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

MERCURY
2. HEALTH EFFECTS
reduced vital capacity), diffuse pulmonary infiltrates, and evidence of interstitial pneumonitis (McFarland
and Reigel 1978).
Very little information was located regarding respiratory effects associated with intermediate-duration
exposures. However, two studies noted chronic coughs in subjects exposed to metallic mercury vapor for
several weeks (Schwartz et al. 1992; Sexton et al. 1976). No respiratory symptoms and no abnormalities
were noted upon examining chest X-rays or the results of pulmonary function tests in a group of chloralkali
workers exposed for an average of >6 years to levels of mercury ranging from near 0 to 0.27 mg/m 3 (85% of
the group was exposed at or below 0.1 mg/m3 ) (Smith et al. 1970).
Respiratory effects in animals have been observed following acute inhalation exposure of metallic mercury
vapors. Rats exposed to 27 mg/m3 of elemental mercury vapors for 2 hours then observed for 15 days
displayed dyspnea and death due to asphyxiation (Livardjani et al. 1991b). Respiratory tract lesions
included lung edema, necrosis of the alveolar epithelium and hyaline membranes, and occasional lung
fibrosis.
Exposure to 28.8 mg/m 3 of mercury vapor lasting from 1 to 20 hours produced effects ranging from mild to
moderate pathological changes (unspecified) (Ashe et al. 1953). For exposures lasting 30 hours, marked
cellular degeneration and some necrosis were observed in the lungs of 1 rabbit. Less severe respiratory
changes (unspecified mild-to-moderate pathological changes) were reported in rabbits following exposure to
metallic mercury vapor at 6 mg/m 3 for 7 hours a day, 5 days a week for 1–11 weeks (Ashe et al. 1953). The
usefulness of these results is limited because the study did not specify the pathological changes nor
distinguish between primary and secondary effects (i.e., pathological changes secondary to induced shock).
Congested lungs were observed in rats exposed to 1 mg/m 3 metallic mercury vapors for 100 hours
continuously per week for 6 weeks (Gage 1961). In rats exposed to 3 mg/m 3 mercury vapor for only 3 hours
a day, 5 days a week for 12–42 weeks, pathological examination revealed no significant changes in the
respiratory system (Kishi et al. 1978). The potential for oral exposure was not quantified in these studies;
however, it is likely that most of the exposure was via inhalation.
Organic Mercury. Dyspnea, respiratory depression, and respirations frequently obstructed by mucus were
observed in a farmer who had treated grain with phenylmercuric acetate for several seasons (Brown 1954).
An autopsy revealed purulent bronchopneumonia. It is unclear whether the respiratory effects were direct
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