Risk language and dialectsBMJ 1998; 316 doi: https://doi.org/10.1136/bmj.316.7139.1242b (Published 18 April 1998) Cite this as: BMJ 1998;316:1242
Expressing risk in relative rather than absolute terms is important
- D M Campbell, Public health medicine specialist
- Public Health Protection, Auckland Healthcare, Private Bag 92-605, Auckland 1, New Zealand
- Liverpool Women's Hospital, Liverpool L8 7SS
- Furness General Hospital, Barrow in Furness LA14 2LT
- Royal Liverpool University Hospital, Liverpool L7 8XP
- Marie Stopes International, Leeds LS2 8AJ
EDITOR—Calman and Royston remind health professionals of their obligation to communicate risk in a language and dialect with which individuals or groups are comfortable.1 It is not only in clinical medicine that appropriate communication of risk is essential. The environmental health literature is littered with examples of failed dialogue.
Communities often create risk dichotomies, demanding absolute safety and being unable to perceive any grey areas between safe and dangerous. On occasion this may be correct—for example, should we evacuate or not? Environmental standards tend to dichotomise. If the standard is 15 ppb, people may deduce that 14 ppb is safe and 16 ppb dangerous. Expressing risk in relative rather than absolute terms, as shown by Calman and Royston, avoids making an environmental standard into a watershed figure with all results above the standard perceived as dangerous and everything below the standard as safe. Risk numbers should be expressed in ranges, such as 1-9 ppb as low risk, 10-19 as moderate risk, etc.
Several elements of risk can be used to describe risk to communities. Among these are concentrations (for example, g/l); exposures (how much is likely to be inhaled?); probabilities (how likely is it to happen?); quantities (how much effluent was released?); and risk levels (expected deaths per year). All of these outline different …