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Design issues in cross-sectional biomarkers studies: Urinary biomarkers of PAH exposure and oxidative stress.

Kang D, Lee KH, Lee KM, Kwon HJ, Hong YC, Cho SH, Strickland PT

Department of Preventive Medicine, Seoul National University, College of Medicine, Institute of Environmental Medicine, SNUMRC, Seoul 110-799, South Korea.

Cross-sectional biomarker studies can provide a snapshot of the frequency and characteristics of exposure/disease in a population at a particular point in time and, as a result, valuable insights for delineating the multi-step association between exposure and disease occurrence. Three major issues should be considered when designing biomarker studies: selection of appropriate biomarkers, the assay (laboratory validity), and the population validity of the selected biomarkers. Factors related to biomarker selection include biological relevance, specificity, sensitivity, biological half-life, stability, and so on. The assay attributes include limit of detection, reproducibility/reliability, inter-laboratory variation, specificity, time, and cost. Factors related to the population validity include the frequency or prevalence of markers, greater inter-individual variation than intra-individual variation, intra-class correlation coefficients (ICC), association with potential confounders, invasiveness of specimen collection, and subject selection. Three studies are selected to demonstrate different features of cross-sectional biomarker studies: (1) characterizing the determinants of the biomarkers (study I: urinary PAH metabolites and environmental particulate exposure), (2) relationship of multiple biomarkers of exposure and effect (study II: relationship between urinary PAH metabolites and oxidative stress), and (3) evaluating gene-environmental interaction (study III: effect of genetic polymorphisms of GSTM1 on the association of green tea consumption and urinary 1-OHPG levels in shipbuilding workers).

Published 5 December 2005 in Mutat Res, 592(1): 138-46.
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