- noun a substance that is toxic, persistent and likely to accumulate in organisms
- noun any substance that could be dangerous to people in the workplace, e.g. a poisonous raw material, fumes or by-product from a production process. Employers have a duty to assess the risks from hazardous substances to their staff and customers, and to ensure that no one is exposed to danger.
- Any substance that, by virtue of its composition or capabilities, is likely to be harmful, injurious, or lethal.