If an electrician is exposed to high levels of mercury and becomes ill, how do doctors detect it if the blood levels are no longer high?

Difficult: Detecting mercury is most reliable from blood or urine, but fades a few days after last exposure. Hair testing is long-term positive, but is a test not standardized, and is not helpful for inorganic (elemental) mercury if that is the type of exposure implied for this case...it is best for organic mercury from seafood. Read more: http://labtestsonline.org/understanding/analytes/mercury/tab/test/