**6. Advantages and limitation in eco-toxicological profiling based on biological samples collected non-invasively**

Main disadvantages of these techniques are the difficulty in making difference between external and internal contamination – as regards hair samples. Also in case of hair samples the results vary intensively once with color, age and gender without existing a good correlation between the same parameters. The lack of a standardized procedure of analysis make more difficult to establish the reliability of results in order to estimate the method uncertainty and making real laboratory intercomparisons. Also a large number of studies showed that there are no correlation between the contaminant level from hair samples and blood samples in case of the same person.

As regards the study performed by us using of such sampling matrixes made possible to evaluate the impact of certain environmental contaminants on humans and animals (grown for consumption purposes) which are living in such contaminated areas. Also through the significant number of subjects that were monitored we was able to conclude that the environmental contaminants are uptake by humans mainly through food web chains (as a result of consumption of contaminated vegetables and animals). This is the same in case of home grown animals which are similarly exposed to these environmental contaminants mainly through the consumed contaminated food.
