Exposure biology is an emerging branch of exposure science. The terminology was originated from 'exposure biology program', a novel research area supported by US NIEHS, of which objectives were to develop new methodology of environmental exposure and to explore causal association between the health effects and environmental toxicants in human populations. While there have been spectacular improvements in genomics and biomedical sciences, we still have many knowledge gaps in etiologies and mechanisms of environmental cancers and diseases. In spite of the dramatic advances in genomic analysis, lack of accurate information on exposure to environmental toxic compounds impedes understanding those etiology and gene-environmental interactions. Recently, early products of the exposure biology program can be found in exposome, adductomics, biosensors, system biology, etc. The present lecture was prepared as an introduction to the concept of exposure biology and some application studies to encourage young biologists to apply their expertise for public health.