Toxicity Identification Evaluation TIE Methods

Assessments of the risk connected to the contamination should rely on a multidisciplinary approach based on both chemical and biological techniques and should be able to address both exposure and effects. Traditional chemical 

In order to identify compounds responsible for specific effects (i.e., endocrine disrupting or AhR hgands) observed in field studies, TIE or bioassay directed analysis approaches have increasingly been apphed over the last decade. In such approaches, sensitive bioassays are used to direct the fractionation of a sample extract until its complexity is sufficiently reduced to enable identification of those compoimds responsible for the activity measured in the bioassay. This strategy is based on differential extraction and fractionation methods and identification by chemical and biochemical analysis. TIE is a well-established technique having been originally developed by 

In a more recent work, Puglisi et al. [96] introduced the relevance of using approaches based on non-exhaustive extraction techniques. Usually, approaches are based on total extraction of contaminants, and then, they do not take into account the importance of bioavailabUity and aging processes. Tenax and cyclodextrin extractions over time were carried out to determine the bioavailable fractions. Results obtained in this study showed that the adoption of a bio availability-based assessment of contamination led to a large reduction of the toxicity signal (Fig. 5). The total extract had 70 pM this signal was reduced to 19 pM for the cyclodextrin-assessed bioavailable fraction and to only 3 pM for the Tenax-assessed bioavailable fraction. 

From this study, we can conclude that coupling of non-exhaustive extraction and bioanalyses leads to a more realistic and, generally much lower estimated risk for the toxicity of the extracts as compared to commonly 

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