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MERCURY A-6
APPENDIX A
MINIMAL RISK LEVEL (MRL) WORKSHEET
Chemical Name: Mercury inorganic
CAS Number: 7439-97-6
Date: June 15, 2001
Profile Status: Final Draft
Route: [ ] Inhalation [ X ] Oral
Duration: [ X ] Acute [ ] Intermediate [ ] Chronic
Key to figure: 7
Species: Rat
Minimal Risk Level: 0.007 [ X ] mg/kg/day [ ] mg/m 3
Reference: NTP. 1993. NTP technical report on the toxicology and carcinogenesis studies of mercuric
chloride (CAS no. 7487-94-7) in F344/N rats and B6C3F 1 mice (gavage studies). NTP TR408.
Experimental design: Fischer 344 rats (5/sex/group) were administered 0, 0.93, 1.9, 3.7, 7.4, or 14.8 mg
Hg/kg/day as mercuric chloride once daily for 14 days, excluding weekends. The mercuric chloride was
administered in deionized water via gavage. Body weights were measured and a complete necropsy was
performed. Organ weights were obtained for the brain, heart, kidney, liver, lung, and thymus.
Effects noted in study and corresponding doses: The relative and absolute kidney weights were
significantly increased for males exposed to at least 1.9 mg Hg/kg/day and for females exposed to at least
3.7 mg Hg/kg/day. An increased incidence of renal tubular necrosis (graded minimal in severity) was
observed in 3 of 5 males and 1 of 5 females at the 3.7 mg Hg/kg/day dose level. At 7.4 mg Hg/kg/day, 5/5
males and 3/5 females had minimal-to-mild effects, and at 14.8 mg Hg/kg/day all animals exhibited
mild-to-moderate effects.
Dose and end point used for MRL derivation: 0.93 mg Hg/kg/day; no renal effects.
[ X ] NOAEL [ ] LOAEL
Uncertainty Factors used in MRL derivation: 100
[ ] 1 [ ] 3 [ ] 10 (for use of a LOAEL)
[ ] 1 [ ] 3 [ X ] 10 (for extrapolation from animals to humans)
[ ] 1 [ ] 3 [ X ] 10 (for human variability)
Was a conversion factor used from ppm in food or water to a mg/body weight dose?
If so explain: No.