Arsenic, inorganic Quickview (CASRN 7440-38-2)

Status of Data for Arsenic, inorganic

File First On-Line: 02/10/1988; Last Significant Revision: 06/01/1995

Category (section)	Status	Last Revised
Oral RfD Assessment	On-line	02/01/1993
Inhalation RfC Assessment	No data
Carcinogenicity Assessment	On-line	04/10/1998
Under Re-Assessment

Synonyms

7440-38-2 Arsenic Gray-arsenic

Arsenic, inorganic Arsenic, inorganic

Chronic Health Hazard Assessments for Noncarcinogenic Effects

Reference Dose for Chronic Oral Exposure (RfD)

Critical Effect	Point of Departure*	UF	MF	RfD
Hyperpigmentation, keratosis and possible vascular complications	NOAEL : 0.0008 mg/kg-day	3	1	3 x10-4 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)
  • Human chronic oral exposure, Tseng, 1977; Tseng et al., 1968
• 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
  • A (Human carcinogen)
• Weight-of-Evidence Narrative:
  • Based on sufficient evidence from human data. An increased lung cancer mortality was observed in multiple human populations exposed primarily through inhalation. Also, increased mortality from multiple internal organ cancers (liver, kidney, lung, and bladder) and an increased incidence of skin cancer were observed in populations consuming drinking water high in inorganic arsenic.
  • 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
1.5 per mg/kg-day	Time- and dose-related formulation of the multistage model

Drinking Water Unit Risks
5x10-5 per ug/L

Risk Level	Concentration
E-4 (1 in 10,000)	2 ug/L
E-5 (1 in 100,000)	2x10-1 ug/L
E-6 (1 in 1,000,000)	2x10-2 ug/L

• Dose-Response Data (Carcinogenicity, Oral Exposure)
  • Tumor Type: Skin cancer
  • Test Species: Human
  • Route: Oral, Drinking water
  • Reference: Tseng, 1977; Tseng et al., 1968; U.S. EPA, 1988

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Quantitative Estimate of Carcinogenic Risk from Inhalation Exposure

Inhalation Unit Risk(s)	Extrapolation Method
4.3 x10-3 per ug/m3	Absolute-risk linear model

Inhalation Concentrations at Specified Risk Levels

Risk Level	Concentration
E-4 (1 in 10,000)	2x10-2 ug/m3
E-5 (1 in 100,000)	2x10-3 ug/m3
E-6 (1 in 1,000,000)	2x10-4 ug/m3

• Dose-Response Data (Carcinogenicity, Inhalation Exposure)
  • Tumor Type: Lung cancer
  • Test Species: Human, male
  • Route: Inhalation, Occupational exposure
  • Reference: Brown and Chu, 1983a,b,c; Lee-Feldstein, 1983; Higgins, 1982; Enterline and Marsh, 1982