toxicant

This term is primarily used in scientific, regulatory, and toxicological contexts to describe the specific agent causing toxicity. While "toxin" is often used interchangeably in casual speech, "toxicant" is the more precise term for any poisonous substance, including synthetic chemicals like pesticides or industrial pollutants, whereas "toxin" typically refers to poisons produced naturally by biological organisms.

Because it is a technical term, it carries a neutral, clinical tone. It is rarely used in everyday conversation, where "poison" or "chemical" would be more common. In a professional report, using "toxicant" signals a focus on the chemical properties and the measurable effect on a biological system.