Final answer:
The Precautionary principle refers to situations where policy action is proposed due to substantial environmental risk, even with inconclusive scientific evidence.
Step-by-step explanation:
The principle that refers to situations in which policy action is proposed because the environmental risk is substantial, even if scientific evidence for that risk is inconclusive, is the Precautionary principle. This principle states that when the effects of a human activity are poorly understood, we must presume that some level of harm may exist to the environment, and thus must proceed with that activity carefully. The Precautionary principle suggests that it is best to be cautious in the face of incomplete knowledge about potential harm.