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CASRN: 145733

Update: August 1993

Current Massachusetts Regulatory Limit
MMCL = 0.1 mg/L. ORS has adopted the MCL published by the U.S. EPA as part of the Phase V rule (57 FR 31776: 7-17-92).

Federal Regulatory Limit
The MCL for endothall is equal to the MCLG of 0.1 mg/L.

Basis for Criteria

The MCLG is derived based on the RfD presented below and assuming that a 70 kg adult ingests 2 L/day drinking water. A 20% relative source contribution factor is incorporated in this value.

RfD: 2 x 10-2 mg/kg/day
UF: 100 (10 for intra-species; 10 for inter-species)
MF: 1 Confidence in RfD: Medium

Purebred beagle dogs were fed diets containing 1, 100, 300 or 800 mg disodium endothall per kg of diet for 24 months. The intermediate and high dose levels dogs exhibited increased organ weight and organ to body weight ratios of stomach and small intestine. A NOAEL of 2 mg/kg/day was identified from this study (Fed Reg, 1992).

Critical Effects
Acute exposure to endothall for relatively short periods of time at levels above the MCL may cause depressed breathing and heart rate. Longer-term exposure at levels above the MCL may result in increased organ weights and increased organ to body weight ratios of stomach and intestine.

Cancer Assessment: 

There is inadequate evidence to state whether endothall has the potential to cause cancer from lifetime exposure in drinking water.


Analytical Information
: 0.009 mg/L 

Analytical Methods
U.S. EPA Method 548.1

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 US EPA Drinking Water Analytical Methods .

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 US EPA Current Drinking Water Health Advisories .

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 Please note that the information in IRIS may differ from that used in the derivation process as published in the Federal Register notice.

Federal Register. July 25, 1990. Part II. Environmental Protection Agency. 40 CFR Part 141 et al. National Primary and Secondary Drinking Water Regulations; Synthetic Organic Chemicals and Inorganic Chemicals; Proposed Rule. (55 FR 30370)

Federal Register. July 17, 1992. Part III. Environmental Protection Agency. 40 CFR Parts 141 and 142. National Primary Drinking Water Regulations; Synthetic Organic Chemicals and Inorganic Chemicals; Final Rule. (57 FR 31776).