Abstract
<jats:p>The Ames test is a widely used in vitro bioassay for the assessment of direct DNA-reactive effects. However, the limits of biological detection (LOBD) for many genotoxic substances are not sufficient to reach the threshold of toxicological concern (TTC) limit, which is 0.15 μg per person/day for food contact materials (FCMs). The Ames test has been improved over the years in terms of lower sample volumes, higher throughput and achieving lower LOBD-values for many genotoxins. The liquid media- based Ames MPFTM is already an improvement over the agar-based plate Ames test. The Ames MPFTM is a fluctuation assay performed in liquid media. Instead of counting colonies as indication for mutagenicity, DNA reactivity is assessed visually through a colour change in the indicator medium. However, despite the improved sensitivity the Ames MPFTM offers, the desired TTC threshold has still not been reached for many genotoxins (Rainer et al., 2021). An in-house developed liquid media-based Ames test, called Sense Ames, was modified to detect genotoxins at even lower LOBD and with lower sample volumes. In this study, ten recycled plastic extracts were tested with a Salmonella Typhimurium strain TA98 with and without metabolic activation (+/–S9) and the performance of two Ames test formats (Ames MPFTM vs. Sense Ames) was compared by their lowest effect concentration (LEC) values. In six out of ten samples, the Sense Ames showed lower LEC values than the Ames MPFTM. Therefore, the Sense Ames is a promising bioassay for reaching lower LOBD values compared to other existing Ames test formats and an important step towards achieving the desired TTC threshold for genotoxins.</jats:p>