| Summary: | Endocrine disruptors (EDs) have been associated with various disorders including disrupted reproductive, metabolic and immune function. We are exposed to EDs via environment and through our diet, thus it is of real importance to monitor its main components, such as milk, for ED contamination, its composition and biological effects. The aim of the thesis is to assess biological activity of various environmental contaminants gaining entry to the food chain as well as to analyze a variety of milk samples for their total estrogenic hormonal load and its chemical composition. The assessment of environmental contaminants has been performed employing estrogenic reporter gene assay (RGA) and revealed number of industrial chemicals, possessing estrogenic activities, some quite substantial, including UV-filters, parabens, phthalates, pesticides and their metabolites. For the analysis of milk samples two assays have been developed and validated according to EU 2002/657/EC criteria i.e. estrogenic RGA and ultra high performance liquid chromatography tandem mass spectrometry (LC-MS/MS) targeted method. Results of a screening of a range of milk samples revealed an extensive milk contamination with both natural and man-made EDs. The chemical contamination did not translate to enhanced estrogenic load as only 3% of samples presented an increased response which origins have not been confirmed. Performed risk assessment suggested possible risk to children in vulnerable windows of development which should not be underestimated. Also employment of fractionation with subsequent combined biological and untargeted chemical analysis has been investigated and provided an insight into the possible origin of biological activity while analysis of milk for the presence of masked EDs revealed higher concentrations of contaminants resulting in an enhanced estrogenic load. Overall, the thesis underlines the importance of constant screening of food commodities for ED contamination and highlights the advantages of employing combined biological and chemical assays to facilitate accurate risk assessment.
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