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Bromoform Quickview (CASRN 75-25-2)

Health assessment information on a chemical substance is included in IRIS only after a comprehensive review of toxicity data by U.S. EPA health scientists from several Program Offices, Regional Offices, and the Office of Research and Development.

Disclaimer: This QuickView represents a snapshot of key information. We suggest that you read the IRIS Summary to put this information into complete context.

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Status of Data for Bromoform

File First On-Line: 09/30/1987; Last Significant Revision: 12/01/1993

Category (section)
Last Revised
Oral RfD Assessment Yes 09/30/1987
Inhalation RfC Assessment Discussion 12/01/1993
Carcinogenicity Assessment Yes 09/01/1990
  • 75-25-2
  • Bromoform
  • Methane, tribromo-
  • Methenyl tribromide
  • Tribromomethane
Bromoform Source Documents
Chronic Health Hazard Assessments for Noncarcinogenic Effects

Reference Dose for Chronic Oral Exposure (RfD)

Critical Effect
Point of Departure*
Hepatic lesions NOEL : 1.79 x101 mg/kg-day 1000 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.

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Reference Concentration for Chronic Inhalation Exposure (RfC)

Information reviewed but value not estimated. See IRIS Summary.

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Carcinogenicity Assessment for Lifetime Exposure
  • Weight-of-Evidence Characterization
    • B2 (Probable human carcinogen - based on sufficient evidence of carcinogenicity in animals)
  • Weight-of-Evidence Narrative:
    • Based on inadequate human data and sufficient evidence of carcinogenicity in animals, namely an increased incidence of tumors after oral administration of bromoform in rats and intraperitoneal administration in mice. Bromoform is genotoxic in several assay systems. Also, bromoform is structurally related to other trihalomethanes (e.g., chloroform, bromodichloromethane, dibromochloromethane) which have been verified as either probable or possible carcinogens.
    • This may be a synopsis of the full weight-of-evidence narrative. See IRIS Summary.

Quantitative Estimate of Carcinogenic Risk from Oral Exposure

Oral Slope Factor(s)
Extrapolation Method
7.9 x10-3 per mg/kg-day Linearized multistage procedure, extra risk
Drinking Water Unit Risks
2.3x10-7 per µg/L
Risk Level
E-4 (1 in 10,000) 4x102 µg/L
E-5 (1 in 100,000) 4x101 µg/L
E-6 (1 in 1,000,000) 4 µg/L

Quantitative Estimate of Carcinogenic Risk from Inhalation Exposure

Inhalation Unit Risk(s)
Extrapolation Method
1.1 x10-6 per µg/m3 Linearized multistage procedure, extra risk

Inhalation Concentrations at Specified Risk Levels

Risk Level
E-4 (1 in 10,000) 9x101 µg/m3
E-5 (1 in 100,000) 9 µg/m3
E-6 (1 in 1,000,000) 9x10-1 µg/m3

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