It is not uncommon that a group of scientists from many different disciplines join a working group, discuss a topic of interest and edit a volume of articles related to this topic. They may even agree on a jointly written introduction or conclusion . The study group "Environmental Standards" established in 1987 as an expert panel of the German Academy of Sciences and Technology in Berlin broke with that common tradition and became involved in a fascinating, but also pain-staking experiment to compose a document on setting environmental standards that has been literally written and authorized by all group members. The group consisted of eleven individuals representing the following disciplines: physics, chemistry, biology, engineering , law , psychology, and sociology/economics. The study group had two major goals: First, to provide a document that summarizes the state of the art in each discipline with respect to the topic of environmental standards. Since it is impossible to cover all environmental hazards in one book, the panel members agreed to limit the discussion of the scientific material to one major case study: the effects of ionizing radiation. This topic was selected because the scientific data base is well developed in this area and levels of anthropogenic release can be compared with natural background levels . These two conditions are rarely met by most chemical hazards.
The ever-increasing release of harmful agents due to human activities have led in some areas of the world to heavy pollution. In order to protect human health and the environment, environmental standards that shall limit the release and the concentration of those toxic agents in the environment and hence the exposure to it have to be established. The related assessment and decision-making procedures have to be based on solid scientific data about the effects and mechanisms of these agents as well as on ethical, social and economic aspects. For risk evaluation, the knowledge of the dose response curve is an essential prerequisite. Dose responses without a threshold dose are most critical in this connection. Such dose responses are assumed for mutagenic and carcinogenic effects, which, therefore, dominate also the discussion in this book. In the environmentally important low dose range, risk estimation can only be achieved by extrapolation from higher doses with measurable effects. The extrapolation is accompanied with uncertainties which makes risk evaluation as well as risk communication frequently problematic. In order to ensure rational efficient and fair decisions beyond a sound scientific assessment the dialogue between disciplines, with the affected people and with the general public is necessary. In this book, the whole range of relevant and essential aspects of risk evaluation and standard setting is addressed. Starting with the ethical foundations, the sound analysis of recent scientific findings sets the frame for further reflections by theory of cognition, psychosocial sciences, and jurisprudence. The authors end up with concluding recommendations for coping with the recent problems of standard setting in the field of environmentally relevant low doses. The book is designed to a readership of scientists, legislators, administrators, and the interested public.
Studies on the effects of hyperthermia have aroused great interest in recent years. On the one hand, it has been demonstrated. that hyperthermia may be a useful treatment modality for tumors, in combination with ionizing radia tion or cytotoxic drugs. On the other hand, it is of great scientific interest to study the effects of increased temperature on biological systems. Although hyperthermia has been used in the treatment of cancer for cen turies, its therapeutic success was doubtful. However, since it has been shown that radiation-induced cell killirtg can be remarkably enhanced by hyperthermia, many investigations have been performed with cells in vitro, tumors in situ, and normal tissues. From these studies it has been concluded that many biological phenomena and their characteristics which are found in tumors may be conducive to the use of hyperthermia in cancer therapy. Many researchers are studying the cell-killing mechanisms of heat and fac tors that modify cell thermosensitivity. A very fascinating biological phenomenon is the general observation that living cells can enhance their thermoresistance within hours of heat treatment. The development of such thermotolerance is apparently a universal process, and its mechanism is of general scientific interest. Metabolic and physiological processes are changed during and after hyperthermic treatment. These changes exert a strong feedback on the thermo sensitivity of cells and tissues, and also in fluence the heating characteristics of tissues, especially in tumors.
Tumour therapy depends essentially on being able to destroy the clonogenic activity of tumour cells while keeping the damage to the normal tissue low. Clinical experience shows that tumour response varies greatly even if tumours with the same localisation, clinical, and histopathological staging are compared. Some tumours appear to be resistant to conventional radiotherapy (X-rays, y-rays or fast electrons) or chemotherapy. In these cases new therapy modalities are necessary. Combined therapy modalities seem to have advan tages for some resistant tumours; one possibility of such a treatment is to combine radiotherapy or chemotherapy with hyperthermia. This means that the local tumour, the tumour region or even the whole body of the patient has to be heated to temperatures between 40° to 45° C (in case of whole body hyperthermia to 42° C maximal) for a certain time (usually 30-60 min are adequate). Hyperthermia has a long tradition in medicine as a treatment modality for various diseases. Inscriptions of the old Egyptians and texts of the Greeks have pointed out its importance. Usually whole body hyperthermia has been used by the induction of fever. Local hyperthermia began around 1900 when Westermark treated unre sectable cervix carcinomas with hot water in a metallic coil. By the beginning of this century an increase of radiation effects was hy pothesised with hypothermia and later observed. However, only in the 1960s and 1970s were systematic investigations started which showed radiosensitisation and chemosensitisation by hyperthermia in cells and tissues including tumours.
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