United States
Environmental Protection
Agency
Office of Water
4601
EPA 811-F-9 5-003 z-T
October 1995
National Primary Drinking
Water Regulations
Picloram
CHEMICAL/PHYSICAL PROPERTIES
CAS NUMBER: 1918-02-1
COLOR/ FORM/ODOR:
Colorless crystals or powder with a
chlorine-like odor; forms water soluble
salts
M.P.: 218-219° C B.P.: _° C
VAPOR PRESSURE: 6.2x1 O*7 mm Hg, 25° C
OCTANOL/WATER PARTITION (Kow):
DENSITY/SPEC. GRAV.: N/A
N/A
SOLUBILITY: 430 mg/L of water at 25° C;
Soluble in water
SOIL SORPTION COEFFICIENT:
Kocaverage= 13; moderate mobility
in soil
ODOR/TASTE THRESHOLDS: N/A
BlOCONCENTRATION FACTOR:
BCF=31 in fish; not expected to
bioconcentrate in aquatic organisms.
HENRY'S LAW COEFFICIENT:
N/A; negligible volatilization
TRADE NAMES/SYNONYMS:
4-amino-3,5,6-trichloropicolinicacid;
"Agent White"; Tordon
DRINKING WATER STANDARDS
MCLG: 0.5 mg/L
MCL: 0.5 mg/L
HAt(child): 1- to 10- day: 20 mg/L
Longer-term: 0.7 mg/L
WEALTH EFFECTS SUMMARY
Acute: EPA has found picloram to potentially cause
the following health effects frorh acute exposures at
levels above the MCL: damage to central nervous sys-
tem, weakness, diarrhea, weight loss.
Drinking water levels which are considered "safe" for
short-term exposures: For a 10-kg (22 Ib.) child consum-
ing 1 liter of water per day, a one- to ten-day exposure to
20 mg/L or up to a 7-year exposure to 0.7 mg/L.
Chronic: Picloram has the potential to cause the
following health effects from long-term exposures at
levels above the MCL: liver damage.
Cancer: There is inadequate evidence to state whether
or not picloram has the potential to cause cancer from a
lifetime exposure in drinking water.
USAGE PATTERNS
Picloram is a systemic herbicide used in salt form for
controlling annual weeds on crops, and in combination
l/ith 2,4-D or 2,4,5-T against perennials on non-crop-
lands for brush control.
Picloram is used to control bitterweed, knapweed,
leafy spurge, locoweed, larkspur, mesquite, prickly pear,
and snakeweed on rangeland in the western states.
EPA estimates that 300,000 Ibs. of picloram were
produced in the US in 1982.
RELEASE PATTERNS
Picloram is released to the environment primarily from
its application as a herbicide, and also during its produc-
tion and handling. Since picloram is not a listed chemical
in the Toxics Release Inventory, data on releases during
its manufacture and handling are not available.
ENVIRONMENTAL FATE
Picloram is the most persistent of the chlorobenzoic
acid herbicides.
If picloram is released to soil it will not be expected to
adsorb to the soil and may leach to groundwater, a
conclusion supported by the detection of picloram in
some groundwater samples. However, picloram is an
aromatic amine, and some aromatic amines have been
shown to bind to humic materials which may be present
in some moist soils; this binding may decrease leaching
processes. It will not be expected to hydrolyze or evapo-
rate from soils or surfaces. It may be subject to significant
biodegradation in soils and ground water, with reported
half-lives in soils ranging from 55-100 days or more.
If released to water it will not be expected to adsorb to
sediments, to evaporate, or to appreciably hydrolyze. It
will be subject to significant near surface photolysis with
reported half-lives ranging from 2.3-41.3 days. Based on
biodegradation in soils and groundwater, it may be sub-
ject to degradation in surface waters. As an aromatic
amine, its rate of degradation in water and soil mav be
October 1995
Technical Version
-------
increased due to oxidation by free radicals, adsorption to
humic materials followed by oxidation, and catalytic
oxidation by cations, although no experimental data
specific to picloram were found.
If released to the atmosphere it will be subject to
significant deposition and washout due to its low vapor
pressure (will adsorb to particulate matter) and significant
water solubility. It may also be subject to significant direct
photolysis. The estimated vapor phase half-life in the
atmosphere is 12.21 days as a result of reaction with
photochemically produced hydroxyl radicals.
Picloram is not expected to bioconcentrate in aquatic
organisms based on a reported BCF of 31 in fish and
estimated BCFs of 1 to 20.
General human exposure will occur mainly through its
manufacture and use as a herbicide.
OTHER REGULATORY INFORMATION
MONITORING:
FOR GROUND/SURFACE WATER SOURCES:
INITIAL FREQUENCY- 4 quarterly samples every 3 years
REPEAT FREQUENCY- If no detections during initial round:
2 quarterly per year if serving >3300 persons;
1 sample per 3 years for smaller systems
TRIGGERS - Return to Initial Freq. if detect at >. 0.0001 mg/L
ANALYSIS:
REFERENCE SOURCE METHOD NUMBERS
EPA 600/4-88-039 515.1; 515.2; 555
TREATMENT:
BEST AVAILABLE TECHNOLOGIES
Granular Activated Charcoal
FOR ADDITIONAL INFORMATION:
4 EPA can provide further regulatory and other general information:
• EPA Safe Drinking Water Hotline - 800/426-4791
4 Other sources of lexicological and environmental fate data include:
• Toxic Substance Control Act Information Line - 202/554-1404
• Toxics Release Inventory, National Library of Medicine - 301/496-6531
• Agency for Toxic Substances and Disease Registry - 404/639-6000
• National Pesticide Hotline - 800/858-7378
October 1995
Technical Version
Page 2
------- |