Elimination
Chromium is normally excreted through the kidneys in urine, with some excretion through the bile
and feces; minor routes of excretion include breast milk, sweat, hair, and nails.
-inhalation exposure :
Normal urinary levels of chromium in humans have been reported to range from 0.24-1.8 µg/L with a median level of 0.4 µg/L. Humans exposed to 0.05-1.7 mg chromium (III)/m3 as chromium sulfate and 0.01-0.1mg chromium (VI)/m3 as potassium dichromate (8-hour time-weighted average) had urinary excretion levels from 0.0247 to 0.037 mg chromium (III)/L.
In occupational settings, urinary concentrations of chromium are principally the reflection of the hexavalent soluble quantity recently absorbed. Workers exposed mainly to chromium (V)compounds had higher urinary chromium concentrations than workers exposed primarily to chromium () compounds.
The hexavalent form of chromium is not detected in urine, indicating that chromium (V)is rapidly reduced before excretion.
A study of tannery workers indicated two half-times one in the order of hours, the other in the order of several daysfor urinary excretion of chromium ().
Correlation between respiratory exposure to chromium (V)and urinary excretion of chromium has been demonstrated in welders and workers in the plating industry. In welders exposed to soluble chromium (V),three half-times (7h, 15-30 days and three to five years) were identified.
-oral exposure :
Given the low absorption of chromium compounds by the oral route, the major pathway of elimination after oral exposure is through the feces.
Daily urinary excretion levels of chromium were nearly identical in men and women (averages of 0.17 and 0.20 µg/L, respectively; 0.18 µg/L combined) who ate normal dietary levels of chromium ( 60 µg chromium ()day). When chromium intake was supplemented fivefold with chromium chloride, urinary excretion also increased fivefold.
-dermal exposure :
Information regarding the excretion of chromium in humans after dermal exposure to chromium compounds is limited.