The Precautionary Principle contributes to both risk management and risk assessment in a fundamental and significant way. The principle, in its basic form, is that if an action or policy could reasonably be expected to cause harm to the public or the environment, or if the chance of harm occurring is higher than a given threshold, then the burden of proof that the action or policy can be conducted safely falls on those taking the action.
In other words, instead of "prove to me that it's risky" before an action or policy could be prevented, it's "prove to me that it's not risky" before it can be approved. Another, simpler way to say it is "First, do no harm", or "Better safe than sorry".
So application of this principle requires that the party conduct risk assessment before receiving approval, and functions in the larger sphere of risk management by requiring proof of safety or a level of acceptable risk.
This principle was applied at the Earth Summit in Rio de Janiero in 1992, as Article 15 states:
In order to protect the environment, the precautionary approach shall be widely applied by States according to their capabilities. Where there are threats of serious or irreversible damage, lack of full scientific certainty shall not be used as a reason for postponing cost-effective measures to prevent environmental degradation.