The added value of the 90-day repeated dose oral toxicity test for industrial chemicals with a low (sub)acute toxicity profile in a high quality dataset: An update

A previous retrospective analysis of substances in the ECHA CHEM database concluded that, for industrial chemicals with a 'low (sub)acute toxicity profile', further testing in the 90-day study is unlikely to change this profile (Taylor et al., 2014). We have further tested this hypothesis by assessing the outcome of substances with testing proposals for which a prediction was made in that paper that the NOAEL based on the 90-day study would be 1000 mg/kg bw/d. Indeed, for seven out of ten substances for which data was available, the profile was shown to be held. For three substances, the reduced NOAEL was explained by renal effects in the rats, two of which had been seen in the 28-day study but had been dismissed by the study submitter. We conclude that the low toxicity profile will be even more protective if the NOEL is used from the 28-day study and an independent expert view is taken of the human relevance of any effects reported in the 28-day study.