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TRADE OR OTHER NAMES: Mecoprop is commonly called MCPP. Trade names include Kilprop, Mecopar,Triester-II,
Mecomin-D, Triamine-II (with MCPA and 2.4-DP), Triplet (with 2,4-D and dicamba), TriPower (with MCPA and
dicamba), Trimec (with 2,4-D and dicamba), Trimec-Encore (with MCPA and dicamba), and U46 KV Fluid (41, 43).
REGULATORY STATUS: Mecoprop is a general use pesticide (GUP).
INTRODUCTION: Mecoprop is a selective, hormone-type phenoxy herbicide. It is applied postemergence and is used on
ornamentals and sports turf, for forest site preparation, and on drainage ditch banks for selective control of surface creeping
broadleaf weeds such as clovers, chickweed, lambsquarters, ivy, plantain and others. It is also used on wheat, barley, and
oats (41, 43). Mecoprop is absorbed by plant leaves and translocated to the roots. It affects enzyme activity and plant
growth (6). It acts relatively slowly requiring three to four weeks for control (43). The U.S. EPA has classified mecoprop as
toxicity class III- slightly toxic. Products containing mecoprop bear the Signal Word "Caution" (41). It is available as a
liquid concentrate, granules, and is sprayed on fertilizer pellets to produce weed and feed products (45).
- Acute Toxicity: Mecoprop has a low acute toxicity to test animals. The LD50, the oral dose that kills half of the test
animals, is 930 -1210 mg/kg for rats and 650 mg/kg for mice (41, 43, 44). The LD50 for rats exposed dermally is greater
than 4000 mg/kg (41, 40). Mecoprop is irritating to skin and eyes. It causes redness and swelling and can cause cloudy
vision (46). The concentration in air which kills half of the test animals, the LC50 (4 hours) for rats, is greater than 12.5
mg/l air (6).
- Chronic Toxicity: No information is currently available.
- Reproductive Effects: No information is currently available.
- Teratogenic Effects: Mecoprop is a teratogen in rats at moderate to high doses. Oral doses of 125 mg/kg/day of MCPP
in pregnant rats from days 6 to 15 of gestation caused increased intra-uterine deaths, decreased body lengths, and an
increased incidence of delayed or absent bone formation in offspring. Mecoprop is not teratogenic in rabbits (45).
- Mutagenic Effects: Studies show that mecoprop may be mutagenic at very high doses. Tests of mecoprop on four
strains of salmonella and on s. colelicolor showed no mutagenic effects (43). However, MCPP caused an increase in
sister chromatid exchange after single oral doses of 470 and 3,800 mg/kg in Chinese hamsters (45).
- Carcinogenic Effects: A study of people employed in the manufacture of phenoxy herbicides including mecoprop
showed an association between these herbicides and cancer of soft tissues and non-Hodgkin's lymphoma (47). However,
other data do not support this conclusion (49). Thus, it is not clear if occupational exposures to phenoxy herbicides can
- Organ Toxicity: Oral doses of 9 mg/kg/day to female rats and 27 mg/kg/day to male rats cause kidney damage (45).
- Fate in Humans and Animals: Mecoprop is eliminated unchanged in the urine of mammals(6).
- Effects on Birds: Mecoprop is practically non-toxic to birds. The LC50 is greater than 5,620 ppm for mallard ducks and
5,000 ppm for bobwhite quail (45). The LD50 (oral) is 740 mg/kg for Japanese quail and 700 mg/kg for bobwhite quail
- Effects on Aquatic Organisms: Mecoprop is virtually non-toxic to fish. Available data indicate a low potential of
mecoprop to bioaccumulate in fish (45). The LC50 (96 hours) is 124 ppm for rainbow trout and greater than 100 ppm
for bluegill sunfish (6, 45).
- Effects on Other Animals (Nontarget species): Mecoprop is not toxic to bees (41).
- Breakdown of Chemical in Soil and Groundwater: The duration of mecoprop's residual activity in soil is about two
months. Adsorption of mecoprop increases with an increase in organic matter in the soil. Unaged MCPP and its salt
forms are very mobile in a variety of soils (6). Because of this high mobility, it may potentially leach into groundwater
(45). However, in general, phenoxy herbicides such as MCPP are not sufficiently persistent to reach groundwater (45).
- Breakdown of Chemical in Surface Water: No information is currently available.
- Breakdown of Chemical in Vegetation: No information is currently available.
PHYSICAL PROPERTIES AND GUIDELINES
It exists as a mixture of two optically active isomers of which one, the R+ form, mecoprop-p is herbicidally active (6). It is
stable to heat, hydrolysis, reduction, and oxidation. It is acidic. Solutions of the salts of mecoprop are stable for several
years under normal storage conditions. In cooler temperatures, the salt may crystallize out of solution but will re-dissolve on
warming (41, 45).
Physical Properties: Properties are of the acid form unless otherwise noted.
- Appearance:Mecoprop is an odorless, white to light brown crystalline solid.
- Chemical Name: 2-(4-chloro-2-methyl phenoxy) propionic acid
- CAS Number: 7085-19-0 (acid) 1929-86-8 (potassium salt) 1432-14-0 (diethanolamine salt) 28473-03-2 (isooctyl
- Molecular Weight: 214.6
- Water Solubility: all forms are very soluble in water at 20 degrees C (6)Soluble in acetone, alcohol, benzene, diethyl
ether, and ethyl acetate (6)
- Solubility in Other Solvents: In acetone, diethyl ether, ethanol > 1000
- Melting Point: 94-95 degrees C (6)
- Vapor Pressure: 0.31 mPa (20 degrees C)
- Partition Coefficient: 1.26 at pH 7 (6)
- Adsorption Coefficient: Not Available
Exposure Guidelines: Guidelines are for the acid form unless otherwise noted.
- ADI: Not Available
- MCL: Not Available
- RfD: 1 x 10 to the minus 3 mg/kg/day (48)
- PEL: Not Available
- HA: Not Available
- TLV: Not Available
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References for the information in this PIP can be found in Reference List Number 7
DISCLAIMER: The information in this profile does not in any way replace or supersede the information on the pesticide
product label/ing or other regulatory requirements. Please refer to the pesticide product label/ing.