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

MERCURY
2. HEALTH EFFECTS
compounds has not been separated in this section, but the specific inorganic compound responsible for any
effect is noted both in the text and in Table 2-2 and Figure 2-2.
Health effects following oral exposure to organic mercury were observed in humans and animals. The
majority of the studies used to derive the NOAELs and LOAELs shown in Table 2-3 and Figure 2-3
concern exposure to methylmercuric chloride; however, in several studies, exposure was to methylmercuric
acetate, methylmercuric hydroxide, methylmercuric dicyanidiamide, or phenylmercuric acetate. These
chemicals are discussed together in Table 2-3 and Figure 2-3. In order to facilitate a comparison of studies
using different compounds of mercury (either organic or inorganic), all doses are expressed in terms of the
mercury exposure (mg Hg/kg/day) rather than to the mercury compound (HgX or RHgX/kg/day) to which
one is exposed. For example, a dose of 1 mg/kg (when the compound is methylmercuric chloride) refers to
1 mg/kg mercury rather than 1 mg/kg methylmercuric chloride.
2.2.2.1 Death
Inorganic Mercury. A lethal dose of mercuric chloride was estimated to be 10–42 mg Hg/kg for a 70-kg
adult (Gleason et al. 1957). Death from oral exposure to inorganic mercury is usually caused by shock,
cardiovascular collapse, acute renal failure, and severe gastrointestinal damage (Gleason et al. 1957;
Murphy et al. 1979; Troen et al. 1951). Eighteen cases of human poisoning (suicide attempts in some
cases) were reported by Troen et al. (1951); 9 patients died following oral ingestion of single doses of
mercuric chloride (range, 29–>50 mg Hg/kg). The most common findings in these cases were gastrointestinal
lesions (e.g., mild gastritis to severe necrotizing ulceration of the mucosa) and renal involvement
(e.g., albuminuria, anuria, and uremia). Death of a 50-year-old woman due to ingestion of an unspecified
amount of mercurous chloride in Chinese medicine has also been reported (Kang-Yum and Oransky 1992).
The death was attributed to renal failure.
In rats, the oral LD 50 values (lethal dose, 50% kill) ranged from 25.9 to 77.7 mg Hg/kg as mercuric chloride
(Kostial et al. 1978). The signs of acute mercury toxicity in animals were similar to those described above
for humans. Male rats appeared to be slightly more sensitive to the lethal effects of mercuric chloride; 2 of
5 male rats and no female rats died when given gavage doses of 14.8 mg Hg/kg, 5 days a week for 2 weeks
(Dieter et al. 1992; NTP 1993). Mice showed slightly less toxicity, with no deaths at 14.8 mg Hg/kg, death
in 1 male at 29 mg Hg/kg, and deaths in 5 of 5 males and 4 of 5 females at 59 mg Hg/kg when administered
by gavage over the same period (NTP 1993).
75