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

MERCURY 278
2. HEALTH EFFECTS
serotonergic synthesis and/or catabolism have also been observed following mercury exposure (Sharma et al.
1982; Tsuzuki 1981).
Collectively, the above information shows the high sensitivity of the nervous system to mercury toxicity and
indicates that persons exposed to sufficiently high amounts of mercury may experience adverse neurological
symptoms.
Reproductive Effects. Studies in humans indicate that metallic mercury vapor does not cause infertility
or malformations following paternal exposure (Alcser et al. 1989; Lauwerys et al. 1985) but may cause an
increase in the rate of spontaneous abortions (Cordier et al. 1991). No correlation was observed between
levels of testosterone, luteinizing hormone, or follicle-stimulating hormone and occupational exposure to
metallic mercury vapor, indicating that the pituitary control of testosterone secretion was not affected
(Erfurth et al. 1990; McGregor and Mason 1991). However, in vitro studies have shown that mercury can
adversely affect human spermatozoa. Inorganic (mercuric chloride) and organic (methylmercuric chloride)
mercury decreased the percentage of motile spermatozoa in vitro (Ernst and Lauritsen 1991). Incubation of
human spermatozoa with inorganic mercury resulted in mercury deposits localized in the membranes of the
midpiece and tailpiece. The lack of mercury grains in spermatozoa with methylmercury exposure may be
due to the inability of spermatozoa or the semen plasma to demethylate methylmercury in the 15-minute
incubation period (Ernst and Lauritsen 1991).
Female dentists and dental assistants exposed to metallic mercury vapors had increased reproductive failures
(spontaneous abortions, stillbirths, and congenital malformations) and irregular, painful, or hemorrhagic
menstrual disorders (Sikorski et al. 1987). Correlations were observed between the incidence of these effects
and hair mercury levels.
Rowland et al. (1994) report that female dental assistants with a high occupational exposure to mercury were
found to be less fertile than controls. The probability of conception with each menstrual cycle (called
"fecundability" by the authors) in women who prepared 30 or more amalgams per week and who were
evaluated as having 4 or more poor mercury-hygiene practices was only 63% of that of unexposed controls.
Hygiene was incorporated into the evaluation of the results of this study because occupational groups with
roughly the same potential for exposure often contain subjects whose actual exposures are quite different,
depending on their particular work environment and their work (and personal) hygiene practices within that
environment. Rowland et al. (1994) found that 20% of the women in their final evaluation who prepared