Do we really want to REACH out to in vitro?

To comply with international regulations on chemicals, such as REACH (registration, evaluation, and authorization of chemicals), an enormous amount of toxicity testing is required. Traditional tests will fall short, since these strongly rely on in vivo studies, in particular for neurotoxicity. Therefore, a shift to alternative/in vitro toxicity testing is essential, in particular for neurotoxicity testing. However, the use of in vitro models and in vitro endpoints appears far from well accepted. This brief personal view highlights some of the concerns regarding in vitro research, e.g. using clonal cell lines such as PC12 cells and SH-SY5Y cells, to illustrate that many of these concerns may not be justified. A better characterization of specific in vitro models as well as a better understanding of the motive for using these in vitro models for neurotoxicity testing in the scientific community is necessary. The future of neurotoxicity testing will involve an increased use of in vitro experiments that are carefully designed with respect to compatibility of the exposure paradigm, the in vitro model and the chosen endpoint(s).