A full picture of the considerations of uncertainty needs to be provided to the decision makers, one that fully outlines the sources of the uncertainty, the different scientific opinions supporting it, assumption made when assessing the uncertainty, and the impact such an uncertainty would have on the likely potential receiving environment should it be realised

Considerations of remaining uncertainties should be included in the risk assessment report.

These considerations may include:

1. Identification of major information gaps and, where appropriate, indication of whether gathering additional data (either before the release or after it by monitoring) would significantly increase the overall confidence in the results of the risk assessment;
2. An analysis of uncertainty, including its types (e.g. gaps in the available information, limitations of the assessment methodology);
3. Discussion on the level of scientific support to issues where there is uncertainty, including an analysis of different scientific views;
4. Discussion of any assumption used in assessing the risks, including its strengths and weaknesses;
5. Discussion of the potential for uncertainties to impact on the overall conclusions of the risk assessment; and
6. Identification of any threats of serious or irreversible damage to the environment (basis for the adoption of the precautionary approach).

Example – Uncertainty and a precautionary approach

“The implementation of an approach based on the precautionary principle should start with a scientific evaluation, as complete as possible, and where possible, identifying at each stage the degree of scientific uncertainty. Decision-makers need to be aware of the degree of uncertainty attached to the results of the evaluation of the available scientific information. Judging what is an "acceptable" level of risk for society is an eminently political responsibility. Where possible, a report should be made which indicates the assessment of the existing knowledge and the available information, providing the views of the scientists on the reliability of the assessment as well as on the remaining uncertainties. If necessary, it should also contain the identification of topics for further scientific research.”

Source: Commission for the European Communities (2000).