Literature review and evaluation of biomarkers, matrices and analytical methods for chemicals selected in the research program Human Biomonitoring for the European Union (HBM4EU)

Humans are potentially exposed to a large amount of chemicals present in the environment and in the workplace. In the European Human Biomonitoring initiative (Human Biomonitoring for the European Union = HBM4EU), acrylamide, mycotoxins (aflatoxin B1, deoxynivalenol, fumonisin B1), diisocyanates (4,4'-methylenediphenyl diisocyanate, 2,4- and 2,6-toluene diisocyanate), and pyrethroids were included among the prioritized chemicals of concern for human health. For the present literature review, the analytical methods used in worldwide biomonitoring studies for these compounds were collected and presented in comprehensive tables, including the following parameter: determined biomarker, matrix, sample amount, work-up procedure, available laboratory quality assurance and quality assessment information, analytical techniques, and limit of detection. Based on the data presented in these tables, the most suitable methods were recommended. According to the paradigm of biomonitoring, the information about two different biomarkers of exposure was evaluated: a) internal dose = parent compounds and metabolites in urine and blood; and b) the biologically effective = dose measured as blood protein adducts. Urine was the preferred matrix used for deoxynivalenol, fumonisin B1, and pyrethroids (biomarkers of internal dose). Markers of the biological effective dose were determined as hemoglobin adducts for diisocyanates and acrylamide, and as serum-albumin-adducts of aflatoxin B1 and diisocyanates. The analyses and quantitation of the protein adducts in blood or the metabolites in urine were mostly performed with LC-MS/MS or GC-MS in the presence of isotope-labeled internal standards. This review also addresses the critical aspects of the application, use and selection of biomarkers. For future biomonitoring studies, a more comprehensive approach is discussed to broaden the selection of compounds.

Biomonitoring of Multiple Mycotoxins in Urine by GC-MS/MS: A Pilot Study on Patients with Esophageal Cancer in Golestan Province, Northeastern Iran

A pilot study to investigate the occurrence of 10 mycotoxins (deoxynivalenol, DON; 3-acetyldeoxynivalenol, 3-ADON; 15-acetyldeoxynivalenol, 15-ADON; fusarenon-X, FUS-X; diacetoxyscirpenol, DAS; nivalenol, NIV; neosolaniol, NEO; zearalenone, ZON; zearalanone, ZAN; T-2 toxin, T-2; and HT-2 toxin, HT-2) in esophageal cancer patients was performed with the urinary biomarkers approach in Golestan, Iran. Urine multimycotoxin analysis was performed by dispersive liquid–liquid microextraction and gas chromatography–tandem mass spectrometry (GC–MS/MS) analysis, and values were normalized with urinary creatinine (μg/g). Four mycotoxins, namely NEO (40%), HT-2 (17.6%), DON (10%), and HT-2 (5.8%), were detected in the analyzed urine samples. DON was only detected in the control group (5.09 μg/g creatinine), while T-2 (44.70 μg/g creatinine) was only present in the esophageal cancer group. NEO and HT-2 were quantified in both control and case groups, showing average of positive samples of 9.09 and 10.45 μg/g creatinine for NEO and 16.81 and 29.09 μg/g creatinine for HT-2, respectively. Mycotoxin co-occurrence was observed in three samples as binary (NEO/HT-2 and T-2/HT-2) and ternary (DON/NEO/HT-2) combinations, reaching total concentrations of 44.58, 79.13, and 30.04 µg/g creatinine, respectively. Further investigations are needed to explore a causal association between mycotoxin contamination and esophageal cancer. For this pilot study in Golestan, the low sample size was a very limiting factor.

Determination of aflatoxin M1 and deoxynivalenol biomarkers in infants and children urines from Bangladesh

The mycotoxins aflatoxin B1 (AFB1) and deoxynivalenol (DON) are found worldwide in crops and dietary staples. The prevalence and levels of these contaminants can vary greatly, and data in Bangladeshi food commodities are scarce. To characterize human exposure, we have conducted biomonitoring, analyzing AFM1 (a metabolite of AFB1) and DON levels in urines of adult cohorts in Bangladesh. Yet, AFM1 and DON occurrence has not been studied in the very young population of this country. Thus, the same methods, HPLC-FD for AFM1 and LC-MS/MS for DON analysis, were now applied to determine these biomarkers in urines of infants (n = 49) and young children (n = 105) in Rajshahi and Dhaka district. Overall, AFM1 and DON detection frequency was 43.5% and 33.4%, with 34.7% and 11.5% in infant and 47.6% and 39.4% in children urines, respectively. The mean AFM1 levels in all infants (9.1 ± 14.3, max 55.6 pg/mL) and children (8.8 ± 12.9, max 75.3 pg/mL) were not significantly different. The AFM1 mean level was slightly higher in Dhaka (9.4 ± 12.4) compared to Rajshahi (8.5 ± 13.9 pg/mL) district. The average DON level was about 2-fold higher in infant (3.8 ± 2.9, max 6.8 ng/mL) than children urines (1.6 ± 1.8, max 8.6 ng/mL), and higher in Rajshahi (2.1 ± 2.3 ng/mL) than Dhaka (1.4 ± 1.6 ng/mL) district. The biomarker-based estimated average daily DON intake (29.6 ± 108.3 ng/kg bw in infants and 36.4 ± 81.8 ng/kg bw in children) or the maximum exposure (560 ng/kg bw) do not exceed the current maximum provisional tolerable daily intake value of 1 µg/kg bw for DON, although DON exposure in infants and children is higher than that of Bangladeshi adults. The AFM1 urine levels in young children are somewhat lower than those found previously in adult cohorts in Bangladesh, but the frequent detection of this biomarker for AFB1 exposure raises further concerns, also for this vulnerable part of the population. Therefore, continuous surveillance for aflatoxins in Bangladeshi food commodities is clearly required, first to identify major sources of intake and then to reduce exposure.

Risks to human and animal health related to the presence of deoxynivalenol and its acetylated and modified forms in food and feed

Deoxynivalenol (DON) is a mycotoxin primarily produced by Fusarium fungi, occurring predominantly in cereal grains. Following the request of the European Commission, the CONTAM Panel assessed the risk to animal and human health related to DON, 3-acetyl-DON (3-Ac-DON), 15-acetyl-DON (15-Ac-DON) and DON-3-glucoside in food and feed. A total of 27,537, 13,892, 7,270 and 2,266 analytical data for DON, 3-Ac-DON, 15-Ac-DON and DON-3-glucoside, respectively, in food, feed and unprocessed grains collected from 2007 to 2014 were used. For human exposure, grains and grain-based products were main sources, whereas in farm and companion animals, cereal grains, cereal by-products and forage maize contributed most. DON is rapidly absorbed, distributed, and excreted. Since 3-Ac-DON and 15-Ac-DON are largely deacetylated and DON-3-glucoside cleaved in the intestines the same toxic effects as DON can be expected. The TDI of 1 μg/kg bw per day, that was established for DON based on reduced body weight gain in mice, was therefore used as a group-TDI for the sum of DON, 3-Ac-DON, 15-Ac-DON and DON-3-glucoside. In order to assess acute human health risk, epidemiological data from mycotoxicoses were assessed and a group-ARfD of 8 μg/kg bw per eating occasion was calculated. Estimates of acute dietary exposures were below this dose and did not raise a health concern in humans. The estimated mean chronic dietary exposure was above the group-TDI in infants, toddlers and other children, and at high exposure also in adolescents and adults, indicating a potential health concern. Based on estimated mean dietary concentrations in ruminants, poultry, rabbits, dogs and cats, most farmed fish species and horses, adverse effects are not expected. At the high dietary concentrations, there is a potential risk for chronic adverse effects in pigs and fish and for acute adverse effects in cats and farmed mink.

Comparison of Data from a Single-Analyte and a Multianalyte Method for Determination of Urinary Total Deoxynivalenol in Human Samples

Deoxynivalenol (DON) exposure is estimated by the combined measures of urinary DON and DON-glucuronides. In this study, data from single-mycotoxin (SM) and a multimycotoxin (MM) methods were compared for 256 Swedish adult urine samples. Both methods included β-glucuronidase predigestion, immunoaffinity enrichment, and LC-MS/MS. However, the specific reagents, apparatus, and conditions were not identical in part because the MM method measures additional mycotoxins. DON was detected in 88 and 63% of samples using the SM and MM methods, respectively, with the following mean and median concentrations: SM, mean = 5.0 ng/mL, SD = 7.4, range of positives = 0.5-60.2 ng/mL, median = 2.5 ng/mL, IQR = 1.0-5.5 ng/mL; MM, mean = 4.4 ng/mL, SD = 12.9, range of positives = 0.5-135.2 ng/mL, median = 0.8 ng/mL, IQR = 0.3-3.5. Linear regression showed a significant, albeit modest, correlation between the two measures (p = 0.0001, r = 0.591). The differences observed may reflect subtle handling differences in DON extraction and quantitation between the methods.

Biomonitoring of Mycotoxins in Urine: Pilot Study in Mill Workers

Contamination of grains with mycotoxins results in a dietary background exposure of the general population. In occupational settings such as during processing of raw materials as in milling, an additional mycotoxin exposure by inhalation is possible. Biomonitoring is an integrative approach to assess human exposure from various sources and by all routes. To investigate possible workplace exposure to mycotoxins, a pilot study was conducted that compared levels of urinary biomarkers in mill workers to those in a control group with dietary mycotoxin intake alone. Workers (n = 17) from three grain mills in North Rhine Westphalia, Germany, provided spot urines during shift; volunteers (n = 13, IfADo staff) with matched age structure served as control group. The mycotoxins selected for biomarker analysis were citrinin (CIT) deoxynivalenol (DON), ochratoxin A (OTA), and zearalenone (ZEN). Immunoaffinity columns (CIT, DON, ZEN) or liquid-liquid extraction (OTA) was employed for urine sample cleanup prior to targeted analysis by liquid chromatography with tandem mass spectrometry (LC-MS/MS) or by high-performance liquid chromatography (HPLC). In addition, mycotoxin metabolites that may be formed in the organism were analyzed, including deepoxy-deoxynivalenol (DOM-1), ochratoxin alpha (OTα), dihydrocitrinone (DH-CIT), and α- and β-zearalenol (α- and β-ZEL), as well as phase II metabolites that were hydrolyzed with β-glucuronidase/arylsulfatase prior to sample cleanup. All analyte concentrations were adjusted for creatinine (crea) content in the spot urine samples. Citrinin, DON, OTA, and ZEN were detected in nearly all urine samples from mill workers and controls. Interestingly, DH-CIT was found at higher mean levels than the parent compound (~0.14 and 0.045 µg/g crea, respectively), suggesting an effective metabolism of CIT in humans. Other metabolites DOM-1, OTα, and α- and β-ZEL were detected less frequently in urine. Deoxynivalenol was detected at the highest concentrations (mean ~6 µg/g crea), followed by OTA (mean ~0.08 µg/g crea); ZEN (mean ~0.03 µg/g crea) and its metabolites appeared in urine at lower levels. Mycotoxin biomarker levels in urine from mill workers and controls were not significantly different. From these results it is concluded that biomarker levels measured in urine samples from the two cohorts reflect mainly dietary mycotoxin exposure. An additional occupational (inhalational) exposure of mill workers, if any, is apparently low at the investigated workplaces.

Human biomonitoring of multiple mycotoxins in the Belgian population: Results of the BIOMYCO study

Mycotoxins are important food contaminants responsible for health effects such as cancer, nephrotoxicity, hepatotoxicity or immunosuppression. The assessment of mycotoxin exposure is often based on calculations combining mycotoxin occurrence data in food with population data on food consumption. Because of limitations inherent to that approach, the direct measurement of biomarkers of exposure in biological fluids has been proposed as a suitable alternative to perform an accurate mycotoxin exposure assessment at individual level. For this reason, the BIOMYCO study was designed to assess mycotoxin exposure in Belgian adults and children using urinary biomarkers of exposure. Morning urine was gathered in a representative part of the Belgian population according to a standardised study protocol, whereby 155 children (3-12 years old) and 239 adults (19-65 years old) were selected based on random cluster sampling. These urine samples were analysed for the presence of 33 potential biomarkers with focus on aflatoxins, citrinin (CIT), fumonisins, trichothecenes, ochratoxin A (OTA), zearalenone and their metabolites using two validated LC-MS/MS methods. Nine out of the 33 analysed mycotoxins were detected whereby deoxynivalenol (DON), OTA, CIT and their metabolites were the most frequently detected. Deoxynivalenol-15-glucuronide was the main urinary DON biomarker and was found in all urine samples in the ng/mL range. Furthermore deoxynivalenol-3-glucuronide was quantified in 91% of the urine samples collected from children and in 77% of the samples collected from adults. Deoxynivalenol was detected in 70% and 37% of the samples of children and adults respectively. For the first time deepoxy-deoxynivalenol-glucuronide was detected in children's urine (17%). In the samples collected by adults, the prevalence was 22%. Whereas all these mycotoxins contaminated the urine samples in the ng/mL range, CIT and OTA were present in much lower concentrations (pg/mL). OTA contaminated 51% and 35% of the samples collected by children and adults respectively. CIT and its metabolite were present in 72% and 6% of children's urine, whereas they contaminated 59% and 12% of adult's urine. Finally, α-zearalenol and β-zearalenol-14-glucuronide were found in respectively one and two samples from adults. The exposure to DON, OTA and CIT was compared between subgroups and urinary mycotoxin concentrations differed significantly among age and gender. Based on the urinary levels, the daily intake of DON and OTA was estimated and evaluated whereby, depending on the used method, 16-69% of the population possibly exceeded the tolerable daily intake for DON and 1% for OTA. The BIOMYCO study is the first study whereby a multi-toxin approach was applied for mycotoxin exposure assessment in adults and children on a large-scale. Moreover, it is the first study that described the exposure to an elaborated set of mycotoxins in the Belgian population. Biomarker analysis showed a clear exposure of a broad segment of the Belgian population to DON, OTA and CIT. The risk assessment based on these data indicates a potential concern for a number of individuals whereby young children need special attention because of the relatively higher food intake per kg body weight.

Deoxynivalenol Exposure Assessment for Pregnant Women in Bangladesh

The trichothecene mycotoxin deoxynivalenol (DON) is a contaminant of crops worldwide and known to cause adverse health effects in exposed animals and humans. A small survey reported the presence of DON in maize samples in Bangladesh, but these data are insufficient to assess human exposure, and also, biomonitoring data are still scarce. The present study applied biomarker analysis to investigate the DON exposure of pregnant women in Bangladesh. Urine samples were collected from pregnant women living in a rural (n = 32) and in a suburban (n = 22) area of the country. Urines were subjected to enzymatic hydrolysis of glucuronic acid conjugates and to immunoaffinity column clean-up prior to LC-MS/MS analysis of DON and its de-epoxy metabolite DOM-1. The limits of detection (LOD) for DON and DOM-1 in urine were 0.16 ng/mL and 0.10 ng/mL, respectively. DOM-1 was not detected in any of the urines, whilst DON was detectable in 52% of the samples at levels ranging from 0.18–7.16 ng/mL and a mean DON concentration of 0.86 ± 1.57 ng/mL or 2.14 ± 4.74 ng/mg creatinine. A significant difference in mean urinary DON levels was found between the rural (0.47 ± 0.73 ng/mL) and suburban (1.44 ± 2.20 ng/mL) cohort, which may be related to different food habits in the two cohorts. Analysis of food consumption data for the participants did not show significant correlations between their intake of typical staple foods and DON levels in urine. The biomarker concentrations found and published urinary excretion rates for DON were used to estimate daily mycotoxin intake in the cohort: the mean DON intake was 0.05 µg/kg b.w., and the maximum intake was 0.46 µg/kg b.w., values lower than the tolerable daily intake of 1 µg/kg b.w. These first results indicate a low dietary exposure of pregnant women in Bangladesh to DON. Nonetheless, further biomonitoring studies in children and in adult cohorts from other parts of the country are of interest to gain more insight into DON exposure in the population of Bangladesh.

Developments in mycotoxin analysis: an update for 2013-2014

This review highlights developments in the determination of mycotoxins over a period between mid-2013 and mid-2014. It continues in the format of the previous articles of this series, emphasising on analytical methods to determine aflatoxins, Alternaria toxins, ergot alkaloids, fumonisins, ochratoxins, patulin, trichothecenes and zearalenone. The importance of proper sampling and sample preparation is briefly addressed in a dedicated section, while another chapter summarises new methods used to analyse botanicals and spices. As LC-MS/MS instruments are becoming more and more widespread in the determination of multiple classes of mycotoxins, another section is focusing on such newly developed multi-mycotoxin methods. While the wealth of published methods during the 12 month time span makes it impossible to cover every single one, this exhaustive review nevertheless aims to address and briefly discuss the most important developments and trends.

Assessment of multi-mycotoxin exposure in southern Italy by urinary multi-biomarker determination

Human exposure assessment to deoxynivalenol (DON), aflatoxin B1 (AFB1), fumonisin B1 (FB1), zearalenone (ZEA) and ochratoxin A (OTA) can be performed by measuring their urinary biomarkers. Suitable biomarkers of exposure for these mycotoxins are DON + de-epoxydeoxynivalenol (DOM-1), aflatoxin M1 (AFM1), FB₁, ZEA + α-zearalenol (α-ZOL) + β-zearalenol (β-ZOL) and OTA, respectively. An UPLC-MS/MS multi-biomarker method was used to detect and measure incidence and levels of these biomarkers in urine samples of 52 volunteers resident in Apulia region in Southern Italy. The presence of ZEA + ZOLs, OTA, DON, FB1 and AFM1 were detected in 100%, 100%, 96%, 56% and 6%, of samples, respectively. All samples contained biomarkers of two or more mycotoxins. The mean concentrations of biomarkers ranged from 0.055 ng/mL (FB1) to 11.89 ng/mL (DON). Urinary biomarker concentrations were used to estimate human exposure to multiple mycotoxin. For OTA and DON, 94% and 40% of volunteers, respectively exceeded the tolerable daily intake (TDI) for these mycotoxins. The estimated human exposure to FB1 and ZEA was largely below the TDI for these mycotoxins for all volunteers.

Developments in mycotoxin analysis: an update for 2012-2013

This review highlights developments in mycotoxin analysis and sampling over a period between mid-2012 and mid-2013. It covers the major mycotoxins: aflatoxins, Alternaria toxins, ergot alkaloids, fumonisins, ochratoxins, patulin, trichothecenes and zearalenone. A wide range of analytical methods for mycotoxin determination in food and feed were developed last year, in particular immunochemical methods and liquid chromatography coupled to tandem mass spectrometry (LC-MS/MS)-based methods. After a section on sampling and sample preparation, due to the rapid spread and developments in the field of LC-MS/MS multimycotoxin methods, a separate section has been devoted to this area of research. It is followed by a section on mycotoxins in botanicals and spices, before continuing with the format of previous reviews in this series with dedicated sections on method developments for the individual mycotoxins.

Multiple mycotoxin exposure determined by urinary biomarkers in rural subsistence farmers in the former Transkei, South Africa

Subsistence farmers are exposed to a range of mycotoxins. This study applied novel urinary multi-mycotoxin LC-MS/MS methods to determine multiple exposure biomarkers in the high oesophageal cancer region, Transkei, South Africa. Fifty-three female participants donated part of their maize-based evening meal and first void morning urine, which was analysed both with sample clean-up (single and multi-biomarker) and by a 'dilute-and-shoot' multi-biomarker method. Results were corrected for recovery with LOD for not detected. A single biomarker method detected fumonisin B1 (FB1) (87% incidence; mean±standard deviation 0.342±0.466 ng/mg creatinine) and deoxynivalenol (100%; mean 20.4±49.4 ng/mg creatinine) after hydrolysis with β-glucuronidase. The multi-biomarker 'dilute-and-shoot' method indicated deoxynivalenol-15-glucuronide was predominantly present. A multi-biomarker method with β-glucuronidase and immunoaffinity clean-up determined zearalenone (100%; 0.529±1.60 ng/mg creatinine), FB1 (96%; 1.52±2.17 ng/mg creatinine), α-zearalenol (92%; 0.614±1.91 ng/mg creatinine), deoxynivalenol (87%; 11.3±27.1 ng/mg creatinine), β-zearalenol (75%; 0.702±2.95 ng/mg creatinine) and ochratoxin A (98%; 0.041±0.086 ng/mg creatinine). These demonstrate the value of multi-biomarker methods in measuring exposures in populations exposed to multiple mycotoxins. This is the first finding of urinary deoxynivalenol, zearalenone, their conjugates, ochratoxin A and zearalenols in Transkei.

LC-MS/MS-based multibiomarker approaches for the assessment of human exposure to mycotoxins

Mycotoxins are toxic fungal secondary metabolites that frequently contaminate food and feed worldwide, and hence represent a major hazard for food and feed safety. To estimate human exposure arising from contaminated food, so-called biomarker approaches have been developed as a complementary biomonitoring tool besides traditional food analysis. The first methods based on radioimmunoassays and enzyme-linked immunosorbent assays as well as on liquid chromatography were developed in the late 1980s and early 1990s for the carcinogenic aflatoxins and in the last two decades further tailor-made methods for some major mycotoxins have been published. Since 2010, there has been a clear trend towards the development and application of multianalyte methods based on liquid chromatography–electrospray ionization tandem mass spectrometry for assessment of mycotoxin exposure made possible by the increased sensitivity and selectivity of modern mass spectrometry instrumentation and sophisticated sample cleanup approaches. With use of these advanced methods, traces of mycotoxins and relevant breakdown and conjugation products can be quantified simultaneously in human urine as so-called biomarkers and can be used to precisely describe the real exposure, toxicokinetics, and bioavailability of the toxins present. In this article, a short overview and comparison of published multibiomarker methods focusing on the determination of mycotoxins and relevant excretion products in human urine is presented. Special attention is paid to the main challenges when analyzing these toxic food contaminants in urine, i.e., very low analyte concentrations, appropriate sample preparation, matrix effects, and a lack of authentic, NMR-confirmed calibrants and reference materials. Finally, the progress in human exposure assessment studies facilitated by these analytical methods is described and an outlook on probable developments and possibilities is presented.

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