High-risk group and high-risk life stage: Key issues in adverse effects of environmental agents on human health.

Our previous studies analyzing umbilical cords show that human fetuses are exposed to multiple environmental agents. Fetuses are at a high-risk life stage in human life and our results revealed that there is a presence of potential high-risk group in Japanese babies. It suggests the necessity to develop a new method of evaluating health risk factors to human fetuses of the possible long-term effects caused by prenatal exposure to multiple environmental agents. Its main goal is to find the potential high-risk group in the next generation and to prevent the long-term effects caused by fetal exposure to multiple chemicals. Recently, we introduced our attempts to apply toxicogenomic analysis of gene expressions in umbilical cords using DNA microarray to the future health risk assessment. Our trial showed that it could be used as an effective newborn screening to detect potential high-risk groups focusing on the exposure level and the susceptibility. To improve future children's health, it is necessary to develop a risk reduction method, in addition to the establishment of the new risk assessment, to avoid multiple chemical exposures and to reduce the concentration level of persistent chemicals in the human body. Worldwide cooperation is urgently required focusing on the high-risk group and high-risk life stage. (Reprod Med Biol 2004; 3: 51-58).