Hazard communication should aim to convey to the potentially affected public the most objective information on the real levels of risk to which they are or might be exposed. Communicating about hazards often involves relaying complex technical facts in lay terms without losing accuracy.
Perhaps the greatest challenge in risk communication is in situations where there is uncertainty about the level or nature of the risk. Although hazard assessment can often be undertaken with high levels of scientific certainty, risk assessment relies to a greater extent on model assumptions, and therefore the levels of uncertainty - and the scope for producing widely differing assessments of risk - is far greater. It is crucial that risk communication fully respects the precautionary principle in the light of any such uncertainties, and that any realistic doubts and gaps in knowledge are communicated to the public.
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 making draft proposals for standardization of hazard communication terminology and symbols in order to enhance risk management of chemicals and facilitate both international trade and translation of information into the end-user's language.