Bis(2-ethylhexyl) phthalate

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Bis(2-ethylhexyl) phthalate
Bis(2-ethylhexyl) phthalate
Identifiers
CAS number 117-81-7 YesY
ChemSpider 8040 YesY
UNII C42K0PH13C YesY
KEGG C03690 YesY
ChEBI CHEBI:17747 N
ChEMBL CHEMBL402794 N
Jmol-3D images Image 1
Properties
Molecular formula C24H38O4
Molar mass 390.56 g mol−1
Melting point −50 °C (−58 °F; 223 K)
Boiling point 385 °C (725 °F; 658 K)
Except where noted otherwise, data are given for materials in their standard state (at 25 °C (77 °F), 100 kPa)
 N (verify) (what is: YesY/N?)
Infobox references

Bis(2-ethylhexyl) phthalate (di-2-ethylhexyl phthalate, diethylhexyl phthalate, DEHP; dioctyl phthalate, DOP), is an organic compound with the formula C6H4(C8H17COO)2. DEHP is the most common of the class of phthalates which are used as plasticizers, accounting for an almost 54% market share in 2010.[1] It is the diester of phthalic acid and the branched-chain 2-ethylhexanol. This colorless viscous liquid is soluble in oil, but not in water. DEHP is a High Production Volume Chemical.

Production and use[edit]

The 3 stereoisomers of DEHP

Due to its suitable properties and the low cost, DEHP is widely used as a plasticizer in manufacturing of articles made of PVC.[2] Plastics may contain 1% to 40% of DEHP. It is also used as a hydraulic fluid and as a dielectric fluid in capacitors. DEHP also finds use as a solvent in glowsticks.

Approximately three billion kilograms are produced annually worldwide.[2] It is estimated that at least 241 million pounds of dioctyl phthalates were produced in the US in 1999, so DEHP is a High Production Volume Chemical. Four companies operating five facilities are the primary U.S. producers of DEHP: Aristech Chemical Company in Neville Island, Pennsylvania; Hatco Chemical Company in Fords, New Jersey; Teknor Apex Company in Brownsville, Tennessee and Hebronville, Massachusetts; and Tennessee Eastman Company in Kingsport, Tennessee.[3]

Industrial production entails the reaction of phthalic anhydride with 2-ethylhexanol:

C6H4(CO)2O + 2 C8H17OH → C6H4(CO2 C8H17)2 + H2O

2-Ethylhexanol is chiral, and the resultant DEHP consists of a mixture of (R,R)-, (S,S)-, and (R,S)-isomers (left).


Environmental exposure[edit]

DEHP has a low vapor pressure, but the temperatures for processing PVC articles are often high, leading to release of elevated levels, raising concerns about health risks (see outgassing). It can be absorbed from food and water. Higher levels have been found in milk and cheese. It can also leach into a liquid that comes in contact with the plastic; it extracts faster into nonpolar solvents (e.g. oils and fats in foods packed in PVC). Food and Drug Administration (FDA) therefore permits use of DEHP-containing packaging only for foods that primarily contain water. The US EPA limits for DEHP in drinking water is 6 ppb. DEHP levels in some European samples of milk, were found at 2000 times higher than the EPA Safe Drinking Water limits (12,000 ppb). Levels of DEHP in some European cheeses and creams were even higher, up to 200,000 ppb.[4] The U.S. agency OSHA's limit for occupational exposure is 5 mg/m3 of air.

Use in medical devices[edit]

DEHP has been used as a plasticiser in medical devices such as intravenous tubing and bags, catheters, nasogastric tubes, dialysis bags and tubing, and blood bags and transfusion tubing, and air tubes. For this reason, concern has been expressed about leachates transported into the patient, especially for those requiring extensive infusions, e.g. newborns in intensive care nursery settings, hemophiliacs, and kidney dialysis patients. According to the European Commission Scientific Committee on Health and Environmental Risks (SCHER), exposure to DEHP may exceed the tolerable daily intake in some specific population groups, namely people exposed through medical procedures such as kidney dialysis.[5] The American Academy of Pediatrics has advocated not to use medical devices that can leach DEHP into patients and, instead, to resort to DEHP-free alternatives.[citation needed] In July 2002, the U.S. FDA issued a Public Health Notification on DEHP, stating in part, "We recommend considering such alternatives when these high-risk procedures are to be performed on male neonates, pregnant women who are carrying male fetuses, and peripubertal males" noting that the alternatives were to look for non-DEHP exposure solutions;[6] they mention a database of alternatives.[7] The CBC documentary The Disappearing Male raised concerns about sexual development in male fetal development, miscarriage (as DEHP is an androgen antagonist (not a pseudo-estrogen) found in polyvinyl chloride (PVC) plastic products, many cosmetics and fragrances, and numerous other consumer products), and as a cause of dramatically lower sperm counts in men.[8]

Metabolism[edit]

DEHP hydrolyzes to mono-ethylhexyl phthalate (MEHP) and subsequently to phthalate salts.[citation needed] The released alcohol is susceptible to oxidation to the aldehyde and carboxylic acid.[2]

Effects on living organisms[edit]

Toxicity[edit]

The acute toxicity of DEHP is low in animal models: 30 g/kg in rats (oral) and 24 g/kg in rabbits (dermal).[2] Concerns instead focus on its potential as an endocrine disruptor.

Development[edit]

In one study, the level of phthalates and DEHP metabolites in the blood of pregnant women was significantly correlated with decreased penis width, shorter anogenital distance, and incomplete descent of testes of their newborn sons, replicating effects identified in animals.[9][10] Approximately 25% of US women have phthalate levels similar to those in the study.[10] However, the study author cautioned that replication of these results are needed to strengthen any links between phthalates and adverse health outcomes.[9]

Obesity[edit]

A study on CDC data, published in Environmental Health Perspectives (EHP), "revealed that American men with abdominal obesity or insulin resistance (a precursor to diabetes) were more likely to have high levels of [DEHP and DBP] metabolites in their urine than men without those problems."[11]

Cardiotoxicity[edit]

A clinically relevant dose and duration of exposure to DEHP has been shown to have a significant impact on the behavior of cardiac cells in culture. This includes an uncoupling effect that leads to irregular rhythms in vitro. This is observed in conjunction with a significant decrease in the amount of gap junctional connexin proteins in cardiomyocytes treated with DEHP.[12]

Alternative plasticizers[edit]

Manufacturers of flexible PVC articles can choose among several alternative plasticizers offering similar technical properties as DEHP. These alternatives include other phthalates such as diisononyl phthalate (DINP), di-2-propyl heptyl phthalate (DPHP), diisodecyl phthalate (DIDP), and non-phthalates such as 1,2-cyclohexane dicarboxylic acid diisononyl ester (DINCH), dioctyl terephthalate (DOTP), and citrate esters.

Government and industry response[edit]

Taiwan[edit]

In October 2009, Consumers' Foundation, Chinese Taipei (CFCT) published test results[13] that found 5 out of the sampled 12 shoes contained over 0.1% of phthalate plasticizer content, including DEHP, which exceeds the government's Toy Safety Standard (CNS 4797). CFCT recommend that users should first wear socks to avoid direct skin contact.

In May 2011, the illegal use of the plasticizer DEHP in clouding agents for use in food and beverages has been reported in Taiwan.[14] An inspection of products initially discovered the presence of plasticizers. As more products were tested, inspectors found more manufacturers using DEHP and DINP.[15] The Department of Health confirmed that contaminated food and beverages had been exported to other countries and regions, which reveals the widespread prevalence of toxic plasticizers.

For more details on this topic, see 2011 Taiwan food scandal.

European Union[edit]

Fears that toxic chemicals were ingested by children when chewing plastic toys prompted the European Commission to order a temporary ban on phthalates in 1999, the decision of which is based on an opinion by the Commission’s Scientific Committee on Toxicity, Ecotoxicity and the Environment (CSTEE). A proposal to make the ban permanent was tabled shortly after but stuck in Council because EU ministers disagreed over how far it should go. Until 2004, EU banned the use of DEHP along with several other phthalates (DBP, BBP, DINP, DIDP and DNOP) in toys for young children.[16] In 2005, the Council and the Parliament compromised to propose a ban on three types of phthalates (DINP, DIDP, and DNOP) “in toys and childcare articles which can be placed in the mouth by children”. Therefore more products than initially planned will thus be affected by the directive.[17] In 2008, six substances were considered to be of very high concern (SVHCs) and added to the Candidate List including Musk Xylene, MDA, HBCDD, DEHP, BBP, and DBP. In 2011, those six substances have been listed for Authorization in Annex XIV of REACH by Regulation (EU) No 143/2011.[18] According to the regulation, phthalates including DEHP, BBP and DBP will be banned from February 2015.[19]

In 2012, Danish Environment Minister Ida Auken decided to ban four industrial chemicals including DEHP, DBP, DIBP and BBP, pushing Denmark ahead of the European Union which had already started a process of phasing out phthalates.[20] However, it was postponed by two years and would take effect in 2015 and not in December 2013, which was the initial plan. The reason is that the four phthalates are far more common than expected and that producers cannot phase out phthalates as fast as the Ministry of Environment requested.[21]

In 2012, France became the first country in EU to ban the use of DEHP in paediatircs, neonatology and maternity wards in hospitals. The ban will come into effect on 1 July 2015. This is an important first step towards the phase out of phthalates in all medical devices in Europe. The current EC proposal for a Regulation on Medical Devices only requires that phthalates are labelled, either on the sales package or on the device itself, meaning that health professionals and patients might not be aware that devices used for treating diseases contain phthalates.[22]

Mainland China[edit]

On 19 November 2012, Drunkard Liquor, one of China’s high-end liquor brand was exposed illegal use of plasticizer DEHP in the liquor.[23] It was reported that the amount of plasticizer was 2.6 times more than the standard. The company suspected the authority of the test, even had a suspicion whether the liquor was from Drunkard Liquor Company. However, influenced by the incident, most listed companies in the industry of liquor experienced great fluctuation in stock price, which produces high impact in the society.

References[edit]

  1. ^ "Market Study Plasticizers". Ceresana. May 2011. 
  2. ^ a b c d Peter M. Lorz; Friedrich K. Towae; Walter Enke; Rudolf Jäckh; Naresh Bhargava; Wolfgang Hillesheim (2005), "Phthalic Acid and Derivatives", Ullmann's Encyclopedia of Industrial Chemistry, Weinheim: Wiley-VCH, doi:10.1002/14356007.a20_181.pub2 
  3. ^ "Toxicological Profile for Di(2-ethylhexyl)phthalate (DEHP)CAS#: 117-81-7". Toxicological Profile. ATSDR. 2002. p. 176. Retrieved 17 March 2014. 
  4. ^ Sharman, M; Read, WA; Castle, L; Gilbert, J (1994). "Levels of di-(2-ethylhexyl)phthalate and total phthalate esters in milk, cream, butter and cheese". Food additives and contaminants 11 (3): 375–85. doi:10.1080/02652039409374236. PMID 7926171. 
  5. ^ "Phthalates in school supplies". GreenFacts Website. Retrieved 2009-06-10. 
  6. ^ FDA Public Health Notification: PVC Devices Containing the Plasticizer DEHP, USFDA July 12, 2002
  7. ^ Products for Hazard: DEHP, Sustainable Hospitals
  8. ^ The Disappearing Male – Sunday February 14, 2010 at 3 pm on CBC-TV, CBC
  9. ^ a b Shanna H. Swan (October 2008). "Environmental phthalate exposure in relation to reproductive outcomes and other health endpoints in humans". Environmental Research 108 (2): 177–184. 
  10. ^ a b Janet Pelley (2008-11-12). "Plasticizer may make boys less masculine". Env. Sci. Tech. 
  11. ^ Emily Main. "Fat's Hidden Trigger". Archived from the original on 2008-08-29. 
  12. ^ Gillum, N; Karabekian, Z; Swift, LM; Brown, RP; Kay, MW; Sarvazyan, N (2009). "Clinically relevant concentrations of di (2-ethylhexyl) phthalate (DEHP) uncouple cardiac syncytium". Toxicology and applied pharmacology 236 (1): 25–38. doi:10.1016/j.taap.2008.12.027. PMC 2670944. PMID 19344669. 
  13. ^ "《消費者報導雜誌》342期 第4至11頁「跟著流行走?踩著危機走!園丁鞋逾4成可塑劑超量」" (in zh-tw). Consumers' Foundation, Chinese Taipei (CFCT). 
  14. ^ FOOD SCARE WIDENS:Tainted additives used for two decades: manufacturer, Taipei Times, May 29, 2011
  15. ^ 生活中心綜合報導 (2011-05-23). "塑化劑危機!台灣海洋深層水等4廠商飲料緊急下架" (in zh-tw). NOWnews. Retrieved 2011-5-25查閱. 
  16. ^ "EU ministers agree to ban chemicals in toys". EurActiv.com. 2004-10-07. 
  17. ^ "Phthalates to be banned in toys and childcare articles". EurActiv.com. 2005-06-27. 
  18. ^ http://www.intertek.com/uploadedFiles/Intertek/Divisions/Consumer_Goods/Media/PDFs/Sparkles/2011/sparkle559.pdf
  19. ^ "First REACH substance bans to apply from 2014". European Solvents Industry Group. 2011-02-18. 
  20. ^ "Denmark defies EU with planned ban on phthalate chemicals". EurActiv.com. 2012-08-27. 
  21. ^ http://www.dehp-facts.com/module/news/display/newsdisplay.aspx?news=45
  22. ^ http://healthierhospitals.org/media-center/news-updates/france-first-eu-country-ban-use-dehp-paediatrics-neonatology-and-maternity
  23. ^ "白酒塑化剂事件" (in Chinese). 

External links[edit]