Rapid and sensitive UHPLC-MS/MS methods for dietary sample analysis of 43 mycotoxins in China total diet study

INTRODUCTION

Mycotoxins are toxic metabolites produced by fungi that commonly contaminate foods. As recommended by the World Health Organization, total diet study (TDS) is the most efficient and effective way to estimate the dietary intakes of certain chemical substances for general populations. It requires sensitive and reliable analytical methods applicable to a wide range of complex food matrices and ready-to-eat dishes.

OBJECTIVES

A novel strategy with high selectivity and sensitivity, incorporating three methods based on ultra-high-performance liquid chromatography coupled with tandem mass spectrometry (UHPLC-MS/MS), was designed for measuring 43 mycotoxins in dietary samples in a China TDS.

METHODS

The 43 mycotoxins were divided into 3 groups for analysis to achieve better performance. For each group, an UHPLC-MS/MS method was developed to determine the target compounds after clean-up by solid phase extraction. A total of 21 isotope internal standards were employed for accurate quantitation. Method validation in terms of linearity, selectivity, sensitivity, accuracy, and precision was performed for all the 43 mycotoxins in 12 complex food matrices.

RESULTS

The limits of detection (LODs) and limits of quantitation (LOQs) were 0.002-1 ng mL^-1 and 0.006-3 ng mL^-1, respectively. The method recoveries of the 43 mycotoxins spiked in 12 food categories were in the range of 60.3%-175.9% after internal standard correction, with relative standard deviations (RSDs) below 13.9%. For practical application, this method was utilized for 72 dietary samples collected from 6 provinces in the 6th China TDS. More than 80% of the samples were found contaminated by mycotoxins. DON, SMC, FB₁, ZEN, BEA, ENNB₁, and ENNB were most detected.

CONCLUSIONS

The proposed methods with high sensitivity, accuracy, and robustness provide powerful tools for multi-mycotoxin monitoring and dietary exposure assessment, allowing 43 mycotoxins, including some emerging mycotoxins, to be accurately investigated in a total diet study for the first time.

Dietary intake of protein and fat of 12- to 36-month-old children in a Dutch Total Diet Study

Purpose

This study attempted gaining insight into the intake of protein and fat of 12- to 36-month-old children in the Netherlands.

Methods

In 2017, a Total Diet Study (TDS) was carried out in the Netherlands including following three age groups: 12–17-, 18–23- and 24- to 36-month-old children. Protein and fat concentrations of 164 composite samples were analysed and combined with the consumption data from the Dutch National Food Consumption Survey 2012–2016 (DNFCS).

Results

Median protein intake of the 12- to 35-month-old Dutch children based on the TDS was 35 g/day with main contributions from the food subgroups “milk and milk-based beverages”, “beef” and “yoghurts and desserts”. Median fat intake was 34 g/day with main contributions from the food subgroups “margarines”, “cheeses” and “milk and milk-based beverages”. For the youngest age group (12- to 18-month-old children), (ready to drink) follow-on formula was one of the main contributors to the fat intake.

Conclusion

Compared to the EFSA reference values, protein intake of the Dutch 12- to 36-month-old children is high, whereas fat intake follows the reference intake. A TDS is a suitable instrument to estimate macronutrient intakes.

Supplementary Information

The online version contains supplementary material available at 10.1007/s00394-021-02653-6.

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.

Evaluation of the Multimycotoxin-Degrading Efficiency of Rhodococcus erythropolis NI1 Strain with the Three-Step Zebrafish Microinjection Method

The multimycotoxin-degrading efficiency of the Rhodococcus erythropolis NI1 strain was investigated with a previously developed three-step method. NI1 bacterial metabolites, single and combined mycotoxins and their NI1 degradation products, were injected into one cell stage zebrafish embryos in the same doses. Toxic and interaction effects were supplemented with UHPLC-MS/MS measurement of toxin concentrations. Results showed that the NI1 strain was able to degrade mycotoxins and their mixtures in different proportions, where a higher ratio of mycotoxins were reduced in combination than single ones. The NI1 strain reduced the toxic effects of mycotoxins and mixtures, except for the AFB1+T-2 mixture. Degradation products of the AFB1+T-2 mixture by the NI1 strain were more toxic than the initial AFB1+T-2 mixture, while the analytical results showed very high degradation, which means that the NI1 strain degraded this mixture to toxic degradation products. The NI1 strain was able to detoxify the AFB1, ZEN, T-2 toxins and mixtures (except for AFB1+T-2 mixture) during the degradation experiments, which means that the NI1 strain degraded these to non-toxic degradation products. The results demonstrate that single exposures of mycotoxins were very toxic. The combined exposure of mycotoxins had synergistic effects, except for ZEN+T-2 and AFB1+ZEN +T-2, whose mixtures had very strong antagonistic effects.

Risk assessment of aflatoxins in food

EFSA was asked to deliver a scientific opinion on the risks to public health related to the presence of aflatoxins in food. The risk assessment was confined to aflatoxin B1 (AFB1), AFB2, AFG1, AFG2 and AFM1. More than 200,000 analytical results on the occurrence of aflatoxins were used in the evaluation. Grains and grain-based products made the largest contribution to the mean chronic dietary exposure to AFB1 in all age classes, while 'liquid milk' and 'fermented milk products' were the main contributors to the AFM1 mean exposure. Aflatoxins are genotoxic and AFB1 can cause hepatocellular carcinomas (HCCs) in humans. The CONTAM Panel selected a benchmark dose lower confidence limit (BMDL) for a benchmark response of 10% of 0.4 μg/kg body weight (bw) per day for the incidence of HCC in male rats following AFB1 exposure to be used in a margin of exposure (MOE) approach. The calculation of a BMDL from the human data was not appropriate; instead, the cancer potencies estimated by the Joint FAO/WHO Expert Committee on Food Additives in 2016 were used. For AFM1, a potency factor of 0.1 relative to AFB1 was used. For AFG1, AFB2 and AFG2, the in vivo data are not sufficient to derive potency factors and equal potency to AFB1 was assumed as in previous assessments. MOE values for AFB1 exposure ranged from 5,000 to 29 and for AFM1 from 100,000 to 508. The calculated MOEs are below 10,000 for AFB1 and also for AFM1 where some surveys, particularly for the younger age groups, have an MOE below 10,000. This raises a health concern. The estimated cancer risks in humans following exposure to AFB1 and AFM1 are in-line with the conclusion drawn from the MOEs. The conclusions also apply to the combined exposure to all five aflatoxins.

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.

A mycotoxin-dedicated total diet study in the Netherlands in 2013: Part II – occurrence

The occurrence of 59 natural toxins was determined in 88 composite food and drink samples of a mycotoxin-dedicated total diet study performed in the Netherlands in 2013. Composite food samples were prepared by pooling foods from a food category (as consumed, e.g. peeled, cooked, etc.) according to their consumption by population groups in the Netherlands. A multi-targeted method based on QuEChERs extraction, dilute and shoot and analysis by liquid chromatography-tandem mass spectrometry was applied to the 88 composite samples. Dedicated methods with lower detection limits for patulin, aflatoxins and trichothecenes were also applied to specific food types. Thirty samples (34%) were positive for one or more mycotoxins. Patulin, aflatoxin M1, zearalenone and plant toxins, with the exception of scopolamine in liquorice, were not detected in any of the composite samples. Aflatoxin B1 was only detected, but not at quantifiable levels, in the composites that contained peanuts. Fumonisin B1 was only found at 18 μg/kg in breakfast cereals consumed by the population group of 7-69 years, whereas ochratoxin A occurred at low levels around 1 μg/kg in liquorice, legumes and coffee. Grains and grain-based food composites were positive for ergot alkaloids, enniatins B and B1 and deoxynivalenol (DON). The levels of DON in the positive samples were lower compared to other studies, with the exception of breakfast cereals for infants with a DON concentration of 116 μg/kg. This specific composite sample may have contained an ingredient with a concentration exceeding the maximum legal limit of 200 μg/kg. Alternaria toxins (alternariol and alternariol methyl ether) were detected at levels ranging from 1.0 to 8.9 μg/kg in a number of composite samples, including tomato products, nuts, cereal products, chocolate and wine. Mycophenolic acid and roquefortine C cooccurred in mould-ripened cheese composites, while mycophenolic acid also was found in dried fruit and liquorice composite samples.

A mycotoxin-dedicated total diet study in the Netherlands in 2013: Part III – exposure and risk assessment

In a mycotoxin-dedicated total diet study (mTDS) performed in the autumn and winter of 2013 in the Netherlands, 48 mycotoxins, including patulin, aflatoxins, ochratoxin A, fumonisins, zearalenone, trichothecenes, ergot alkaloids, Alternaria toxins, beauvericin and enniatins, were quantified. Analyses were performed in 88 composite samples representative for the consumption pattern of the Dutch population. This article presents the results of the exposure assessment and subsequent risk assessment of these mycotoxins. Exposure was assessed by combining individual food consumption data obtained from the Dutch National Food Consumption Surveys (DNFCS) for young children aged 2-6 years and the population aged 7-69 years with the analytical results of the mTDS, using a lower bound and an upper bound scenario for levels below the limit of detection. Wherever possible, exposure estimates were compared with toxicological reference values, including health-based guidance values. The high level of exposure (95th percentile) exceeded the toxicological reference value regardless of the substitution scenario for ochratoxin A in the population aged 7-69 years, for the sum of T-2 and HT-2 toxins for children aged 2-6 years and for alternariol and alternariol monomethyl ether in both examined populations. The margin of exposure was too small for aflatoxin B1. For the remaining 23 mycotoxins with a toxicological reference value, the estimated exposure was below this level.