Back in the olden days of the 1960s to 1980s there was more health risks involved with commercial diving. This was partly to do with the lifestyle, conditions but mostly the decompression models used, which were very aggressive. Bone necrosis being one such long-term illness.
If I recall my numbers correctly, the North Sea lost 13% of their mixed gas offshore oilfield divers in 1973. That nonsense soon ended for many reasons.