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CASRN: 1918021

Update: August 1993

Current Massachusetts Regulatory Limit
MMCL = 0.5 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 picloram is equal to the MCLG of 0.5 mg/L

Basis for Criteria
The MCLG is derived based on the RfD presented below and assumes that a 70 kg adult ingests 2 L/day of drinking water. A relative source contribution factor of 20% is incorporated into the final value.

RfD: 7 x 10-2 mg/kg/day
UF: 100 (10 = interspecies; 10 = intraspecies)
MF: 1 Confidence in RfD: Medium

Critical Effects
Acute exposure to picloram for relatively short periods of time at levels above the MCL could result in damage to the central nervous system, weakness, diarrhea and weight loss. Chronic lifetime exposure to concentrations above the MCL may produce liver damage.

Reduced food consumption and reduced body weight were observed at 175 mg/kg/day in a dog study in which male and female dogs (6/sex/group) were fed diets containing 0, 7, 35, or 175 mg/kg/day of picloram. Increased absolute and relative liver weights were also noted at 35 mg/kg/day in males and 175 mg/kg/day in males and females. Elevated serum alkaline phosphatase was also noted at 175 mg/kg/day. The RfD was based on a NOEL of 7 mg/kg/day (U.S. EPA, 1992).

Cancer Assessment: D
There is inadequate evidence to state whether or not picloram has the potential to cause cancer from a lifetime exposure in drinking water.

Chlorinated organic

Analytical Information
: 0.001 mg/L

Analytical Methods
U.S. EPA Methods 515.1; 515.2; 555

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).

U.S. EPA (U.S. Environmental Protection Agency). May 1, 1992. Integrated Risk Information System (IRIS). U.S. Environmental Protection Agency. Washington, D.C.