Mercury - Toxicology of Metals - page 685

6.2.2.4 The Immune System
A more detailed discussion of the effect of mercuric
mercury on the immune system can be found in Chap-
ter 12. Only some clinical reports are reviewed here.
Idiosyncratic reactions to mercury and mercury com-
pounds on local contact have been described by many
authors. Cell-mediated immune responses with skin
manifestation have been seen in connection with mer-
cury applied locally to skin and mucous membranes.
Typical manifestations are erythema and contact der-
matitis. Thiomersal and ammoniated mercury are
common causes (North American Contact Dermatitis
Group, 1973). Exposure to metallic mercury may give
rise to sensitization, for example, from amalgam teeth
fi llings and other dental exposure (Feuerman, 1975;
Finne et al ., 1982; Frykholm, 1957; Spreng, 1963; Strass-
burg and Schubel, 1967; White and Brandt, 1976). One
side effect of amalgam fi llings that is not particularly
unusual is oral lichen. Larsson (1998) describes accu-
mulation of mercury in the tissue affected and accu-
mulation of dendritic cells. Little et al . (2001) showed
that a culture of human oral keratocytes, on exposure
to subtoxic concentrations of HgCl 2 (10

and CD45RA+ and the total number of CD4+ T lym-
phocytes were signifi cantly lower than in the controls.
The numbers of CD57+ and CD16+ NK (natural killer)
cells were also found to be negatively correlated with
the mercury concentration in urine (Park et al ., 2000).
Another group of 19 workers exposed to mercury
vapor had a mean urinary secretion of mercury of
9.7 + 5.5

g/L. In this group, Vimercati et al . (2001)
found an inverse correlation between mercury in urine
and the numbers of CD13+ and CD15+ leukocytes and
NK cells. A reduced capacity for chemotaxis in poly-
morphonuclear leukocytes was also found. Loftenius
et al . (1998) studied the effect of amalgam removal
on mononuclear lymphocytes from 10 patients. They
found no statistically signifi cant change in the number
of cell types. However, they found a rise in IL-6 in
plasma after 48 hours. The mercury concentration in
plasma rose by some 10%.
In 47 chloralkali workers with mercury exposure cor-
responding to 5.9 nmol/mmol creatinine, an increase
in autoantibodies against myeloperoxidase and protei-
nase 3 was observed. This increase was correlated with
the mercury concentration in urine (Ellingsen et al .,
2000a).
For acrodynia (pink disease) and Kawasaki disease
see Chapter 12.

µ

mol/L),
expresses ICAM-1, which in turn induces T-cell bind-
ing, release of TNF-

µ

, and interleukin-8 and down-
regulation of interleukin-1

α

. This induces activation
of the immune system, which is not seen in experi-
ments with cutaneous keratocytes. Bronchial asthma
has also been reported in connection with exposure to
phenylmercury (Mathews, 1968).
In an examination of 48 workers exposed to mercury
with an average elimination in the urine of 24

α

6.2.2.5 Thyroid
A study on 41 chloralkali workers with a mean
urinary excretion of 27fg/g creatinine showed a sig-
nifi cantly higher concentration of both free T4 and the
free T4/free T3 ratio compared with unexposed refer-
ents. Moreover, serum-free T3 was inversely associ-
ated with cumulative mercury exposure. The authors
suggested that the effect indicated an inhibitory effect
by mercury on 5'-deiodinases, selenoprotein enzymes
(Barregard et al ., 1994). Ellingsen et al . (2000b) reported
fi nding impaired thyroid function in a group of 47
chloralkali workers compared with 47 controls. The
exposed workers showed a statistically signifi cant rise
in reverse T3 (rT 3 )—a rise that was dose-related. The
mean urinary concentration of mercury was 10.6

g/g cre-
atinine, a signifi cant reduction of chemotactic migration
and chemical reduction capacity in neutrophile leuco-
cytes was found (Perlingeiro and Queiroz, 1995; 1994).
An increase in the T-cell concentration in blood, CD3−,
CD4−, and CD8− cells has been reported in workers
exposed to mercury (Moszczynski et al ., 1996). In a group
with low exposure, a decrease of the TNF

µ

-concentra-
tion in serum has been reported (Soleo et al ., 1997).
Effects on the immune system of occupational expo-
sure to mercury vapor have been studied in several
worker populations. The workers were exposed to
mercury levels below and around the threshold value
for permitted exposure, which corresponds to a urinary
secretion rate of mercury of some 50

α

µ g/g

creatinine, with a range of 2.0-30.1.

6.2.2.6 Testicles
Exposure to mercury vapor causes mercury to accu-
mulate in the testicles, where it is eliminated very slowly.
Lee and Dixon (1975) observed inhibition of sperma-
togenesis in mice given mercuric chloride, 1 mg/kg
intraperitoneally. Daily administration of HgCl 2 to
mice in a dose that did not affect body weight caused
a reduced sperm count, modifi ed sperm morphology,
and lower fertility. It was possible to offset this effect by
administering vitamin E (Rao and Sharma, 2001).

g/g creatinine.
These results were summarized by Moszczynski (1999)
and reported statistically signifi cant deviations in the
number of cell elements, cytokine concentrations, and
immunoglobulin concentrations. Both stimulating and
inhibitory effects were found.
In a later study, 20 workers exposed to mercury
vapor had mean urinary secretion of mercury of 45
µ

µ

g/L. The study reported that the number of CD4+