people were hospitalized, with Luis Arturo Osuna Vázquez remaining in grave condition with brain and lung damage while authorities await medical determinations.
- Ferromex has said containment and cleanup work concluded and described the derailment as occurring in an unpopulated area, while local families and advocates say on-site cleanup was incomplete and demand broader health monitoring and environmental testing.
- The Procuraduría Federal de Protección al Ambiente closed and inspected the area, ordered sanctions and will require a formal remediation program within 15 days, and U.S. and Mexican agencies are jointly monitoring the nearby cross‑border watershed for contamination.
- The episode is reviving local mistrust because Grupo México has a history of major contamination cases and experts warn that runoff and sediment can transport sulfide compounds into groundwater and downstream waterways, which could prolong ecological and health risks.