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

MERCURY
2. HEALTH EFFECTS
reversible within 12 weeks after exposure cessation and was associated with a decrease in the mercury
concentration in brain tissue to below 10 µg/g wet weight (w/w). Mice exposed to an unspecified
concentration of metallic mercury vapor intermittently for more than 3 weeks exhibited progressive
neurological dysfunction (i.e., wobbling and unresponsiveness to light), beginning 22 days after initial
exposure, and subsequently died 4 days later (Ganser and Kirschner 1985).
No studies were located regarding neurological effects in animals following chronic inhalation exposure to
inorganic mercury.
Organic Mercury. Exposure to organic mercury via inhalation is extremely rare. The only reports of even
its potential occurrence come from a few case histories. Case reports have described neurological effects in
humans after inhalation exposure to organic mercury; however, no quantitative data were provided.
Following acute inhalation exposure of dust containing methylmercury, four men had initial symptoms
including numbness and tingling of limbs, unsteadiness in gait, difficulty in performing fine movements
(e.g., buttoning a shirt), irritability, and constricted vision (Hunter et al. 1940). At least 2 years after these
occupational exposures, the subjects had not fully recovered from their symptoms. Acute high-level
exposure to an unspecified alkyl mercury compound has reportedly caused neurological symptoms (e.g.,
ataxia, unsteady gait, slurred speech, memory difficulties, tremors) in exposed workers (Hook et al. 1954;
Lundgren and Swensson 1949).
A case study reporting neurological effects in a boy after exposure to mercury vapor released from paint
containing phenylmercuric acetate (Aronow et al. 1990) was discussed under metallic mercury because the
exposure was to metallic mercury vapors released from the paint.
Dimethylmercury is extremely volatile, and extremely toxic (in the 5 mg/kg body weight range). The
following case history describes an accidental death due to an occupational spill of only a few drops of
dimethylmercury. The primary exposure route is thought to have been dermal, but dimethylmercury is so
volatile that inhalation exposure might also have occurred. Blayney et al. (1997) provided the first account
of this tragic event. The case history was subsequently detailed by Nierenberg et al. (1998). The exposure
occurred to a 48-year-old female chemistry professor who was admitted to the hospital 5 months
(154 days) after, as best as can be determined, she inadvertently spilled several drops (estimated at
0.4–0.5 mL, about 1,500 mg) of dimethylmercury from the tip of her pipette onto the back of her
disposable latex gloves. The spill was cleaned and the gloves disposed of. Hair analysis on a long strand
65