MCPA

Substance overview Plus
Name:
MCPA
CAS Number:
94-74-6
Synonyms:
2-Methyl-4-chlorophenoxyacetic acid
Approval number:
HSR003327, Approved with controls
UN Class:
 
UN Number:
 
Molecular weight:
200.6213
Relative density:
1.56
Water solubility:
273.9 mg/L
Classification Acute Tox. 4 Plus
Classification route species:
(dermal)
Classification description:
H312: Harmful in contact with skin.
Classification key study:

Oral Route
SPECIES: Mouse
ENDPOINT: LD50
VALUE: 439 mg/kg
REFERENCE SOURCE: Lewis, R.J. Saxs Dangerous Properties of Industrial Materials. 9th ed. Volumes 1-3. New York, NY: Van Nostrand Reinhold, 1996. 791 **PEER REVIEWED** [HSDB]

Classification Acute Tox. 4 Plus
Classification route species:
(oral)
Classification description:
H302: Harmful if swallowed.
Classification key study:

Oral Route
SPECIES: Mouse
ENDPOINT: LD50
VALUE: 439 mg/kg
REFERENCE SOURCE: Lewis, R.J. Saxs Dangerous Properties of Industrial Materials. 9th ed. Volumes 1-3. New York, NY: Van Nostrand Reinhold, 1996. 791 **PEER REVIEWED** [HSDB]

Classification Acute Tox. 4 Plus
Classification route species:
(inhalation)
Classification description:
H332: Harmful if inhaled.
Classification key study:

Oral Route
SPECIES: Mouse
ENDPOINT: LD50
VALUE: 439 mg/kg
REFERENCE SOURCE: Lewis, R.J. Saxs Dangerous Properties of Industrial Materials. 9th ed. Volumes 1-3. New York, NY: Van Nostrand Reinhold, 1996. 791 **PEER REVIEWED** [HSDB]

Classification Eye Damage 1 Plus
Classification route species:
 
Classification description:
H318: Causes serious eye damage.
Classification key study:

Eye Irritation
R-PHRASE: R 41 [IUCLID] [NCLASS]

Classification STOT Rep. Exp. 1 Plus
Classification route species:
 
Classification description:
H372: Causes damage to organs <or state all organs affected, if known> through prolonged or repeated exposure <state route of exposure if it is conclusively proven that no other routes of exposure cause the hazard>.
Classification key study:
Repeated dose toxicity:

Oral Route
Primary Organ Effected: Renal toxicity (Kidney)
Secondary Organ(s) Effected: Renal toxicity (Kidney)
Short-term studies of toxicity of less than 12 months’ duration using MCPA, MCPA 2-EHE
or MCPA DMA were performed in rats and dogs. In a 3-month study in rats, the NOAEL was 150 ppm (equal to 12 mg/kg bw per day) for increased serum creatinine and kidney weight at 450 ppm (equal to 35 mg/kg bw per day). In dogs, the overall NOAEL from five studies of 13 or 52 weeks’ duration was 6 ppm (equal to 0.2 mg/kg bw per day) for increased serum creatinine and urea and increased pigmentation in the proximal tubules at 30 ppm (equal to 1 mg/kg bw per day).
The Meeting concluded that the dog was an unsuitable surrogate for humans because of its relatively low renal capacity to excrete MCPA ion, leading to higher toxicity than in other species. Therefore, the Meeting established an ADI of 0–0.1 mg/kg bw per day for MCPA ion, based on the overall NOAEL of 12 mg/kg bw per day from four subchronic studies in rats for changes in clinical chemistry parameters indicative of effects on the kidneys at 35 mg/kg bw per day and using a 100-fold safety factor.

Classification Aquatic Acute 1 Plus
Classification route species:
 
Classification description:
H400: Very toxic to aquatic life.
Classification key study:
Bioaccumulation: Bioaccumulative: No
A BCF of 1 was determined for trout at MCPA aqueous concns of 10-100 mg/l and using an exposure period of 10-28 day(1). In a model aquatic ecosystem study, BCFs of <1 were measured in fish and snails for the sodium salt of 2-methyl-4-chlorophenoxyacetic acid(2,3). According to a classification scheme(3), these BCF values suggest the potential for bioconcentration in aquatic organisms is low. MCPA is absorbed through leaves or roots and is readily translocated in plants(4). ((1) Murty AS; Tox of Pest to Fish, Vols I, II; CRC Press, FL pp. 70, 74 (1986) (2) Virtanen M et al; Chemosphere 7: 431-42 (1979) (3) Franke C et al; Chemosphere 29: 1501-14 (1994) (4) Ahrens WH; Herbicide Handbook of the Weed Science Society of America 7th ed. Champaign, IL: Weed Sci Soc Amer p. 182 (1994))**PEER REVIEWED**
[HSDB]
Biodegradation in water: readily biodegradable
Short term toxicity to fish: SPECIES: Oncorhynchus mykiss (Rainbow trout)
TYPE OF EXPOSURE: Static
DURATION: 96 hr
ENDPOINT: LC50
VALUE: 91 ppm (= 91 mg/l)
REFERENCE SOURCE: [USEPA PESTICIDES DATABASE]

Toxicity to freshwater algae and cyanobacteria: Chronic Endpoint: NOEC
Chronic Value: <0.014 mg/L
ACUTE
SPECIES: Navicula pelliculosa (Algae)
TYPE OF EXPOSURE:
DURATION: 96 hr
ENDPOINT: EC50
VALUE: 0.21 mg/l
REFERENCE SOURCE: AH Marks and Company Ltd Bradford [IUCLID]
CHRONIC
SPECIES: other aquatic plant
TYPE OF EXPOSURE:
DURATION: 14 day
ENDPOINT: NOEC
VALUE: < 0.014 mg/l
REFERENCE SOURCE: AH Marks and Company Ltd Bradford [IUCLID]
Classification Hazardous to soil organisms
Hazardous to terrestrial vertebrates Plus
Classification route species:
 
Classification description:
 
Classification key study: