What is the defining feature of a substance classified as Extremely Hazardous under SARA?

The defining feature of a substance classified as Extremely Hazardous under the Superfund Amendments and Reauthorization Act (SARA) is its potential for significant environmental impact. The classification is based on the risks these substances pose to human health and the environment in the event of accidental releases or spills. This includes their ability to cause harm not only in the immediate vicinity but also to larger ecosystems and communities.

Substances categorized as Extremely Hazardous are generally those that can have severe, lasting effects on the environment, including toxicity to aquatic life and the potential for long-range environmental transport. This classification serves as a means of prioritizing regulatory efforts and response measures to minimize risks associated with these materials.

While other characteristics such as flammability might play a role in safety assessments, they do not define the primary concern of environmental impact as effectively as the potential for significant harm to ecosystems and public health, which is the crux of the Extremely Hazardous classification under SARA.