The substitution principle in sustainability is the maxim of how processes, services, and products should be replaced with alternatives that result in a lower environmental impact.
An example of a strong, hazard-based interpretation of the substitution principle in application regarding chemicals considers the overall impact: "hazardous chemicals should be substituted by less hazardous alternatives or preferably alternatives that mitigates identifiable hazards impacts".[1]
The principle has historically been promoted by environmental groups. This concept is becoming increasingly mainstream, being a key concept in green chemistry and a central element of EU REACH regulation.[2] Critics of the principle claim it is very difficult to implement in reality, especially in terms of legislation.
Nonetheless, the concept is an important one and a key driver behind identifying "Substances of Very High Concern" in REACH and the development of hazardous substance lists such as the SIN List and the 'ETUC Trade Union Priority List'. EU-funded projects such as SubsPort are under development to aid the identification and development of safer substitutes for hazardous chemicals.[3]