title: Interpersonal and temporal variability of urinary cotinine in elderly subjects.
abstract: Although a single measurement of urinary cotinine is often used for biological monitoring, the validity of this measurement for estimating long-term exposure has not been well evaluated. The purpose of this study was to determine the efficacy of using a single measurement per person to estimate long-term smoking exposure in an elderly population. Analysis was conducted using a cohort of elderly subjects for whom multiple urinary cotinine measurements had been collected over eight weeks. The mixed-effects model of urinary cotinine indicated that interpersonal variability was greater than temporal variability. The efficacy of using single measurements to track the mean long-term exposure of a population is supported by the relatively consistent population averages. The classification of high and low exposure groups using a single measurement or using eight measurements produced similar group distributions. When using cut-off levels of 20 and 100 μg cotinine/g creatinine, 9.3% and 5.6% of individual exposures were misclassified, respectively, when using a single measurement. Urinary cotinine can be a useful biomarker for characterizing exposure to tobacco smoke. Although the incidence of misclassification decreased with an increase in the number of measurements, a single measurement of the urinary cotinine level may accurately represent long-term exposure to tobacco smoke.
authors: Graduate School of Public Health and Institute of Health and Environment, Seoul National University, Seoul, Republic of Korea.
authors: Kiyoung
authors: K
authors: Lee
authors: Soogil
authors: S
authors: Lim
authors: Scott
authors: S
authors: Bartell
authors: Yun-Chul
authors: YC
authors: Hong
mesh_terms: D000368:Aged; D000393:Air Pollutants / Q000652:urine*; D015415:Biomarkers / Q000652:urine; D015331:Cohort Studies; D003367:Cotinine / Q000652:urine*; D004784:Environmental Monitoring / Q000379:methods*; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D012016:Reference Values; D014028:Tobacco Smoke Pollution / Q000032:analysis*
chemical_list: D000393:Air Pollutants; D015415:Biomarkers; D014028:Tobacco Smoke Pollution; D003367:Cotinine