Environmental factors play an important role in determining the health of children. Children make up more than one-third of the world's population, and numerous studies point to the vulnerability of this group. Environmental factors strongly contribute to the health of children, whose health is affected differently than the health of adults. From conception to adolescence, rapid growth and development of the child affects the increased exposure to certain environmental factors. This process is most pronounced during embryonic development because the growth of cells is particulary accelerated and creates more opportunities through which individual factors could cause mutations and congenital anomalies. For example, during the first years of life the developing of nervous system takes place. Since the nervous system has a limited capacity for repairing structural damage, if the cells in the developing brain are destroyed by chemicals such as lead or mercury, or if the vital connections between nerve cells can not be formed the critical periods of vulnerability, there is a risk that these disorders could result in dysfunction of which will be permanent and irreversible. The consequences can be the loss of intelligence and behavioral changes. Neglected, abandoned and malnourished children suffer the most. They often live in unhealthy housing conditions, conditions with a lack of clean water and sanitation, and have limited access to health care and education. The World Health Organization estimates that more than 30% of the global burden of disease in children can be attributed to environmental factors. Special vulnerability of children should be the basis for the development of health policy in the protection of children's health and access to risk assessment. Lack of appropriate studies should not hamper efforts to reduce exposure to or implementation of specific interventions and prevention strategies.