Neurodevelopmental disorders in children have increased significantly in recent years (according to the European Joint Research Centre), which adds urgency to the need to evaluate new and existing chemicals for their potential activity in this area. This is difficult when the existing OECD DNT study, TG 426, is entirely based on in vivo studies (very resource-intensive in terms of animals and time) and, in the EU, is not a standard test requirement at a regulatory level; such testing is only performed when concerns are triggered by structure-activity relationships or evidence of neurotoxicity in systemic adult studies, so the study is rarely used. The result? The proportion of chemicals that are being/have been tested for their DNT potential is woefully small, leading to uncertainties in the establishment of safe levels of exposure for pregnant women and young children in particular. A recent JRC report calls for the development of alternative DNT methodologies to rapidly and cost-effectively screen large numbers of chemicals. It examines the existing in vitro cellular models, how well they address critical human neurodevelopmental processes and key events identified in DNT adverse outcome pathways (AOPs), and their use in the development of DNT-specific integrated approaches to testing and assessment (IATA). The data and knowledge generated from such testing should help with the development of an OECD guidance document on this, and of a comprehensive testing strategy which will provide some confidence in the safety of the thousands of untested (in DNT terms) chemicals to which pregnant women, infants and children may be exposed.

European Commission. Joint Research Centre (2018). Strategic aims for improving the regulatory assessment of developmental neurotoxicity (DNT) using non-animal methods.

European Union Reference Laboratory for Alternatives to Animal Testing (2017). Status report on the development, validation and regulatory acceptance of alternative methods and approaches. EUR 28823 EN.

OECD Test Guideline 426: Developmental Neurotoxicity Study. Adopted 16 October 2007.



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