A train loaded with "Class 1" carcinogenic chemicals derailed. What impacts will the vinyl chloride leak have?

It is reported that on February 3rd local time, a freight train carrying the dangerous chemical vinyl chloride derailed in Ohio, USA.

The accident site is a small town on the Pennsylvania border with about 4,700 residents. When a cloud of black smoke rose, people living near the accident immediately began to evacuate. The five derailed pressure tank cars at the accident site were carrying 100,000 gallons (about 380 cubic meters) of vinyl chloride. In order to avoid an explosion, the railway and state authorities began to release and burn the vinyl chloride on February 6.

What exactly is vinyl chloride, the protagonist of this chemical leak? What environmental problems will this accident cause? Will it really affect the entire Ohio ecology?

Image source: CCTV

01

What is vinyl chloride?

Vinyl chloride is a colorless, flammable gas with an ether-like odor. It has a density greater than that of air, is slightly soluble in water, and is soluble in most organic solvents such as ethanol and benzene. It is an important chemical raw material.

Vinyl chloride is toxic. In the list of carcinogens published by the World Health Organization's International Agency for Research on Cancer, vinyl chloride is listed as a "Class 1" carcinogen. Other "Class 1" carcinogens include formaldehyde, asbestos, and the radioactive element radium-224. High concentrations of vinyl chloride may have an anesthetic effect. After inhalation, symptoms include dizziness, fatigue, shortness of breath, and unsteady standing. In severe cases, it may cause unconsciousness. Therefore, when using vinyl chloride, be sure to pay attention to ventilation.

Image source: drawn by the author

02

Vinyl chloride has a wide range of uses

The main use of vinyl chloride is to prepare polyvinyl chloride (PVC) plastic, and PVC plastic is closely related to our lives.

PVC plastic is one of the most commonly used thermoplastics and is often used to make raincoats, tablecloths, curtains, handbags, etc. In addition, polyvinyl chloride has excellent chemical corrosion resistance, so it is also used to make corrosion-resistant pipes and artificial leather. However, due to the addition of a variety of plasticizers during its processing and the easy release of toxic hydrogen chloride gas at high temperatures, which will have an impact on human health, polyvinyl chloride cannot be used for food packaging.

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03

Once it is released, it will cause great harm to the environment

Vinyl chloride gas is highly flammable and can easily explode when exposed to open flames or high temperatures.

In this accident, after the train derailed, the sparks from the collision ignited the vinyl chloride and then caused the tank to explode. The pictures taken by local residents on the overseas social media Twitter showed that the accident site was full of flames and thick smoke. It is reported that the fire lasted from 21:00 on February 3 to the next morning. In order to prevent a larger explosion, after weighing various considerations, the Ohio emergency department implemented on-site discharge of vinyl chloride on February 6.

From a scientific point of view, such crude and reckless operation will probably cause serious environmental problems.

Because long-term testing and accurate data are needed to evaluate the impact and problems caused by this accident, this article can only make speculations based on existing knowledge and public media information.

Five days after the accident, on February 8, local authorities lifted the evacuation order, and the Ohio and Pennsylvania governments said that the toxin levels in hundreds of air samples collected in the accident area and surrounding residential areas were below dangerous standards. The Ohio Environmental Protection Agency said that some "substances" were immediately toxic to fish, but the quality of drinking water was still safe.

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Does that mean the impact of the accident is over?

I'm afraid not. In addition to the toxicity of vinyl chloride itself causing environmental pollution, vinyl chloride can also participate in photochemical smog reactions in the natural environment, producing large amounts of ozone, aldehydes, and other complex toxic substances. At the same time, the toxic gas hydrogen chloride produced by the combustion of vinyl chloride can irritate human skin and mucous membranes, and can also cause soil acidification and water pollution. These toxic substances will flow into rivers through rainwater after circulating in the atmosphere, causing serious and irreversible damage to soil and water quality.

Ohio, which has one of the most fertile lands in the United States, will suffer irreversible damage to its soil and water quality after suffering the leakage and combustion of 100,000 gallons (about 380 cubic meters) of vinyl chloride and the subsequent "attack" of a series of chemical pollutants.

Although, as mentioned above, the local environmental protection department in Ohio stated that the quality of drinking water is still safe, the impact of these chemicals on the local environment is likely to be a very long-lasting process. Therefore, only subsequent continuous monitoring can further determine the specific impact of this chemical leak on the local environment.

Chemical industry plays a vital role in the national economy and people's lives. However, once an accident occurs involving hazardous chemicals, the damage is often serious and difficult to remedy. Only by strengthening safety awareness, standardizing operations, and enforcing strict requirements in every link such as production and transportation can we prevent and control major safety risks of hazardous chemicals as much as possible.

Produced by: Science Popularization China

Author: Denovo

Producer: China Science Expo

The pictures in this article are from the copyright gallery and are not authorized for reproduction.