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

MERCURY 266
2. HEALTH EFFECTS
acute and intermediate durations (Ashe et al. 1953). However, it is unclear whether these changes represent
direct toxic effects on the heart or whether they were secondary to shock.
The bulk of information available regarding cardiovascular effects after oral exposure of animals to mercury
generally supports findings seen in human inhalation studies. Oral administration of 7 mg Hg/kg/day as
inorganic mercury (mercuric chloride) for a year or 0.4 mg Hg/kg/day as organic mercury (methylmercuric
chloride) for up to 28 days in rats resulted in elevated blood pressure (Carmignani et al. 1989; Wakita 1987).
At higher concentrations (28 mg Hg/kg/day as mercuric chloride for 180 days), decreases in cardiac
contractility were observed; these effects were suggested to be due to direct myocardial toxicity (Carmignani
et al. 1992). Biphasic effects on myocardial tissue have been demonstrated on isolated papillary muscles
from rat ventricles (Oliveira and Vassallo 1992). At low mercury concentrations, an increase in contractile
force was observed, whereas at 5–10-fold higher concentrations dose-related decreases in contractile force
were observed. The increases in contractile force were suggested to be due to inhibition of Na+-K+-ATPase,
and the decreases were suggested to be due to inhibition of Ca2+-ATPase of the sarcoplasmic reticulum.
Based on these results, it would appear that children with hypersensitivity to mercury may exhibit tachycardia
and elevated blood pressure following inhalation, oral, or dermal exposure to mercury or to mercurycontaining
compounds. In addition, low-level exposure to mercury for extended periods may cause elevated
blood pressure in exposed populations. Chronic-duration inhalation exposures or intermediate-duration oral
exposures may also be associated with increased mortality due to ischemic heart or cerebrovascular disease;
however, the data supporting this conclusion are more limited.
Gastrointestinal Effects. Both inhalation and oral exposures to mercury have resulted in gastrointestinal
toxicity. Mercurial stomatitis (inflammation of the oral mucosa, occasionally accompanied by excessive
salivation) is a classic symptom of mercury toxicity and has been observed following inhalation exposure to
both inorganic and organic mercury (Bluhm et al. 1992a; Brown 1954; Campbell 1948; Fagala and Wigg
1992; Garnier et al. 1981; Haddad and Sternberg 1963; Hallee 1969; Hill 1943; Hook et al. 1954; Karpathios
et al. 1991; Sexton et al. 1976; Snodgrass et al. 1981; Tennant et al. 1961; Vroom and Greer 1972).
Mercuric chloride is caustic to the tissues of the gastrointestinal tract, and persons who have ingested large
amounts of this form of mercury have exhibited blisters, ulceration, and hemorrhages throughout the gastrointestinal
tract (Afonso and deAlvarez 1960; Chugh et al. 1978; Murphy et al. 1979; Samuels et al.