Prudent precaution in clinical trials of nanomedicines.

Clinical trials of nanotechnology medical products present complex risk management challenges that involve many uncertainties and important risk-risk trade-offs. This paper inquires whether the precautionary principle can help to inform risk management approaches to nanomedicine clinical trials. It concludes that prudent precaution may be appropriate for ensuring the safety of such trials, but that the precautionary principle itself, especially in its more extreme forms, does not provide useful guidance for specific safety measures.