title: Design issues in cross-sectional biomarkers studies: urinary biomarkers of PAH exposure and oxidative stress.
abstract: 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).
authors.affiliation: Department of Preventive Medicine, Seoul National University, College of Medicine, Institute of Environmental Medicine, SNUMRC, Seoul 110-799, South Korea. dhkang@snu.ac.kr
authors.forename: Daehee
authors.initials: D
authors.lastname: Kang
authors.forename: Kyoung-Ho
authors.initials: KH
authors.lastname: Lee
authors.forename: Kyoung-Mu
authors.initials: KM
authors.lastname: Lee
authors.forename: Ho-Jang
authors.initials: HJ
authors.lastname: Kwon
authors.forename: Yun-Chul
authors.initials: YC
authors.lastname: Hong
authors.forename: Soo-Hun
authors.initials: SH
authors.lastname: Cho
authors.forename: Paul T
authors.initials: PT
authors.lastname: Strickland
mesh_terms: D016588:Anticarcinogenic Agents; D015415:Biomarkers / Q000652:urine*; D003430:Cross-Sectional Studies; D004249:DNA Damage; D020022:Genetic Predisposition to Disease; D006801:Humans; D018384:Oxidative Stress; D011084:Polycyclic Aromatic Hydrocarbons / Q000009:adverse effects / Q000633:toxicity*; D015203:Reproducibility of Results; D012107:Research Design; D013662:Tea
chemical_list: D016588:Anticarcinogenic Agents; D015415:Biomarkers; D011084:Polycyclic Aromatic Hydrocarbons; D013662:Tea