The vapor from elemental mercury metal is a neurotoxin. Most dentists have levels of mercury in their urine of 10 micrograms per liter (1 microgram is 10−6 grams), which is about twice that of their patients. The legal safe maximum exposure limit for mercury in urine is 4.053 x 1017atoms of mercury per liter of urine. Does this level mean that the average dentist is at risk for mercury poisoning? In other words, is this amount, 10 micrograms per liter of urine, above or below the legal safe limit? Show your work and justify your answer. How do you account for the amount per liter?