Dibromochloromethane Quickview (CASRN 124-48-1)

Status of Data for Dibromochloromethane

File First On-Line: 09/30/1987; Last Significant Revision: 01/01/1992

Category (section)	Status	Last Revised
Oral RfD Assessment	On-line	03/01/1991
Inhalation RfC Assessment	No data
Carcinogenicity Assessment	On-line	01/01/1992

Synonyms

124-48-1 Chlorodibromomethane Dibromomonochloromethane

Methane, dibromochloro- Monochlorodibromomethane Dibromochloromethane

Chronic Health Hazard Assessments for Noncarcinogenic Effects

Reference Dose for Chronic Oral Exposure (RfD)

Critical Effect	Point of Departure*	UF	MF	RfD
Hepatic lesions	NOEL : 21.4 mg/kg-day	1000	1	2 x10-2 mg/kg-day

* The Point of Departure listed serves as a basis from which the Oral RfD was derived. See Discussion of Conversion Factors and Assumptions for more details.

• Principal and Supporting Studies (Oral RfD)
  • Rat, subchronic gavage bioassay, NTP, 1985
• Confidence in the Oral RfD
  • Study -- Medium
  • Database -- Medium
  • RfD -- Medium

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Reference Concentration for Chronic Inhalation Exposure (RfC)

Not Assessed under the IRIS Program.

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Carcinogenicity Assessment for Lifetime Exposure

• Weight-of-Evidence Characterization
  • C (Possible human carcinogen)
• Weight-of-Evidence Narrative:
  • Based on inadequate human data and limited evidence of carcinogenicity in animals; namely, positive carcinogenic evidence in B6C3Fl mice (males and females), together with positive mutagenicity data, and structural similarity to other trihalomethanes, which are known animal carcinogens.
  • This may be a synopsis of the full weight-of-evidence narrative. See IRIS Summary.

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Quantitative Estimate of Carcinogenic Risk from Oral Exposure

Oral Slope Factor(s)	Extrapolation Method
8.4 x10-2 per mg/kg-day	Linearized multistage procedure, extra risk

Drinking Water Unit Risks
2.4x10-6 per ug/L

Risk Level	Concentration
E-4 (1 in 10,000)	4x101 ug/L
E-5 (1 in 100,000)	4 ug/L
E-6 (1 in 1,000,000)	4x10-1 ug/L

• Dose-Response Data (Carcinogenicity, Oral Exposure)
  • Tumor Type: Hepatocellular adenoma or carcinoma
  • Test Species: Mouse/ B6C3F1, female
  • Route: Oral, Gavage
  • Reference: NTP, 1985

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Quantitative Estimate of Carcinogenic Risk from Inhalation Exposure

• Not Assessed under the IRIS Program.