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2,4-D

Technical Fact Sheet

As of 2011, NPIC stopped creating technical pesticide fact sheets. The old collection of technical fact sheets will remain available in this archive, but they may contain out-of-date material. NPIC no longer has the capacity to consistently update them. To visit our general fact sheets, click here. For up-to-date technical fact sheets, please visit the Environmental Protection Agency’s webpage.

Molecular Structure - 2,4-D

Laboratory Testing: Before pesticides are registered by the U.S. EPA, they must undergo laboratory testing for short-term (acute) and long-term (chronic) health effects. Laboratory animals are purposely given high enough doses to cause toxic effects. These tests help scientists judge how these chemicals might affect humans, domestic animals, and wildlife in cases of overexposure.

Chemical Class and Type:

Physical / Chemical Properties:

2,4-D and associated forms8,9
Active Ingredient CASRN Form Vapor pressurea Henry's constant Molecular weight Solubility in water (mg/L)b Log Kow Koc
2,4-D acid 94-75-7 White to brown crystalline solid 1.9 x 10-5 Pa
1.4 x 10-7 mmHg
8.6 x 10-6 atm·m3/mol 221 pH 5: 29,934 ± 2957b
pH 7: 44,558 ± 674
pH 9: 43,134 ± 336
0.001 M sol'n
pH 5: 2.14
pH 7: 0.177
pH 9: 0.102
20-136
2,4-D salt 2702-72-9 White powder Salt dissociates to acid in water 243.03 45,000 mg/L Salt dissociates to acid in water
2,4-D-diethanolamine salt (DEA) 5742-19-8 Cream colored powder 9.98 x 10-8 mmHg 326.18 806,000 mg/L 2.24 x 10-2
-1.65
2,4-D dimethyl amine salt (DMA) 2008-39-1 Amber aqueous liquid 1.33 x 10-5 Pa
1 x 10-7 mmHg
1.4 x 10-16 atm·m3/mol 266.13 pH 5: 320,632 ± 3645
pH 7: 729,397 ± 86,400
pH 9: 663,755 ± 94,647
See values for 2,4-D acid above 72-136
2,4-D -isopropylamine (IPA) salt 5742-17-6 Amber aqueous liquid Salt dissociates to acid in water 280.04 pH 5: 174,000 mg/L
pH 7: 436,000 mg/L
pH 9: 331,000 mg/L
Salt dissociates to acid in water
2,4-D tri-isopropanolamine (TIPA) salt 32341-80-3 Amber aqueous liquid Salt dissociates to acid in water 412.31 pH 5: 461,000 mg/L
pH 7: 461,000 mg/L
pH 9: 104,000 mg/L
Salt dissociates to acid in water
2,4-D BEE 1929-73-3 Dark amber liquid 3.2 x 10-4 Pa
2.4 x 10-6 mmHg
321.2 Practically insoluble in water 4.1
2,4-D 2-ethylhexyl ester (EHE) 1928-43-4 Dark amber liquid 4.8 x 10-4 Pa
3.6 x 10-6 mmHg
333.27 0.0867 mg/L 5.78
2,4-D -isopropyl ester (IPE) 94-11-1 Pale amber liquid 1.87 Pa
5.3 x 10-6 mbar
2.2 x 10-6 atm·m3/mol 263.12 Practically insoluble in water 253.8 ± 44.4 600
aVapor pressure measured at 25 °C bSolubility in water given for unbuffered solution

Uses:

Mode of Action:

Target Organisms

Non-target Organisms

Acute Toxicity:

Oral

LD50/LC50: A common measure of acute toxicity is the lethal dose (LD50) or lethal concentration (LC50) that causes death (resulting from a single or limited exposure) in 50 percent of the treated animals. LD50 is generally expressed as the dose in milligrams (mg) of chemical per kilogram (kg) of body weight. LC50 is often expressed as mg of chemical per volume (e.g., liter (L)) of medium (i.e., air or water) the organism is exposed to. Chemicals are considered highly toxic when the LD50/LC50 is small and practically non-toxic when the value is large. However, the LD50/LC50 does not reflect any effects from long-term exposure (i.e., cancer, birth defects or reproductive toxicity) that may occur at levels below those that cause death.

Dermal

Inhalation

Signs of Toxicity - Animals

Signs of Toxicity - Humans

TOXICITY CLASSIFICATION - 2,4-D
High Toxicity Moderate Toxicity Low Toxicity Very Low Toxicity
Acute Oral LD50 Up to and including 50 mg/kg
(≤ 50 mg/kg)
Greater than 50 through 500 mg/kg
(>50-500 mg/kg)
Greater than 500 through 5000 mg/kg
(>500-5000 mg/kg)
Greater than 5000 mg/kg
(>5000 mg/kg)
Inhalation LC50 Up to and including 0.05 mg/L
(≤0.05 mg/L)
Greater than 0.05 through 0.5 mg/L
(>0.05-0.5 mg/L)
Greater than 0.5 through 2.0 mg/L
(>0.5-2.0 mg/L)
Greater than 2.0 mg/L
(>2.0 mg/L)
Dermal LD50 Up to and including 200 mg/kg
(≤200 mg/kg)
Greater than 200 through 2000 mg/kg
(>200-2000 mg/kg)
Greater than 2000 through 5000 mg/kg
(>2000-5000 mg/kg)
Greater than 5000 mg/kg
(>5000 mg/kg)
Primary Eye Irritation Corrosive (irreversible destruction of ocular tissue) or corneal involvement or irritation persisting for more than 21 days (Acid, Ester) Corneal involvement or other eye irritation clearing in 8 - 21 days Corneal involvement or other eye irritation clearing in 7 days or less (Ester) Minimal effects clearing in less than 24 hours (Ester)
Primary Skin Irritation Corrosive (tissue destruction into the dermis and/or scarring) Severe irritation at 72 hours (severe erythema or edema) Moderate irritation at 72 hours (moderate erythema) Mild or slight irritation at 72 hours (no irritation or erythema) (Ester, Salt)
The highlighted boxes reflect the values in the "Acute Toxicity" section of this fact sheet. Modeled after the U.S. Environmental Protection Agency, Office of Pesticide Programs, Label Review Manual, Chapter 7: Precautionary Labeling. http://www.epa.gov/oppfead1/labeling/lrm/chap-07.pdf

NOAEL: No Observable Adverse Effect Level

NOEL: No Observed Effect Level

LOAEL: Lowest Observable Adverse Effect Level

LOEL: Lowest Observed Effect Level

Chronic Toxicity:

Animals

Humans

Exposure: Effects of 2,4-D on human health and the environment depend on how much 2,4-D is present and the length and frequency of exposure. Effects also depend on the health of a person and/or certain environmental factors.

Endocrine Disruption:

Carcinogenicity:

Animals

Humans

Reproductive or Teratogenic Effects:

Animals

Humans

Fate in the Body:

Absorption

Distribution

Metabolism

Excretion

Medical Tests and Monitoring:

The "half-life" is the time required for half of the compound to break down in the environment.

1 half-life = 50% remaining
2 half-lives = 25% remaining
3 half-lives = 12% remaining
4 half-lives = 6% remaining
5 half-lives = 3% remaining

Half-lives can vary widely based on environmental factors. The amount of chemical remaining after a half-life will always depend on the amount of the chemical originally applied. It should be noted that some chemicals may degrade into compounds of toxicological significance.

Environmental Fate:

Soil

Water

Air

Plants

Indoor

Food Residue

Ecotoxicity Studies:

Birds

Fish and Aquatic Life

Terrestrial Invertebrates

Regulatory Guidelines:

Date Reviewed: November 2008

Please cite as: Jervais, G.; Luukinen, B.; Buhl, K.; Stone, D. 2008. 2,4-D Technical Fact Sheet; National Pesticide Information Center, Oregon State University Extension Services. http://npic.orst.edu/factsheets/archive/2,4-DTech.html.

References:

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