Reciprocal of risk: practical certainty that injury will not result from a hazard under defined conditions.

Note 1. Safety of a drug or other substance in the context of human health: the extent to which a substance may be used in the amount necessary for the intended therapeutic purpose with a minimum risk of adverse health effects.

Note 2. Safety (toxicological): The high probability that injury will not result from exposure to a substance under defined conditions of quantity and manner of use, ideally controlled to minimise exposure.