Methylmercury (MeHg)

CASRN 22967-92-6

RfD (mg/kg-day)	System	Basis	PoD	Composite UF	Confidence
1 x10^-4 (High end of BMDL05 range)	Nervous, Developmental	Developmental neuropsychological impairment	BMDL₅ : 1.472 x10^-3 mg/kg-day	10	High
1 x10^-4 (Low end of BMDL05 range)	Nervous, Developmental	Developmental neuropsychological impairment	BMDL₅ : 8.57 x10^-4 mg/kg-day	10	High

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.

Not assessed under the IRIS Program.

Not assessed under the IRIS Program.

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