In a letter to the transportation company Norfolk Southern, the Environmental Protection Agency (EPA) listed the hazardous materials released in the Ohio train derailment earlier this month. The incident has sparked health concerns among those living in the area.

One of the materials listed is vinyl chloride, which is a carcinogen. Short-term exposure to vinyl chloride can affect the central nervous system, resulting in dizziness, drowsiness and headaches. Long-term exposure to it can cause liver damage, including a rare liver cancer. Vinyl chloride is used to make PVC plastic and vinyl products.

When it burns, vinyl chloride becomes phosgene and hydrogen chloride — both of which are safe in small enough concentrations. Phosgene was used as a choking agent in World War I, as it is toxic. Hydrogen chloride is irritating to the eyes, throat, skin and nose.

Another chemical listed is ethylene glycol monobutyl ether. Brief exposure to it can irritate the eyes, skin and respiratory tract. Ethylene glycol monobutyl ether can affect the central nervous system, blood, kidneys and liver. Long-term exposure defats the skin.

Ethylhexyl acrylate may also be a carcinogen if swallowed, as it causes stomach cancer in animals. Contact can be irritating and it can cause dizziness, drowsiness and more.

Isobutylene is highly flammable and can cause headache, dizziness, lightheadedness and fatigue. Higher levels can cause coma and death.

Butyl acrylate is also highly flammable. It can burn skin and eyes and irritate the throat and lungs. Repeated exposure can permanently damage the lungs.

According to the EPA, these chemicals were detected in the Ohio River, which supplies water to more than 5 million people. As of Feb. 12, the EPA said it had not detected concerning levels of the hazardous substances in the air.

In that letter to Norfolk Southern, the EPA also acknowledges that the company may be liable for the costs of cleaning up the site under the federal “Superfund” law.