What is vinyl chloride, the chemical released from the East Palestine train cars?


From the time that Beaver County Emergency Services opened a dedicated phone line Monday afternoon until that midnight, it received more than 250 calls, some from as far as Philadelphia, asking when the black cloud would be coming their way.

The calls began shortly after Norfolk Southern released vinyl chloride from five derailed train cars carrying the chemical in East Palestine, Ohio. Following a severe temperature fluctuation inside the train cars, officials decided to poke holes in the tankers and set the chemical inside afire, preventing an explosion that could have sent fumes and shrapnel a mile outward.

About 5:30 p.m., images of a fire billowing a thick black cloud captured the attention of the entire region, and beyond. Soon, the cloud established a horizontal presence in the sky that appeared to hover over the site.

The plume drifted into northern Beaver County, clipping a portion of Lawrence County. By the time it was no longer detectable, about 7:30 p.m., it had traveled about five miles from the derailment site, according to radar data from the National Weather Service in Pittsburgh. Bill Modzelewski, a meteorologist with the agency, said the plume rose to about 3,000 feet.

Ohio Environmental Protection Agency Office of Emergency Response representative Mike Eberle addresses reporters at East Palestine Elementary School on Tuesday, Feb. 7, 2023, in East Palestine, Ohio. About 50 cars, including 10 carry hazardous materials, derailed in a fiery crash Friday night. Ohio and Pennsylvania residents living close to the wreckage were forced to evacuate the area and aren’t being allowed into their homes, authorities said Tuesday.

Officials of several Ohio counties urged some residents to shelter in place, citing noxious odors. In Beaver County, residents within a mile evacuated. Gov. Josh Shapiro had cautioned people within that radius that they risked permanent lung damage within a matter of hours or days. Everyone else was told the air was safe.

On Tuesday evening, the U.S. Environmental Protection Agency released the results of its air monitoring before and after the controlled release, showing elevated levels of particulate matter, but otherwise no alarming readings for some of the most worrying byproducts of the burn: hydrochloric acid and a poisonous gas called phosgene. Both can be created when vinyl chloride burns.

What is vinyl chloride?

Vinyl chloride is a colorless gas and liquid mainly used in the manufacture of plastic materials such as polyvinyl chloride, used in industrial settings and plastics such as PVC pipe.

According to the Occupational Safety and Health Administration, it has a “pleasant odor” at high concentrations. When burned, it decomposes into various gasses, potentially including hydrogen chloride and trace amounts of phosgene.

The National Cancer Institute says inhalation of vinyl chloride gas can lead to an increased risk of liver, brain and lung cancers, as well as lymphoma.

There is no federal standard for how much vinyl chloride is safe in the air. For workers, OSHA’s exposure limits are 1 part per million over eight to 10 hours, and no more than 5 parts per million during a 15-minute period. One part per million is equivalent to putting one drop of a liquid from an eyedropper into 10 gallons of water.

Inhaling a lot all at once can lead to dizziness, headaches and confusion and can cause death by respiratory and nervous system depression, according to the Environmental Protection Agency and relevant literature on the chemical.

Norfolk Southern said Monday that it had success burning off the chemical. Authorities said they would continue to monitor the scene for contaminants.

According to the Agency for Toxic Substances and Disease Registry, “vinyl chloride in the air breaks down in a few days, resulting in the formation of several other chemicals including hydrochloric acid, formaldehyde, and carbon dioxide.”

But it’s not just venting into the air.

“The cloud that was really being produced was not vinyl chloride but what it was being turned into — the combustion product,” said James Fabisiak, director of the Center for Healthy Environments & Communities at the University of Pittsburgh’s School of Public Health.

He was especially concerned about phosgene, a gas that was used as a weapon in World War I, because it can cause lung damage after acute exposure.

Mr. Fabisiak said that once it’s in the sky, phosgene disperses, so he’s not worried about long-term exposure. Rather, he said, it was the people who were near the burn and the plume when it was close to the ground who should monitor their respiratory symptoms for a few days, paying attention to a new or aggravated cough, trouble breathing or a sore throat.

EPA’s data showed that readings at monitors during and after the release, including 10 in Pennsylvania, showed no detectable concentration of phosgene. The readings did pick up some hydrochloric acid in the air but the levels were below what the EPA considers to be dangerous. The monitors also detected hydrogen cyanide — an acid that’s used as rodent poison and in industrial manufacturing and is hazardous to humans — but also at levels below federal exposure guidelines.

On Wednesday, the EPA posted an update that volatile organic compound counts rose downwind of the derailment the night before, but were below levels considered problematic. Particulate matter remained high.

Are these chemicals toxic?

Vinyl chloride gas, hydrogen chloride and phosgene are toxic. Phosgene is colorless and, according to the Centers for Disease Control and Prevention, has a “suffocating odor.” Exposure could cause coughing, burning in the throat and eyes, vomiting, chest pain and difficulty breathing.

Hydrogen chloride is “corrosive to any tissue it contacts,” according to Agency for Toxic Substances and Disease Registry. Those exposed briefly to low levels can expect throat irritation, but at high levels, a person is at risk of lung damage and suffocation. Some may also develop a type of asthma called reactive airways dysfunction syndrome from exposure. When hydrogen chloride reacts with water in the air, it forms hydrochloric acid, which is irritating and can also cause suffocation at certain levels.

“When you burn vinyl chloride, you can make a variety of different products, but we don’t know in this instance,” said Chris Reddy, a scientist at Woods Hole Oceanographic Institute who studies chemical spills. In other words, it is not a guarantee that phosgene was produced at high enough levels to sicken people.

“Fire is its own beast,” said Mr. Reddy. Many environmental factors, like wind and temperature, can affect the outcome of a chemical spill, and because the vinyl chloride burned, that means it’s harder to study.

But he said wind should dilute airborne chemicals.

“This is a very potent, short-lived and hazardous chemical, but it doesn’t last long. It’s very reactive, but it’s not going to build up in water or food,” he said. “You will not have to sell your house because it’s contaminated. This is a short, unfortunate punch in the face, and we’ll just have to get through it.”

People also have to be in the path of the toxic chemical to become sick. “Things have to be unfortunately aligned,” said Mr. Reddy. “The dose makes the poison.”

Both vinyl chloride and phosgene are heavier than air and would remain closer to the ground than other chemicals, Mr. Fabisiak said. That’s one reason that plume modeling, which was conducted by federal and state environmental agencies to determine an evacuation radius before Monday’s burn, is difficult when the plume involves different organic chemicals.

Some will rise when emitted, and others will linger near the ground, he said.

Is the air safe to breathe?

According to the EPA, while its monitors detected particulate matter from the fire on Monday and Tuesday, the agency said it “did not detect chemical contaminants of concern in the hours following the controlled burn.”

It also warned on Tuesday that “residents in the area and tens of miles away may smell odors coming from the site.”

“This is because the byproducts of the controlled burn have a low odor threshold. This means people may smell these contaminants at levels much lower than what is considered hazardous.”

On Tuesday morning, the EPA deployed a plane with air-monitoring equipment to collect information on what chemical compounds were in the air column below it.

The aircraft had been deployed in the past to categorize pollution from the Deepwater Horizon oil spill and natural disasters such as hurricanes. It can also detect radiation exposure.

A fact sheet about the plane says it can provide near real-time data, which had not been made available publicly.

Pittsburgh Post-Gazette, 8 February 2023
; https://post-gazette.com