Shortly after a single injection of Cd a much higher deposition of Cd was observed in growing hair (anaphase) than in resting
hair (telophase). Shifting the time of the administration between 7 d before the onset of matrix production and full hair
growth did not appreciably alter the initial deposition in spite of the rapid decline of Cd in blood plasma between the injection
and the start of hair growth. After the initial deposition the concentration decreased in growing as well as in resting hair.
In growing hair this is attributed to the addition of new matrix containing less Cd due to its declining supply via blood.
In the resting hair it may reflect the decline of Cd in the follicular tissue adhering to the hair roots. The study demonstrates
that the deposition of internal Cd in hair occurs mainly in those sections of hair growing at the time of the actual intake
of Cd into the organism. The quantity of Cd found in a particular section of hair in the absence of external contamination,
therefore, indicates first and foremost the quantity of Cd taken up into the blood stream—after ingestion or inhalation—at
the time of the actual formation of this section notwithstanding the actual body burden at that time.