Principles for the Testing and Evaluation of Drugs for Carcinogenicity

activities both occupational and non-occupational. Nor are doctors practising in coastal areas the only ones who may be faced with diving accidents or a patient with the bends, as subaqua clubs may use inland waters and divers may be brought off an oil rig by helicopter and have travelled a considerable distance before having an attack of decompression sickness. The author points out that the growth of underwater operations has been relatively slow compared with climbing and space travel, but his explanation that this is due to an instinctive and subconscious distrust of the sea derived from man's primitive origins is unconvincing. If man distrusts the sea it is surely because he has sound practical reasons for doing so. The hazards of the ocean are familiar and real for seafaring people. The descriptions of underwater accidents underline the need for strict training and discipline for subaqua enthusiasts in order to avoid errors which can so easily be fatal. This is essential reading for anyone concerned with the health and safety of a subaqua group especially as there is a tendency for them to go to greater depths than hitherto. Decompression sickness in subaqua swimmers is always a possibility and it raises the problem of the general availability of compression chambers for emergency treatment. A list of such facilities available in Britain would be a useful appendix for the next edition. The chapters on the physiological effects of nitrogen, oxygen and carbon dioxide at raised ambient pressures summarize present knowledge clearly. Work in compressed air in caissons or tunnels may be carried out anywhere in the British Isles. Doctorswho are involved in the care of compressed air workers will find this book useful and particularly the section on decompression, although it deals mainly with divers. For the problems peculiar to caisson and tunnel workers it will be necessary to seek information elsewhere but the reference list is helpful here. There are useful lists of references for further reading at the end of each chapter.