How the Media Got the Vinyl Chloride Risk All Wrong
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 health risks, most of which have been just plain wrong.
There is, in fact, strong evidence that vinyl chloride not only is not deadly but is, in fact, considerably less toxic than many common, everyday drugs and chemicals. Likewise, its cancer risks have also been wildly overstated. It is easy to call a chemical a carcinogen, but in the absence of context, dose, and length of exposure, this term means little.
Fortunately, there is a longstanding, highly regarded organization that provides information on the health risks of individual chemicals. The National Fire Prevention Association (NFPA) describes itself as “a global self-funded nonprofit organization, established in 1896, devoted to eliminating death, injury, property and economic loss due to fire, electrical and related hazards.” The group maintains a database of more than 3,000 chemicals—a critical tool for first responders or other workers who must deal with the aftermath of a chemical spill or fire. Here we can begin to understand the real risks of vinyl chloride.
NFPA uses color-coded “safety diamonds” to provide easily read information about chemicals that firefighters may encounter. They quickly cover a chemical’s health hazards, flammability, and stability (that is, whether it can spontaneously explode), along with any special warnings—for example, when exposure to water must be avoided.
NFPA classifies health hazards on a scale of 0 to 4, where 0 indicates little or no hazard and 4 is reserved for deadly chemicals that can kill even with short exposure. Vinyl chloride has a 2 rating—a “moderate” hazard, described as posing a “temporary or minor, reversible injury [that may be] harmful if swallowed, inhaled, or absorbed through the skin.”
To put this in perspective, both alcohol and chloroform—the latter was used for general anesthesia for 125 years—are also rated 2. Both alcohol and chloroform are also known carcinogens.
The disconnect between the data and the coverage becomes even more apparent when data from animal models of toxicity are considered. One common measure of toxicity is the LD50, which stands for “lethal dose 50 percent”—the amount of material given at once (usually orally) that kills half of the test animals. Although these data cannot be quantitatively applied to human beings, LD50 values are useful for identifying which chemicals are very
Article from Reason.com