What classification indicates a substance is highly toxic?

The classification indicating that a substance is highly toxic is defined by the intensity of its harmful effects on living organisms. A substance deemed "highly toxic" has the potential to cause serious adverse health effects or even death with relatively low exposure levels. This classification refers specifically to materials that can result in significant toxicity upon minimal contact or ingestion.

When assessing the toxicity of substances, highly toxic compounds are recognized for their ability to pose severe risks to health, attracting regulatory scrutiny. This classification emphasizes the importance of careful management and usage to prevent exposure.

In contrast, substances labeled as “relatively non-toxic,” “moderately toxic,” and “slightly toxic” provide information about lower levels of toxicity. While “moderately toxic” and “slightly toxic” indicate increased risks compared to non-toxic substances, they do not reflect the extreme danger that highly toxic substances present.