A Norfolk Southern freight train carrying hazardous materials careened off the tracks on 3 February after suffering a broken axle, investigators later determined.
No one was harmed in the incident but around 50 cars came off the rails as a result of the accident, around 20 of which were carrying toxic chemicals, prompting more than 2,000 local residents to be temporarily evacuated from the area due to health concerns arising from the leak.
A number of the railcar tankers were transporting vinyl chloride, which is used to make plastic pipes, wires, cable coating, car parts and packaging.
It is associated with an increased risk of a rare form of liver cancer, hepatic angiosarcoma, along with primary liver cancer, brain and lung cancers, lymphoma and leukaemia, according to Cancer.gov.
As part of the clean up operation, five of the tankers containing vinyl chloride had to be intentionally breached by emergency crews, who diverted the substance into an excavated trench and carried out a controlled burn to prevent an explosion, sending noxious black clouds billowing into the atmosphere.
One of the substances released as a result of the necessity of doing so was phosgene, a gas deployed as a chemical weapon in the First World War because it can cause eye irritation, dry burning throat and vomiting.
Hydrogen chloride is also released by burning vinyl chloride and that too can irritate the skin, nose, eyes and throat, according to the US Centers for Disease Control and Prevention.
Other toxic chemicals on board the train, according to a Norfolk Southern inventory published by the Environmental Protection Agency, were butyl acrylate, ethylhexyl acrylate and ethylene glycol monobutyl ether.
The three are typically used as components in the manufacture of resins, adhesives, sealants, coatings and paints and can likewise irritate the skin and eyes or cause headaches, nausea and vomiting following exposure.
Environmental remediation work is ongoing, Norfolk Southern has said, along with air, soil and water monitoring in coordination with state and federal agencies.
The derailment has raised questions about the frequent use of rail transportation in the US to move vast quantities of toxic and dangerous substances in close proximity to communities.
However, Ian Jefferies, head of the Association of American Railroads trade group, said 99.9 per cent of all hazardous materials shipments reach their destinations safely.
Federal Railroad Administration data meanwhile shows that hazardous chemicals were only released during 11 train accidents nationwide in 2022 – out of roughly 535 million miles covered – with only two injuries reported.
Over the course of the past decade, releases of hazardous materials peaked at 20 in both 2018 and 2020.
“Railroads are the safest form of moving goods across land in the country without question,” Mr Jefferies said.
“But railroads are also working to drive toward zero incidents. Until we reach that goal, we haven’t got to where we want to be.”
Hazardous materials account for around 7-8 per cent of the 30 million shipments that railroads deliver across the country every year.
But because of the way railroads mix freight together, at least a couple of cars of toxic materials can be found on almost any train other than grain or coal trains, which would pose too great a fire hazard.
Additional reporting by agencies