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DICHLOROPHENOXYACETIC ACID (2,4-D)
CASRN: 94757

Update: November 1993

Current Massachusetts Regulatory Limit
MMCL: 0.07 mg/L. ORS has adopted the MCL published by the U.S. EPA as part of the Phase II rule (56 FR 3526; 1/30/91). 

Federal Regulatory Limit
The MCL is equal to the MCLG of 0.07 mg/kg/day. 

Basis for Criteria
The MCLG is based on liver and kidney effects seen in test animals. The MCLG of 0.07 mg/L is based on the RfD presented below and assumes that a 70 kg adult ingests 2 L/day of water. The MCLG incorporates a relative source contribution factor of 0.2.

RfD: 1 x 10-2 mg/kg/day
UF: 100 (10 = intraspecies; 10 = interspecies) MF: 1

Critical Effects
The RfD is based on the results of a 90 day rat oral bioassay. (Dow 1983) In this study, hematological, hepatic and renal toxicity were demonstrated. 2,4-D was fed to rats at doses of 0, 1, 5, 15 or 45 mg/kg/day. A NOAEL of 1 mg/kg/day was identified from this study. 

Cancer Assessment
2,4-D has been classified in U.S. EPA's Group D for carcinogenicity, based upon inadequate data from animal studies. 

Class
Phenoxy Herbicide

Analytical Information

Analytical Methods
515.1 GC/ECD

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
Dow Chemical Company. 1983. Accession No. 251473. Available from U.S. EPA. Write to FOI, U.S. EPA, Washington, D.C.

Federal Register. July 1, 1991. Environmental Protection Agency. 40 CFR Parts 141, 142, and 143. National Primary Drinking Water Regulations; Monitoring for Volatile Organic Chemicals; MCLGs and MCLs for Aldicarb, Aldicarb Sulfoxide, Aldicarb Sulfone, Pentachlorophenol, and Barium; Final Rule. (56 FR 30266).