Assessment of mycotoxin exposure in the Belgian population using biomarkers: aim, design and methods of the BIOMYCO study

Co-occurrence of mycotoxins: A review on bioanalytical methods for simultaneous analysis in human biological samples, mixture toxicity and risk assessment strategies

Mycotoxins are the toxic chemical substances that are produced by various fungal species and some of these are harmful to humans. Mycotoxins are ubiquitous in nature and humans could be exposed to multiple mycotoxins simultaneously. Unfortunately, exposure to mixed mycotoxins is not very well studied. Various studies have demonstrated the capacity of mycotoxins to show synergistic effect in the presence of other mycotoxins, thus, increasing the risk of toxicity. Hence, it is important to monitor mixed mycotoxins in human biological samples which would serve as a crucial information for risk assessment. Through this review paper, we aim to summarize the mixture toxicity of mycotoxins and the various bio-analytical techniques that are being used for the simultaneous analysis of mixed mycotoxins in human biological samples. Different sample preparation and clean-up techniques employed till date for eliminating the interferences from human biological samples without affecting the analyses of the mycotoxins are also discussed. Further, a brief introduction of risk assessment strategies that have been or could be adopted for multiple mycotoxin risk assessments is also mentioned. To the best of our knowledge, this is the first review that focuses solely on the occurrence of multiple mycotoxins in human biological samples as well as their risk assessment strategies.

Assessment of Human Exposure to Five Alternaria Mycotoxins in China by Biomonitoring Approach

This biomonitoring study was conducted to investigate the concentration levels of five Alternaria mycotoxins in urine samples from 269 healthy volunteers living in the Yangtze River Delta, China. Alternariol (AOH), alternariol monomethyl ether (AME), tenuazonic acid (TeA) and tentoxin (TEN) were detected in 38.3%, 48.7%, 63.9% and 23.4% of urine samples with the concentrations ranging from 0.057 to 45.8 ng/mL, 0.020 to 0.802 ng/mL, 0.050 to 80.6 ng/mL and 0.021 to 0.939 ng/mL, respectively. Altenuene (ALT) was not detected in any urine sample. Based on the urinary concentrations, the probable daily intake (PDI) values of Alternaria mycotoxins were calculated, and 100%, 99.2–100%, 0.372% and 1.12% of participants exceeded the threshold of toxicological concern (TTC) values for AOH, AME, TeA and TEN, respectively. This study revealed high potential health risks related to the contaminations of major Alternaria mycotoxins in China and highlighted the necessity for more toxicological studies to provide better basis for further comprehensive risk assessments.

Risk assessment of multiple-mycotoxin exposure for consumers of chestnuts in Shandong Province markets in China

In this study, 321 chestnut samples from Shandong Province in China were analysed for the presence of mycotoxins. We screened for 14 mycotoxins including aflatoxins (AFs: AFB₁, AFB₂, AFG₁, AFG₂), deoxynivalenol (DON), 3-acetyldeoxynivalenol (3-ADON), 15-acetyldeoxynivalenol (15-ADON), T-2 toxin (T-2), zearalenone (ZEA), ochratoxin A (OTA), fumonisins (FB₁, FB₂, FB₃), and penicillic acid (PeA). Mycotoxins were detected in 56.4% of the samples, and 11 of these mycotoxins were found. Thirty samples from the Shandong Province markets were deemed positive for AFs (9.3%) and had an AFB₁ level of >2 μg/kg or a sum of AFB₁, AFB₂, AFG₁, and AFG₂ that was >4 μg/kg, which exceed the maximum tolerable level of the European regulations standards (EC/188/2006). The contamination level for total mycotoxins found in chestnuts was in the range of 0.6-2,791.0 μg/kg. The estimated daily intake (EDI) values for each individual mycotoxin and for all of the mycotoxins collectively were calculated by both a deterministic approach and a probabilistic approach. For risk characterisation, dietary exposure to DON, ZEA, FBs, and OTA through consumption of chestnuts, analysed according to both approaches, showed no health risk to Chinese adolescents and adults from exposure to either individual mycotoxins or in combination, but more concern should be paid to the AFs for adolescents and adults at a high consumption level. This is believed to be the first work performing risk assessment of multiple mycotoxins specifically for adolescents, including the recently isolated FBs and PeA, which have recently emerged as mycotoxins of concern, in chestnuts of Shandong Province in China.

Mycotoxins Exposure of French Grain Elevator Workers: Biomonitoring and Airborne Measurements

It is now recognized that additional exposure to mycotoxins may occur through inhalation of contaminated dust at a workplace. The aim of this study was to characterize the multi-mycotoxin exposure of French grain elevator workers using biomonitoring and airborne measurements. Eighteen workers participated in the study. Personal airborne dust samples were analyzed for their mycotoxin concentrations. Workers provided multiple urine samples including pre-shift, post-shift and first morning urine samples or 24 h urine samples. Mycotoxin urinary biomarkers (aflatoxin B1, aflatoxin M1, ochratoxin A, ochratoxin α, deoxynivalenol, zearalenone, α-zearalenol, β-zearalenol, fumonisin B1, HT-2 toxin and T-2 toxin) were measured using a liquid chromatography–high-resolution mass spectrometry method. Grain elevator workers were highly exposed to organic airborne dust (median 4.92 mg.m⁻³). DON, ZEN and FB1 were frequent contaminants in 54, 76 and 72% of air samples, respectively. The mycotoxin biomarkers quantified were DON (98%), ZEN (99%), α-ZEL (52%), β-ZEL (33%), OTA (76%), T-2 (4%) and HT-2 (4%). DON elimination profiles showed highest concentrations in samples collected after the end of the work shift and the urinary DON concentrations were significantly higher in post-shift than in pre-shift-samples (9.9 and 22.1 µg/L, respectively). ZEN and its metabolites concentrations did not vary according to the sampling time. However, the levels of α-/β-ZEL were consistent with an additional occupational exposure. These data provide valuable information on grain worker exposure to mycotoxins. They also highlight the usefulness of multi-mycotoxin methods in assessing external and internal exposures, which shed light on the extent and pathways of exposure occurring in occupational settings.

Mycotoxins-Biomonitoring and Human Exposure

Mycotoxins are secondary metabolites produced by fungal species that commonly have a toxic effect on human and animal health. Different foodstuff can be contaminated and are considered the major source of human exposure to mycotoxins, but occupational and environmental exposure can also significantly contribute to this problem. This review aims to provide a short overview of the occurrence of toxigenic fungi and regulated mycotoxins in foods and workplaces, following the current literature and data presented in scientific papers. Biomonitoring of mycotoxins in plasma, serum, urine, and blood samples has become a common method for determining the exposure to different mycotoxins. Novel techniques are more and more precise and accurate and are aiming toward the simultaneous determination of multiple mycotoxins in one analysis. Application of liquid chromatography (LC) methodologies, coupled with tandem mass spectrometry (MS/MS) or high-resolution mass spectrometry (HRMS) has become a common and most reliable method for determining the exposure to mycotoxins. Numerous references confirm the importance of mycotoxin biomonitoring to assess the exposure for humans and animals. The objectives of this paper were to review the general approaches to biomonitoring of different mycotoxins and the occurrence of toxigenic fungi and their mycotoxins, using recent literature sources.

Reviewing the Analytical Methodologies to Determine the Occurrence of Citrinin and its Major Metabolite, Dihydrocitrinone, in Human Biological Fluids

Until now, the available data regarding citrinin (CIT) levels in food and the consumption of contaminated foods are insufficient to allow a reliable estimate of intake. Therefore, biomonitoring configuring analysis of parent compound and/or metabolites in biological fluids, such as urine or blood, is being increasingly applied in the assessment of human exposure to CIT and its metabolite, dihydrocitrinone (DH-CIT). Most studies report urinary levels lower for the parent compound when compared with DH-CIT. A high variability either in the mean levels or in the inter-individual ratios of CIT/DH-CIT between the reported studies has been found. Levels of DH-CIT in urine were reported as being comprised between three to seventeen times higher than the parent mycotoxin. In order to comply with this objective, sensitive analytical methodologies for determining biomarkers of exposure are required. Recent development of powerful analytical techniques, namely liquid chromatography coupled to mass spectrometry (LC-MS/MS) and ultra-high-performance liquid chromatography (UHPLC-MS/MS) have facilitated biomonitoring studies, mainly in urine samples. In the present work, evidence on human exposure to CIT through its occurrence and its metabolite, in biological fluids, urine and blood/plasma, in different countries, is reviewed. The analytical methodologies usually employed to evaluate trace quantities of these two molecules, are also presented. In this sense, relevant data on sampling (size and pre-treatment), extraction, cleanup and detection and quantification techniques and respective chromatographic conditions, as well as the analytical performance, are evidenced.

The toxicity of graphene oxide affected by algal physiological characteristics: A comparative study in cyanobacterial, green algae, diatom

Though the main toxic mechanisms of graphene oxide (GO) to algae have been accepted as the shading effect, oxidative stress and mechanical damage, the effect of algal characteristics on these three mechanisms of GO toxicity have seldom been taken into consideration. In this study, we investigated GO toxicity to green algae (Chlorella vulgaris, Scenedesmus obliquus, Chlamydomonas reinhardtii), cyanobacteria (Microcystis aeruginosa) and diatoms (Cyclotella sp.). The aim was to assess how the physiological characteristics of algae affect the toxicity of GO. Results showed that 10 mg/L of GO significantly inhibited the growth of all tested algal types, while S. obliquus and C. reinhardtii were found to be the most susceptible and tolerant species, respectively. Then, scanning electron microscopy (SEM) and transmission electron microscopy (TEM) were used to observe the physiological characteristics of the assessed algae. The presence of locomotive organelles, along with smaller and more spherical cells, was more likely to alleviate the shading effect. Variations in cell wall composition led to different extents of mechanical damage as shown by Cyclotella sp. silica frustules and S. obliquus autosporine division being prone to damage. Meanwhile, growth inhibition and cell division were significantly correlated with the oxidative stress and membrane permeability, suggesting the latter two indicators can effectively signal GO toxicity to algae. The findings of this study provide novel insights into the toxicity of graphene materials in aquatic environments.

Mycotoxin exposure assessments in a multi-center European validation study by 24-hour dietary recall and biological fluid sampling

The European Food Consumption Validation (EFCOVAL) project includes 600 men and women from Belgium, the Czech Republic, France, the Netherlands, and Norway, who had given serum and 24-hour urine samples, and completed 24-hour dietary recall (24-HDR) interviews. Consumption, according to 24-HDR, was matched against the European Food Safety Authority (EFSA) databases of mycotoxin contaminations, via the FoodEx1 standard classifications, producing an indirect external estimate of dietary mycotoxin exposure. Direct, internal measurements of dietary mycotoxin exposure were made in serum and urine by ultra-performance liquid chromatography coupled to tandem mass spectrometry. For the first time, mycotoxin exposures were thoroughly compared between two 24-HDRs, and two 24-hour urine samples collected during the same days covered by the 24-HDRs. These measurements were compared to a single-time point serum measurement to investigate evidence of chronic mycotoxin exposure. According to 24-HDR data, all 600 individuals were exposed to between 4 and 34 mycotoxins, whereof 10 found to exceed the tolerable daily intake. Correlations were observed between two time points, and significant correlations were observed between concentrations in serum and urine. However, only acetyldeoxynivalenol, ochratoxin A, and sterigmatocystin were found to have significant positive correlations between 24-HDR exposures and serum, while aflatoxin G1 and G2, HT-2 toxin, and deoxynivalenol were associated between concurrent 24-HDR and 24-hour urine. Substantial agreements on quantitative levels between serum and urine were observed for the groups Type B Trichothecenes and Zearalenone. Further research is required to bridge the interpretation of external and internal exposure estimates of the individual on a time scale of hours. Additionally, metabolomic profiling of dietary mycotoxin exposures could help with a comprehensive assessment of single time-point exposures, but also with the identification of chronic exposure biomarkers. Such detailed characterization informs population exposure assessments, and aids in the interpretation of epidemiological health outcomes related to multi-mycotoxin exposure.

Ochratoxin A in human blood plasma samples from apparently healthy volunteers in Nanjing, China

This study was conducted to investigate the exposure to ochratoxin A (OTA) of populations living in Nanjing, China. Plasma samples were collected from 147 healthy adults (age 18-63 years) and analyzed for OTA by a reliable and sensitive ultra-high-performance liquid chromatography tandem mass spectrometry (UPLC-MS/MS) method (limit of detection 0.04 ng/mL). After enzymatic hydrolysis by β-glucuronidase/arylsulfatase, OTA was detected in 80.9% plasma samples with mean concentration of 0.26 ± 0.59 ng/mL (range 0.04-6.59 ng/mL). The estimated daily intakes of OTA based on plasma concentrations (mean 0.51 ng/kg bw/day, max 12.99 ng/kg bw/day) were lower than the tolerable daily intake published by European Food Safety Authority (EFSA) or Joint FAO/WHO Expert Committee on Food Additives (JFECFA) indicative of rare risks related to the OTA exposure in the investigated area. This study provides a valuable insight on human exposure to OTA in China. Further studies in children and elder people and in adult cohorts from other regions are recommended.

Occupational Exposure to Mycotoxins: Current Knowledge and Prospects

Occupational exposure to mycotoxins is supposedly very frequent, but it is rarely reported in the scientific literature. Several recent studies described occupational exposure to the aflatoxin B1 (AFB1) mycotoxin in different occupational settings. Previously, exposure to other mycotoxins was shown in the animal husbandry and food processing sectors, confirming that occupational exposure cannot be negligible. However, no guidelines or standard methodologies are available for helping occupational hygienists to consider mycotoxin exposure in their interventions. This article reviews the literature on this problem and recommends some actions for the better management of this risk factor in occupational settings, especially where environmental conditions are favorable to fungal presence.

Exposure Assessment to Mycotoxins in a Portuguese Fresh Bread Dough Company by Using a Multi-Biomarker Approach

Mycotoxins are toxic mold metabolites that can persist in environment long after the fungi species responsible for their production disappear. Critical workplace for mycotoxins presence has already been studied and nowadays it is possible to recognize that exposure to mycotoxins through inhalation occurs due to their presence in dust. This study aimed to assess occupational co-exposure to multiple mycotoxins in a fresh bread dough company, an occupational setting not studied until now. Occupational exposure assessment to mycotoxins was done using a LC-MS/MS urinary multi-biomarker approach. Twenty-one workers and nineteen individuals that were used as controls participated in the study. Workers/controls (spot-urine) and environment (settled dust) samples were collected and analyzed. Concerning workers group, DON-GlcA, and OTA were the most prevalent biomarkers (>LOD), 66% and 90.5%, respectively. In the control group, OTA was also one of the most detected (68%) followed by CIT (58%) and DON-GlcA (58%). DON was the mycotoxin measured in high amounts in the settled dust sample (58.2 ng/g). Both workers and controls are exposed to several mycotoxins simultaneously. The workers group, due to their high contact with flour dust, revealed a higher exposure to DON. Considering these results, risk management measures must be applied including specific and adequate health surveillance programs in order to avoid exposure and consequently the associated health consequences.

Multiple mycotoxin analysis in nut products: Occurrence and risk characterization

Nuts consumption plays an important role in Mediterranean diet, being a good source of proteins, vitamins, minerals and unsaturated fatty acids. However, nuts can be also a source of harmful mycotoxins with negative impact on human health. In this work, the occurrence of 16 mycotoxins belonging to different chemical classes, was assessed in several nut products. The analytical method used was based on modified QuEChERS (Quick, Easy, Cheap, Effective, Rugged and Safe) procedure followed by liquid chromatography-tandem mass spectrometry (LC-MS/MS) analysis. An extensive evaluation of different sorbents used in dispersive SPE (d-SPE) cleanup step of QuEChERS was performed. Detection limits achieved were less than 3.5 μg/kg for all the compounds and the average recoveries varied from 70 to 91%, with relative standard deviations (RSD) ≤13%. Twelve out of sixteen mycotoxins under study were found in the 37 nut samples analysed. Overall, deoxynivalenol (DON), aflatoxin-G2 (AFG₂), and fusarenon-X (FUS X) were the compounds more commonly detected. The higher contamination value was observed in a cashew sample containing 336.5 μg/kg of DON. The combination of occurrence and consumption data allowed to assess the exposure and characterize the associated risk of nut products consumption by the Portuguese population.

Studies on the Presence of Mycotoxins in Biological Samples: An Overview

Mycotoxins are fungal secondary metabolites with bioaccumulation levels leading to their carry-over into animal fluids, organs, and tissues. As a consequence, mycotoxin determination in biological samples from humans and animals has been reported worldwide. Since most mycotoxins show toxic effects at low concentrations and considering the extremely low levels present in biological samples, the application of reliable detection methods is required. This review summarizes the information regarding the studies involving mycotoxin determination in biological samples over the last 10 years. Relevant data on extraction methodology, detection techniques, sample size, limits of detection, and quantitation are presented herein. Briefly, liquid-liquid extraction followed by LC-MS/MS determination was the most common technique. The most analyzed mycotoxin was ochratoxin A, followed by zearalenone and deoxynivalenol—including their metabolites, enniatins, fumonisins, aflatoxins, T-2 and HT-2 toxins. Moreover, the studies were classified by their purpose, mainly focused on the development of analytical methodologies, mycotoxin biomonitoring, and exposure assessment. The study of tissue distribution, bioaccumulation, carry-over, persistence and transference of mycotoxins, as well as, toxicokinetics and ADME (absorption, distribution, metabolism and excretion) were other proposed goals for biological sample analysis. Finally, an overview of risk assessment was discussed.

Mycotoxin Contamination in Sugarcane Grass and Juice: First Report on Detection of Multiple Mycotoxins and Exposure Assessment for Aflatoxins B₁ and G₁ in Humans

This study was conducted to investigate the natural co-occurrence of multiple toxic fungal and bacterial metabolites in sugarcane grass and juice intended for human consumption in Upper Egypt. Quantification of the target analytes has been done using the "dilute and shoot" approach followed by liquid chromatography-tandem mass spectrometry (LC-MS/MS). A total number of 29 and 33 different metabolites were detected in 21 sugarcane grass and 40 juice samples, respectively, with a trend of concentrations being higher in grass than in juice. Among the regulated mycotoxins, only aflatoxin B₁ (AFB₁) and aflatoxin G₁ (AFG₁) were detected. The prevalence of AFB₁ was in 48% of grass samples and in 58% of juice with a maximum concentration of 30.6 μg/kg and 2.10 μg/kg, respectively. AFG₁ was detected in 10% of grass samples (7.76 μg/kg) and 18% of juice samples (34 μg/kg). Dietary exposure was assessed using a juice frequency questionnaire of adult inhabitants in Assiut City. The assessment revealed different levels of exposure to AFB₁ between males and females in winter and summer seasons. The estimated seasonal exposure ranged from 0.20 to 0.40 ng/kg b.w./day in winter and from 0.38 to 0.90 ng/kg b.w./day in summer.

Strategies for estimating human exposure to mycotoxins via food

In this review, five strategies to estimate mycotoxin exposure of a (sub-)population via food, including data collection, are discussed with the aim to identify the added values and limitations of each strategy for risk assessment of these chemicals. The well-established point estimate, observed individual mean, probabilistic and duplicate diet strategies are addressed, as well as the emerging human biomonitoring strategy. All five exposure assessment strategies allow the estimation of chronic (long-term) exposure to mycotoxins, and, with the exception of the observed individual mean strategy, also acute (short-term) exposure. Methods for data collection, i.e. food consumption surveys, food monitoring studies and total diet studies are discussed. In food monitoring studies, the driving force is often enforcement of legal limits, and, consequently, data are often generated with relatively high limits of quantification and targeted at products suspected to contain mycotoxin levels above these legal limits. Total diet studies provide a solid base for chronic exposure assessments since they provide mycotoxin levels in food based on well-defined samples and including the effect of food preparation. Duplicate diet studies and human biomonitoring studies reveal the actual exposure but often involve a restricted group of human volunteers and a limited time period. Human biomonitoring studies may also include exposure to mycotoxins from other sources than food, and exposure to modified mycotoxins that may not be detected with current analytical methods. Low limits of quantification are required for analytical methods applied for data collection to avoid large uncertainties in the exposure due to high numbers of left censored data, i.e. with levels below the limit of quantification.

Challenges in risk assessment of multiple mycotoxins in food

Most fungi are able to produce several mycotoxins simultaneously and, consequently, to contaminate a wide variety of foodstuffs. Therefore, the risk of human co-exposure to multiple mycotoxins is real, raising a growing concern about their potential impact on human health. Besides, government and industry regulations are usually based on individual toxicities, and do not take into account the complex dynamics associated with interactions between co-occurring groups of mycotoxins. The present work assembles, for the first time, the challenges posed by the likelihood of human co-exposure to these toxins and the possibility of interactive effects occurring after absorption, towards knowledge generation to support a more accurate human risk assessment. Regarding hazard assessment, a physiologically-based framework is proposed in order to infer the health effects from exposure to multiple mycotoxins in food, including knowledge on the bioaccessibility, toxicokinetics and toxicodynamics of single and combined toxins. The prioritisation of the most relevant mixtures to be tested under experimental conditions that attempt to mimic human exposure and the use of adequate mathematical approaches to evaluate interactions, particularly concerning the combined genotoxicity, were identified as the main challenges for hazard assessment. Regarding exposure assessment, the need of harmonised food consumption data, availability of multianalyte methods for mycotoxin quantification, management of left-censored data, use of probabilistic models and multibiomarker approaches are highlighted, in order to develop a more precise and realistic exposure assessment. To conclude, further studies on hazard and exposure assessment of multiple mycotoxins, using harmonised methodologies, are crucial towards an improvement of data quality and a more reliable and robust risk characterisation, which is central for risk management and, consequently, to prevent mycotoxins-associated adverse effects. A deep understanding of the nature of interactions between multiple mycotoxins will contribute to draw real conclusions on the health impact of human exposure to mycotoxin mixtures.

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.