Were parents right in the 1970s to stop their children having whooping cough vaccine in response to claims that it could cause brain damage? Almost certainly not, as further research, and later, preventable, outbreaks of the disease demonstrated.
But how could they have known?
Why, too, do ministers ban beef on the bone for the slight risk of further exposure to new-variant Creutzfeldt-Jakob disease, when at the same time no one in government seriously proposes banning cigarettes, which we know for certain kill people?
The way we assess risk, and what we choose to do about it, can be difficult to fathom (though perhaps less so in the case of tobacco, which helps chancellor Gordon Brown balance the Budget to the tune of£10bn every year). But an understanding of it is vital to public health and health education work.
The US Department of Energy's environmental management programme has a useful collection of articles, links and other resources at its What is Risk?
site, as does the less health related Environmental Protection Agency. But if your tastes are more technical, there are better sources.
The US Risk Assessment and Policy Association, which takes an interest in the critical evaluation of risk assessment methodologies and in the use of risk assessment in policy making, and its journal, titled, a little inevitably, Risk, offer a wealth of full-text articles and reports of excruciating thoroughness.
But how can patients assess the benefits and risks of treatment options?
The Foundation for Informed Medical Decision Making Inc offers what it calls a range of 'shared decision-making programmes'. Or videos to you and me.
It's not much, but it's a start. Perhaps they'll put them in butchers' shops too.
T-bone steak? Maybe not.