Providing members of the public with insufficient or inaccurate information about a hazard may deprive them of the opportunity to take precautionary or preventive action and can have serious detrimental consequences – in some cases, literally costing lives.
If public authorities understate the risks or hazards from accidents, activities or products, or information is simply withheld, this can lead to a vicious circle of poor communication and a breakdown of trust. The public no longer trusts information from official sources – applying their own very pragmatic version of the precautionary principle. Public authorities are then reinforced in their view that the public is irrational, so are less inclined to share information on hazards for fear that there will be an overreaction.
If risks are overstated, this may cause unwarranted psychological stress, which itself may constitute or cause a significant and measurable health impact among the public. Effective hazard communication must therefore steer a course between causing complacency and causing alarm. On the other hand, the phenomenon of information-induced health problems should never be cited as grounds for withholding information from the public, where that information could enable appropriate precautionary action to be taken to mitigate a significant threat to health or the environment.
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.