What we know about the Ohio train derailment

• The train, which derailed on Feb. 3, was carrying hazardous materials, including at least five tanker cars of vinyl chloride, a colorless but hazardous and carcinogenic gas used to produce PVC plastic and vinyl products.

The latest

• Transportation Secretary Pete Buttigieg sent a letter on Feb. 19 to the CEO of Norfolk Southern emphasizing the "urgent need" for the company to "demonstrate unequivocal support for the people of East Palestine and the surrounding areas."
• "It is imperative that your company be unambiguous and forthright in its commitment to take care of the residents — now and in the future," Buttigieg said.
• "Until the number of derailments is zero and rail workers are confident in being fully equipped to do their jobs safely, everyone involved in our rail system must make safety improvements a priority," Buttigieg said.
• The letter also outlines previous train derailments, including two in 2011 and 2012 involving Norfolk Southern trains, that forced people near the crash sites to evacuate and the suggestions made by two federal agencies to help prevent future incidents, including the installation of electronic braking systems.
• "Rather than support these efforts to improve rail safety, Norfolk Southern and other rail companies spent millions of dollars in the courts and lobbying members of Congress to oppose common-sense safety regulations, stopping some entirely and reducing the scope of others. As a result, Congress enacted language that undermined the ability of USDOT to sustain the [Electronically Controlled Pneumatic] brake requirements, and they were ultimately withdrawn under the Trump administration," the letter continued.
• "Soon I will be laying out several steps that Norfolk Southern, and all major railroads, should take immediately to improve rail safety for workers and communities—in addition to prioritized actions planned at our department in furtherance of our safety mission," Buttigieg added.

Catch up quick: Norfolk Southern officials said some of the cars carrying the vinyl chloride were not breached during the crash but were at risk of exploding, so crews released and burned their contents on Feb. 6, creating a massive smoke plume above the town for several hours.

• Hundreds of people evacuated East Palestine before the release and burn of the vinyl chloride but were allowed to return two days later.
• Some East Palestine residents who have returned have complained of smells, headaches, nausea and other ailments, according to the Washington Post.
• DeWine said on Feb. 14 he authorized the operation of the release and burning of the vinyl chloride at the crash site, saying officials faced two bad options between potentially letting a car containing the material explode or doing the release.

Mechanical issue

A mechanical issue with an axle of one of the 150 cars is believed to be the cause of the derailment of at least 50 of the cars, though the National Transportation Safety Board has not yet made an official determination of the cause.

• Security footage captured in Salem, Ohio — around 20 miles west of East Palestine — before the derailment showed sparks or flames under at least one of the cars on the train, which was transporting goods from Madison, Illinois, to Conway, Pennsylvania.
• At least four other tanker cars involved in the derailment were carrying at least four other different chemicals — ethylene glycol monobutyl ether, ethylhexyl acrylate, isobutylene and butyl acrylate, according to a list sent by Norfolk Southern to the EPA, which released it on Feb. 12.
• In the list, Norfolk Southern said the cars carrying the butyl acrylate and the ethylhexyl acrylate were breached and either all or some of the chemicals were released during the crash.
• It labeled the status of the car carrying ethylene glycol monobutyl ether as "unknown," while it said the isobutylene car was burned but not breached.

What risks the chemicals may pose to humans

Acute exposure to high levels of vinyl chloride, a classified human carcinogen, in the air has been linked to central nervous system effects, while chronic exposure has been shown to cause liver damage, including a rare form of liver cancer, according to the EPA.

• When vinyl chloride burns it decomposes into hydrogen chloride and phosgene, according to the International Programme on Chemical Safety.
• Phosgene is highly poisonous and was used extensively during World War I as a choking agent, while hydrogen chloride is irritating and corrosive to any tissue with which it comes into contact.

Monitoring environmental impact

The Environmental Protection Agency has said it has not detected any "levels of concern" of hazardous substances released during or after the crash, though the agency is continuing to monitor the air throughout East Palestine, including inside at least 210 homes.

• The EPA said it was also investigating soil and surface water contamination near the crash site and had collected spilled material in a nearby stream, Sulphur Run.
• It said Norfolk Southern had installed a dam and water bypass system in the stream to prevent contamination of downstream waters, though it did not say when they were installed.
• In a letter sent to the company on Feb. 10, the EPA said substances released during the incident "were observed and detected in samples from Sulphur Run, Leslie Run, Bull Creek, North Fork Little Beaver Creek, Little Beaver Creek, and the Ohio River" and were also observed entering storm drains.
• DeWine said Wednesday that the water in East Palestine's municipal system is safe to drink based on the Ohio Environmental Protection Agency's results from the latest water tests.

Assessing wildlife impact

The Ohio Department of Natural Resources estimates that 3,500 fish of 12 different species, none of which are endangered, died after the crash across approximately 7.5 miles of streams south of the town, ODNR director Mary Mertz said on Tuesday.

• Mertz added the department does not have evidence of non-aquatic species being affected by chemicals released during or after the derailment.
• Tiffani Kavalec, chief of the Ohio EPA's Division of Surface Water, said the stream Sulphur Run remains polluted but the agency believes the contamination is contained and not moving downstream.

Federal response

On Feb. 17, Ohio Gov. Mike DeWine (R) said the Department of Health and Human Services will help state health authorities set up a clinic in East Palestine so that any resident, including those without insurance, may visit a doctor over any health concerns.

• The clinic will open in the coming days, and information on its location and hours will soon be available, DeWine said. There will be local mental health resources available to residents as well.
• The Federal Emergency Management Agency is also sending a team to East Palestine "to support ongoing operations, including incident coordination and ongoing assessments of potential long term recovery needs,” the agency said in a joint statement with DeWine the same day.
• "Just got word—FEMA will deploy a Senior Response Official and Incident Management Assistance Team tomorrow to monitor and support," Sen. Sherrod Brown (D-Ohio) said on Twitter. "This will be a huge help to the community."
• DeWine and Brown both previously spoke with President Biden and requested federal assistance.

Context: The day before, DeWine said that despite being in "daily contact" with FEMA, the agency said "Ohio is not eligible for assistance at this time." The agency typically responds to disasters that involve extensive property damage.

• The state filed a request to "preserve our rights" to receive help from the agency if the state becomes eligible, he later said.
• "We believe that the railroad should continue to pay, and we're going to insist that they pay," DeWine said. "Whatever damages have been caused, the railroad is responsible for those damages."

Lawsuits and liability questions

The EPA sent Norfolk Southern a "General Notice of Potential Liability" letter on Feb. 10, in which it said it had determined that the company "may be responsible under [Comprehensive Environmental Response, Compensation and Liability Act] for cleanup of the Site or costs EPA has incurred in cleaning up the Site."

• Connor Spielmaker, a senior communications manager at Norfolk Southern, told Axios on Monday that the company received the EPA’s letter and has "confirmed to them that we have and will continue to perform or finance environmental monitoring and remediation."
• So far, at least four class action lawsuits have been filed against Norfolk Southern over the crash, alleging negligence.
• A spokesperson for Norfolk Southern did not directly respond to Axios' questions on the class-action lawsuits or the status of the car carrying the ethylene glycol monobutyl ether.
• DeWine said Tuesday the train was not considered a "high-hazardous material train" despite the chemicals onboard, meaning Norfolk Southern was not required to notify the state of the contents of the cars. He also called on Congress to review how high-hazardous trains are classified.

Norfolk Southern's response to community

In a press release on Feb. 14, the company said it has donated $1.2 million to around 1,000 families to cover expenses they incurred from their evacuations and was in the process of providing aid to local businesses.

• It said it has so far completed more than 400 in-home air tests with the EPA, which have not "shown any detections of substances related to the incident and does not indicate a health risk."
• The company said on Feb. 13 it has donated $220,000 to the town's fire department to replace breathing apparatuses used by firefighters, $25,000 to the Ohio Red Cross to support a shelter set up at East Palestine High School, and around 100 air purifiers for residents.
• On Feb. 15, Norfolk Southern pulled out of a town hall with local, state, and federal officials due to concern over the "growing physical threat" to its employees and members of the community, but it did not elaborate on what the threat entailed.
• People at the town hall, which occurred without representatives from the railway company, sought answers for the potential of long-term exposure to chemicals released during and after the derailment, and what health dangers residents may face.

Go deeper: Ohio derailment prompts calls to investigate federal oversight of trains

Editor's note: This story has been updated with additional details throughout.