IRIS

Chromium(VI)

CASRN 18540-29-9 | DTXSID7023982

Toxicological Review (PDF) (70 pp, 195 K)
IRIS Summary (PDF) (34 pp, 203 K)
Status: Chromium(VI) is in step 5 at this time; see Quick Check.

Key IRIS
Values
Assessment
Status
Chemical
Documents
Other EPA
Information

Noncancer Assessment

Reference Dose for Oral Exposure (RfD) (PDF) (34 pp, 203 K) Last Updated: 09/03/1998

System	RfD (mg/kg-day)	Basis	PoD	Composite UF	Confidence
Other	3 x 10^-3	None reported	NOAEL (ADJ): 2.5 mg/kg-day	300 MF: 3	Low

Reference Concentration for Inhalation Exposure (RfC) (PDF) (34 pp, 203 K) Last Updated: 09/03/1998

System	RfC (mg/m³)	Basis	PoD	Composite UF	Confidence
Respiratory	8 x 10^-6 (Chromic acid mists and dissolved Cr(VI) aerosols)	Nasal septum atrophy	LOAEL (ADJ): 7.14 x 10^-4 mg/m³	90	Low
Respiratory	1 x 10^-4 (Cr(VI) particulates)	Lactate dehydrogenase in bronchioalveolar lavage fluid	BMCL₁₀ (HEC): 3.4 x 10^-2 mg/m³	300	Medium

Cancer Assessment

Weight of Evidence for Cancer (PDF) (34 pp, 203 K) Last Updated: 09/03/1998

WOE Characterization	Framework for WOE Characterization
A (Human carcinogen) (Inhalation route)	Guidelines for Carcinogen Risk Assessment (U.S. EPA, 1986)
D (Not classifiable as to human carcinogenicity) (Oral route)	Guidelines for Carcinogen Risk Assessment (U.S. EPA, 1986)
Carcinogenic potential cannot be determined (Oral route)	Proposed Guidelines for Carcinogen Risk Assessment (U.S. EPA, 1996)
Known/likely human carcinogen (Inhalation route)	Proposed Guidelines for Carcinogen Risk Assessment (U.S. EPA, 1996)

Basis:

Under the current guidelines (EPA, 1986), Cr(VI) is classified as Group A - known human carcinogen by the inhalation route of exposure. Carcinogenicity by the oral route of exposure cannot be determined and is classified as Group D. Under the proposed guidelines (EPA, 1996), Cr(VI) would be characterized as a known human carcinogen by the inhalation route of exposure on the following basis. The oral carcinogenicity of Cr(VI) cannot be determined. No data were located in the available literature that suggested that Cr(VI) is carcinogenic by the oral route of exposure.
This may be a synopsis of the full weight-of-evidence narrative.

Quantitative Estimate of Carcinogenic Risk from Oral Exposure (PDF) (34 pp, 203 K)

Information reviewed but value not estimated.

Quantitative Estimate of Carcinogenic Risk from Inhalation Exposure (PDF) (34 pp, 203 K)

Inhalation Unit Risk: 1.2 x 10^-2 per µg/m³
Extrapolation Method: Multistage, extra risk
Tumor site(s): Respiratory
Tumor type(s): Lung cancer (Mancuso, 1975)

Additional EPA toxicity information may be available by visiting the following sites:

Human Health Benchmarks for Pesticides (HHBP). This database provides human health benchmarks for pesticides that may be present in drinking water.
Office of Pesticide Programs Pesticide Chemical Search. This database provides links to health effects information and registration status for pesticides.
Chemistry Dashboard. This database provides information on chemical structures, experimental and predicted physicochemical, and toxicity data.

Chromium(VI) is being reassessed.

Assessment Manager(s): Catherine Gibbons (gibbons.catherine@epa.gov), Alan Sasso (sasso.alan@epa.gov)

Step	Assessment Materials Released to the Public	Release Date	Public Meeting Date
1	Problem Formulation Materials	08/2014	10/2014
1	Preliminary Assessment Materials	03/2019	04/2019
4	Public Comment Draft	10/2022	TBD
4	Peer Review Draft	N/A	03/2023
7	Post Final Assessment	TBD