Neurotoxicity assessment in children and in the lab
Recent epidemiological studies have indicated that exposure to low doses of environmental neurotoxic chemicals during early brain development could have deleterious effects on cognitive development in childhood. It is of outmost importance to protect future generations through regulatory measures against such chemicals. Towards this goal, the EU-funded DENAMIC (Developmental neurotoxicity assessment of mixtures in children) project investigated the neurotoxic effects of low-concentration mixtures of biocides and a number of common environmental pollutants in children and experimental studies. The objective was to characterise a number of individual chemicals or mixtures, and pollutants for their neurotoxic effect. Researchers developed novel tools, testing methods and procedures for screening the neurotoxicity of over 30 chemicals. Importantly, the cellular methods developed for screening neurotoxicity proved reliable at predicting adverse in vivo effects. In vivo studies in rodents revealed that exposure early on in life led to persistent effects on behaviour, cognition, and motor activity. Researchers also addressed the exposure timing, the critical windows during neuronal development and consequences on susceptibility. Furthermore, they elucidated the molecular downstream pathways responsible for some of the observed behaviour and cognitive effects. Interestingly, they discovered that exposure to a combination of chemicals at their individual non-toxic levels may lead to neurodevelopmental toxicity. In the epidemiological part of the project, the consortium studied prenatal and neonatal exposure in existing cohorts to find that the European population has been exposed to low concentrations of neurotoxic chemicals. Their analysis unveiled various associations between neurotoxic chemicals exposure and neuropsychological and behavioural development in children. Differences in exposure levels in different EU regions were also detected. The DENAMIC epidemiological data suggested that the existing risk assessment, which is based on exposure to individual chemicals, may be underestimating the human risk. As a result, current policies should be reconsidered to reduce the impact of combined exposure to environmental chemicals on child development.
Keywords
Neurotoxicity, chemical, cognitive development, biocide, DENAMIC, behaviour, children, exposure
