In 2018, EFSA published its guidance on uncertainty analysis, a critical aspect in scientific assessments, establishing a concise framework to allow risk assessors to characterise, document and explain uncertainties in the most appropriate manner. EFSA has now finalised its additional guidance on how best to report and communicate scientific uncertainty to a target audience. Although primarily aimed at “EFSA communicators”, the document provides informative advice for risk assessors and communicators in other institutions that provide scientific advice.

A second recently finalised publication provides guidance on the genotoxicity assessment of chemical mixtures. Chemical characterisation of mixtures as “simple” (i.e. fully characterised) or complex (containing a proportion of substances that are not chemically identified) is of critical importance, with EFSA providing the following guidance:

  • If a mixture contains one or more substances that are genotoxic in vivo, the mixture itself is considered genotoxic. If a simple mixture does not contain any genotoxic substances, it is of no concern with respect to genotoxicity.
  • For complex mixtures, genotoxicity testing is required of either the unidentified fraction or the complex mixture itself. If clear negative results are obtained in an adequate set of in vitro assays, the complex mixture should be considered non-genotoxic. If one or more positive in vitro results are obtained, follow-up in vivo studies should be considered. Positive in vivo test results mean that the mixture should be considered genotoxic. Where follow-up in vivo tests are negative, the possible limitations of the testing should be weighed up in an uncertainty analysis before reaching a conclusion on genotoxic potential.

European Food Safety Authority (2019). Guidance on communication of uncertainty in scientific assessments.

Genotoxicity assessment of chemical mixtures.


The above items were taken from the March 2019 issue of Toxicology and Regulatory News which is sent automatically to members of bibra.

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