Increasing urinary cotinine concentrations at elevated temperatures: the role of conjugated metabolites

Biomarkers of Exposure to Secondhand and Thirdhand Tobacco Smoke: Recent Advances and Future Perspectives

Smoking is the leading preventable disease worldwide and passive smoking is estimated to be the cause of about 1.0% of worldwide mortality. The determination of tobacco smoke biomarkers in human biological matrices is key to assess the health effects related to the exposure to environmental tobacco smoke. The biomonitoring of cotinine, the main nicotine metabolite, in human biofluids-including urine, serum or saliva-has been extensively used to assess this exposure. However, the simultaneous determination of cotinine together with other tobacco biomarkers and the selection of alternative biological matrices, such as hair, skin or exhaled breath, would enable a better characterization of the kind and extent of tobacco exposure. This review aims to perform a critical analysis of the up-to-date literature focused on the simultaneous determination of multiple tobacco smoke biomarkers studied in different biological matrices, due to the exposure to secondhand smoke (SHS) and thirdhand smoke (THS). Target biomarkers included both tobacco-specific biomarkers-nicotine and tobacco specific nitrosamine biomarkers-and tobacco-related biomarkers, such as those from polycyclic aromatic hydrocarbons, volatile organic compounds, metals and carbon monoxide. To conclude, we discuss the suitability of determining multiple biomarkers through several relevant examples of SHS and THS exposure.

Stability of alcohol and tobacco consumption biomarkers in a real rising main sewer

Since alcohol and tobacco consumption are among the leading causes of population health harm, it is very important to understand the consumption behaviour to develop effective harm reduction strategies. Wastewater-based epidemiology (WBE) is a potential tool for estimating their consumption, but there are several uncertainties that need to be determined, including the stability of biomarkers in the sewer. Utilizing a real rising main sewer, this study investigated the stability of alcohol and tobacco consumption biomarkers. Rhodamine and acesulfame were used as flow tracer and benchmarker to understand the transportation of wastewater in the sewer with a hydraulic retention time between 2.7 and 5.0 h. Ethyl sulphate (EtS) and ethyl glucuronide (EtG), two biomarkers of alcohol consumption, were found to have different in-sewer stability, with EtS much more stable than EtG. The degradation rate of EtS is approximately 8% per hour, while EtG has a half-life of 1.9 h. Formation of nicotine, cotinine and trans-3'-hydroxycotinine, three biomarkers for tobacco consumption, was observed during the experiment, probably due to deconjugation of their glucuronide chemicals. The deconjugation process has prevented the determination of actual stability of the three chemicals. However, it is suggested that cotinine is relatively stable, while nicotine and trans-3'-hydroxycotinine degrade to a certain degree in the sewer system. According to our findings, the in-sewer degradation is more important during the interpretation of alcohol consumption estimation than for tobacco consumption estimation.

Single gas chromatography method with nitrogen phosphorus detector for urinary cotinine determination in passive and active smokers

Nicotine is a major addictive compound in cigarettes and is rapidly and extensively metabolized to several metabolites in humans, including urinary cotinine, considered a biomarker due to its high concentration compared to other metabolites. The aim of this study was to develop a single method for determination of urinary cotinine, in active and passive smokers, by gas chromatography with a nitrogen phosphorus detector (GC-NPD). Urine (5.0 mL) was extracted with 1.0 mL of sodium hydroxide 5 mol L-1, 5.0 mL of chloroform, and lidocaine used as the internal standard. Injection volume was 1 μL in GC-NPD. Limit of quantification was 10 ng mL-1. Linearity was evaluated in the ranges 10-1000 ng mL-1 and 500-6000 ng mL-1, with determination coefficients of 0.9986 and 0.9952, respectively. Intra- and inter-assay standard relative deviations were lower than 14.2 %, while inaccuracy (bias) was less than +11.9%. The efficiency of extraction was greater than 88.5%. Ruggedness was verified, according to Youden's test. Means of cotinine concentrations observed were 2,980 ng mL-1 for active smokers and 132 ng mL-1, for passive smokers. The results revealed that satisfactory chromatographic separation between the analyte and interferents was obtained with a ZB-1 column. This method is reliable, precise, linear and presented ruggedness in the range evaluated. The results suggest that it can be applied in routine analysis for passive and active smokers, since it is able to quantify a wide range of cotinine concentrations in urine.

Nicotine metabolism in African Americans and European Americans: variation in glucuronidation by ethnicity and UGT2B10 haplotype

Nicotine is the major addictive agent in tobacco smoke, and it is metabolized extensively by oxidation and glucuronide conjugation. The contributions of ethnicity and UGT2B10 haplotype on variation in nicotine metabolism were investigated. Nicotine metabolism was evaluated in two populations of smokers. In one population of African American and European American smokers (n = 93), nicotine and its metabolites were analyzed in plasma and 24-h urine over 3 days while participants were abstinent and at steady state on the nicotine patch. In a second study of smokers (n = 84), the relationship of a UGT2B10 haplotype linked with D67Y to nicotine and cotinine glucuronidation levels was determined. We observed that both African American ethnicity and the UGT2B10 D67Y allele were associated with a low glucuronidation phenotype. African Americans excreted less nicotine and cotinine as their glucuronide conjugates compared with European Americans; percentage of nicotine glucuronidation, 18.1 versus 29.3 (p < 0.002) and percentage of cotinine glucuronidation, 41.4 versus 61.7 (p < 0.0001). In smokers with a UGT2B10 Tyr67 allele, glucuronide conjugation of nicotine and cotinine was decreased by 20% compared with smokers without this allele. Two key outcomes are reported here. First, the observation that African Americans have lower nicotine and cotinine glucuronidation was confirmed in a population of abstinent smokers on the nicotine patch. Second, we provide the first convincing evidence that UGT2B10 is a key catalyst of these glucuronidation pathways in vivo.

Intérêt des différents marqueurs biologiques dans l'évaluation du tabagisme

Tobacco exposure can be assessed by the measurement of several markers in biological fluids. These markers are more or less specific for tobacco and the different methods to measure them out differ in terms of sensibility, specificity, ease of use and cost. The clinician prescribing a dosage for a patient has to take all these parameters into account to make an accurate choice. In this article, we have analysed the usefulness of the main biological tobacco markers in the follow-up of smokers and compared their methods of dosage. We propose several indications and point out the interest of relevant markers to realize objective measurements of smoking habits.

Simultaneous determination of the tobacco smoke uptake parameters nicotine, cotinine and thiocyanate in urine, saliva and hair, using gas chromatography-mass spectrometry for characterisation of smoking status of recently exposed subjects

A method using gas chromatography (GC)-mass spectrometry (MS) for the simultaneous determination of the smoke uptake parameters thiocyanate, nicotine and cotinine in human tissues is reported. Nicotine, cotinine and thiocyanate, in combination with a phase-transfer catalyst, were extracted from urine, saliva and hair into dichloromethane (DCM). Thiocyanate was alkylated in the DCM-layer to form a pentafluorobenzyl derivative. The biochemical markers in DCM were directly injected into the GC system and separated on a DB-1MS column using a 9.4 min temperature program. The method was validated in urine and saliva between the limits of quantitation (1.0-15 microg ml(-1) thiocyanate, 0.010-3.0 microg ml(-1) nicotine and cotinine in urine, 0.010-1.0 microg ml(-1) nicotine and cotinine in saliva). The calibration curves were found to be linear (r > 0.996), the within- and between-day accuracy's were 83-120%, the repeatability coefficients of variation were 3-20% and the limits of detection were 0.060 ng ml(-1) thiocyanate and 0.60 ng ml(-1) nicotine and cotinine. The results of the analysis of the biomarkers in the urine of 44 volunteers were used to develop a predictive model for smoking status, using discriminant analysis. The classification model correctly classified 93.2% of cross-validated grouped cases. Saliva samples were used to confirm the results of the classification method.

Determination of urinary and salivary cotinine using gas and liquid chromatography and enzyme-linked immunosorbent assay

The objective of this study was to compare cotinine concentrations in urine and saliva using gas chromatography (GC), high-performance liquid chromatography (HPLC) and enzyme-linked immunosorbent assay (ELISA). Ninety-four subjects were selected (27 smokers and 67 non-smokers) and interviewed using questionnaire. Of the non-smokers, 39 had been exposed to environmental tobacco smoke (ETS) and 28 had not been exposed to ETS. Cotinine levels among smokers were highest using all three measurements, followed by ETS exposed subjects and non-smokers. Cotinine levels in urine, using HPLC, correlated significantly with levels measured using ELISA (r=0.92) and GC-nitrogen-phosphorus detection (NPD) (r=0.92). Salivary cotinine levels measured using ELISA did not correlate significantly with either HPLC (r=0.37) or GC-NPD (r=0.33) measurements. Multiple regression models were used to adjust for age, gender, drug use and health status, and it was found that cotinine levels in urine and saliva were significantly correlated with smoking pack-year. The authors conclude that urinary cotinine concentration is a more accurate biomarker for ETS than salivary cotinine concentration.

Quantification of nicotine, chlorpyrifos and their metabolites in rat plasma and urine using high-performance liquid chromatography

This study describes a high-performance liquid chromatographic method for the separation and quantification of nicotine, its metabolites nornicotine and cotinine, the insecticide chlorpyrifos (O,O-diethyl-O[3,5,6-trichloro-2-pyridinyl]phosphorothioate), and its metabolites chlorpyrifos-oxon (O,O-diethyl-O[3,5,6-trichloro-2-pyridinyl]phosphate), and TCP (3,5,6-trichloro-2-pyridinol) in rat plasma and urine. The compounds were separated using gradient mobile phase of methanol, acetonitrile and water (pH 3.20) at a flow-rate of 0.8 ml/min in a period of 17 min, and gradient UV detection ranging between 260 and 280 nm. The retention times ranged from 3.4 to 16.7 min. The limits of detection were ranged between 20 and 150 ng/ml, while limits of quantitation were 50-200 ng/ml. Average percentage recovery of five spiked plasma samples were 84.7+/-8.3, 78.2+/-7.6, 80.1+/-7.6, 79.0+/-6.4, 74.0+/-7.4, 87.6+/-7.5, and from urine 85.1+/-5.2, 75.9+/-7.0, 82.1+/-6.1, 79.5+/-6.1, 71.3+/-7.4 and 81.3+/-6.9 for nicotine, nornicotine, cotinine chlorpyrifos, chlorpyrifos-oxon and TCP, respectively. Intra-day accuracy and precision for this method were ranged between 2.2-3.6 and 2.1-2.8%, respectively. The relationship between peak areas and concentration was linear over range between 200 and 2000 ng/ml. This method was applied to analyze the above chemicals and metabolites following combined oral administration in rats.

Tone abnormalities are associated with maternal cigarette smoking during pregnancy in in utero cocaine-exposed infants

OBJECTIVE

Maternal cigarette smoking, alcohol use, and other factors confound studies of in utero cocaine exposure. Our goal was to determine whether in utero cocaine exposure is associated with an abnormal neurologic examination in infants, while controlling for concomitant cigarette smoke exposure and other confounding variables.

DESIGN

Healthy newborns with birth weights > or =2000 g were prospectively enrolled into a race-matched study of cocaine-exposed and cocaine-unexposed infants. Urine and meconium samples were analyzed for illicit drugs, the cocaine metabolite, benzoylecgonine, and the nicotine metabolite, cotinine. A detailed neurological examination was performed at approximately 6 weeks of age by an examiner blinded to history.

RESULTS

At 6 weeks of age, 40 cocaine-exposed infants and 56 cocaine-unexposed infants were examined. Tone abnormalities were the only neurologic abnormalities discovered, predominantly generalized hypertonia. Logistic models found that maternal urine cotinine levels were predictive of an abnormal neurologic examination, whereas cocaine exposure or benzoylecgonine levels were not. No interaction was found between maternal cigarette smoking and cocaine exposure. Race, ethanol exposure, prenatal care, homelessness, and head circumference were not predictive of an abnormal tone examination. The odds ratio for an abnormal examination was 2.9 (95% confidence interval: 1.04-8.25), if the maternal urine cotinine level was >200 ng/mL.

CONCLUSION

Our findings suggest that maternal cigarette smoking may be the major predictor of tone abnormalities reported in cocaine-exposed infants.

Effects of tobacco products on the attachment and growth of periodontal ligament fibroblasts

BACKGROUND

Cigarette smoking is one of the most significant risk factors in the development and further advancement of inflammatory periodontal disease, however, the role of either nicotine or its primary metabolite cotinine in the progression of periodontitis is unclear. This study aimed to investigate the effects of nicotine and cotinine on the attachment and growth of fibroblasts derived from human periodontal ligament (PDL).

METHODS

Primary cultures were prepared from the roots of extracted premolar teeth. Cells were used at both low (P3 to P5) and high (P11 to P13) passage. Cell numbers were determined over 14 days using either the 3-(4,5-dimethylthiazol-2-yl)-2, 5-diphenyl tetrazolium bromide (MTT) assay or with a Coulter counter. Cultures were exposed to culture medium supplemented with 1) 15% fetal calf serum (FCS) only; 2) 1% FCS only; 3) 1% FCS and nicotine (concentration range 5 ng/ml to 10 mg/ml); or 4) 1% FCS and cotinine (concentration range 0.5 ng/ml to 10 microg/ml).

RESULTS

Nicotine significantly (P <0.05, by ANOVA) inhibits attachment and growth of low passage cells at concentrations >1 mg/ml and high passage PDL fibroblasts at concentrations >0.5 mg/ml. Cotinine, at the highest concentration used (10 microg/ml), appeared to inhibit attachment and growth of both low and high passage fibroblasts but this was not statistically significant (P >0.05, by ANOVA).

CONCLUSIONS

Tobacco products inhibit attachment and growth of human PDL fibroblasts. This may partly explain the role of these substances in the progression of periodontitis.