New Details Surrounding Cause of Ohio Train Derailment Revealed by NTSB

The National Transportation Safety Board has released new details about the cause of the fiery Ohio train derailment that led to a toxic chemical leak.

In a Tuesday press release, the NTSB said that after identifying and examining the rail car that started the February 3 derailment, additional surveillance video from a nearby residence showed "a wheel bearing in the final stage of overheat failure moments before the derailment."

Previously, the board had only confirmed that the incident was caused by "a mechanical issue with one of the rail car axles."

Pressure to investigate what caused the derailment has mounted in recent days as residents in East Palestine, Ohio, have raised concern about the potential health and ecological impact the accident has had on the town.

Around 50 carriages of a Norfolk Southern train that was carrying vinyl chloride fell off the tracks earlier this month, resulting in a huge fire. Thousands were forced to evacuate from their homes out of fears that hazardous materials were released into the air, and since returning home, some have reported that their animals have died from what they believe to be chemical exposure.

Ohio Derailment Update NTSB
Smoke rises from a derailed cargo train in East Palestine, Ohio, on February 4. Inset: The National Transportation Safety Board logo on a podium on July 16, 2008, shortly before a press conference at a training facility in Virginia. The NTSB has released new details about the cause of the fiery Ohio train derailment that led to a toxic chemical leak. Dustin Franz/Paul J. Richards/AFP

In the latest press release, the NTSB said that the wheelset that's suspected to have caused the derailment has been collected as evidence for "metallurgical examination." It will be examined by engineers with the board's materials laboratory in Washington, D.C.

Investigators have discovered that 11 hazardous materials rail cars were involved in the incident. Once all the tank cars are decontaminated, the NTSB's team will complete another examination of those cars.

"NTSB continues to work with the investigative parties to determine what exactly caused the derailment and to evaluate the emergency response efforts," Tuesday's statement read. The board expects to publish its preliminary report in two weeks.

In the original explanation of events, the NTSB said that an engineer, a conductor and a conductor trainee were all on board during the derailment but that no one had been injured.

On Monday, freshman Senator J.D. Vance announced his office would investigate the accident and probe matters including "the quality of the braking system used, the durability of the repair parts in the trains, and the Transportation Department's regulatory approach to our nation's rail system."

In a Monday statement, the Environmental Protection Agency (EPA) said that no "levels of concern" have been detected in the East Palestine community at this time.

"As of February 12, we have screened 291 homes and no detections of vinyl chloride or hydrogen chloride were identified. There are 181 remaining homes to screen," the agency tweeted. "At this time, EPA has not detected any levels of concern in the community that can be attributed to the incident."