revised final - Agency for Toxic Substances and Disease Registry ...

MERCURY
2. HEALTH EFFECTS
pathological changes (unspecified) were also seen for 1-hour exposures. As the duration of exposure
increased to 30 hours, extensive cell necrosis in the kidneys became evident. These results and the
following results are limited as to their usefulness because the pathological changes are not described.
In an intermediate-duration study, rabbits exposed to mercury vapor concentrations of 0.86 mg/m 3 for
7 hours a day, 5 days a week for 12 weeks exhibited moderate pathological kidney changes that were
reversible with cessation of exposure (Ashe et al. 1953). Larger doses (6 mg/m3 ) administered for 7 hours a
day, 5 days a week for up to 11 weeks, produced effects that ranged from mild, unspecified, pathological
changes to marked cellular degeneration and widespread necrosis (Ashe et al. 1953).
In rats, slight degenerative changes (i.e., dense deposits in tubule cells and lysosomal inclusions) in the
renal tubular epithelium were evident following exposure to 3 mg/m3 mercury vapor for 3 hours a day,
5 days a week for 12–42 weeks (Kishi et al. 1978).
Low-level chronic-duration inhalation exposures to 0.1 mg/m 3 metallic mercury vapor for 7 hours a day,
5 days a week for 72–83 weeks in rats, rabbits, and dogs produced no microscopic evidence of kidney
damage (Ashe et al. 1953). Only two dogs were tested in the study.
Organic Mercury. An autopsy of a man who died after acute high-level exposure to alkyl mercury vapor
revealed necrosis of the tubule epithelium, swollen granular protoplasm, and nonstainable nuclei in the
kidneys (Hook et al. 1954). No studies were available on renal effects following intermediate or chronic-
duration exposure to organic mercury vapors in humans.
No studies were located regarding renal effects in animals after inhalation exposure to organic mercury.
Endocrine Effects
Metallic Mercury. A 13-year-old boy exposed to mercury vapors for 2 weeks developed a thyroid
enlargement with elevated triiodothyronine, and thyroxine; and low thyroid-stimulating hormone levels
(Karpathios et al. 1991). Serum-free thyroxine (T4) and the ratio of free thyroxine to free 3,5,3'-triiodo­
thyronine (T3) were found to be slightly, but significantly, higher in workers with the highest exposure
concentrations in a study of chloralkali workers exposed an average of 10 years to metallic mercury vapor
(Barregard et al. 1994a, 1994b). Further, serum-free T3 was inversely associated with cumulative mercury
exposure, suggesting a possible inhibitory effect of mercury on 5'-deiodinases, which is responsible for the
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