Study objective: The validity of self reported smoking in population surveys remains an important question. An associated question is what would be the value of measuring serum cotinine concentrations in such surveys to obtain validated smoking data. Design: Cross sectional analysis of data on self reported smoking and serum cotinine among a random population sample of 5846 persons aged 25 to 64 years, who participated in the FINRISK-92 survey. Main results: Among self reported regular smokers, 97.2% of men and 94.9% of women had a cotinine concentration of 10 ng/ml or higher in serum. Of those participants who reported to have smoked at any time during their life but not during the previous month, 6.3% of men and 5.2% of women had a serum cotinine concentration of at least 10 ng/ml. Among never smokers 2.5% of men and 2.7% of women had detectable level of cotinine in their serum. The validity of self reporting was similar among subjects from different areas, ages, and socioeconomic groups. Conclusions: In a sample of the general population in Finland the validity of self reported smoking is high, and most of the few self reported non-smokers who had cotinine in their serum had only low or moderate levels.B oth in clinical and in community settings there has been a concern about the validity of self reported smoking. Mainly, three biological measurements have been used to validate self reported smoking: carbon monoxide, thiocyanate, and cotinine. 3 The aim of our paper is to study the validity of self reported smoking in a cardiovascular risk factor population survey by comparing self reports with results of measurements of cotinine levels in serum.Nicotine metabolises rapidly and extensively, primarily in the liver. N-oxidation of nicotine to nicotine-1'-N-oxide occurs in humans. This metabolite has been shown to convert back to nicotine. In humans, the urinary elimination phase of the metabolite parallels that of the parent nicotine, indicating a formation rate limited excretion. It has been estimated that approximately 4% of the nicotine dose is excreted as nicotine-1'-N-oxide. Furthermore, it has been estimated that the quantitative disposition of nicotine is as follows: an average of 9% of the dose seems to be excreted as intact nicotine, and about 70% of nicotine seems to be converted to cotinine. Cotinine is the major plasma metabolite of nicotine and persists for a considerable time period in plasma, with a half life of approximately 16 hours. Only a minor fraction of the generated cotinine is excreted by the kidneys, but cotinine is further metabolised to more polar water soluble substances. According to recent human data the major metabolite found in urine is hydroxylated cotinine.

Nine different oral fluid (OF) collection devices were studied to evaluate their suitability for collecting samples for drug analysis. The devices were Greiner Bio-One, Orasure Intercept, Immunalysis Quantisal, StatSure Saliva.Sampler, Cozart, Sarstedt Salivette, Malvern Medical OraCol, Acro Biotech Salicule, and Varian OraTube. For comparison, OF was also collected into plastic tubes. The volume of collected OF was quantified for samples collected both in vitro and from volunteers. Drug recovery was studied by collecting OF fortified at 1000 ng/mL with amphetamine, 3,4-methylenedioxymethamphetamine, cocaine, Delta(9)-tetrahydrocannabinol, morphine, codeine, diazepam, and alprazolam with the devices in vitro and analyzing the samples with gas chromatography-mass spectrometry. Recovery of ethanol was measured from 0.2% in OF by headspace gas chromatography-flame-ionization detection. The stability of drugs in the samples was studied by analyzing the samples after 0, 14, and 28 days storage. The study shows that there are substantial differences between the OF collection devices on the market. Some are well suited for collecting samples for toxicological analysis, but some give quite poor results.

In recent years, the interest in the use of oral fluid as biological matrix has increased significantly, particularly for detecting driving under the influence of drugs (DUID). In this study, the relationship between the oral fluid and blood concentrations of drugs of abuse in drivers suspected of DUID is Nevertheless the data reflect the variability of the OF/B ratios in drivers under the influence of drugs.The wide range of the ratios, however, does not allow reliable calculation of the blood concentrations from oral fluid concentrations.

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