title: Measuring problems in estimating the exposure to passive smoking using the excretion of cotinine.
abstract: Quality control studies on cotinine measurements following low level environmental tobacco smoke (ETS) exposure are rare. The exposure to ETS was controlled and systematically changed in a series of experiments in a climatic chamber. Healthy nonsmoking volunteers were exposed to ETS simultaneously. The duration and level of exposure varied using high (8, 17 and 25 ppm CO), and low (2 and 5 ppm CO) exposure levels. The variation between radioimmunoassay (RIA) and gas chromatography (GC) was high as was the variation between the results of RIA laboratories. There was also a high within-laboratory-variation. A 1:10 dilution seems to be preferable over a 1:3 dilution. Freezing the urine samples immediately after collection led to the detection of higher cotinine values than freezing the samples 24 h after collection. Highly reliable data for cotinine were obtained when the urine samples were kept frozen immediately after collection and fractionated sampling over 48-72 h was used. Our data show that estimating low-level ETS exposure by measuring urinary cotinine is highly susceptible to uncontrolled variation and errors. Sufficiently reliable estimates of low-level ETS exposure can be made only when fractionated sampling over 48-72 h is used and when the urine samples are kept frozen just after collection.
mesh_terms: D002849:Chromatography, Gas; D003367:Cotinine / Q000032:analysis* / Q000097:blood / Q000652:urine; D004305:Dose-Response Relationship, Drug; D005615:Freezing; D006801:Humans; D009538:Nicotine / Q000032:analysis / Q000097:blood / Q000652:urine; D011760:Pyrrolidinones / Q000032:analysis*; D011863:Radioimmunoassay / Q000592:standards; D012463:Saliva / Q000032:analysis; D013223:Statistics as Topic; D014028:Tobacco Smoke Pollution / Q000032:analysis*
chemical_list: D011760:Pyrrolidinones; D014028:Tobacco Smoke Pollution; D009538:Nicotine; D003367:Cotinine