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BARIUM
CASRN: 7440393

Update: August 1993

Current Massachusetts Regulatory Limit
MMCL = 2 mg/L. ORS has adopted the MCL that U.S. EPA promulgated as part of the Phase II Rule. 

Federal Regulatory Limit
The MCL of 2 mg/L is equal to the MCLG (Fed. Reg. 1991a, 1991b, 1991c). 

Basis for Criteria
The MCLG is based on the RfD (presented below) derived from the Wones et al., study. It assumes that a 70 kg adult ingests 2 L/day of water. Since this value is based on a human study that considers contributions from food and air, no relative source contribution was applied for drinking water exposures.

RfD = 7 x 10-2 mg/kg/day
UF = 3; MF = 1; Confidence in RfD: Medium

The MCLG is based on a NOAEL of 7.5 mg/L identified from the Wones et al., 1990 study in humans (Fed. Reg. 1991c).


Critical Effects
The critical effect is increased blood pressure in human subjects. The RfD is based on an adjusted NOAEL of 0.21 mg/kg/d derived from a subchronic drinking water study in humans (Wones et al., 1990). 

Cancer Assessment D
There is currently no cancer assessment for barium.
 

Class
Heavy barium

Analytical Information

Analytical Methods
208.2 GF AA
200.7A ICP

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

Federal Register. January 30, 1991b. Part III. Environmental Protection Agency. 40 CFR Parts 141 and 142. National Primary Drinking Water Regulations; Proposed Rule. (56 FR 3600).

Federal Register. July 1, 1991c. Part XII. Environmental Protection Agency. 40 CFR Parts 141, 142, and 143. National Primary Drinking Water Regulations; Final Rule.(56 FR 30266).

Wones, R.G., B.L. Stapler and L.P. Frohman. 1990. Lack of Effect of Drinking Water Barium on Cardiovascular Risk Factor. Environ. Health Perspect. 85: 1-13.