Dichloromethane CASRN 75-09-2 | IRIS

IRIS

Dichloromethane

CASRN 75-09-2 | DTXSID0020868

Toxicological Review (PDF) (567 pp, 5.1 M)
IRIS Summary (PDF) (44 pp, 337 K)

Noncancer Assessment

Reference Dose for Oral Exposure (RfD) (PDF) (44 pp, 337 K) Last Updated: 11/18/2011

System	RfD (mg/kg-day)	Basis	PoD	Composite UF	Confidence
Hepatic	6 x 10 ^-3	Hepatic effects (hepatic vacuolation, liver foci)	BMDL ₁₀ (HED): 0.19 mg/kg-day	30	High

Reference Concentration for Inhalation Exposure (RfC) (PDF) (44 pp, 337 K) Last Updated: 11/18/2011

System	RfC (mg/m³)	Basis	PoD	Composite UF	Confidence
Hepatic	6 x 10 ^-1	Hepatic effects (hepatic vacuolation)	BMDL ₁₀ (HEC): 17.2 mg/m³	30	Medium/High

Cancer Assessment

Weight of Evidence for Cancer (PDF) (44 pp, 337 K) Last Updated: 11/18/2011

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

Basis:

Following U.S. EPA (2005) Guidelines for Carcinogen Risk Assessment, dichloromethane is "likely to be carcinogenic in humans," based predominantly on evidence of carcinogenicity at two sites in 2-year bioassays in male and female B6C3F1 mice (liver and lung tumors) with inhalation exposure (NTP, 1986) and at one site in male B6C3F1 mice (liver tumors) with drinking water exposure (Serota et al., 1986b; Hazleton Laboratories, 1983).
This may be a synopsis of the full weight-of-evidence narrative.

Quantitative Estimate of Carcinogenic Risk from Oral Exposure (PDF) (44 pp, 337 K)

Oral Slope Factor: 3.3 x 10^-3 per mg/kg-day
Extrapolation Method: Multistage model with linear extrapolation from the point of departure (BMDL₁₀), includes application of age-dependent adjustment factors (ADAFs).
Tumor site(s): Hepatic
Tumor type(s): Hepatocellular carcinomas or adenomas (Serota et al., 1986b)
Note: EPA has concluded that dichloromethane is carcinogenic by a mutagenic mode of action. Thus, based on the EPA cancer guidelines (2005), the oral slope factor (OSF) addressing lifetime exposure includes application of ADAFs. The OSF is recommended for lifetime exposures. EPA has also provided an adult-based cancer slope factor of 2 x 10^-3 per mg/kg-day. This adult-based cancer slope factor can be used instead of the OSF when assessing cancer risk associated with exposure scenarios that don’t include early life (< 16 years of age) or when other calculations by the user are necessary (e.g., when applying ADAFs to age-specific exposure estimates).

Quantitative Estimate of Carcinogenic Risk from Inhalation Exposure (PDF) (44 pp, 337 K)

Inhalation Unit Risk: 1.7 x 10^-8 per µg/m³
Extrapolation Method: Multistage model with linear extrapolation from the point of departure (BMDL₁₀), includes application of age-dependent adjustment factors (ADAFs).
Tumor site(s): Hepatic, Respiratory
Tumor type(s): Hepatocellular carcinomas or adenomas, bronchoalveolar carcinomas or adenomas (Mennear et al., 1988; NTP, 1986)
Note: EPA has concluded that dichloromethane is carcinogenic by a mutagenic mode of action. Thus, based on the EPA cancer guidelines (2005), the inhalation unit risk (IUR) addressing lifetime exposure includes application of ADAFs. The IUR is recommended for lifetime exposures. EPA has also provided an adult-based cancer unit risk of 1 x 10^-8 per µg/m³. This adult-based cancer unit risk can be used instead of the IUR when assessing cancer risk associated with exposure scenarios that don’t include early life (< 16 years of age) or when other calculations by the user are necessary (e.g., when applying ADAFs to age-specific exposure estimates).

Nov 2011: IRIS Toxicological Review of Dichloromethane (Methylene Chloride) (Final Report) (Report)

Aug 2011: IRIS Toxicological Review of Dichloromethane (Methylene Chloride) (Interagency Science Discussion Draft) (Report)

Mar 2010: IRIS Toxicological Review of Dichloromethane (Methylene Chloride) (External Review Draft) (Report)

Sep 2009: IRIS Toxicological Review of Dichloromethane (Methylene Chloride) (Interagency Science Consultation Draft) (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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