As the saying goes: Safety rules are written in blood…
In 1914, after the Titanic disaster, a first Convention for the Safety of Life at Sea was adopted and evolved then towards the International Safety Management Code of the International Maritime Organization (IMO), created in 1948.
The 1926 US Air Commerce Act required pilots and aircraft to be examined and licensed, and accidents investigated. The Chicago Convention in 1944 started what would become the International Civil Aviation Organization (ICAO).
The International Labour Organization (ILO) was created in 1919 as part of the Versailles Treaty. In 1950, together with the World Health Organization (from this survey), the ILO considered that a Risk Assessment and Occupational Safety and Health (OSH) Management System was fundamental to the well-being of workers.
The 1972 Robens Report introduced as fundamental concept the need to apply a policy-based approach to OSH, which became the core of the 1981 OSH Convention (#155) and Recommendation (#164). With prevention as main goal, the process is cyclical: development, implementation and review of a policy, rather than linear, to ensure that the national systems are continuously improved and able to address new issues.
Coming from the 1920 Health Organization, the World Health Organization (WHO) was created in 1948. A Safety Management System for hospitals can be found in the US Occupational Safety and Health Administration (OSHA).
The International Atomic Energy Agency (IAEA) was established in 1957. In the wake of the Chernobyl accident in 1986, one of its key commitments is to promote a Safety Culture and Safety Standards within the whole branch.
By 1944, research on Human Factors had been carried out by Alphonse Chapanis and Paul Fitts, and Ergonomics (adapt the working environment to humans instead of the other way around) got first applications. Shigeo Shingō introduced in 1961 the Poka-yoke (mistake-proof) concept to prevent errors to become defects in automotive production. In the late 1980s, Dante Orlandella and James Reason proposed the Swiss cheese model, still used in risk management and analysis.
Note: the IMO, ICAO, ILO, WHO and IAEA are all specialized agencies of the United Nations.