What are dioxins and did the Ohio train crash release them into the air?

After the 38-car train crash in East Palestine, Ohio, some officials are raising concerns about the types of toxic substances that tend to linger in the environment.

Last week, U.S. senators from Ohio sent a letter to the state’s environmental protection agency expressing concern that dioxin could be released when some of the chemicals in the wrecked train were intentionally burned for safety reasons. He joined a number of city residents and environmentalists across the U.S. in calling on state and federal environmental agencies to test the soil around the site where the tanker truck ran.

Here’s a look at dioxins, their potential harm and whether they can be created by burning vinyl chloride on Norfolk Southern trains.

Highly toxic, persistent compound

Dioxin refers to a group of toxic chemical compounds that can persist in the environment for a long time, according to the World Health Organization. They are created through combustion and stick to dust particles.

Residents near the fire may have been exposed to dioxin in the air that landed on their skin or they breathed it into their lungs, said Frederick Guengerich, a toxicologist at Vanderbilt University.

Skin exposure to high concentrations can cause what’s called chloracne — intense skin inflammation, Guengerich said.

But the main way that dioxin enters the human body is not directly through burning. It is through the consumption of meat, milk, fish and shellfish that have become contaminated. Such contamination takes time.

“That’s why it’s important for authorities to examine this site now,” said Ted Schettler, a doctor with a degree in public health who directs the Science and Environmental Health Network, a coalition of environmental organizations.

“Because it’s important to determine if dioxin is in the soil and in the surrounding area.”

Does burning vinyl chloride create dioxins?

Linda Birnbaum, a dioxin researcher, toxicologist and former director of the National Institute of Environmental Health Sciences, said that burning vinyl chloride creates dioxin. Other experts agree that the accident could have caused it.

The “extraordinary black plume” seen in East Palestine indicates the combustion process left many complex carbon compounds, said Murray McBride, a soil and plant scientist at Cornell University.

McBride said it will be difficult to say whether the compound was released until tests are completed where the train cars are released.

That may be why citizens, politicians, environmentalists and public health professionals are all calling on state and federal environmental agencies to conduct tests at derailment sites.

Route to the environment

There are already some levels of dioxin in the environment – they can be created by certain industrial processes, or even by people burning garbage in their backyard, McBride said.

Once released, dioxins can remain in the soil for decades. They can damage plants, including plants. They accumulate in the food chain in oil and other fats.

In East Palestine, it’s possible that soot particles from the plume carried dioxin to nearby farms, where it could stick to the soil, McBride said.

“If you have animals grazing in the fields, they will pick up some of the dioxins from the soil particles,” he said. “And some of it enters the body, and then accumulates in fat tissue.”

Eventually, these dioxins can make their way up the food chain to humans. Bioaccumulation means that more dioxins can enter humans than are found in the environment after an accident.

“[Animals] It doesn’t metabolize and get rid of dioxins like other chemicals,” Schettler said, and it’s stored in animal fats that humans eat, like fish, and gets worse over time, causing worse health effects.

Should residents be concerned?

Birnbaum and Schettler agree that residents have reason to be concerned about dioxin from this accident.

Although it’s in small amounts from other sources, the amount of vinyl chloride burned from train cars can make up more than usual, McBride said.

“That’s my concern, that there might be an unusual concentration,” he said. “But again, I’m waiting for this soil to be analyzed.”

It takes between seven and 11 years for these chemicals to start breaking down in the human or animal body. And dioxin has been linked to cancer, developmental problems in children and reproductive problems and infertility in adults, according to the National Institute of Environmental Health Sciences.

However, Guengerich thinks that other potential health risks from derailment – such as concerns that exposure to vinyl chloride itself can cause cancer – may be more compelling than dioxin: the list,” he said.

Even so, most experts think it’s important to test the soil for dioxins – even though the process can be difficult and expensive.

“The right conditions for dioxin have formed,” Schettler said. “It will be very important to determine from a public health perspective, and to assure the public.”