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

MERCURY A-7
APPENDIX A
Was a conversion used from intermittent to continuous exposure?
If so, explain: Yes. To estimate an equivalent continuous exposure concentration, the average concentration
was multiplied by 5 days/7 days.
NOAEL (ADJ)
= 0.93 mg/kg/day x (5 days/7 days)
= 0.66 mg/kg/day
MRL = NOAEL (ADJ) ÷ UF = 0.66 mg/kg/day ÷ 100 = 0.007 mg/kg/day
If an inhalation study in animals, list the conversion factors used in determining human equivalent
concentration (HEC): None.
Additional studies or pertinent information which lend support to this MRL: Several other studies
examining the effects of oral exposure to inorganic mercury salts have also shown renal toxicity in humans
as a result of acute oral exposures. Kidney effects (i.e., heavy albuminuria, hypoalbuminemia, edema, and
hypercholesterolemia) have been reported after therapeutic administration of inorganic mercury (Kazantzis
et al. 1962). Acute renal failure has been observed in a number of case studies in which mercuric chloride
has been ingested (Afonso and deAlvarez 1960; Murphy et al. 1979; Samuels et al. 1982). Autopsy of a 35year-old
man who ingested a lethal dose of mercuric chloride and exhibited acute renal failure showed pale
and swollen kidneys (Murphy et al. 1979). A case study reported acute renal failure characterized by
oliguria, proteinuria, hematuria, and granular casts in a woman who ingested 30 mg mercury/kg as mercuric
chloride (Afonso and deAlvarez 1960). Another case study reported a dramatic increase in urinary protein
secretion by a patient who ingested a single dose of 15.8 mg mercury/kg as mercuric chloride (assuming a
body weight of 70 kg) (Pesce et al. 1977). The authors of the report surmised that the increased excretion
of both albumin and β 2-microglobulin were indicative of mercury-induced tubular and glomerular
pathology. Acute renal failure that persisted for 10 days was also observed in a 19-month-old child who
ingested an unknown amount of powdered mercuric chloride (Samuels et al. 1982). Decreased urine was
also observed in a 22-year-old who attempted suicide by ingesting approximately 20 mg mercury/kg
(Chugh et al. 1978).
Agency Contact (Chemical Manager): John Risher