Conclusion: Evidence shows that measure is not effective
Warning labels can be striking and colorful stickers, placed on the containers of hazardous substances to deter children. One example is the Mr Yuk stickers with a picture of a scowling face and protruding tongue, developed by the national poison Center in Pittsburgh, United States. The efficacy of this intervention was measured by observing changes in poisonings before and after the introduction of warning labels to a certain population, as well as observing children's behavior toward the warning labels.
Two studies examining the effectiveness of warning labels were found (Fergusson et al., 1982; Vernberg et al, 1984). Both are quite old, both are also cited in the Harborview Injury Prevention Research centre Best Practice review (http://depts.washington.edu/hiprc/practices/topic/poisoning/warninglabels.html). One study showed an increase in children's handling of the labeled medicine. The other study showed no effect of the intervention, but did hint that the warning labels may increase the risk of poisoning. This shows that the measure has not proven to be effective and may even be dangerous.
Recommendations (for research & practice)
Suggestions for further research:
An appropriate approach to examine whether a different type of warning sticker is effective in deterring children from handling medicine is a randomized controlled trial. Such study should examine children of different age categories, keeping in mind the developmental differences between, for instance, a toddler and a 4-year old.
Suggestions for practice and policy:
At this time, these colorful warning stickers cannot be advocated for use as a deterrent for children. This is especially true for toddlers, who may not understand the meaning of the sticker's image (even though older children may benefit from its appearance). Both studies did acknowledge the possibility that more training might have resulted in a more positive effect from the Mr. Yuk stickers.
Review Date: 15/12/2010
First, the findings on Harborview was studied. Then more recent studies were sought out by the Dutch Consumer Safety Institute.
The outcomes of the study were reviewed by an expert in the field of child safety in the summer of 2010.
A controlled field trial of a poisoning prevention method (version 1)
D.M. Fergusson, L.J. Horwood, A.L. Beautrais ...[et al.] (1982)
The deterrent effect of poison-warning stickers (version 1)
Katherine Vernberg, Paula Culver-Dickinson, Daniel A. Spyker (1984)