Determination of perfluorooctanoic acid and perfluorooctanesulfonate in human tissues by liquid chromatography/single quadrupole mass spectrometry.

A method is described that permits the measurement of the levels of perfluorooctanoic acid (PFOA) and perfluorooctane sulfonate (PFOS) in human liver, kidney, adipose tissue, brain, basal ganglia, hypophysis, thyroid, gonads, pancreas, lung, skeletal muscle and blood, even in subjects not occupationally exposed to these compounds. The purification of samples involved the use of trifunctional (tC18) and strong anion-exchange (SAX) solid-phase extraction cartridges, and the analysis utilized a high-performance liquid chromatograph coupled to a single quadrupole mass spectrometer (LC/MS). The analyses were conducted on a mixed-bed reversed-phase column by gradient runs using 3 mM ammonium acetate/methanol mixtures at different proportions as the mobile phase. The detector was used in electrospray negative ion mode by recording simultaneously the ions m/z 413.0 (PFOA) and 499.0 (PFOS). Perfluorononanoic acid (PFNA), added to the samples before the purification, was used as the internal standard (ion monitored = m/z 463.6). The recovery rates of the extraction procedure ranged from 79.6 to 95.6% (CV% 1.7-7.4%) for PFOA, from 79.7 to 100.8% (CV% = 1.2-7.1) for PFOS, and from 89.1 to 102.3% (CV% = 0.9-5.2 %) for PFNA. The calibration curves were linear up to at least 400 ng of analytes per gram of tissue. The detection limits (signal-to-noise ratio = 3) were 0.1 ng/g for both PFOA and PFOS measured in all tissues except adipose tissue, where the limits were about 0.2 ng/g. The content of analytes in tissues varied from 0.3 to 3.8 ng/g (respectively: basal ganglia and lung) for PFOA, and from 1.0 to 13.6 ng/g (respectively: skeletal muscle and liver) for the linear isomer of PFOS. The method is suitable to evaluate the content of PFOA and PFOS in different tissues taken from the general population exposed to very low concentrations of these pollutants.

Urban air and tobacco smoke in benzene exposure in a cohort of traffic policemen.

Benzene (B) is a typical micro-pollutant present in air, especially urban air. In this study a possible correlation between personal benzene exposure and S-phenylmercapturic acid (S-PMA) as a biomarker of internal dose was evaluated in a cohort of traffic policemen. The results confirm that S-PMA is significantly correlated to benzene measured in personal air. B and S-PMA were analyzed considering seasonality, work quarters, time spent indoors, outdoors, and directing traffic, but no significant differences were recorded.

High-pressure liquid chromatographic-mass spectrometric determination of sorbic acid in urine: verification of formation of trans,trans-muconic acid.

An LC-MS method is described for the determination of urinary sorbic acid (SA), a common food additive, which allows to measure down to 4 microg/L of the compound. The method involves an acidic hydrolysis followed by solid-phase extraction. The method was applied to two volunteers who ingested SA and to 36 individuals with no dietary restriction. The results confirm that a little aliquot of ingested SA is found in urine also in humans. The significant correlation found between urinary levels of SA and trans,trans-muconic acid (MA) seems to indicate that the measurement of SA in urine could allow to estimate the amount of MA excreted following a dietary intake of SA and, consequently, to enhance the specificity of MA as a biomarker of benzene exposure. A point of clarification in future studies will be the actual chemical form of SA excreted, since our results clearly demonstrate that without hydrolysis only a very little amount of SA can be found even in subjects heavily exposed to SA.

Determination of urinary S-phenylmercapturic acid, a specific metabolite of benzene, by liquid chromatography/single quadrupole mass spectrometry.

A high-performance liquid chromatography/single quadrupole mass spectrometry (LC/MS) method is described for the determination of urinary S-phenylmercapturic acid (S-PMA), a specific metabolite of benzene. Urine samples were spiked with [13C6]S-PMA (used as the internal standard) and acidified; then they were purified by solid-phase extraction (SPE) on C18 cartridges. Analyses were conducted on a reversed-phase column by gradient runs with 1% aqueous acetic acid/methanol mixtures at different proportions as the mobile phase. The detector was used in electrospray negative ion mode (ESI-), the ions m/z 238 for S-PMA and 244 for [13C6]S-PMA being recorded simultaneously. The detection limit (for a signal-to-noise ratio = 3) was 0.2 microg/L, thus allowing for the measurement of background excretion of S-PMA in the general population. The use of the internal standard allowed us to obtain good precision (CV% values < 3%) and a linear calibration curve within the range of interest for monitoring occupational exposure to benzene (up to 500 microg/L). The method was applied to assay the metabolite concentration in a group of 299 workers (68 smokers and 231 non-smokers) occupationally exposed to relatively low levels of benzene (environmental concentration = 0.4-220 microg/m3, mean 11.4 microg/m3 and 236 non-exposed subjects (134 smokers and 102 non-smokers). The results clearly showed that smoking must be taken into account for the correct interpretation of the results of S-PMA measurements for the assessment of work-related benzene exposure. When only non-smokers were selected, the mean excretion of S-PMA was significantly higher in workers exposed to benzene (1.2 +/- 0.9 microg/g creatinine) than in the control group (0.7 +/- 0.6 microg/g creatinine) (p < 0.001), thus confirming the role of S-PMA as a biomarker of benzene on a group basis, even for relatively low exposure degrees.

A field method for sampling toluene in end-exhaled air, as a biomarker of occupational exposure: correlation with other exposure indices.

A sensitive and rapid method for the determination of toluene in exhaled air is described. We have developed a device for direct breath sampling consisting of a sampler inserted into an empty 58 mL glass vial closed by a Teflon rubber septum. The sorbent cartridge functions as a diffusive sampler and employs a Tenax resin (300 mg, 35/50 mesh) to trap volatile organic compounds from the exhaled air. End-exhaled air is collected "in field" by removing the septum from the vial, by forcibly exhaling into the device through a suitable Teflon tube, and then by sealing the bottle quickly. Environmental toluene levels ranged from 13 to 191 mg/m3, while the concentrations of the solvent in alveolar air, in blood and urine ranged from 159 to 3354 ng/L, from 3.6 to 53.5 microg/L, and from 8.7 to 142.4 microg/L respectively. The correlation coefficients (r) of biological measurements towards environmental toluene levels were 0.822, 0.850 and 0.846 for alveolar air, blood and urine samples, respectively. The breath sampler allowed the rapid and non-invasive collection of data on elimination of toluene.

Interest of genotyping and phenotyping of drug-metabolizing enzymes for the interpretation of biological monitoring of exposure to styrene.

In the field of occupational and/or environmental toxicology, the measurement of specific metabolites in urine may serve to assess exposure to the parent compounds (biological monitoring of exposure). Styrene is one of the chemicals for which biological monitoring programs have been validated and implemented in environmental and occupational medicine. However, inter-individual differences in the urinary excretion exist both for the main end-products (mandelic acid and phenylglyoxylic acid) and for its specific mercapturic acids (phenylhydroxyethylmercapturic acids, PHEMA). This limits to a certain extent the use of these metabolites for an accurate assessment of styrene exposure. In a group of 26 volunteers selected with relevant genotypes, and exposed to styrene vapours (50 mg/m3, 8 h) in an inhalation chamber, we evaluated whether genotyping or phenotyping relevant drug-metabolizing enzymes (CYP2E1, EPHX1, GSTM1, GSTT1 and GSTP1) may help to explain the observed inter-individual variability in the urinary metabolite excretion. Peripheral blood lymphocytes were used for genotyping and as reporter cells for the phenotyping of CYP2E1 and EPHX1. The GSTM1 genotype was clearly the most significant parameter explaining the variance in urinary PHEMA excretion (6-fold lower in GSTM1 null subjects; P < 0.0001) so that systematic GSTM1 genotyping should be recommended routinely for a correct interpretation of PHEMA urinary levels. Variant alleles CYP2E1*6 (7632T>A) and His113EPHX1 were associated with a significant reduction of, respectively, the expression (P = 0.047) and activity (P = 0.022) of the enzyme in peripheral blood lymphocytes. In combination with GSTM1 genotyping, the phenotyping approach also contributed to improve the interpretation of urinary results, as illustrated by the combined effect of CYP2E1 expression and GSTM1 allelic status that explained 77% of the variance in PHEMA excretion and allows the recommendation of mercapturates as specific and reliable biomarkers of exposure to styrene.

Measurement of urinary N-acetyl-S-(N-methylcarbamoyl)cysteine by high-performance liquid chromatography with direct ultraviolet detection.

A new high-performance liquid chromatographic (HPLC) method is described for the determination of urinary N-acetyl-S-(N-methylcarbamoyl)cysteine (AMCC), the final product of the conjugation reaction between a metabolic intermediate of N,N-dimethylformamide (DMF) and glutathione. Urine samples were purified by C(18) solid-phase extraction and then directly analysed by HPLC with an Aminex Ion Exclusion HPX-87H column maintained at 25 degrees C and a UV detector set at 196 nm. Under isocratic conditions (2.4 mM sulphuric acid, flow-rate=0.6 ml/min) AMCC eluted at 20.2 min. The reproducibility (C.V.%) was 1.3-2.7% (intra- and inter-assay, N = 5); the accuracy was 98.0+/-1.7% at 10 mg/l and 101.9+/-1.5% at 800 mg/l (mean+/-SD, N = 3). AMCC was measured in urine from 22 exposed subjects. A strong correlation was found between AMCC and environmental DMF [AMCC (mg/g creatinine)=3.40xDMF (mg/m(3)) + 3.07; r=0.95], while in the urine of 20 unexposed subjects the concentration of AMCC was constantly below the detection limit of the method (0.9 mg/l in urine). The method described appears to be useful for the biological monitoring of DMF exposure.

Exposiçäo profissional aos anestésicos voláteis: 2. monitorizaçäo ambiental e monitorizaçäo biológica / Occupational exposure as volatile anesthetics: 2. physiologic and environmental monitoring

Säo apresentados vários aspectos da monitorizaçäo ambiental e monitorizaçao biológica, valores-limites propostos e resultados laboratoriais de amostras coletadas durante a realizaçäo de cirurgias.

Exposiçäo profissional aos anestésicos voláteis: 1. Biotransformaçäo, efeitos adversos e dados epidemiologicos / Occupational exposure at inhalation anesthetics: 1. Biotransformation, adverse effects and epidemiological data

A utilizaçäo de anestésicos voláteis em cirurgias consiste em sério risco profissional, näo devidamente divulgado, monitorado e investigado nos hospitais brasileiros. No presente trabalho säo apresentados os principais anestésicos voláteis empregados nas atividades cirúrgicas, as reaçöes de biotransformaçäo e seus produtos, os efeitos adversos e os dados epidemiológicos divulgados pela literatura científica. A finalidade desta publicaçäo é informar e conscientizar os profissionais da área e estimular a contribuir para o esclarecimento de vários aspectos ainda näo definitivamente conclusivos.

The development of benthonic phytocoenosis on artificial substrates in the ticino river.

Changes in the taxonomic composition, chlorophyll a concentration, dry weight, percentage organic carbon and nitrogen and several indices of diversity, including "Margalef's index" were followed during the development of phytobenthonic communities on glass slides. These data suggest that, in this environment, the algal community resembles the nearby natural community after 4 weeks. The taxonomic development can be divided into two phases. During the first 2 weeks the phytocoenosis is dominated by a rather diverse and variable diatom assemblage. Later Cyanophyta dominate. The diversity decreases during colonization as reflected by all indices considered.