The need for developmental neurotoxicity studies in risk assessment for developmental toxicity

The estimated frequencies of neurodevelopmental disorders in children are relatively high, i.e. around 12%. The developing central nervous system appears to be especially susceptible to toxic insults and several developmental neurotoxicants, some with widespread occupational or consumer exposure, have been identified in humans and experimental animals. Cross-species comparability between human and experimental animals supports the assumption that developmental neurotoxicity (DNT) effects in animals indicate a potential to affect development in humans. The proposed Organization for Economic Cooperation and Development (OECD) developmental neurotoxicity study (TG 426) provides an outline of behavioural and morphological endpoints that are relevant to human neurodevelopment, and the guideline is expectedly adopted during 2006. Hopefully, this may contribute to inclusion of sufficient regulatory testing for DNT in the new EU chemical regulation REACH (Registration, Evaluation, Authorisation and Restriction of Chemicals). At present, DNT testing is not included in REACH and that gives rise to concern, as there is a recognized need for DNT testing in order to protect the susceptible developing brain.