Acrolein Exposure in U.S. Tobacco Smokers and Non-Tobacco Users: NHANES 2005-2006.

BACKGROUND: Acrolein is a highly reactive α,ß unsaturated aldehyde and respiratory irritant. Acrolein is formed during combustion (e.g., burning tobacco or biomass), during high-temperature cooking of foods, and in vivo as a product of oxidative stress and polyamine metabolism. No biomonitoring reference data have been reported to characterize acrolein exposure for the U.S. OBJECTIVES: Our goals were to a) evaluate two acrolein metabolites in urine--N-acetyl-S-(3-hydroxypropyl)-L-cysteine (3HPMA) and N-acetyl-S-(2-carboxyethyl)-L-cysteine (CEMA)--as biomarkers of exposure to acrolein for the U.S. population by age, sex, race, and smoking status; and b) assess tobacco smoke as a predictor of acrolein exposure. METHODS: We analyzed urine from National Health and Nutrition Examination Survey (NHANES 2005-2006) participants ≥ 12 years old (n = 2,866) for 3HPMA and CEMA using ultra-high-performance liquid chromatography coupled with electrospray ionization tandem mass spectrometry (UPLC/ESI-MSMS). Sample-weighted linear regression models stratified for non-tobacco users versus tobacco smokers (as defined by serum cotinine and self-report) characterized the association of urinary 3HPMA and CEMA with tobacco smoke exposure, adjusting for urinary creatinine, sex, age, and race/ethnicity. RESULTS: 3HPMA and CEMA levels were higher among tobacco smokers (cigarettes, cigars, and pipe users) than among non-tobacco users. The median 3HPMA levels for tobacco smokers and non-tobacco users were 1,089 and 219 µg/g creatinine, respectively. Similarly, median CEMA levels were 203 µg/g creatinine for tobacco smokers and 78.8 µg/g creatinine for non-tobacco users. Regression analysis showed that serum cotinine was a significant positive predictor (p < 0.0001) of both 3HPMA and CEMA among tobacco smokers. CONCLUSIONS: Tobacco smoke was a significant predictor of acrolein exposure in the U.S. population.

Validation of a LC-MS/MS method for quantifying urinary nicotine, six nicotine metabolites and the minor tobacco alkaloids--anatabine and anabasine--in smokers' urine.

Tobacco use is a major contributor to premature morbidity and mortality. The measurement of nicotine and its metabolites in urine is a valuable tool for evaluating nicotine exposure and for nicotine metabolic profiling--i.e., metabolite ratios. In addition, the minor tobacco alkaloids--anabasine and anatabine--can be useful for monitoring compliance in smoking cessation programs that use nicotine replacement therapy. Because of an increasing demand for the measurement of urinary nicotine metabolites, we developed a rapid, low-cost method that uses isotope dilution liquid chromatography-tandem mass spectrometry (LC-MS/MS) for simultaneously quantifying nicotine, six nicotine metabolites, and two minor tobacco alkaloids in smokers' urine. This method enzymatically hydrolyzes conjugated nicotine (primarily glucuronides) and its metabolites. We then use acetone pretreatment to precipitate matrix components (endogenous proteins, salts, phospholipids, and exogenous enzyme) that may interfere with LC-MS/MS analysis. Subsequently, analytes (nicotine, cotinine, hydroxycotinine, norcotinine, nornicotine, cotinine N-oxide, nicotine 1'-N-oxide, anatabine, and anabasine) are chromatographically resolved within a cycle time of 13.5 minutes. The optimized assay produces linear responses across the analyte concentrations typically found in urine collected from daily smokers. Because matrix ion suppression may influence accuracy, we include a discussion of conventions employed in this procedure to minimize matrix interferences. Simplicity, low cost, low maintenance combined with high mean metabolite recovery (76-99%), specificity, accuracy (0-10% bias) and reproducibility (2-9% C.V.) make this method ideal for large high through-put studies.

Perchlorate, nitrate, and iodide intake through tap water.

Perchlorate is ubiquitous in the environment, leading to human exposure and potential impact on thyroid function. Nitrate can also competitively inhibit iodide uptake at the sodium-iodide symporter and thus reduce thyroid hormone production. This study investigates the intake of perchlorate, nitrate, and iodide attributable to direct and indirect tap water consumption. The National Health and Nutrition Examination Survey collected tap water samples and consumption data from 3262 U.S. residents during the years 2005-2006. The median perchlorate, nitrate, and iodide levels measured in tap water were 1.16, 758, and 4.55 µg/L, respectively. Measured perchlorate levels were below the United States Environmental Protection Agency (U.S. EPA) drinking water equivalent level for perchlorate (24.5 µg/L). Significant correlations were found between iodide and nitrate levels (r = 0.17, p < 0.0001) and perchlorate and nitrate levels (r = 0.25, p < 0.0001). On the basis of 24 h recall, 47% of the study participants reported drinking tap water; 89% reported either direct or indirect consumption of tap water. For the adult population (age ≥ 20 yrs) the median tap water consumption rate was 11.6 mL/kg-day. Using individual tap water consumption data and body weight, we estimated the median perchlorate, nitrate, and iodide dose attributable to tap water as 9.11, 11300, and 43.3 ng/kg-day, respectively, for U.S. adults. This perchlorate exposure dose from tap water is relatively small compared to the total perchlorate exposure dose previously characterized for the U.S. adults (median 64 ng/kg-day) and the U.S. EPA reference dose (700 ng/kg-day).

Picogram measurement of volatile n-alkanes (n-hexane through n-dodecane) in blood using solid-phase microextraction to assess nonoccupational petroleum-based fuel exposure.

We describe here a new method for the analysis of alkanes ( n-hexane, n-heptane, n-octane, n-nonane, n-decane, n-undecane, and n-dodecane) in blood using headspace solid-phase microextraction gas chromatography/mass spectrometry. This method is used to measure picogram per milliliter levels of n-alkanes in blood that may result from nonoccupational exposure to alkanes and other volatile nonpolar compounds from common sources such as petroleum-based fuel. This alkane signature is useful in distinguishing typical fuel biomarkers (e.g., benzene and toluene) from other confounding exposure sources such as cigarette smoke. Development of this method required special attention to sample handling as alkanes are not highly soluble in aqueous matrixes and exist as ubiquitous compounds found in many laboratory materials and the environment. In particular, significant n-hexane contamination ( approximately 0.4 ng/mL) occurred from collecting blood samples in vacutainers. This residue was removed by boiling the vacutainer stoppers in methanol followed by vacuum baking. For all the alkanes, the calculated accuracy demonstrated for the water-based standards ranged from 3.3% to 17% as deduced from the difference of the lowest and middle standards from the curve fit. Quality control data among runs over a 10 month period were found to vary from 14% to -29%, with a few exceptions. The resulting quantification limits for n-hexane through n-decane ranged from 0.069 to 0.132 ng/mL. In the analysis of 1200 blood samples from people with no known occupational exposure, median blood levels for all n-alkanes were below these quantification limits. n-Hexane levels above the method detection limit were, however, found in 1.3% of the samples.

Quantification of 31 volatile organic compounds in whole blood using solid-phase microextraction and gas chromatography-mass spectrometry.

The prevalence of exposure to volatile organic compounds (VOCs) has raised concern about possible health effects resulting from chronic human exposure. To support studies exploring the relation between VOC exposure and health effects, we developed an automated analytical method using solid-phase microextraction (SPME), capillary gas chromatography (GC), and quadrupole mass spectrometry (MS). This method quantifies trace levels (low parts per trillion) of 14 halogenated alkanes, 5 halogenated alkenes, 10 aromatic compounds, and 2 other VOCs in human blood. Detection limits for the SPME-GC-MS method range from 0.005 to 0.12 microg/L, with linear calibration curves spanning three orders of magnitude. The improved throughput of this method will enable us to expand biomonitoring efforts to assess nonoccupational VOC exposure in large epidemiological studies.

Measurement of trihalomethanes and methyl tertiary-butyl ether in tap water using solid-phase microextraction GC-MS.

The prevalence of water disinfection byproducts in drinking water supplies has raised concerns about possible health effects from chronic exposure to these compounds. To support studies exploring the relation between exposure to trihalomethanes (THMs) and health effects, we have developed an automated analytical method using headspace solid-phase microextraction coupled with capillary gas chromatography and mass spectrometry. This method quantitates trace levels of THMs (chloroform, bromodichloromethane, dibromochloromethane, and bromoform) and methyl tertiary-butyl ether in tap water. Detection limits of less than 100 ng/L for all analytes and linear ranges of three orders of magnitude are adequate for measuring the THMs in tap water samples tested from across the United States. THMs are stable for extended periods in tap water samples after quenching of residual chlorine and buffering to pH 6.5, thus enabling larger epidemiologic field studies with simplified sample collection protocols.