ECETOC helps improve and expand read-across techniques for chemical safety assessments

The concept of ‘read-across’ in chemical safety assessments took a large step forward at a workshop organised by the Centre for chemical safety assessment, ECETOC.

Read-across is a technique for inferring information about one substance’s properties (relating to safety testing end-points such as skin irritation, or toxicity) by using data from another substance (or substances) that has similar properties. For the REACH legislation, these properties can also relate to different types of studies carried out on the substances (such as carcinogenicity studies, or fish early life stage tests). Read-across is one of the most commonly used alternative approaches for filling in data gaps in registrations submitted under the REACH Regulation. It avoids unnecessary animal testing as there is no need to carry out testing of all substances, one by one, to fulfil the information requirements.

To improve and expand read-across techniques for chemical safety assessments, ECETOC organised a workshop together with the European Environmental Mutagen and Genomics Society at their annual meeting. The workshop explored options to go beyond the traditional read-across, where a formula is derived from chemical descriptors to make a prediction. New computer- and biology-based approaches were presented. These include the use of modelling for kinetics / PBPK as well as structural similarities and molecular design. In addition, a concept called RASAR (read-across structure activity relationships), where conventional chemical similarity is combined with computer-based learning was introduced. Finally, a biological technique (metabolomics) was shown to be able to enhance the quality of read-across.

Bennard van Ravenzwaay, Chair of the ECETOC Scientific Committee and one of the workshop organisers, said: “All of these techniques, which go beyond the classical read-across concept, are an important advance to chemical safety assessments. They offer the possibility of expanding our options and increasing the replacement of animal tests. Combining computer-based predictions and biological approaches will help to increase the use and quality of read-across, which means more substances can be assessed in a shorter time, at a lower cost and and drastically reduce animal tests.”

The results of the workshop are now published in Mutation Research/Genetic Toxicology and Environmental Mutagenesis (Volume 853, May 2020, 50317).