Metabolomics analysis of urine from rats administered with long-term, low-dose acrylamide by ultra-performance liquid chromatography-mass spectrometry.

1. To study the toxic effect of chronic exposure to acrylamide (AA) at low-dose levels, we applied metabolomics approach based on ultra-performance liquid chromatography/mass spectrometry (UPLC-MS). A total of 40 male Wistar rats were randomly assigned to different groups: control, low-dose AA (0.2 mg/kg.bw), middle-dose AA (1 mg/kg.bw) and high-dose AA (5 mg/kg.bw). The rats continuously received AA via drinking water for 16 weeks. Rat urine samples were collected at different time points for measurement of metabolomic profiles. 2. Thirteen metabolites, including the biomarkers of AA exposure (AAMA, GAMA and iso-GAMA), were identified from the metabolomic profiles of rat urine. Compared with the control group, the treated groups showed significantly increased intensities of GAMA, AAMA, iso-GAMA, vinylacetylglycine, 1-salicylate glucuronide, PE (20:1(11Z)/14:0), cysteic acid, L-cysteine, p-cresol sulfate and 7-ketodeoxycholic acid, as well as decreased intensities of 3-acetamidobutanal, 2-indolecarboxylic acid and kynurenic acid in rat urine. Notably, three new candidate biomarkers (p-cresol sulfate, 7-ketodeoxycholic acid and 1-salicylate glucuronide) in rat urine exposed to AA have been found in this study. 3. The results indicate exposure to AA disrupts the metabolism of lipids and amino acids, induces oxidative stress.

Profiling of mercapturic acids of acrolein and acrylamide in human urine after consumption of potato crisps.

SCOPE: Acrolein (AC) and acrylamide (AA) are food contaminants generated by heat treatment. We studied human exposure after consumption of potato crisps by monitoring excretion of mercapturic acids (MAs) in urine. METHODS AND RESULTS: MA excretion was monitored in human urine collected up to 72 h after ingestion of a test meal of experimental (study 1: 1 mg AA/150 g) or commercially available (study 2: 44 µg AA plus 4.6 µg AC/175 g) potato crisps. MA contents were analysed after purification via SPE using HPLC-ESI-MS/MS. On the basis of the area under the curve values of MAs excreted in urine, the total excretion of AC-related MAs exceeded that of AA-related MAs up to 12 times in study 1 and up to four times in study 2. Remarkably, AC content of potato crisps of study 2 was found to be only about 1/10 the AA content, as determined by isotope dilution headspace GC/MS. CONCLUSION: Our results indicate substantially higher exposure to AC from potato crisps than to AA. Total AC in such foods may encompass bioavailable AC forms not detected by headspace GC/MS. Both findings may also apply to other heat processed foods.

Biological effects of acrylamide after daily ingestion of various foods in comparison to water: a study in rats.

SCOPE: Acrylamide (AA), classified as a genotoxic carcinogen, is generated by heating foods. We studied whether the food matrix modulates bioavailability and/or biotransformation and investigated kinetics and biological effectiveness of AA in rats. METHODS AND RESULTS: AA was given to the animals at a daily intake level of AA containing foods for up to 9 days, resulting in an exposure of 50 or 100 µg AA/kg body weight (b.w.)/day. Positive controls received the same dosages of AA in water, negative controls just water. As biomarkers urinary mercapturic acids, hemoglobin adducts, plasma levels of AA and glycidamide (GA) and DNA integrity in white blood cells and hepatocytes were measured. Altogether, no significant differences in bioavailability of AA from water and the different food matrices were observed. Only with bread crust, biomarkers indicated a slightly reduced bioavailability. Monitoring glycidamide valine adduct adducts did not provide evidence for treatment-related significantly enhanced GA-haemoglobin adduct formation in blood although glycidamide mercapturic acid excretion in urine indicated significant GA formation. CONCLUSIONS: The results suggest AA at dietary intake levels, exceeding estimated human mean intake by a factor of at least 100 to become detoxified in Sprague-Dawley rats to a major extent through glutathione coupling.

Acrylamide in children--exposure assessment via urinary acrylamide metabolites as biomarkers.

UNLABELLED: Acrylamide (AA), a substance classified as probably carcinogenic to humans, was detected for the first time in food products in 2002. AA can be primarily found in foods containing carbohydrates and proteins, where it is formed during the heating process. Exposure assessment based on food consumption data revealed an average daily intake of AA between 0.3 and 0.8 microg/kg BW/day. These data have been confirmed by human biomonitoring using haemoglobin adducts of AA in blood or the specific mercapturic acids in urine. However, human biomonitoring data on the internal exposure of children were only sporadically available. Especially data about the excretion of both relevant mercapturic acids were missing. The mercapturic acids other than the haemoglobin adducts give the recent AA exposure of the last 24h. In this study, we quantify the internal exposure of AA and the genotoxic metabolite glycidamide (GA) in 110 children with regard to their exposure through diet and/or environmental tobacco smoke. MATERIAL AND METHODS: Hundred and ten 5-6-year-old children were randomly selected. Their dietary habits as well as their exposure to the environmental tobacco smoke were assessed by means of a questionnaire. By means of spot urine samples, mercapturic acids of acrylamide (AAMA) and mercapturic acids of glycidamide (GAMA) were analysed with LC-ESI-MS/MS. RESULTS: Median (95th percentile) urinary levels were 36.0 (152.7) microg AAMA/l and 13.4 (55.9) microg GAMA/l. Based on the metabolite levels, the median uptake of acrylamide was calculated to be 0.54 microg/kg BW/d. A number of associations with the consumption of French fries, various potato products, as well as fried cereals could be found. Significant results were found for French fries. No correlations between the exposure to environmental smoke and cotinine levels in urine were found. CONCLUSION: This is the first study to show the presence of AAMA and GAMA in urine specimens of 110 children, thus providing evidence for a background exposure by nutrition. Median (95th percentile) uptake of AA in children was 0.54 (1.91) microg/kg bodyweight and day, exceeding exposure in adults by 50%. These findings support the efforts to minimize AA formation and contamination in food. Comparing our findings with that of other human studies, there are hints that children have a higher AA intake than adults and that children more effectively oxidize AA. Both findings indicate that children might be the most vulnerable group of the population.

Simultaneous determination of mercapturic acids derived from ethylene oxide (HEMA), propylene oxide (2-HPMA), acrolein (3-HPMA), acrylamide (AAMA) and N,N-dimethylformamide (AMCC) in human urine using liquid chromatography/tandem mass spectrometry.

Mercapturic acids are highly important and specific biomarkers of exposure to carcinogenic substances in occupational and environmental medicine. We have developed and validated a reliable, specific and very sensitive method for the simultaneous determination of five mercapturic acids derived from several high-production chemicals used in industry, namely ethylene oxide, propylene oxide, acrylamide, acrolein and N,N-dimethylformamide. Analytes are enriched and cleaned up from urinary matrix by offline solid-phase extraction. The mercapturic acids are subsequently separated by means of high-performance liquid chromatography on a Luna C8 (2) column and specifically quantified by tandem mass spectrometric detection using isotopically labelled analytes as internal standards. The limits of detection (LODs) for N-acetyl-S-2-carbamoylethylcysteine (AAMA) and N-acetyl-S-2-hydroxyethylcysteine (HEMA) were 2.5 microg/L and 0.5 microg/L urine, while for N-acetyl-S-3-hydroxypropylcysteine (3-HPMA), N-acetyl-S-2-hydroxypropylcysteine (2-HPMA) and N-acetyl-S-(N-methylcarbamoyl)cysteine (AMCC) it was 5 microg/L. These LODs were sufficient to detect the background exposure of the general population. We applied the method on spot urine samples of 28 subjects of the general population with no known occupational exposure to these substances. Median levels for AAMA, HEMA, 3-HPMA, 2-HPMA and AMCC in non-smokers (n = 14) were 52.6, 2.0, 155, 7.1 and 113.6 microg/L, respectively. In smokers (n = 14), median levels for AAMA, HEMA, 3-HPMA, 2-HPMA and AMCC were 243, 5.3, 1681, 41.7 and 822 microg/L, respectively. Due to the simultaneous quantification of these mercapturic acids, our method is well suited for the screening of workers with multiple chemical exposures as well as the determination of the background excretion of the general population.