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Acrylamide (AA) is a heat-induced food contaminant considered as genotoxic carcinogen. The present study investigated the influence of nutritional and lifestyle preferences on human AA exposure. A 10-day human study was performed with ten volunteers without nutritional preferences (omnivores) and ten vegans. Volunteers self-reported their daily routine and dietary habits. Overall mean AA intake, calculated from contents of diet duplicates, was 0.32 ± 0.19 µg/kg body weight (bw)/day with marked inter-day and inter-volunteer variabilities. Vegans ingested more AA (0.38 ± 0.23 µg/kg bw/day) than omnivore volunteers without dietary restrictions (0.26 ± 0.10 µg/kg bw/day). Excretion kinetics of urinary AA-related mercapturic acids N-acetyl-S-(2-carbamoylethyl)-L-cysteine and N-acetyl-S-(2-hydroxy-2-carbamoylethyl)-L-cysteine were essentially concordant with the respective dietary AA intake. Disproportionately enhanced AA-related biomarker excretion could be traced back to reportedly inadvertent, passive exposure to tobacco and/or fire smoke, as evidenced by the respective urinary exposure biomarkers, cotinine and N-acetyl-S-(2-cyanoethyl)-L-cysteine. Although the study is based on the comparison of small volunteer groups, the results confirm the association of AA exposure biomarkers with documented dietary preferences and lifestyle factors. Some additional contribution of endogenous background AA exposure was demonstrated individually. Disproportionately enhanced AA exposure is suggested to result from passive exposure to tobacco and/or barbecue smoke.

Abstract: New metabolites of styrene, three isomeric vinylphenylmercapturic acids (2-, 3-, and 4-VPMA), were recently identified by LC–ESI-MS in the urine of mice. In this study, 4-VPMA together with traces of 2- and 3-VPMA were found also in the urine of hand-lamination workers, which were exposed to styrene vapours at concentrations ranging from 23 to 244mg/m3. Concentrations of 4-VPMA in these end-of-shift samples were 4.59±3.64ng/mL (mean±S.D.; n =10), those found next morning after the work-shift were 2.14±2.07ng/mL (mean±S.D.; n =10). Strong correlation (R =0.959) was found in the next-morning samples between concentrations of 4-VPMA and phenylglyoxylic acid, whereas correlations found between 4-VPMA and mandelic acid in both end-of-shift and next-morning samples were much weaker. The excretion of 4-VPMA accounted for only about 3.5×10−4% of the absorbed dose of styrene. Despite very low metabolic yield, formation of VPMAs clearly indicates occurrence and extent of styrene ring oxidation considered to be a toxicologically relevant metabolic pathway. [Copyright &y& Elsevier]

Abstract: Hydroxyalkyl mercapturic acids (HAMA) are the main urinary metabolites of several alkylating substances that possess a carcinogenic potential, like acrolein, 1,3-butadiene, ethylene oxide, propylene oxide and glycidol. These alkylating substances are used extensively in industrial processes, but they do also occur environmentally, e.g. in tobacco smoke. The aim of this study was the determination of six HAMA, as biomarkers of exposure, in human urine of smokers and non-smokers. We applied a sensitive analytical method, using hydrophilic interaction liquid chromatography with tandem mass spectrometry (HILIC–MS/MS) for the determination of 2-hydroxyethyl mercapturic acid (HEMA, biomarker for ethylene oxide), 2-hydroxypropyl mercapturic acid (2-HPMA, biomarker for propylene oxide), 3-hydroxypropyl mercapturic acid (3-HPMA, biomarker for acrolein), 2,3-dihydroxypropyl mercapturic acid (DHPMA, biomarker for glycidol) as well as 3,4-dihydroxybutyl mercapturic acid and 3-monohydroxybutenyl mercapturic acids (DHBMA and MHBMA, biomarkers for 1,3-butadiene). Background concentrations of four HAMA were detected in each urine sample we analyzed. The mercapturic acids HEMA and MHBMA were detected in 55% and 10% of the samples, respectively. In the urine of non-smokers (n =54) we observed median levels of 206, 1.6, 12.1, 146, 159, and <5.0μg/g creatinine for DHPMA, HEMA, 2-HPMA, 3-HPMA, DHBMA and MHBMA, respectively. Among smokers (n =40) median levels of DHPMA, HEMA, 2-HPMA, 3-HPMA, DHBMA and MHBMA were determined to be 217, 4.9, 46.2, 884, 211 and <5.0μg/g creatinine, respectively. The excretion rate of the biomarkers HEMA, 2-HPMA and 3-HPMA was distinctly higher in smokers than in non-smokers. Furthermore, our study revealed a comparatively high background level of DHPMA in urine of smokers and non-smokers whose origin is still unknown. The presented data may contribute to the evaluation of reference values for urinary HAMA levels in the general population. [Copyright &y& Elsevier]

Abstract: Benzene and toluene are important industrial chemicals and ubiquitous environmental pollutants. The urinary mercapturic acids of benzene and toluene, S-phenylmercapturic acid (S-PMA) and S-benzylmercapturic acids (S-BMA) are specific biomarkers for the determination of low-level exposures. We have developed and validated a fast, specific and very sensitive method for the simultaneous determination of S-PMA and S-BMA in human urine using an automated multidimensional LC–MS–MS-method that requires no additional sample preparation. Analytes are stripped from urinary matrix by online extraction on a restricted access material, transferred to the analytical column and subsequently determined by tandem mass spectrometry using isotopically labelled S-PMA as internal standard. The lower limit of quantification (LLOQ) for both analytes was 0.05μg/L urine and sufficient to quantify the background exposure of the general population. Precision within series and between series for S-PMA and S-BMA ranged from 1.0% to 12.2%, accuracy was 108% and 100%, respectively. We applied the method on spot urine samples of 30 subjects of the general population with no known exposure to benzene or toluene. Median levels (range) for S-PMA and S-BMA in non-smokers (n =15) were 0.14μg/L (<0.05–0.26μg/L) and 8.2 (1.6–77.4μg/L), respectively. In smokers (n =15), median levels for S-PMA and S-BMA were 1.22μg/L (0.17–5.75μg/L) and 11.5μg/L (0.9–51.2μg/L), respectively. Due to its automation, our method is well suited for application in large environmental studies. [Copyright &y& Elsevier]

Abstract: Two analytical methods (HPLC-fluorimeter [HPLC-FLD] and tandem mass spectrometry LC/MS/MS) are available to assay phenyl-hydroxyethylmercapturic acids (PHEMAs), the mercapturic acids of styrene in humans. In the past, each method was used to check different populations of subjects, but until now no attempt has been made to compare the two methods. This study was designed to verify whether the two methods actually give comparable results. The influence of different conditions of sample storage in altering the concentration of PHEMAs was also investigated. Urine samples were collected at the beginning and at the end of the workshift from 10 workers exposed to different levels of styrene. Each sample was analysed both by LC/MS/MS after storage under different conditions (respectively, at −20 and +4°C, and after repeated freezing–thawing cycles), and by HPLC-FLD (in the same conditions of storage). Strong correlations were found between the two methods both for total PHEMAs and for each of the isomers measured, including the minor (S,R)-M1. Also an alternative approach, the Bland–Altman test, confirmed the agreement between the two methods. The different storage conditions tested did not decrease the concentration of PHEMAs but, surprisingly, a clear trend to increase was shown, particularly for (R,R)-M1, (S,R)-M2 and (R,R)-M2 in samples stored at +4°C for 1 week. In conclusion, the study demonstrates that the methods give comparable results. Indirectly, this confirms also the main characteristics of PHEMAs, showed in the previous experiments: low biotransformation rates of styrene into PHEMAs; large inter-individual variability; and the presence of a clear preference in the excretion of the isomers deriving from (S)-styrene oxide. PHEMAs appear stable under different storage conditions, but further studies are needed to explain the increase of levels that occurs when samples are not kept frozen. To avoid pre-analytical errors, samples collected for biomonitoring or research purposes should be frozen as soon as possible, and thawed only one time just before the analysis. [Copyright &y& Elsevier]

Abstract: We developed a LC–MS/MS method for the quantitative determination of the mercapturic acid (MA) metabolites of acrylamide (AA) AAMA and of its oxidative metabolite glycidamide (GA) GAMA in urine samples from the general population. The method requires 4mL of urine which is solid phase extracted prior to LC–MS/MS analysis. The metabolites are detected by ESI-tandem mass spectrometry in negative ionisation mode and quantified by isotope dilution. Detection limits ranged down to 1.5μg/L urine for both AAMA and GAMA. The imprecision expressed as R.S.D. lay between 2% and 6% for both analytes (intra- and inter-assay). First results on a small group of 29 persons out of the general population ranged from 5 to 338μg/L AAMA and &#60;LOD to 45μg/L GAMA in urine. Only in one urine sample GAMA could not be detected. With this sensitive, reliable and rapid method we can determine the internal exposure of the general population to acrylamide in terms of the mercapturic acids. Especially the determination of GAMA is of great toxicological importance because GA is the ultimate carcinogenic agent in AA metabolism. The method therefore provides better insight into the metabolism of acrylamide in humans and furthermore supports risk assessments. [Copyright &y& Elsevier]

A minireview is presented concerning the use of mercapturic acids as biological exposure index for electrophilic chemicals. Besides pure analytical aspects, this minireview considers possible issues in relation to (a) the added value of mercapturic acids as compared to other well validated biomarkers of exposure and (b) the high inter-individual variability in mercapturic acids excretion. Recent field and/or experimental studies confirm the usefulness of mercapturic acids as biological exposure index for electrophilic chemicals and suggest the interest of a toxicogenetic approach for a better interpretation of the results of biological monitoring. [ABSTRACT FROM AUTHOR]

Abstract: Acrylamide (AA), a widely used industrial monomer which is categorised to be carcinogenic, was found to be generated in starch-containing foods during the heating process. This discovery has caused reasonable concern about possible health risks to humans due to dietary acrylamide uptake. In order to gain more information on human metabolism of acrylamide and to contribute to the assessment of the human carcinogenic risk due to AA uptake we measured the mercapturic acid of AA and its epoxide glycidamide (GA) i.e. N-acetyl-S-(2-carbamoylethyl)-l-cysteine (AAMA) and N-(R,S)-acetyl-S-(2-carbamoyl-2-hydroxyethyl)-l-cysteine (GAMA) in human urine. The relation between AAMA and GAMA is important in this context because GA is thought to be the ultimate carcinogenic metabolite of AA. The median levels in smokers (n=13) were found to be about four times higher than in non-smokers (n=16) with median levels of 127μg/l versus 29μg/l for AAMA and 19μg/l versus 5μg/l for GAMA. Therefore cigarette smoke proved to be an important source of acrylamide exposure. The level of AAMA in the occupationally non-exposed collective (n=29) ranged from 3 to 338μg/l, the level of GAMA from

It was the aim of this study to ascertain whether xylenes form phenylmercapturic acids via aromatic epoxides in the human metabolism. Aromatic epoxides are suspected to exert mutagenic properties. Therefore we developed an LC/MS/MS procedure for the determination of these mercapturic acids. Using this method we were able to detect dimethylphenylmercapturic acid (DPMA) in urine samples of persons occupationally exposed to xylenes. The unequivocal LC/MS/MS detection of phenylmercapturic acid metabolites of xylene thanks to authentic standards was verified with an independent GC/MS method. Xylene concentrations in the air of the workplaces ranged between 0.7 and 58.1 ppm (median 12.6 ppm). The excretion of methylhippuric acid in the urine samples of the workers (n=27) ranges from 19.8 to 2332.5 mg/l (median 450.9 mg/l). DPMA was detected in only 9 samples of 27 exposed persons. According to a rough calculation DPMA is only formed in a ratio of 0.0003% respective to the xylene main metabolite MHA. That means that even under occupationally relevant xylene exposure potential mutagenic potencies should be negligible. DPMA in urine is not sensitive enough for general biomonitoring purposes due to the low ratio of excretion. MHA should therefore be used for biomonitoring from now on. Furthermore, our results show that irrespective of the structure of xylene isomers there is no preferences in metabolism. [ABSTRACT FROM AUTHOR]

The objective of this study was to test the infiuence of genetic polymorphisms for metabolic enzymes (CYP2E1, mEH, GSTM1 and GSTT1) implicated in the biotransformation of styrene in humans on the interpretation of urinary biomarkers of exposure. Thirty workers from a fibreglass-reinforced plastics factory took part in the study. Ambient styrene concentration was determined during the whole workshift by passive sampling. Urine was collected at the end of the shift for the determination of mandelic acid (MA) and phenylglyoxylic acid (PGA) (major biotransformation pathway), N-acetyl-S-(1-phenyl-2-hydroxy)ethyl-L-cysteine (M1) and N-acetyl-S-(2-phenyl-2-hydroxy)ethyl-[sub L]-cysteine (M2) (minor metabolic pathway) and creatinine. The average airborne styrene concentration of 18.2 ppm (range: 0.9-68.9 ppm) was very close to the current threshold limit value (TLV-TWA) recently adjusted by ACGIH from 50 to 20 ppm. There was a better correlation between external and internal exposure as estimated by urinary MA + PGA (r=0.92; p<0.0001) compared with urinary M1 + M2 (r=0.74; p<0.0001). To investigate to what extent genetic polymorphisms in metabolic enzymes could explain interindividual variations observed in the concentration of urinary biomarkers related to a given external exposure, two 'metabolic indexes' (derived from the ratio between the sum of urinary metabolites for a specific pathway and ambient styrene concentration) were calculated for each worker and compared for different allelic combinations. Monovariate analyses showed that GSTM1 polymorphism was clearly the most significant parameter infiuencing urinary concentrations of mercapturic acids. Based on GSTM1 allelic status, two different biological exposure indexes (BEIs) for M1 + M2 in post-shift urinary samples corresponding to a 20 ppm styrene concentration are proposed (GSTM1null: 1330 µg g[sup -1] creatinine, GSTM1+: 2878 µg g[sup -1] creatinine). Multivariate regression analyses were also performed and revealed that the presence of the rare CYP2E1*1B allele linked to TaqI polymorphism (A1/A2) was associated with increased urinary concentrations of metabolites from both pathways. Two previously described polymorphisms for the EPHX gene were also tested but seemed not really relevant for interpretation of biomarkers. In conclusion, while CYP2E1 genotyping, particularly assessment of the CYP2E1*1B allelic status, is useful for a more accurate interpretation of the concentration of urinary biomarkers, GSTM1 genotyping is absolutely necessary when considering a biological monitoring programme based on determination of urinary mercapturic acids. [ABSTRACT FROM AUTHOR]

Objective: To evaluate the use of urinary mercapturic acids as a biomarker of human exposure to allyl chloride (3-chloropropene) (AC). During three regular shut down periods in a production factory for AC, both types of variables were measured in 136 workers involved in maintenance operations.Methods: Potential airborne exposure to AC was measured by personal air monitoring in the breathing zone. In total 205 workshifts were evaluated. During 99 workshifts no respiratory protection equipment was used. Mercapturic acid metabolites were measured in urinary extracts by gas chromatography-mass spectrometry (GC-MS).Results: During 86 work shifts when no respiratory protection was used the air concentrations of AC were below the Dutch eight hour time weighted average (8 h-TWA) occupational exposure limit (OEL) of AC (3 mg/m3), whereas in 13 workshifts the potential exposure, as measured by personal air monitoring, exceeded the OEL (3.3 to 17 mg/m3). With the aid of GC-MS, 3-hydroxypropylmercapturic acid (HPMA) was identified as a minor and allylmercapturic acid (ALMA) as a major metabolite of AC in urine samples from the maintenance workers exposed to AC. The concentrations of ALMA excreted were in a range from < 25 micrograms/l (detection limit) to 3550 micrograms/l. The increases in urinary ALMA concentrations during the workshifts correlated well with the 8h-TWA air concentrations of AC (r = 0.816, P = 0.0001, n = 39). Based on this correlation, for AC a biological exposure index (BEI) of 352 micrograms ALMA/g creatinine during an eight hour workshift is proposed. In some urine samples unexpectedly high concentrations of ALMA were found. Some of these could definitely be attributed to dermal exposure to AC. In other cases garlic consumption was identified as a confounding factor.Conclusion: The mercapturic acid ALMA was identified in urine of workers occupationally exposed to airborne AC and the increase in ALMA concentrations in urine during a workshift correlated well with the 8 h-TWA exposure to AC. Garlic consumption, but not smoking, is a potential confounding factor for this biomarker of human exposure to AC. [ABSTRACT FROM AUTHOR]

Voluntary bystanders, simulating a situation of non-occupational exposure to Z- and E-1,3-dichloropropene (Z- and E-DCP), were exposed during field application of this nematocide in the Dutch flower-bulb culture. Environmental monitoring revealed that mean respiratory exposure concentrations of Z- and E-DCP varied from non-detectable levels to 1.12 mg/m 8-h time-weighted average (TWA) for Z-DCP and to 0.91 mg/m 8-h TWA for E-DCP. Biological monitoring was executed by determining urinary mercapturic acid metabolites of Z- and E-DCP according to a method recently validated in occupationally exposed applicators. A linear relationship between respiratory exposure to Z-and E-DCP and the urinary excretion of both mercapturic acids was observed in bystanders. Dermal uptake did not contribute significantly to the internal dose of Z- or E-DCP. The urinary mercapturic acid of Z-DCP was a more sensitive parameter for the detection of exposure than was respiratory air monitoring. In future studies it would be worthwhile to determine the extent of exposure of real bystanders to DCP on the basis of urinary mercapturic acid excretion. [ABSTRACT FROM AUTHOR]