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Biomedical Research

The use of radioactive trace substances and ionizing radiation is common in biomedical research. The basic work is normally carried out in the laboratory and using animal models in order to study chemical, physiological and metabolic processes as well as the turnover of pharmaceuticals. Such investigations are a necessary part of the introduction of new diagnostic and therapeutic methods. In all investigations involving exposure of humans, a careful estimation of the radiation dose to the patient should be made. The associated risk should then be weighted against the benefit for the patient or the society.

1. What ethical guidelines should be followed in research projects involving exposure of patients and healthy volunteers?

According to the Basic Safety Standards (BSS), the exposure of humans for medical research is deemed to be not justified unless it is:

The estimated risks of the irradiation should be explained to those individuals involved who knowingly incur doses while voluntarily helping (other than in their occupation) in the care, support or comfort of patients undergoing medical diagnosis or treatment (BSS II.26 and II.27).

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2. What general principles should be applied in the selection of patients and healthy volunteers in biomedical research?

When selecting subjects for a research project the following general principles should be taken into account:

  • Age: Consideration should be given to the age of the subjects proposed for the investigation. In particular, persons under 18 years of age should not be involved except when problems specific to their age groups are under investigation. It has been suggested that, whenever possible, volunteers should be aged over 50 years.

  • Numbers: The numbers of individuals participating in a research project should be restricted to the minimum necessary to obtain the information required.

  • Multiple studies: Consideration should be given to the risks to an individual who is involved in a series of research investigations. Steps should be taken to prevent individuals repeatedly taking part in research projects thus leading to substantial cumulated radiation dose.

  • Women:The possibility of early pregnancy should always be borne in mind if women of childbearing potential must be used as subjects; and, pregnant women and mothers who are breastfeeding must not be involved in any project except where problems specific to their condition are under investigation and alternative techniques which do not involve ionizing radiation have been considered and rejected.

In addition, when employees who work with radiation are considered as possible volunteers for research, the researcher must ensure that, as volunteers, they are aware of the additional risk arising from their exposure to radiation at work. The legitimate right of the employee to refuse participation in the research project should be respected.

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3. Should dose limitations be applied in the case of healthy volunteers?

No. However, appropriate dose constraints should be authorized for each research programme and the protection should be carefully optimized. For research projects involving use of ionizing radiation, the ICRP and WHO recommend the use of categories of risk arranged according to the radiation dose and estimated level of risk to be received by the subject. The risk may then be evaluated with regard to the expected benefit. These categories are listed in the following table.

Level of Risk Trivial Minor to intermediate Moderate
Risk category: I IIa IIb III
Total detriment ~ 10-6 or less ~ 10-5 ~ 10-4 ~ 10-3 or more
Range of effective doses (adults), mSv < 0.1 0.1 - 1 1 - 10 > 10a
Anticipated level of benefit to society Minor to intermediate Intermediate to moderate Substantial

a To be kept below deterministic thresholds except for therapeutic experiments.

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