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

MERCURY
2. HEALTH EFFECTS
the T-cell line and an observed decrease in the helper/suppressor ratio were suggestive of an autoimmune
response.
In a mercury-producing plant, neutrophil function was found to be significantly reduced in workers with a
mean exposure duration of 8 months (range, 0.5–46 months) (Perlingeiro and Queiroz 1995). In this study,
both chemotactic and chemical-specific reducing activities of the neutrophils of exposed workers were
found to be affected. While improved industrial hygiene practices over a 6-month period resulted in a
decrease in urine mercury concentration in the workers, it did not result in the return of neutrophil migration
activity to within the normal range. There was, however, no observed increase in the incidence of
infections in the mercury-exposed group compared to controls. Based on their observations, Perlingeiro
and Queiroz (1995) suggested that even exposures to levels of mercury considered "safe" in some industrial
settings may lead to impairment of neutrophil function.
Exposure of genetically susceptible mice to mercury vapor for a period of 10 weeks resulted in an
autoimmune response similar to that seen in similar mice after treatment with mercuric chloride by
subcutaneous injections and in drinking water (Warfvinge et al. 1995). This response was manifested as a
syndrome, which included a general stimulation of the immune system, with hyperimmunoglobulinemia,
anti-nucleolar-fibrillarin autoantibodies, and glomerular disease accompanied by vascular immune complex
deposits. Actual inhalation exposure times for the 0.3–1 mg Hg/m 3 exposure concentrations varied from
0.5 to 19 hours a day (5 days a week), but doses for individual exposure groups were also expressed
in µg/kg/week units. The LOAEL for serum antinucleolar antibodies was determined to be an absorbed
dose of 0.170 mg Hg/kg/week (from a 1.5-hour daily exposure to 0.5 mg/m3 ) and the corresponding
NOAEL was a calculated absorbed dose of 0.075 mg/kg/day (from a 0.5-hour daily exposure to
0.0005 mg/m3 ). Higher doses were required for B-cell stimulation and for the development of immune
complex deposits.
The highest NOAEL values and all reliable LOAEL values for immunological effects in each species and
duration category are recorded in Table 2-1 and plotted in Figure 2-1.
Organic Mercury. No studies were located regarding immunological and lymphoreticular effects in
humans or animals after inhalation exposure to organic mercury.
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