With respect to occupational injuries, occupational diseases and work-related illnesses, it is
important to know when injuries or illnesses can be attributed to work. Also, in the case of work
accidents, the attribution to work or conditions at work is sometimes problematic. In many countries, the compensation system has precisely defined which injuries or diseases are occupational. In these circumstances, many illnesses that are (for the larger part) related to work may not be counted. New diseases, for instance certain forms of cancer, allergic reactions, muscular skeletal disorders or mental problems due to work stress, may not be accepted yet as occupational.