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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 The old collection of technical fact sheets will remain available in this archive, but they may contain out-of-date material.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. https://www.epa.gov/sites/default/files/2018-04/documents/chap-07-mar-2018.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: Gervais, J.; 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:

  1. Tomlin, C. D. S. The Pesticide Manual: A World Compendium, 14th ed.; British Crop Protection Council: Surrey, UK, 2006.
  2. WHO. Environmental Health Criteria 84, Environmental Aspects - 2,4-Dichlorophenoxyacetic acid (2,4-D); International Programme on Chemical Safety, World Health Organization: Geneva, Switzerland, 1989.
  3. Reregistration Eligibility Decision (RED) 2,4-D; EPA 738-R-05-002; U.S. Environmental Protection Agency, Office of Prevention, Pesticides and Toxic Substances, Office of Pesticide Programs, U.S. Government Printing Office: Washington, DC, 2005.
  4. Charles, J. M.; Hanley, T. R.; Wilson, R. D.; Van Ravenzwaay, B.; Bus, J. S. Developmental Toxicity Studies in Rats and Rabbits on 2,4-Dichlorophenoxyacetic Acid and its Forms. Toxicol. Sci. 2001, 60, 121-131.
  5. Carlo, G. L.; Cole, P.; MIller, A. B.; Munro, I. C.; Solomon, K. R.; Squire, R. A. Review of a Study Reporting an Association between 2,4-Dichlorophenoxyacetic Acid and Canine Malignant Lymphoma: Report of an Expert Panel. Regul. Toxicol. Pharmacol. 1992, 16, 245-252.
  6. Kamrin, M. A. Pesticide Profiles: Toxicity, Environmental Impact, and Fate; Lewis Publishers: New York, 1997, p 306.
  7. Munro, I. C.; Carlo, G. L.; Orr, J. C.; Sund, K. G.; Wilson, R. M.; Kennepohl, E.; Lynch, B. S.; Jablinske, M.; Lee, N. L. A Comprehensive, Integrated Review and Evaluation of the Scientific Evidence Relating to the Safety of the Herbicide 2,4-D. J. Am. Coll. Toxicol. 1992, 11, (5), 559-664.
  8. FAO. Pesticide Residues in Food - Evaluations Part 1: Residues; FAO Plant Production and Protection Paper 152/1, Food and Agriculture Organization of the United Nations and World Health Organization: Rome, 1988; Vol. 1, pp 179-189.
  9. Hazardous Substances Databank (HSDB), 2,4-D; U.S. Department of Health and Human Services, National Institutes of Health, National Library of Medicine. https://pubchem.ncbi.nlm.nih.gov/source/hsdb/202 (accessed June 2008), updated June 2005.
  10. Pesticide Products. Pest-Bank [CD-ROM] 2007.
  11. Label Review Manual; U.S. Environmental Protection Agency, Office of Prevention, Pesticides and Toxic Substances, Office of Pesticide Programs. https://www.epa.gov/sites/default/files/2018-04/documents/chap-07-mar-2018.pdf (accessed June 2008), updated Sept 2007.
  12. Herbicide Handbook, 8th ed.; Vencill, W.K. Ed.; Weed Science Society of America: Lawrence, KS, 2002; pp 113-115.
  13. Bradberry, S. M.; Proudfoot, A. T.; Vale, J. A. Poisoning Due to Chlorophenoxy Herbicides. Toxicol. Rev. 2004, 23 (2), 65-73.
  14. Peterson, M. E.; Talcott, P. A. Small Animal Toxicology, 2nd ed.; Saunders Elsevier: St. Louis, 2006; pp 734-735.
  15. Campbell, A.; Chapman, M. Handbook of Poisoning in Dogs and Cats; Blackwell Science Ltd.: Oxford, England, 2000; pp 220-221.
  16. Arnold, E. K.; Lovell, R. A.; Beasley, V. R.; Parker, A. J.; Stedelin, J.R. 2,4-D Toxicosis III: An Attempt to Produce 2,4-D Toxicosis in Dogs on Treated Grass Plots. Vet. Hum. Toxicol. 1991, 33 (5), 457-461.
  17. Paulino, C. A.; Guerra, J. L.; Oliveira, G. H.; Palmero-Neto, J. Acute, Subchronic and Chronic 2,4-Dichlorophenoxyacetic Acid (2,4-D) Intoxication in Rats. Vet. Hum. Toxicol. 1996, 38 (5), 348-352.
  18. Reigart, J. R.; Roberts, J. R. Chlorophenoxy Herbicides. Recognition and Management of Pesticide Poisonings, 5th ed.; U.S. Environmental Protection Agency, Office of Prevention, Pesticides and Toxic Substances, Office of Pesticide Programs, U.S. Government Printing Office: Washington, DC, 1999; pp 94-96.
  19. Charles, J. M.; Cunny, H. C.; Wilson, R. D.; Bus, J. S. Comparative Subchronic Studies on 2,4-Dichlorophenoxyacetic Acid, Amine, and Ester in Rats. Fundam. Appl. Toxicol. 1996, 33, 161-165.
  20. Charles, J. M.; Bond, D. M.; Jeffries, T. K.; Yano, B. L.; Stott, W. T.; Johnson, K. A.; Cunny, H. C.; Wilson, R. D.; Bus, J. S. Chronic Dietary Toxicity/ Oncogenicity Studies on 2,4-Dichlorphenoxyacetic Acid in Rodents. Fundam. Appl. Toxicol. 1996, 33, 166-172.
  21. Charles, J. M.; Dalgard, D. W.; Cunny, H. C.; Wilson, R. D.; Bus, J. S. Comparative Subchronic and Chronic Dietary Toxicity Studies on 2,4-Dichlorophenoxyacetic Acid, Amine, and Ester in the Dog. Fundam. Appl. Toxicol. 1996, 29, 78-85.
  22. Hoppin, J. A.; Umbach, D. M.; London, S. J.; Alavanja, M. C. R.; Sandler, D. P. Chemical Predictors of Wheeze among Farmer Pesticide Applicators in the Agricultural Health Study. Am. J. Respir. Crit. Care Med. 2002, 165, 683-689.
  23. Kamel, F.; Tanner, C. M.; Umbach, D. M.; Hoppin, J. A.; Alavanja, M. C. R.; Blair, A.; Comyns, K.; Goldman, S. M.; Korell, M.; Langston, J. W.; Ross, G. W.; Sandler, D. P. Pesticide Exposure and Self-reported Parkinson's Disease in the Agricultural Health Study. Am. J. Epidemiol. 2006, 165 (4), 364-374.
  24. Draft List of Initial Pesticide Active Ingredients and Pesticide Inerts to be Considered for Screening Under the Federal Food, Drug, and Cosmetic Act. Fed. Regist. June 18, 2007, 72 (116), 33486-33503.
  25. Hayes, H. M.; Tarone, R. E.; Cantor, K. P.; Jessen, C. R.; McCurnin, 25. D. M.; Richardson, R. C. Case-Control Study of Canine Malignant Lymphoma: Positive Association With Dog Owner's Use of 2,4-Dichlorphenoxyacetic Acid Herbicides. J. Natl. Cancer Inst. 1991, 83, 1226-1231.
  26. Garabant, D. H.; Philbert, M. A. Review of 2,4-Dichlorophenoxyacetic Acid (2,4-D) Epidemiology and Toxicology. Crit. Rev. Toxicol. 2002, 32 (4), 233-257.
  27. Gandhi, R.; Wandji, S.-A.; Snedeker, S. Critical Evaluation of Cancer Risks from 2,4-D. Rev. Environ. Contam. Toxicol. 2000, 167, 1-33.
  28. Maire, M. A.; Rast, C.; Landkocz, Y.; Vasseur, P. 2,4-Dichlorophenoxyacetic Acid: Effects on Syrian Hamster Embryo (SHE) Cell Transformation, c-Myc Expression, DNA Damage, and Apoptosis. Mutat. Res. 2007, 631, 124-136.
  29. IARC Monographs on the Evaluation of Carcinogenicity Risks to Humans. Overall Evaluations of Carcinogencity: An Updating of IARC Monographs, Volumes 1 to 42; International Agency for Research on Cancer: Lyon, France, 1987; Supplement 7.
  30. Madrigal-Bujaidar, E.; Hernandez-Ceruelos, A.; Chamorro, G. Induction of sister chromatid exchanges by 2,4-dichlorophenoxyacetic acid in somatic and germ cells of mice exposed in vivo. Food Chem. Toxicol. 2001, 39, 941-946.
  31. Collins, T. F. X.; Williams, C. H. Teratogenic Studies with 2,4,5-T and 2,4-D in the Hamster. Bull. Environ. Contam. Toxicol. 1971, 6 (6), 559-567.
  32. Lerda, D.; Rizzi, R. Study of reproductive function in persons occupationally exposed to 2,4-dichlorophenoxyacetic acid (2,4-D). Mutat. Res. 1991, 6 (6), 1, 47-50.
  33. Brand, R. M.; McMahon, L.; Jendrzejewski, J. L.; Charron, A. R. Transdermal absorption of the herbicide 2,4-dichlorphenoxyacetic acid is enhanced by both ethanol consumption and sunscreen application. Food Chem. Toxicol. 2007, 456, 93-97.
  34. Brand, R. M.; Spaulding, M.; Mueller, C. Sunscreens Can Increase Dermal Penetration of 2,4-Dichlorphenoxyacetic Acid. J. Toxicol. Clin. Toxicol. 2002, 40 (7), 827-832.
  35. Pont, A. R.; Charron, A. R.; Brand, R. M. Active ingredients in sunscreens act as topical penetration enhancers for the herbicide 2,4-dicholorphenoxyacetic acid. Toxicol. Appl. Pharmacol. 2004, 195, 348-354.
  36. Kohli, J. D.; Khanna, R. N.; Gupta, B. N.; MDhar, M. M.; Tandon, J. S.; Sircar, K. P. Absorption and Excretion of 2,4-Dichlorophenoxyacetic Acid in Man. Xenobiotica 1974, 4 (2), 97-100.
  37. Sauerhoff, M. W.; Braun, W. H.; Blau, G. E.; Gehring, P. J. The Fate of 2,4-Dichlorophenoxyacetic Acid (2,4-D) Following Oral Administration to Man. Toxicol. 1977, 8, 3-11.
  38. Roberts, T. R. Metabolic Pathways of Agrochemicals - Part 1: Herbicides and Plant Growth Regulators; The Royal Society of Chemistry: Cambridge, UK, 1998; pp 66-74.
  39. Van Ravenzwaay, B.; Hardwick, T. D.; Needham, D.; Pethen, S.; Lappin, G. J. Comparative metabolism of 2,4-dichlorophenoxyacetic acid (2,4-D) in rat and dog. Xenobiotica 2003, 33 (8), 805-821.
  40. Arnold, E. K.; Beasley, V. R. The Pharmacokinetics of Chlorinated Phenoxy Acid Herbicides: A Literature Review. Vet. Hum. Toxicol. 1989, 31 (12), 121-125.
  41. CDC. Third National Report on Human Exposure to Environmental Chemicals; U.S. Department of Health and Human Services, Centers for Disease Control and Prevention: Atlanta, 2005; pp 390-394.
  42. Olsson, A. O.; Baker, S. E.; Nguyen, J. V.; Romanoff, L. C.; Udunka, S. O.; Walker, R. D.; Flemmen, K. L.; Barr, D. B. A liquid chromatographytandem mass spectrometry multiresidue method for quantification of specific metabolites of organophosphorus pesticides, synthetic pyrethroids, selected herbicides, and DEET in human urine. Anal. Chem. 2004, 76 (9), 2453-2461.
  43. OSHA. Occupational Safety and Health Guideline for 2,4-D (Dichlorophenoxyacetic Acid); U.S. Department of Labor, Occupational Safety and Health Administration. https://www.osha.gov/chemicaldata/750 (accessed May 2008), updated April 1999.
  44. Vogue, P.A.; Kerle, E.A.; Jenkins, J.J. OSU Extension Pesticide Properties Database; Oregon State University: Corvallis, OR, 2004.
  45. Wilson, R. D.; Geronimo, J.; Armbruster, J. A. 2,4-D Dissipation in Field Soils After Applications of 2,4-Dimethylamine Salt and 2,4-D Ethylhexyl Ester. Environ. Toxicol. Chem. 1997, 16 (6), 1239-1246.
  46. Boivin, A.; Amellal, S.; Schiavon, M.; van Genuchten, M. T. 2,4-dichlorophenoxyacetic acid (2,4-D) sorption an ddegradation dynamics in three agricultural soils. Environ. Pollut. 2005, 138, 92-99.
  47. Pesticides in Surface and Groundwater of the United States: Summary of Results of the National Water Quality Assessment Program (NAWQA); U.S. Geological Survey: Reston, VA, 1998.
  48. McPherson, A. K.; Moreland, R. S.; Atkins, J. B. Occurrence and Distribution of Nutrients, Suspended Sediment, and Pesticides in the Mobile River Basin, Alabama, Georgia, Mississippi, and Tennessee, 1999-2001; Water-Resources Investigations Report 03- 4203, U.S. Geological Survey: Montgomery, AL, 2003; pp 1-2, 44, 57.
  49. Rice, C. P.; Chernyak, S. M.; McConnell, L. L. Henry's Law Constants for Pesticides Measured as a Function of Temperature and Salinity. J. Agric. Chem. 1997, 45, 2291-2298.
  50. Torstensson, N. T. L.; Lundgren, L. N.; Stenstrom, J. Influence of Climatic and Edaphic Factors on Persistence of Glyphosate and 2,4-D in Forest Soils. Ecotoxicol. Environ. Saf. 1989, 18, 230-239.
  51. Food and Drug Administration Pesticide Program Residue Monitoring 2003; U.S. Food and Drug Administration, Center for Food Safety and Applied Nutrition, Office of Plant and Dairy Foods: Washington, DC, 1993-2003.
  52. Pesticide Data Program Annual Summary, Calendar Year 2006; U.S. Department of Agriculture, Agricultural Marketing Service: Washington, DC, 2007.
  53. Relyea, R. A. The Impact of Insecticides and Herbicides on the Biodiversity and Productivity of Aquatic Communities. Ecolo. Appl. 2005, 15 (2), 618-627.
  54. Intergrated Risk Information System, 2,4-Dichlorphenoxyacetic Acid (2,4-D) (CASRN 94-75-7); U.S. Environmental Protection Agency. http://epa.gov/ncea/iris/subst/0150.htm (assessed April 2008), updated Jan 2008.
  55. ACGIH. TLVs and BEIs, Based on the Documentation of the Threshold Limit Values for Chemical Substances and Physical Agents and Biological Exposure Indices; American Conference of Governmental Industrial Hygienists Worldwide: Cincinnati, 2003; p 24.
  56. Drinking Water Contaminants; U.S. Environmental Protection Agency. https://www.epa.gov/sdwa/drinking-water-regulations-and-contaminants (accessed May 2008), updated Feb 2008.
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