SIGNIFICANCE: The environment can elicit biological responses such as oxidative 
stress (OS) and inflammation as a consequence of chemical, physical, or 
psychological changes. As population studies are essential for establishing 
these environment-organism interactions, biomarkers of OS or inflammation are 
critical in formulating mechanistic hypotheses. Recent Advances: By using 
examples of stress induced by various mechanisms, we focus on the biomarkers 
that have been used to assess OS and inflammation in these conditions. We 
discuss the difference between biomarkers that are the result of a chemical 
reaction (such as lipid peroxides or oxidized proteins that are a result of the 
reaction of molecules with reactive oxygen species) and those that represent the 
biological response to stress, such as the transcription factor NRF2 or 
inflammation and inflammatory cytokines.
CRITICAL ISSUES: The high-throughput and holistic approaches to biomarker 
discovery used extensively in large-scale molecular epidemiological exposome are 
also discussed in the context of human exposure to environmental stressors.
FUTURE DIRECTIONS: We propose to consider the role of biomarkers as signs and to 
distinguish between signs that are just indicators of biological processes and 
proxies that one can interact with and modify the disease process. Antioxid. 
Redox Signal. 28, 852-872.