Thiouracil is a thyrostat inhibiting the thyroid function, resulting in fraudulent weight gain if applied in the fattening of livestock. The latter abuse is strictly forbidden and monitored in the European Union. Recently, endogenous sources of thiouracil were identified after frequently monitoring low-level thiouracil positive urine samples and a "recommend concentration" (RC) of 10 μg/L was suggested by the EURL to facilitate decision-making. However, the systematic occurrence of urine samples exceeding the RC led to demands for international surveys defining an epidemiologic threshold. Therefore, six European member states (France, Poland, The Netherlands, United Kingdom, Norway, and Belgium) have shared their official thiouracil data (2010-2012) collected from bovines, porcines, and small livestock with 95 and 99% percentiles of 8.1 and 18.2 μg/L for bovines (n = 3894); 7.4 and 13.5 μg/L for porcines (n = 654); and 7.4 μg/L (95% only) for small livestock (n = 85), respectively. Bovine percentiles decreased with the animal age (nonadults had significantly higher levels for bovines), and higher levels were observed in male bovines compared to female bovines.
Organic micropollutants such as pharmaceuticals, perfluorinated compounds (PFCs), and pesticides, are important environmental contaminants. To obtain more information regarding their presence in marine organisms, an increasing demand exists for reliable analytical methods for quantification of these micropollutants in biotic matrices. Therefore, we developed extraction procedures and new analytical methods for the quantification of 14 pesticides, 10 PFCs, and 11 pharmaceuticals in tissue of marine organisms, namely blue mussels (Mytilus edulis). This paper presents these optimized analytical procedures and their application to M. edulis, deployed at five stations in the Belgian coastal zone. The methods consisted of a pressurized liquid extraction and solid-phase extraction (SPE) followed by ultra high-performance liquid chromatography coupled to triple quadrupole mass spectrometry for pharmaceuticals and pesticides, and of a liquid extraction using acetonitrile and SPE, followed by liquid chromatography coupled to time-of-flight mass spectrometry for PFCs. The limits of quantification of the three newly optimized analytical procedures in M. edulis tissue varied between 0.1 and 10 ng g(-1), and satisfactory linearities (≥0.98) and recoveries (90-106%) were obtained. Application of these methods to M. edulis revealed the presence of five pharmaceuticals, two PFCs, and seven pesticides at levels up to 490, 5, and 60 ng g(-1), respectively. The most prevalent micropollutants were salicylic acid, paracetamol, perfluorooctane sulfonate, chloridazon, and dichlorvos.
In recent years, the frequent detection of the banned substance thiouracil (TU) in livestock urine has been related to its endogenous formation following consumption of glucosinolate-rich Brassicaceae crops. Besides, TU residues have been recovered in these crops upon plant-derived myrosinase hydrolysis. Through in vitro bovine and porcine static digestive simulations, the influence of gastrointestinal digestion of Brassicaceae-derived matrixes on TU formation was assessed. Following derivatization and LC-MS(2) analysis, TU was detected in colonic suspensions with traditional rapeseed, coarse colza "00" meal, cauliflower, and broccoli ranging from 3.47 to 30.96 μg kg(-1) (bovine) and from 3.55 to 26.34 μg kg(-1) (porcine). In stomach and small intestinal fluids, TU remained unfound, whereas upon rumen simulation TU was detected for coarse colza "00" meal (4.43 μg kg(-1)) and grounded traditional rapeseed (0.35 μg kg(-1)). The origin of this detection was investigated through filter-sterilizing and autoclaving the fecal inoculum causing a significant decrease in TU concentration, thereby reinforcing the possibility of an active bacterial involvement, which however was characterized with a high interanimal variation. In conclusion, these results support the previously proven endogenous origin of TU and acknowledge the active role of the gastrointestinal bacteria in TU formation, through production of an extracellular component.
Mycotoxins may cause deleterious effects (among others nephrogenic, hepatogenic, carcinogenic, teratogenic, neurogenic) in animals and humans, therefore they have been intensely studied and monitored over the years. For citrinin (CIT), a nephrotoxic mycotoxin, however, this has not yet been the case. According to the latest European Food Safety Authority report, a correct risk assessment of CIT was not possible due to the lack of occurrence data. Besides, traces of CIT or its metabolite, dehydrocitrinone are widely (in up to 90% of samples) present in human urine according to recent Belgian and German scientific reports, which might imply chronic exposure. Only recently, a European maximum limit has been set for CIT in cholesterol reducing food supplements including red yeast fermented rice (RYR). During production of RYR through fungal (among others Monascus purpureus) fermentation of rice other components, like CIT, as well as nephrotoxic ochratoxin A (OTA) may form. Consequently, the present work attempted develop to a robust and routinely applicable ultra-high performance liquid chromatographytandem mass spectrometry (UHPLC-MS/MS) method for the analysis of CIT and OTA in food, feed and in RYR food supplements. The method was successfully validated based on EU/657/2002 and EU/519/2014 in RYR food supplements and wheat flour, achieving respective limits of quantification (LOQ) for CIT of 0.4 μg/kg and 0.1 μg/kg and for OTA of 15 μg/kg and 0.4 μg/kg. The average between-day recoveries varied from 72 to 110% with relative standard deviations ≤16%. Single-day validation in rice, curry and apple matrices showed LOQs ranging from 0.3-1.0 μg/kg. Next, the occurrence of CIT/OTA was surveyed in 138 RYR, food and feed samples, proving the potential of this method for future data acquisition within a risk assessment framework specifically for CIT, while also gaining information about the (co-)occurrence of OTA in edible matrices.
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