The U.S. Environmental Protection Agency issued a formal notice to Tetra Tech Inc. on Monday, detailing a significant breach of data integrity by its subcontractor, ALS Houston. The notice follows an investigation into groundwater sampling at the East Palestine, Ohio, train derailment site, where it was discovered that lab analysts had intentionally altered measurements to show false levels of chemicals.
Despite the manipulated data, the EPA confirmed that rigorous, independent validation shows no ongoing exposure to toxic chemicals from the derailment that would endanger public health. The discrepancies were first spotted in September 2025 during a routine quality control check.
Officials noticed that data regarding 2-butoxyethanol—a common solvent used in cleaners and paints—provided by ALS Houston did not match results from “split sampling” conducted at other laboratories.
The investigation reached a turning point in February 2026. Under heavy EPA oversight, the prime contractor, Tetra Tech, informed the agency that ALS Houston had indeed tampered with measurements.
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As a result, two analysts were fired for failing to follow standard operating procedures. The EPA stressed that because the errors were caught quickly, none of the falsified information was ever used to guide health, safety, or cleanup decisions.
“The Trump EPA has never stopped fighting for the East Palestine community and those impacted by this disaster,” said EPA Administrator Lee Zeldin. “My first trip after being sworn in as EPA Administrator was to visit East Palestine alongside Vice President Vance to speak with community members and see firsthand the devastation the incident has caused. EPA does not stand for analysts altering measurements and we are investigating the actions of this subcontractor to the fullest extent of the law.”
The agency has moved to reject all data submitted by ALS Houston and has referred the matter to the EPA’s Office of Inspector General. Additionally, a “Cure Notice” was issued to Tetra Tech, and the agency is currently reviewing all active contracts with the subcontractor to ensure no other projects have been compromised.
Internal records show that the EPA began holding all data from the Houston lab as early as September 2025, ordering Tetra Tech to perform extra validation on samples from the late summer and fall.
By December, the agency sent its own samples to the specialized PHILIS laboratory. Those tests, along with a second round of “double check” re-analysis in January 2026, confirmed that 2-butoxyethanol was not present in the water and there was no risk to the local environment.
The EPA stated it has “zero tolerance” for lab shortcuts and is currently reviewing its internal contracting processes to prevent similar institutional failures in the future. Updated information regarding the ongoing monitoring at East Palestine continues to be posted on the agency’s official website.
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