Agent Name

2-Methyl-4-chlorophenoxyacetic acid

Alternative Name


CAS Number




Major Category



MCPA; ((4-Chloro-o-tolyl)oxy)acetic acid; (4-Chloro-2-methylphenoxy)acetic acid; 2,4-MCPA; 2-Methyl-4-chlorphenoxyessigsaeure [German]; 2M-4Ch; 2M-4Kh; 4-Chloro-o-cresoxyacetic acid; 4-Chloro-o-toloxyacetic acid; 4K-2M; Acme MCPA Amine 4; Agroxon; Agroxone; Anicon M; Anicon kombi; B-Selektonon M; BH Mcpa; Banvel M; Bordermaster; Brominal M & plus; Chiptox; Chwastox 30; Chwastox Extra; Cornox-M; Dicopur-M; Emcepan; Empal; Hedapur M 52; Hedarex M; Hedonal M; Herbicide M; Hormotuho; Hornotuho; Kilsem; Krezone; Kwas 4-chloro-2-metylofenoksyoctowy [Polish]; Kyselina 4-chlor-2-methylfenoxyoctova [Czech]; Legumex DB; Leuna M; Leyspray; Linormone; M 40; MCP; Mephanac; Metaxon; Methoxone; Methylchlorophenoxyacetic acid; Netazol; Okultin M; Phenoxylene 50; Phenoxylene plus; Phenoxylene super; Raphone; Razol dock killer; Rhomenc; Rhomene; Rhonox; Seppic MMD; Shamrox; Soviet technical herbicide 2M-4C; Trasan; U 46 M-Fluid; Ustinex; Vacate; Vesakontuho MCPA; Weedar MCPA Concentrate; Weedone MCPA ester; Zelan; [ChemIDplus] UN3345


Herbicides, Chlorophenoxy


White solid; [Hawley] Slightly beige solid; [MSDSonline]


Used as a post-emergence herbicide for control of annual and perennial broad leaved weeds in cereals, herbage seed crops, flax, rice, vines, peas, potatoes, asparagus, grassland, turf, orchards, roadsides, forestry, and aquatic areas; [HSDB]


A skin, eye, and respiratory tract irritant; May be toxic to human reproduction or development, based on animal studies; [ICSC] May cause skin, eye, nose, and throat irritation; Effects in high dose oral studies of rats include histopathological changes to liver, kidneys, and spleen; [HSDB] Based on animal studies, not likely to cause congenital defects; No human data available; [REPROTOX] Chlorophenoxy herbicides are possibly carcinogenic to humans (Group 2B), but "No adequate data were available on the carcinogenicity of MCPA." [IARC] See "2,4-D."

Exposure Assessment
Vapor Pressure

5.9E-6 mm Hg

Lethal Concentration

LC50 (rat) = 1,370 mg/m3/4h

Explanatory Notes

The Guide in the Emergency Response Guidebook is for "Phenoxyacetic acid derivative pesticide, solid, toxic."

Reference Link

eChemPortal IUCLID Dataset: 2-Methyl-4-chlorophenoxyacetic acid 2000

Adverse Effects

Hepatotoxin, Secondary

Links to Other NLM Databases
Health Studies

Human Health Effects from Hazardous Substances Data Bank:

Toxicity Information


Chemical Information

Search ChemIDplus

Biomedical References

Search PubMed

Related Information in HazMap

Industrial Processes with risk of exposure: