Vinyl chloride is a highly toxic chemical, which is why an evacuation was ordered. It is primarily used in the manufacturing of plastics. However, it is a known carcinogen linked to liver, brain, lung, and some blood cancers. Most of what we know about the long-term effects comes from individuals who have been exposed over long periods of time. We don't know the long-term effects of a massive burst of exposure, like what happened in East Palestine. Nor do we know how the decision to burn the chemical (and others) might affect large swaths of people living around the crash area and downwind.When vinyl chloride is burned, it releases phosgene gas, hydrogen chloride, and dioxins into the air, all of which are highly poisonous to humans and animals. Phosgene gas, in particular, was used heavily during World War I during trench warfare. It is now outlawed by the Chemical Weapons Convention treaty. Exposure to phosgene gas is linked to many chronic health problems, like asthma, pulmonary edema, reproductive and developmental issues, kidney and liver failure, heart failure, and death. Hydrogen chloride exposure is linked to Reactive Airways Dysfunction Syndrome, respiratory problems, and eye and skin irritation. There is a fair amount of worry that the decision to burn the tankers holding vinyl chloride could result in the formation of dioxins. The problem with dioxins is that they are persistent pollutants that remain in the environment and the human body for years which may result in dangerous long-term health effects. Experts have said one of the biggest problems with burning vinyl chloride at the crash site is that they don't know what other chemical compounds may have interacted with each other. That means that while environmental tests were performed to measure the levels of phosgene gas and other pollutants, they don't understand the entire profile of chemicals that resulted from the burn. Therefore, they don't exactly know what they're testing for and what levels are safe.