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The development of the human brain comprises a series of complex spatiotemporal processes. Neurodevelopment is the process of the development of neurons, and includes their proliferation, migration, differentiation, synaptogenesis, apoptosis, gliogenesis, and myelination. It extends from the embryonic period through to adolescence. Environmental changes, particularly in utero, can lead to irreversible neurodevelopmental alterations. Exposure to environmental chemical pollutants, as well as to maternal infections, stress, and nutritional deficiencies, has been suspected of contributing to neurodevelopmental disturbances responsible for sensorimotor, cognitive, or behavioral impairment, and of increasing the incidence of clinical neurodevelopmental disorders (such as autism spectrum disorders [ASDs] and attention deficit/hyperactivity disorder [ADHD]) in children. According to longitudinal epidemiological studies, some relatively new chemicals, as well as older substances (such as toxic metals, persistent organic pollutants, pesticides, bisphenols, phthalates, and fine particles from air pollution), are associated with neurodevelopmental disorders. The effects observed in epidemiology are consistent with the mechanisms of action of these chemicals on neurodevelopment. Biomarker measurements of chemicals in pregnant women and children recently carried out in France and Europe attest to exposure to these substances during periods of neurodevelopmental vulnerability and to the potential risk associated with this exposure.