Exploratory evaluation of several teratogen warning symbols

Previous research has noted potential inadequacies in the warning labels and symbols used with some teratogenic medications. A clear teratogen warning symbol represents an important component of risk mitigation for accidental teratogen exposure.

Several teratogen warning symbols were developed through rapid prototyping and focus groups. A nationally distributed field trial (n = 300) examined the relative effectiveness of 6 candidate symbols, including the symbol in use at the time of the study. Measures included open-ended interpretation, closed-ended preference, and demographic surveys. Each participant was shown a single symbol and asked what it meant, to whom it applied, and what that person should do. Text statements were added to the symbol and participants were asked to reinterpret the warning. Participants were told the intended message of the warning, shown all 6 symbols, and asked to choose the most effective symbol.

Four of 6 symbols achieved levels of correct interpretation close to or exceeding the American National Standards Institute (ANSI) benchmark of 85% and none exceeded the ANSI limit of 5% critical confusion. Symbols elicited varying conceptual responses. Respondents considered 1 symbol to be the most effective, by a 4 to 1 margin. Several outcomes varied by age and by ethnicity.

Several symbols emerged as viable alternatives to the current symbol; however, no 1 symbol was clearly found to be the most effective. Instead, the symbol considered "best" depends on the messages that are considered most essential to the warning. Additionally, it appears a symbol without the addition of text can convey most, but possibly not all, of the meaning required of the warning label. Next steps should include further symbol refinement, closer examination of text additions to symbols, and validation of the candidate symbols and warnings through a large-scale field trial.