In a study which was funded by the U.K. Departmentof Energy (Fox et al, 1984) blood was taken from more than 150 divers and an equal number of control subjects. Of 77 compressed air divers and 76 mixed gas divers, 6 had a few heavily damaged cells. The health risks imposed by these abnormal cells is unknown but the damage they contain is, in most cases, so extreme that they are likely to die at mitosis. No such cells were found in the controls.
This type of finding was unexpected and, because of such low numbers, no correlation was possible with the many associated occupational factors that were also studied. The aberrations observed were typical of those induced by ionizing radiation and were present in air divers as well as mixed gas divers.
In addition, changes have been reported in lymphocytes and heat shock protein expression in divers in the UHMS publication, Undersea and Hyperbaric Medicine.
Undersea Hyperb Med 2000 Spring;27(1):37-41
Hyperbaric stress during saturation diving induces lymphocyte subset changes and heat shock protein expression.
Matsuo H, Shinomiya N, Suzuki S
Department of Microbiology, National Defense Medical College, Tokorozawa, Japan.
To clarify the cellular responses and biochemical markers of hyperbaric stress, we investigated heat shock protein (hsp) expression and subset changes of human peripheral blood lymphocytes during saturation diving. Five healthy male subjects underwent a 39-day saturation dive to the maximal storage pressure of 4.1 MPa [400 meters of sea water (msw)]. During the saturation dive, lymphocyte subset changes were detected using a flow cytometer, and increased expressions of hsp 72/73 and hsp 27 were observed by Western blot analysis. Lymphocyte subset changes included a decrease in CD4:CD8 ratio and in the fraction of CD4+ T cells as well as an increase in NK cells, especially during the 400-msw bottom phase. An increased expression of hsp 27 compared to hsp 72/73 was obvious, especially during the hold period at 100 msw. These results suggest that changes in lymphocyte subsets and hsp expression are useful markers for stress responses during saturation diving. These changes may also be useful for testing the barotolerance of divers for saturation diving.
Other references to lymphocyte suppression and diving are located at
Shinomiya N, Suzuki S, Hashimoto A, Oiwa H.
Effects of deep saturation diving on the lymphocyte subsets of healthy divers.
Undersea Hyperb Med. 1994 Sep;21(3):277-86.
There are also many other possible long-term effects such as subfertility in animals (Hawley et al, 1986), an effect recently studied in man and reported in the International Journal of Andrology.
Int J Androl 2000 Apr;23(2):116-20
Impact of a deep saturation dive on semen quality.
Aitken RJ, Buckingham D, Richardson D, Gardiner JC, Irvine DS
MRC Reproductive Biology Unit, 37 Chalmers Street, Edinburgh EH3 9ET, Scotland.
The demonstration dive ‘Aurora’ has provided an opportunity to study the impact of extreme hyperbaric conditions on male fertility. This operation involved a 33-day diving programme during which divers were exposed to a maximum pressure of 4.6 Mega Pascals (Mpa) for 7 days. At days – 4, + 27, + 34, + 82 and + 263 relative to the initiation of the dive, semen samples were analysed to determine the quality of spermatogenesis and the functional competence of the spermatozoa. A dramatic fall in semen quality was observed in association with the dive and by day + 82 the potential fertility of the men was seriously compromised as evidenced by oligoasthenoteratozoospermic semen profiles and the poor fertilizing potential of the spermatozoa. These studies indicate, for the first time, that the severe hyperbaric conditions associated with deep saturation dives have a profound effect on male reproductive function.
Diving and fertility
Few areas of military activity seem to generate as much myth and legend as diving. It is a common belief that male divers offspring tend to be female, and the mechanism for this is often quoted as a hyperbaric effect on testicular perfusion. In an unpublished study, Edmonds conducted a retrospective review of Royal Australian Navy divers offspring. Of 240 offspring, 122 were conceived before diving activities, the remaining 118 after the divers received their diving qualifications. Edmonds further divided these groups into air divers and oxygen divers and generated 2 contingency tables that were analysed by chi2 test. There was no significant difference between the groups and no support for the hypothesis that divers have a propensity to female offspring (Edmonds, quoted by Commander Robyn Walker, personal communication)
Vol 2 September 2001