The vast majority of vinyl chloride is used to produce PVC products like vinyl siding, wire coverings, and PVC pipe that are used in the construction of buildings. When a building catches fire, vinyl chloride gas is released from these materials at concentrations of 8,000 parts per million. At these concentrations, even a short-term exposure to vinyl chloride gas can cause permanent health damage and even death.
Vinyl chloride is a colorless gas with an odor threshold of 3,000 parts per million. Below this concentration, vinyl chloride is completely imperceptible to the human senses.
Because only 0.25% of PVC products are ever recycled, the vast majority are incinerated or end up in landfills. Levels of vinyl chloride gas as high as 44 parts per million have been observed in the air surrounding landfills. While PVC plastic itself does not usually emit a substantial amount of vinyl chloride in its inter form, PVC has a high chlorine content (53%) and vinyl chloride gas is released when this chlorine slowly breaks down in a landfill setting.
No regulations exist to govern the exposure of communities surrounding vinyl chloride production facilities. These communities, known as "fenceline" communities, are daily exposed to vinyl chloride levels as high as 10.6 parts per million.
These numbers can spike drastically in the event of catastrophic accidental releases and so-called "fugitive emissions" during the normal course of business. In towns like Mossville, Louisiana, which is surrounded by 14 chemical plants—three of which are vinyl chloride production facilities—these emissions are difficult to trace to a single source. Accordingly, residents suffer chronic health problems at alarming rates, yet have little recourse to hold corporations accountable.
Under current EPA regulations, as long as vinyl chloride manufacturers report all releases of vinyl chloride to the EPA's Toxic Release Inventory, the releases themselves are within the bounds of the law.
In 1974, the exposure limit for workers in the manufacture and polymerization of vinyl chloride was lowered from 500 parts per million to only 1 part per million. This only happened after a group of 10 vinyl chloride workers at a plant in Kentucky died of angiosarcoma—an extremely rare form of liver cancer—in the early 1970s, confirming confidential industry studies linking vinyl chloride exposure to angiosarcoma of the liver.
In many ways, 1 ppm is an arbitrary limit, with many experts arguing it may still be hundreds of times too high to be truly safe. A Chinese study conducted in 1999 confirmed that workers exposed to 1 ppm developed genetic mutations of the p-53 protein consistent with angiosarcoma of the liver.
The EPA-mandated ambient air standard for vinyl chloride is only 0.00047 parts per million (or 0.47 parts per billion). This is the level at which vinyl chloride is considered safe for the public.