However, we should realize that to identify a given agent as a thyroid disruptor (and also any EDC) meets numerous difficulties, for example, exposure to usually only one (or just a few chosen) potential EDC under experimental conditions, and even our still limited knowledge regarding physiological processes in the thyroid resulting in diagnostic doubts which thyroid hormone concentration is normal or abnormal, etc. [52]. Here, TG is linked to thyroid gland disorder.