Return to Standards Table

ETHYLENE DIBROMIDE [6]
CASRN: 106934

Update: September 2004

Current Massachusetts Regulatory Limit
MMCL = MMCL = 0.02 ug/L. ORS has lowered the MCL of 0.05 ug/L published by the U.S. EPA as part of the Phase II rule (56 FR 3526; 1/30/91) to 0.02 ug/L.

Federal Regulatory Limit
The MCLG is set to zero based on evidence of carcinogenic potential of ethylene dibromide (EDB). The U.S. EPA MCL is based on the PQL of EDB.

Basis for Criteria
The U.S. EPA promulgated an MCL for EDB of 0.05 ug/L as part of the SDWA Phase II Standards. The Office of Research and Standards (ORS) decided to establish an MMCL lower than the U.S. EPA MCL based on the ability of laboratories in Massachusetts to achieve the 0.02 ug/L detection limit. Establishing a lower limit for the EDB standard is consistent with the goal of ORS to set levels of potentially carcinogenic compounds in Massachusetts drinking waters as close to the concentration which produces an Excess Lifetime Cancer Risk of one in one million or less as is feasible.

In July 2004, the U.S. EPA developed a cancer slope factor of 2 (mg/kg/day)-1 based on an oral gavage study in rats (NCI, 1978) and using the benchmark dose model. Coincidentally, the updated MMCL based on a 1 x 10-6 risk level is identical to the old value set at the PQL.

Critical Effects
The target organs affected by EDB exposure include the lung, liver, spleen, kidney and central nervous system. Repeat exposure may produce effects on the liver, stomach and adrenal cortex along with significant reproductive system toxicity (Fed Reg, 1985).

Cancer Assessment: 
B2

The group B2 cancer classification is based on evidence of increased tumor incidence in rodents. EDB has been tested for carcinogenicity by gavage, inhalation and dermal administration. The NCI (1978), administered TWA doses of 27 and 29 mg/kg/d to male and 26 and 28 mg/kg/d to female rats by gavage for 49 and 61 weeks respectively. Significant increased incidence of squamous cell carcinomas of the stomach (both sexes), hepatocellular carcinomas and neoplastic nodules in the liver (females) and angiosarcomas of the circulatory system (males) were observed upon histological evaluation. The stomach tumors developed after a short latency period and were observed to metastasize to multiple sites.

Class
Dibrominated Nematocide

Analytical Information
PQL
: 0.02 ug/L

Analytical Methods
U.S. EPA 504; microextraction GC

PQLs and analytical methods may have been updated since this guidance value was last revised. Updated analytical methods for drinking water and their associated PQLs may be found at http://www.epa.gov/safewater/methods/methods.html.

Other Regulatory Data
Any Health Advisories, Reference Doses (RfDs), cancer assessments or Cancer Potency Factors (CPFs) referenced in this document pertain to the derivation of the current guidance value. Updated information may be obtained from the following sources:

Health Advisories - The U.S. EPA provides guidance for shorter-term exposures for chemicals based on their non-cancer effects. Current health advisories may be more current than those used to derive MCLs and may be found at http://www.epa.gov/waterscience/drinking/standards/dwstandards.pdf.

RfDs, cancer assessments and CPFs - For specific information pertaining to derivation of drinking water criteria, consult the Federal Register notice that announces the availability of the most current guidance for that chemical. In addition, information on other current RfDs and CPFs as well as cancer assessments for specific chemicals may be found in the U.S. EPA Integrated Risk Information System (IRIS) at http://www.epa.gov/iris/. Please note that the information in IRIS may differ from that used in the derivation process as published in the Federal Register notice.

References
Federal Register. November 13, 1985. Part IV. Environmental Protection Agency. 40 CFR Part 141. National Primary Drinking Water Regulations: Synthetic Organic Chemicals, Inorganic Chemicals and Microorganisms; Proposed Rule. (50 FR 46936).

Federal Register. January 30, 1991. Part II. Environmental Protection Agency. 40 CFR Parts 141, 142, and 143. National Primary Drinking Water Regulations; Final Rule. (56 FR 3526).

NCI (National Cancer Institute) 1978. Bioassay of 1,2-dibromoethane for possible carcinogenicity, CAS No. 106934. NCI Carcinogenicity Tech. Rep. Sec. No. 86 PB-288-428, p. 64. [Also published in CHHA (NIH) 78-1336].