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

MERCURY 181
2. HEALTH EFFECTS
side of her hand. A preliminary laboratory report at 5 months after exposure indicated that the whole-blood
mercury concentration was more than 1,000 µg/L (normal range, 1–8 µg/L; toxic level, >200 µg/L).
Chelation therapy with oral succimer (10 mg/kg orally every 8 hours) was begun on day 168 after exposure.
Whole blood concentrations rose to 4,000 µg/L after one day of chelation, and urinary mercury levels were
234 µg/L (normal range, 1–5 µg/L; toxic level, >50 µg/L). Chelation therapy continued up to the time of the
patients death 298 days postexposure, with blood mercury level falling to around 200 µg/L. Metal analysis
of the patient’s tissues revealed extremely high levels of mercury in the frontal lobe and visual cortex
(average value, 3.1 µg/g [3,100 ppb]), liver (20.1 µg/g), and kidney cortex (34.8 µg/g). The mercury
content in the brain was approximately 6 times that of the whole blood at the time of death, and was much
higher than levels in the brains of nonmercury exposed patients (2–50 ppb).
2.3.2.4 Other Routes of Exposure
Strain and sex differences were observed in renal mercury accumulation 4 hours after a subcutaneous
methylmercuric chloride injection (1 µmol/kg) to 5 strains (BALB/cA, C57BL/6N, CBA/JN, C3H/HeN,
and ICR) of male mice and 3 strains (BALB/cA, C57BL/6N, and ICR) of female mice (Tanaka et al. 1991).
Mercury was distributed to the kidneys, brain, heart, lungs, liver, spleen, carcass, plasma, and red blood
cells of all mice tested. Strain and sex differences were found in renal mercury content. In three strains
(ICR, BALB/cA, and C57BL/6N), males showed higher renal mercury levels than females.
Differences in tissue concentrations in different inbred mice strains were evaluated by Griem et al. (1997).
Female mice from five different strains (C57BL/6, B10.D2, B10.S, A.SW, and DBA/2) received 3 weekly
subcutaneous injections of 0.5 mg Hg/kg body weight for up to 12 weeks. Except for the thymus, in which
mercury concentrations continued to increase, steady state levels were obtained in blood and liver after
4 weeks and in spleen and kidney after 8 weeks. In the closely related strains C57BL/6, B10.D2, and
B10.S, which differ only or primarily at the major histocompatibility complex, mercury concentrations in
blood and liver were about 2-fold lower and renal concentrations were from 3- to 5-fold lower than
measured in A.SW, and DBA/2 strains. Mercury concentrations in the spleen of C57BL/6, B10.D2, B10.S
mice were significantly higher than in the spleen of A.SW, and DBA/2 mice. The higher concentration of
Hg in this immune system organ concentration of C57BL/6, B10.D2, B10.S correlates with the increased
susceptibility of these strains to a mercury chloride-induced systemic autoimmune syndrome. The strains
with lower splenic mercury are more resistant.