The term ALARP arises from UK legislation, particularly the Health and Safety at Work, etc. Act 1974 requires “Provision and maintenance of plant and systems of work that are, so far as is reasonably practicable, safe and without risks to health.” The phrase So Far As is Reasonably Practicable (SFARP) in this and similar clauses are interpreted as leading to a requirement that risks must be reduced to a level that is As Low As is Reasonably Practicable (ALARP). ALARP, used especially in the UK, is a much broader term than ALARA since it is applicable in various fields of the regulation and management of safety-critical and safety-involved systems.
The term “as low as reasonably achievable” (ALARA) used in the optimization principle is synonymous with ALARP. The term is used to describe the risk reduction process outside the UK. The term ALARA, or “as low as reasonably achievable,” is used interchangeably in the United States of America, almost exclusively in the field of radiation protection. ALARA and ALARP are considered to be equivalent in meaning and purpose.