Diethyl phthalate

Diethyl phthalate (DEP) is a phthalate ester, appears as a clear colorless liquid without significant odor. More dense than water and insoluble in water. Hence sinks in water.

Diethyl phthalate[1]
Names
Preferred IUPAC name
Diethyl benzene-1,2-dicarboxylate
Other names
Diethyl phthalate
Identifiers
3D model (JSmol)
ChEBI
ChEMBL
ChemSpider
ECHA InfoCard 100.001.409
KEGG
UNII
Properties
C12H14O4
Molar mass 222.24 g/mol
Appearance colourless, oily liquid
Density 1.12 g/cm3 at 20 °C
Melting point −4 °C (25 °F; 269 K)
Boiling point 295 °C (563 °F; 568 K)
1080 mg/L at 25 °C
log P 2.42
Vapor pressure 0.002 mmHg (25°C)[2]
-127.5·10−6 cm3/mol
Hazards
NFPA 704 (fire diamond)
Flammability code 1: Must be pre-heated before ignition can occur. Flash point over 93 °C (200 °F). E.g. canola oilHealth code 1: Exposure would cause irritation but only minor residual injury. E.g. turpentineReactivity code 0: Normally stable, even under fire exposure conditions, and is not reactive with water. E.g. liquid nitrogenSpecial hazards (white): no code
1
1
0
Flash point 161.1 °C (322.0 °F; 434.2 K)[2]
Explosive limits 0.7%-?[2]
Lethal dose or concentration (LD, LC):
8600 mg/kg (Rat)
NIOSH (US health exposure limits):
PEL (Permissible)
 none[2]
REL (Recommended)
 TWA 5 mg/m3[2]
IDLH (Immediate danger)
 N.D.[2]
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
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Infobox references

Biodegradation

Biodegradation by microorganisms

Biodegradation of DEP in soil occurs by sequential hydrolysis of the two diethyl chains of the phthalate to produce monoethyl phthalate, followed by phthalic acid. This reaction occurs very slowly in an abiotic environment. Thus there exists an alternative pathway of biodegradation which includes transesterification or demethylation by microorganisms, if the soil is also contaminated with methanol, that would produce another three intermediate compounds, ethyl methyl phthalate, dimethyl phthalate and monomethyl phthalate. This biodegradation has been observed in several soil bacteria.[3] Some bacteria with these abilities have specific enzymes involved in the degradation of phthalic acid esters such as phthalate oxygenase, phthalate dioxygenase, phthalate dehydrogenase and phthalate decarboxylase.[4] The developed intermediates of the transesterification or demethylation, ethyl methyl phthalate and dimethyl phthalate, enhance the toxic effect and are able to disrupt the membrane of microorganisms.

Biodegradation by mammals

Recent studies show that DEP, a phthalic acid ester (PAE), is enzymatically hydrolyzed to its monoesters by pancreatic cholesterol esterase (CEase) in pigs and cows. These mammalian pancreatic CEases have been found to be nonspecific for degradation in relation to the diversity of the alkyl side chains of PAEs. .[4]

Toxicity

Little is known about the chronic toxicity of diethyl phthalate, but existing information suggests only a low toxic potential.[5] Studies suggest that some phthalates affect male reproductive development via inhibition of androgen biosynthesis. In rats, for instance, repeated administration of DEP results in loss of germ cell populations in the testis. However, diethyl phthalate doesn't alter sexual differentiation in male rats.[6][7][8][9] Dose response experiments in fiddler crabs have shown that seven-day exposure to diethyl phthalate at 50 mg/L significantly inhibited the activity of chitobiase in the epidermis and hepatopancreas.[10] Chitobiase plays an important role in degradation of the old chitin exoskeleton during the pre-moult phase.[11]

Teratogenicity

When pregnant rats were treated with diethyl phthalate, it became evident that certain doses caused skeletal malformations, whereas the untreated control group showed no resorptions. The amount of skeletal malformations was highest at highest dose.[12] In a following study it was found that both phthalate diesters and their metabolic products were present in each of these compartments, suggesting that the toxicity in embryos and fetuses could be the result of a direct effect.[13]

Future investigation

Some data suggest that exposure to multiple phthalates at low doses significantly increases the risk in a dose additive manner.[14][15][16] Therefore, the risk from a mixture of phthalates or phthalates and other anti-androgens, may not be accurately assessed studying one chemical at a time. The same may be said about risks from several exposure routes together. Humans are exposed to phthalates by multiple exposure routes (predominantly dermal), while toxicological testing is done via oral exposure.[17]

References
  1. "Chemical Information Profile for Diethyl Phthalate" (PDF). Integrated Laboratory Systems, Inc. Archived from the original (PDF) on 1 February 2009. Retrieved 3 March 2009.
  2. NIOSH Pocket Guide to Chemical Hazards. "#0213". National Institute for Occupational Safety and Health (NIOSH).
  3. Cartwright, C.D. (March 2000). "Biodegradation of diethyl phthalate in soil by a novel pathway". FEMS Microbiology Letters. 186 (1): 27–34. doi:10.1016/S0378-1097(00)00111-7. PMID 10779708.
  4. Saito, T.; Peng, H.; Tanabe, R.; Nagai, K.; Kato, K. (December 2010). "Enzymatic hydrolysis of structurally diverse phthalic acid esters by porcine and bovine pancreatic cholesterol esterases". Chemosphere. 81 (1): 1544–1548. Bibcode:2010Chmsp..81.1544S. doi:10.1016/j.chemosphere.2010.08.020. PMID 20822795.
  5. J. Autian (1973). "Toxicity and health threats of phthalate esters: review of the literature". Environmental Health Perspectives. 4: 3–25. doi:10.2307/3428178. JSTOR 3428178. PMC 1474854. PMID 4578674.
  6. Antonia M. Calafat and Richard H. McKee (2006). "Integrating Biomonitoring Exposure Data into the Risk Assessment Process: Phthalates [Diethyl Phthalate and Di(2-ethylhexyl) Phthalate] as a Case Study". Environmental Health Perspectives. 114 (11): 1783–1789. doi:10.1289/ehp.9059. PMC 1665433. PMID 17107868.CS1 maint: uses authors parameter (link)
  7. Paul M. D. Foster et al. (1980). "Study of the testicular effects and changes in zinc excretion produced by some n-alkyl phthalates in the rat". Toxicology and Applied Pharmacology. 54 (3): 392–398. doi:10.1016/0041-008X(80)90165-9. PMID 7394794.CS1 maint: uses authors parameter (link)
  8. P. M. D. Foster et a. (1981). "Studies on the testicular effects and zinc excretion produced by various isomers of monobutyl-o-phthalate in the rat". Chemico-Biological Interactions. 34 (2): 233–238. doi:10.1016/0009-2797(81)90134-4. PMID 7460085.CS1 maint: uses authors parameter (link)
  9. L. Earl Gray Jr. et al. (2000). "Perinatal Exposure to the Phthalates DEHP, BBP, and DINP, but Not DEP, DMP, or DOTP, Alters Sexual Differentiation of the Male Rat". Toxicological Sciences. 58 (2): 350–365. doi:10.1093/toxsci/58.2.350. PMID 11099647.CS1 maint: uses authors parameter (link)
  10. Zou, Enmin; Fingerman, Milton (1999). "Effects of exposure to diethyl phthalate, 4-(tert)-octylphenol, and 2,4,5-trichlorobiphenyl on activity of chitobiase in the epidermis and hepatopancreas of the fiddler crab, Uca pugilator". Comparative Biochemistry and Physiology C. 122 (1): 115–120. doi:10.1016/S0742-8413(98)10093-2. PMID 10190035.
  11. M. A. Baars & S.S. Oosterhuis, "Free chitobiase, a marker enzyme for the growth of crustaceans", NIOZ Annual Report 2006 (PDF), Royal Netherlands Institute for Sea Research, Texel, pp. 62–64, archived from the original (PDF) on 2011-07-20
  12. A. R. Singh, W. H. Lawrence, J. Autian (1972). "Teratogenicity of Phthalate Esters in Rats". Journal of Pharmaceutical Sciences. 61 (1): 51–55. doi:10.1002/jps.2600610107.CS1 maint: uses authors parameter (link)
  13. A. R. Singh, W. H. Lawrence, J. Autian (1975). "Maternal-Fetal transfer of 14C-Di-2-ethylhexyl phthalate and 14C-diethyl phthalate in rats". Journal of Pharmaceutical Sciences. 64 (8): 1347–1350. doi:10.1002/jps.2600640819. PMID 1151708.CS1 maint: uses authors parameter (link)
  14. L. Earl Gray Jr. et al. (2006). "Adverse effects of environmental antiandrogens and androgens on reproductive development in mammals". International Journal of Andrology. 29 (1): 96–104. doi:10.1111/j.1365-2605.2005.00636.x.CS1 maint: uses authors parameter (link)
  15. Kembra L. Howdeshell et al. (2008). "A Mixture of Five Phthalate Esters Inhibits Fetal Testicular Testosterone Production in the Sprague-Dawley Rat in a Cumulative, Dose-Additive Manner". Toxicological Sciences. 105 (1): 153–165. doi:10.1093/toxsci/kfn077. PMID 18411233.CS1 maint: uses authors parameter (link)
  16. Kembra L. Howdeshell et al. (2008). "Mechanisms of action of phthalate esters, individually and in combination, to induce abnormal reproductive development in male laboratory rats". Environmental Research. 108 (2): 168–176. Bibcode:2008ER....108..168H. doi:10.1016/j.envres.2008.08.009. PMID 18949836.CS1 maint: uses authors parameter (link)
  17. Shanna H. Swan (2008). "Environmental phthalate exposure in relation to reproductive outcomes and other health endpoints in humans". Environmental Research. 108 (2): 177–184. Bibcode:2008ER....108..177S. doi:10.1016/j.envres.2008.08.007. PMC 2775531. PMID 18949837.
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