Test Details: Detecting toxic thallium exposure in whole blood specimens. Accidental ingestion may lead to vomiting, diarrheal, and leg pains followed by a severe and sometimes fatal sensorimotor polyneuropathy. Blood thallium levels reflect recent exposure as thallium has a biological half-life of approximately 2 to 4 days. Blood levels greater than 100 µg/L are considered toxic and greater than 300 µg/L indicate severe ingestion.