What is the rule of thumb that calls for leaving a safety margin when the data about a particular substance's potential for harm are uncertain, and when the substance may cause unexpected or unpredictable effects?

precautionary principle

Explanation:

This is a strategy used by policy makers in instances where there is potential harm to the enviroment or human health.

In order to protect the enviroment and human health precautions such as leaving a safety margin when data of a potential harmful substance are uncertain, may cause unexpected or unpredictable effects.

Despite being beneficial a major drawback of this principle is that it limits innovation due to fear.