The residents of East Palestine, Ohio, have more than enough to worry about. A train wreck with black fumes of burning chemicals pouring from a tank is frightening enough. The absolute last thing they need is the news media spreading even scarier—but inaccurate—information about the accident. Yet for weeks, that is precisely what's been going on. Vinyl chloride, a chemical long used to make PVC plastics, is being portrayed as something more suitable for capital punishment than for a routine manufacturing process in a factory. Ohioans, like the rest of the country, are being bombarded by horrifying claims about its...