IRIS

Methylmercury (MeHg)

CASRN 22967-92-6

Noncancer Assessment

Reference Dose for Oral Exposure (RfD) (PDF) (44 pp, 258 K) last updated: 07/27/2001

System RfD (mg/kg-day) Basis PoD Composite UF Confidence
Nervous, Developmental 1 x 10-4
(High end of BMDL05 range)
Developmental neuropsychological impairment BMDL5 : 1.472 x 10-3
mg/kg-day
10 High
Nervous, Developmental 1 x 10-4
(Low end of BMDL05 range)
Developmental neuropsychological impairment BMDL5 : 8.57 x 10-4
mg/kg-day
10 High

 


Reference Concentration for Inhalation Exposure (RfC) (PDF) (44 pp, 258 K)
Not assessed under the IRIS Program.

 

Cancer Assessment

Weight of Evidence for Cancer (PDF) (44 pp, 258 K) last updated: 05/01/1995

WOE Characterization Framework for WOE Characterization
C (Possible human carcinogen) Guidelines for Carcinogen Risk Assessment (US EPA, 1986)
Basis:
  • Based on inadequate data in humans and limited evidence of carcinogenicity in animals. Male ICR and B6C3F1 mice exposed to methylmercuric chloride in the diet had an increased incidence of renal adenomas, adenocarcinomas and carcinomas. The tumors were observed at a single site and in a single species and single sex. The renal epithelial cell hyperplasia and tumors were observed only in the presence of profound nephrotoxicity and were suggested to be a consequence of reparative changes in the cells. Several nonpositive cancer bioassays were also reported. Although genotoxicity test data suggest that methylmercury is capable of producing chromosomal and nuclear damage, there are also nonpositive genotoxicity data.
  • This may be a synopsis of the full weight-of-evidence narrative.

Quantitative Estimate of Carcinogenic Risk from Oral Exposure (PDF) (44 pp, 258 K)

Not assessed under the IRIS Program.

Quantitative Estimate of Carcinogenic Risk from Inhalation Exposure (PDF) (44 pp, 258 K)

Not assessed under the IRIS Program.

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