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

MERCURY 164
2. HEALTH EFFECTS
1990, 1992). Following repeated exposure (5 weeks) of rats to mercury vapor (1 mg/m 3 ), high levels were
detected in the blood and brain (Warfvinge et al. 1992). The absorption of inorganic divalent mercury has
not been measured, but it is estimated to be approximately 40% in dogs (Morrow et al. 1964).
Organic Mercury. No studies were located regarding absorption in humans or animals after inhalation
exposure to compounds of phenyl- or methylmercury. However, indirect evidence indicates organic
mercury can be absorbed readily through the lungs. Following inhalation of 203 Hg-labeled dimethyl­
mercury, radioactivity was excreted within 6 hours, followed by a slower excretion phase (Ostlund 1969).
2.3.1.2 Oral Exposure
Metallic and Inorganic Mercury. Few studies in humans were located regarding absorption of ingested
metallic or inorganic mercury. For metallic mercury, ingesting small amounts such as contained in a
standard thermometer (about 0.1 mL or about 1 g) does not produce symptoms of intoxication (Wright et al.
1980). Reports of ingestion of substantial amounts of elemental mercury indicate that absorption is
negligible (Sue 1994; Wright et al. 1980). Two case histories were identified on acute effects of relatively
large ingestions of metallic mercury. The first case history was described an ingestion of 15 mL (204 g) of
metallic mercury by a 17-year-old male storekeeper who swallowed mercury from the pendulum of a clock
(apparently out of curiosity rather than as a suicide attempt). On admission, and 24 hours later, he was
symptom free, and physical examination was normal. The patient had no gastrointestinal symptoms, and
was treated with a mild laxative and bed rest. The results of serial daily urine mercury estimates were
normal (all less than 15 µg), and did not suggest significant absorption. The radiological investigation
illustrated a characteristic pattern of finely divided globules of mercury in the gastrointestinal tract (Wright
et al. 1980).
A second and massive incidence of ingestion involved a 42-year-old man who had spent much of his life
(since the age of 13) repairing instruments that contained mercury. He intentionally ingested an estimated
220 mL (about 3,000 g) of mercury (Lin and Lim 1993). Upon admission, the patient presented with
significantly elevated mercury blood levels (103 µg/L, normal