IRIS

Chloroprene

CASRN 126-99-8 | DTXSID5020316

Toxicological Review (PDF) (303 pp, 4.63 M)
IRIS Summary (PDF) (30 pp, 307 K)
Systematic Review of Chloroprene (Jan 2018)

Noncancer Assessment

Reference Dose for Oral Exposure (RfD) (PDF) (30 pp, 307 K) Last Updated: 09/30/2010
Information reviewed but value not estimated.

Reference Concentration for Inhalation Exposure (RfC) (PDF) (30 pp, 307 K) Last Updated: 09/30/2010

System	RfC (mg/m³)	Basis	PoD	Composite UF	Confidence
Nervous, Immune, Respiratory	2 x 10 ^-2	Increase in incidence of olfactory atrophy, alveolar hyperplasia, and splenic hematopoietic proliferation in male F344/N rats, female F344/N rats, and female B6C3F1 mice, respectively	BMDL (HEC): 2 mg/m³	100	Medium/High

Cancer Assessment

Weight of Evidence for Cancer (PDF) (30 pp, 307 K) Last Updated: 09/30/2010

WOE Characterization	Framework for WOE Characterization
Likely to be carcinogenic to humans	Guidelines for Carcinogen Risk Assessment (U.S. EPA, 2005)

Basis:

Under the Guidelines for Carcinogen Risk Assessment (U.S. EPA, 2005), there is evidence that chloroprene is "likely to be carcinogenic to humans"
This may be a synopsis of the full weight-of-evidence narrative.

Quantitative Estimate of Carcinogenic Risk from Oral Exposure (PDF) (30 pp, 307 K)

Information reviewed but value not estimated.

Quantitative Estimate of Carcinogenic Risk from Inhalation Exposure (PDF) (30 pp, 307 K)

Inhalation Unit Risk: 3 x 10^-4 per µg/m³
Extrapolation Method: Multistage model with linear extrapolation from the point of departure (BMDL), summed risk.
Tumor site(s): Reproductive, Hepatic, Respiratory, Gastrointestinal, Dermal, Other, Ocular
Tumor type(s): alveolar/ bronchiolar adenoma or carcinoma hemangioma/ hemangiosarcoma (all organs) mammary gland adenocarcinoma, carcinoma, or adenoacanthoma forestomach squamous cell papilloma or carcinoma hepatocellular adenoma or carcinoma Harderian gland adenoma or carcinoma skin sarcoma and Zymbal's gland carcinoma (NTP, 1998)
Note: ADAF -- EPA has concluded that chloroprene is carcinogenic by a mutagenic mode of action. Application of age-dependent adjustment factors (ADAFs) to the inhalation unit risk is recommended in combination with appropriate exposure data when assessing risk associated with early-life exposure.

Jul 2020: External Peer Review of a Report on Physiologically Based Pharmacokinetic (PBPK) Modeling for Chloroprene and a Supplemental Analysis of Metabolite Clearance (July 2020) (Other)

Jan 2018: Systematic Review of Chloroprene: Studies Published Since the 2010 IRIS Assessment to Support Consideration of the Denka Request for Correction (RfC) (Other)

Sep 2010: IRIS Toxicological Review of Chloroprene (Final Report) (Report)

Jul 2010: IRIS Toxicological Review of Chloroprene (Interagency Science Discussion Draft) (Report)

Sep 2009: IRIS Toxicological Review of Chloroprene (External Review Draft) (Report)

Oct 2000: IRIS Toxicological Review of Chloroprene (2000 External Review Draft) (Report)

Aug 1985: Summary Overview of Health Effects Associated with Chloroprene: Health Issue Assessment (Report)

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.

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