A key factor which must be taken into account in respect of risk assessment is the role that value judgements play in decision-making on risks and hazards. The scientific community has a particular responsibility in making the best assessments of risks and hazards and identifying the levels of uncertainty inherent in such assessments. However, even where purely quantitative assessments are involved, scientists may diverge considerably in their opinions. Scientific appraisal does not occur in a political vacuum. When qualitative words such as "unlikely", "significant", "appreciable" or "substantial" are used in describing a level of risk, an exercise of judgement which goes beyond full knowledge of the facts is involved. It is therefore necessary to ensure that, as far as possible, decision-making processes on risk benefit from scientific opinions which are independent from any commercial or political pressure.
While science provides the starting point for assessing risks, a decision on what constitutes an acceptable risk is essentially a value judgement. The acceptability of a risk may depend on many things besides the quantitative assessment of it, e.g. whether it is a chosen risk or an imposed risk; whether the risk could easily be avoided; whether the benefits of a proposed activity or product outweigh the risks arising from it; or whether the distribution of such risks through the population correlates with the distribution of benefits.
Even though part of the risk assessment is a scientific exercise, the fact that assessing risk involves value judgements makes it essential to involve those who will bear the risk in the overall decision-making process. Various models have been used for bringing together experts, regulators and the public to debate risk management, such as consensus conferences, citizens' juries and citizens' advisory committees. However, the use of such methods is the exception rather than the rule. They should be used more extensively, and experiences shared.
This strategy features in the framework of Agenda 21 as formulated at UNCED (Rio de Janeiro, 1992), now coordinated by the United Nations Commission on Sustainable Development and implemented through national and local authorities.
Agenda 21 recommends improving capabilities for determining scientific research priorities at the national, regional and global levels to meet the needs of sustainable development. This process would involve scientific judgements regarding short-term and long-term benefits and possible long-term costs and risks. It should be adaptive and responsive to perceived needs and be carried out via transparent, "user-friendly", risk-evaluation methodology.
In order to ensure transparency in risk assessment, the details of studies submitted for use in risk assessment for licensing purposes should be in the public domain and available in full through the internet.