Urinary cotinine in children and adults during and after semiexperimental exposure to environmental tobacco smoke.
Urinary cotinine (U-cotinine) as a biomarker of environmental tobacco smoke exposure was evaluated in 14 children (age 4-11 y) and in 7 adults who were exposed to environmental tobacco smoke at an air nicotine level of 110 mg/m3 for 2 h in a bus. Nicotine in air and U-cotinine were measured by gas chromatography/mass spectrometry before, during, and after the experiment. U-cotinine rose rapidly to a maximum after a median of 6 h following the end of exposure; remained at an apparent plateau for half a day; and then decreased exponentially, with a mean half-time of 19 h (95% confidence interval 18-20 h; no significant difference between children and adults). The maximum U-cotinine was higher in the children (mean = 22 mg/l) than in the adults (13 mg/l; p = .005); decreased with age among the children (r = -.74; p = .002); and increased as the estimated inhaled nicotine dose increased. Therefore, the findings of the present study showed that young children had higher U-cotinine than adults at the same experimental environmental tobacco smoke exposure, probably because they had a higher relative nicotine dose because of a higher relative ventilation rate, and possibly also because of metabolic differences; the elimination rate did not differ. The long half-time makes U-cotinine a good biomarker of environmental tobacco smoke exposure; the time of sampling is not very critical. Dilution-adjusted concentrations should be employed, and in children, preferably by density correction. A certain urinary cotinine level indicates a lower environmental tobacco smoke exposure in a small child than in an adult.
Willers
S
S
Department of Occupational and Environmental Medicine Malmö University Hospital Lund University, Sweden.
Skarping
G
G
Dalene
M
M
Skerfving
S
S
D000328:Adult; D000375:Aging / Q000378:metabolism / Q000652:urine*; D002648:Child; D002675:Child, Preschool; D003367:Cotinine / Q000652:urine*; D004784:Environmental Monitoring / Q000379:methods; D005260:Female; D008401:Gas Chromatography-Mass Spectrometry; D006801:Humans; D008297:Male; D009538:Nicotine / Q000032:analysis / Q000378:metabolism; D013997:Time Factors; D014028:Tobacco Smoke Pollution / Q000032:analysis*
D014028:Tobacco Smoke Pollution; D009538:Nicotine; D003367:Cotinine