Chemicals in use are also subject to periodic reevaluation. Risk assessment plays a critical role in this process, and is often the driving force behind new regulations and permit conditions. Here is an overview.
Toxicity is an inherent property of all substances.
All chemical substances can produce adverse health effects at some level of exposure. Therefore, risk is a function of both toxicity and exposure. Risk assessment is how we determine risk. In regulating chemicals, scientists must decide how much exposure to a given chemical will be allowed. The dose-response assessment considers the toxic properties of a chemical and estimates the amount of the chemical that could potentially cause an adverse effect.