What agency is responsible for national work place safety regulations?

In the US, national workplace safety regulations are the responsibility of the Occupational Safety and Health Administration (OSHA), within the Department of Labor

In Canada, national workplace safety regulations are the responsibility of the Ministry of Labour, but national responsibilities are very limited in scope and most responsibilities reside at the Provincial level.

In the UK, national workplace safety regulations are the responsibility of the Health and Safety Executive (HSE)

Most countries place this responsibility within their Ministries of Labor or Health.