title: Exposure to environmental tobacco smoke measured by cotinine 125I-radioimmunoassay.
abstract: We describe a polyclonal-antiserum-based 125I-radioimmunoassay for cotinine that is suitable for measuring nonsmokers' passive exposure to tobacco smoke in the environment. The standard curve ranged from 0.25 to 12.0 micrograms/L, with an estimated lower limit of sensitivity of 0.2 microgram/L (95% B/Bo = 0.2 microgram/L; 50% B/Bo = 4.0 micrograms/L). The median within-assay CVs for patients' samples with cotinine values from 0.4 to 1.3, 1.4 to 2.4, 2.5 to 4.6, and 4.7 to 15.6 micrograms/L were 13.9%, 7.2%, 5.1%, and 5.7%, respectively. Between-assay CVs for two quality-control sera with average values of 1.53 and 3.68 micrograms/L were 14.3% and 7.8%, respectively. Analytical recoveries of cotinine from smokers' sera diluted in zero calibrant ranged from 91% to 116%. Cotinine values determined on 79 paired sera and urines from nonsmokers showed significant correlation with self-reported exposure to environmental tobacco smoke (r = 0.49, P less than 0.001 for sera; r = 0.57, P less than 0.001 for urine). The log of the values for serum and urine cotinine were also significantly correlated (r = 0.85, P less than 0.001). Evidently, polyclonal antiserum can be used to develop a cotinine assay for measuring exposure to environmental tobacco smoke that compares well with that described for monoclonal-based assays.
authors.affiliation: Foundation for Blood Research, Scarborough, ME 04074.
authors.forename: G J
authors.initials: GJ
authors.lastname: Knight
authors.forename: G E
authors.initials: GE
authors.lastname: Palomaki
authors.forename: D H
authors.initials: DH
authors.lastname: Lea
authors.forename: J E
authors.initials: JE
authors.lastname: Haddow
mesh_terms: D003367:Cotinine / Q000097:blood / Q000652:urine*; D006801:Humans; D007202:Indicators and Reagents; D007457:Iodine Radioisotopes; D011760:Pyrrolidinones / Q000652:urine*; D011863:Radioimmunoassay; D014028:Tobacco Smoke Pollution / Q000032:analysis*
chemical_list: D007202:Indicators and Reagents; D007457:Iodine Radioisotopes; D011760:Pyrrolidinones; D014028:Tobacco Smoke Pollution; D003367:Cotinine