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CASRN: 7789380

Update: May 2004

Current Massachusetts Regulatory Limit
MMCL = 0.010 mg/L. ORS has adopted the MCL adopted by U.S. EPA under the Disinfectants and Disinfection Byproducts Rule (Fed/ Reg. 1998). 

Federal Regulatory Limit
The MCL for bromate was set at its detection limit of 0.010 mg/L. The MCLG for bromate is zero (Fed. Reg., 1998). 

Basis for Criteria
Bromate is one of the principal byproducts of ozonation in bromide-containing source waters and is addressed under the EPA's Disinfectants and Disinfection Byproducts Rule. Bromate is likely to be carcinogenic in humans. An MCLG of zero is assigned for bromate based on carcinogenic effects. The MCL is based on the bromate PQL.

Critical Effects
Potassium bromate was fed to male F344/N rats at dose levels of 0, 1.1, 6.1, 12.9, and 28.7 mg BrO3-/kg-day and to B6C3F1 mice at dose levels of 0, 6.9, 32.5, and 59.6 mg BrO3-/kg-day. The Maximum Tolerated Dose was reached in the rat study. Statistically significant increases occurred in absolute liver weight, relative and absolute kidney and thyroid weight, and relative spleen weight. A significant dose-dependent increase in the incidence of urothelial hyperplasia in rats was seen in dose groups of 6.1 mg/kg-day and higher. Other effects noted in rats included foci of mineralization of the renal papilla and eosinophilic droplets in the proximal tubule epithelium. A NOAEL of 1.1 mg BrO3-/kg-day and a LOAEL of 6.1 mg BrO3-/kg-day were identified from this study. No effects other than a statistically increased drinking water consumption rate at the highest dose was observed in the mouse study. A NOAEL of 59.6 mg BrO3-/kg-day is the freestanding NOAEL in mice (DeAngelo et al.,1998). 

Cancer Assessment 
Likely To Be Carcinogenic to Humans/B2

Oral cancer risk was calculated based on the incidence of renal tubular tumors, thyroid follicular tumors, and testicular mesotheliomas from the DeAngelo et al. (1998) study.

Oral Cancer Potency Factor = 7 x 10-1 (mg/kg/day)-1 (U.S. EPA, 2001)

inorganic ion

Analytical Information
: The PQL used as the basis for the MCL is 0.010 mg/L.

Analytical Methods
US EPA Method 300.1

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

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

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.

DeAngelo, A.B., George, M.H., Kilburn, S.R. et al. 1998. Carcinogenicity of potassium bromate administered in the drinking water to male B6C3F1 mice and F344/N rats. Toxicol Pathol 26(5):587-594.

Federal Register. December 16, 1998. Part IV. Environmental Protection Agency. 40 CFR Parts 9, 141, and 142. National Primary Drinking Water Regulations; Disinfectants and Disinfection Byproducts; Final Rule. (63 FR 69390).

U.S. EPA. June 6, 2001. Integrated Risk Information System (IRIS). U.S. Environmental Protection Agency. Washington, D.C.