The East Palestine Train Derailment: A Case Study in Acute Chemical Exposure

At approximately 8:55 pm on February 3, 2023, a Norfolk Southern freight train carrying hazardous chemicals derailed near the small town of East Palestine, Ohio — population 4,800 — sending 38 cars off the tracks. Among the derailed cars were tankers containing vinyl chloride, butyl acrylate, ethylhexyl acrylate, and other hazardous substances.

In the days following the derailment, emergency responders faced a decision that would define the East Palestine story: several vinyl chloride tanker cars were damaged and could not be safely removed. There was concern that the vinyl chloride could polymerise — a runaway reaction that could cause an explosion. The decision was made to conduct a controlled burn — to deliberately ignite the vinyl chloride through a "vent and burn" operation that would release the chemical in a controlled flame rather than risk an uncontrolled explosion.

On February 6, 2023, the vent and burn was conducted. A massive black plume rose over East Palestine, visible for miles. The combustion products of burning vinyl chloride include hydrogen chloride, phosgene — the World War I chemical weapon — and, under certain combustion conditions, chlorinated dioxins and furans. Residents had been briefly evacuated and were allowed to return February 8, as state environmental officials indicated air quality had returned to safe levels.

Burning chlorinated compounds produces a specific and well-characterised set of combustion byproducts — the same chemistry that makes PVC incineration a source of dioxins in municipal waste combustion.

Vinyl chloride combustion chemistry When vinyl chloride (CH₂=CHCl) burns completely, it produces carbon dioxide, water, and hydrogen chloride (HCl). Complete combustion is the desired outcome — HCl is irritating but manageable. Incomplete combustion — which occurs at lower temperatures, in oxygen-limited conditions, or at the periphery of the flame — produces an array of partially chlorinated organic compounds, including chlorinated dioxins and furans.

The dioxin question The central analytical question following the East Palestine burn was: did the incomplete combustion of vinyl chloride and other chlorinated chemicals produce dioxins and furans at concentrations that posed health risks to the surrounding community?

EPA and Ohio EPA conducted soil, air, and water sampling in the months following the derailment. Air sampling during and immediately after the burn found elevated hydrogen chloride. Subsequent soil sampling found dioxin concentrations at some locations near the derailment site above EPA residential screening levels — a finding that was initially contested and then accepted as the data accumulated.

The community's concerns about the adequacy of the initial "all clear" and the speed of the return-to-home decision were validated in part by the subsequent finding of dioxin in soil — suggesting that the initial air quality testing in the days following the burn had not captured the full extent of contamination.

The monitoring and sampling response to East Palestine involved multiple agencies, multiple sampling programmes, and a level of public scrutiny that would not have existed without significant community and media pressure.

The official monitoring programmes: • EPA conducted air monitoring using mobile monitoring units in the days and weeks following the derailment • Ohio EPA and EPA conducted water sampling of private wells, surface water (Leslie Run, a creek affected by the derailment), and the Ohio River • Soil sampling was conducted in the vicinity of the derailment site and in surrounding residential areas • Indoor air sampling was offered to residents

The community response to official monitoring: Many East Palestine residents were not satisfied with the official monitoring assurances. They pointed to: • The speed of the initial "all clear" declaration before comprehensive sampling was complete • The selection of sampling locations that may not have captured the full extent of contamination • The lack of early sampling for dioxins, which were not included in initial monitoring protocols • Persistent reports of chemical odours, dead fish, and ill pets that preceded official acknowledgment of contamination

Independent monitoring An independent monitoring programme was conducted by researchers from Texas A&M University and other institutions, which found vinyl chloride and other chemicals in air samples in the weeks following the derailment — at concentrations not detected by the official monitoring. The discrepancy raised legitimate questions about whether official monitoring protocols were adequate for the specific chemical mixture involved.

Long-term health surveillance is the most important thing East Palestine residents need — and also the component of the governmental response that has been most delayed and most contested.

The health effects of concern: Based on the chemicals involved — vinyl chloride, butyl acrylate, dioxins — the health effects of greatest concern in exposed populations include: • Acute respiratory symptoms (already documented in many residents in the weeks following) • Neurological symptoms from vinyl chloride and solvent exposure • Carcinogenic effects from vinyl chloride (IARC Group 1) and dioxins (IARC Group 1) over long latency periods • Immunological effects from dioxin exposure • Developmental effects in children and fetuses from any dioxin exposure that occurred

What long-term surveillance should include: • Biomonitoring: blood and urine testing for vinyl chloride metabolites, dioxin body burden, and other chemical markers in exposed residents — providing a baseline against which future measurements can be compared • A prospective health cohort: documenting health outcomes in exposed residents over years to decades, enabling detection of any excess cancer or other disease incidence • Ongoing environmental monitoring: soil, water, and air sampling at the derailment site and in the surrounding community, including indoor air testing in affected homes

The regulatory gap The East Palestine response exposed a gap in federal environmental emergency response: there is no requirement for long-term biomonitoring or health surveillance following chemical emergency events, even those involving known carcinogens. The initial response is managed through EPA's emergency removal programme; the long-term health surveillance that exposed communities need falls to ATSDR, which has limited resources.

Residents of East Palestine and their physicians can use PollutionProfile's Historical Exposure Recorder to document the specific exposure event — dates, location, duration, and chemical context — in the format needed for future medical reference and for participation in any research programmes that are established to follow the community's health.