Oxybenzone

Oxybenzone[1]
Names
IUPAC name
(2-Hydroxy-4-methoxyphenyl)-phenylmethanone
Other names
Oxybenzone
Benzophenone-3
2-Hydroxy-4-methoxybenzophenone
Identifiers
131-57-7 YesY
3D model (Jmol) Interactive image
ChEBI CHEBI:34283 N
ChEMBL ChEMBL1625 YesY
ChemSpider 4471 YesY
DrugBank DB01428 N
ECHA InfoCard 100.004.575
KEGG D05309 YesY
PubChem 4632
UNII 95OOS7VE0Y YesY
Properties
C14H12O3
Molar mass 228.25 g·mol−1
Density 1.20 g cm−3[2]
Melting point 62 to 65 °C (144 to 149 °F; 335 to 338 K)
Boiling point 224 to 227 °C (435 to 441 °F; 497 to 500 K)
Acidity (pKa) 7.6 (H2O)[3]
Hazards[2]
NFPA 704
Flammability code 1: Must be pre-heated before ignition can occur. Flash point over 93 °C (200 °F). E.g., canola oil Health code 1: Exposure would cause irritation but only minor residual injury. E.g., turpentine Reactivity code 0: Normally stable, even under fire exposure conditions, and is not reactive with water. E.g., liquid nitrogen Special hazards (white): no codeNFPA 704 four-colored diamond
1
1
0
Flash point 140.5 °C (284.9 °F; 413.6 K)
Lethal dose or concentration (LD, LC):
>12800 mg/kg (oral in rats)
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
N verify (what is YesYN ?)
Infobox references

Oxybenzone or benzophenone-3 (trade names Milestab 9, Eusolex 4360, Escalol 567, KAHSCREEN BZ-3) is an organic compound. It is a pale-yellow solid that is readily soluble in most organic solvents. Oxybenzone belongs to the class of aromatic ketones known as benzophenones. It is a component of many sunscreen lotions.

Structure and electronic structure

Being a conjugated molecule, oxybenzone absorbs at lower energies than many aromatic molecules.[4] As in related compounds, the hydroxyl group is hydrogen bonded to the ketone.[5] This interaction contributes to oxybenzone's light-absorption properties. At low temperatures, however, it is possible to observe both the phosphorescence and the triplet-triplet absorption spectrum. At 175 K the triplet lifetime is 24 ns. The short lifetime has been attributed to a fast intramolecular hydrogen transfer between the oxygen of the C=O and the OH.[6]

Production

Oxybenzone is produced by Friedel-Crafts reaction of benzoyl chloride with 3-methoxyphenol(3-hydroxyanisole).[7]

Uses

Oxybenzone is used in plastics as an ultraviolet light absorber and stabilizer.[7] It is used, along with other benzophenones, in sunscreens, hair sprays, and cosmetics because they help prevent potential damage from sunlight exposure. It is also found, in concentrations up to 1%, in nail polishes.[7] Oxybenzone can also be used as a photostabilizer for synthetic resins.[7] Benzophenones can leach from food packaging, and are widely used as photo-initiators to activate a chemical that dries ink faster.[8]

As a sunscreen, it provides broad-spectrum ultraviolet coverage, including UVB and short-wave UVA rays. As a photoprotective agent, it has an absorption profile spanning from 270 to 350 nm with absorption peaks at 288 and 350 nm.[9] It is one of the most widely used organic UVA filters in sunscreens today.[9] It is also found in nail polish, fragrances, hairspray, and cosmetics as a photostabilizer. Despite its photoprotective qualities, much controversy surrounds oxybenzone because of its possible hormonal and photoallergenic effects, leading many countries to regulate its use.

Safety and controversy

Some debate focuses on the potential of oxybenzone as an endocrine disruptor.[9] According to the Environmental Working Group (EWG) oxybenzone is ineffective and harmful.[10] Similar concerns have been expressed for related products including avobenzone, octisalate, octocrylene, homosalate, and octinoxate.[11] Due to the advent of PABA-free sunscreens, oxybenzone is now the most common allergen found in sunscreens.[12][13][14][15]

In vivo studies

Among common sunscreen chemicals, oxybenzone is associated with allergic reactions triggered by sun exposure. In a study of 82 patients with photoallergic contact dermatitis, over one quarter showed photoallergic reactions to oxybenzone.[16]

In a 2008 study of participants ages 6 and up, oxybenzone was detected in 96.8% of urine samples.[17] Humans can absorb anywhere from 0.4% to 8.7% of oxybenzone after one topical application of sunscreen, as measured in urine excretions. This number can increase after multiple applications over the same period of time.[18] Oxybenzone is particularly penetrative because it is the most lipophilic of the three most common UV filters.[19]

When applied topically UV filters, such as oxybenzone, are absorbed through the skin, metabolized, and excreted primarily through the urine.[20] The method of biotransformation, the process by which a foreign compound is chemically transformed to form a metabolite, was determined by Okereke and colleagues through oral and dermal administration of oxybenzone to rats. The scientists analyzed blood, urine, feces, and tissue samples and found three metabolites: 2,4-dihydroxybenzophenone(DHB), 2,2-dihydroxy-4-methoxybenzophenone (DHMB) and 2,3,4-trihydroxybenzophenone (THB).[21][22] To form DHB the methoxy functional group undergoes o-dealkylation; to form THB the same ring is hydroxylated.[20] Ring B in oxybenzone is hydroxylated to form DHMB.[20]

A study done in 2004 measured the levels of oxybenzone and its metabolites in urine. After topical application to human volunteers, results revealed that up to 1% of the applied dose was found in the urine.[23] The major metabolite detected was DHB and very small amounts of THB were found.[23] By utilizing the Ames test in Salmonella typhimurium strains, DHB was determinted to be nonmutagenic.[24]

Effects on coral

Benzophenones (along with three other active ingredients) in sunscreens have been linked to coral bleaching and die-offs.[25][26][27] A 2015 study published by the Archives of Environmental Contamination and Toxicology directly linked oxybenzone to the declining health of coral reefs popular with tourists.[28]

Regulation

Australia

Revised as of 2007, the National Industrial Chemicals Notification and Assessment Scheme (NICNAS)) Cosmetic Guidelines allow oxybenzone for cosmetic use up to 10%.[29]

Canada

Revised as of 2012, Health Canada allows oxybenzone for cosmetic use up to 6%.[30]

European Union

The Scientific Committee on Consumer Products (SCCP) of the European Commission concluded in 2008 that it does not pose a significant risk to consumers, apart from contact allergenic potential.[31] It is allowed in cosmetics up to 10%.

Japan

Revised as of 2001, the Ministry of Health, Labour, and Welfare notification allows oxybenzone for cosmetic use up to 5%.[32]

Sweden

The Swedish Research Council has determined that sunscreens with oxybenzone are unsuitable for use in young children, because children under the age of two years have not fully developed the enzymes that are believed break it down. No regulations have come of this study yet.[7]

United States

Oxybenzone was approved for use in the US by the FDA in the early 1980s. Revised as of April 1, 2013, the FDA allows oxybenzone in OTC sunscreen products up to 6%.[33]

References

  1. ↑ Merck Index, 11th Edition, 6907
  2. 1 2 131-57-7 Methanone
  3. ↑ Fontanals, Núria; Cormack, Peter A.G.; Sherrington, David C.; Marcé, Rosa M.; Borrull, Francesc (2010). "Weak anion-exchange hypercrosslinked sorbent in on-line solid-phase extraction–liquid chromatography coupling to achieve automated determination with an effective clean-up". Journal of Chromatography A. 1217 (17): 2855–61. doi:10.1016/j.chroma.2010.02.064. PMID 20303088.
  4. ↑ Castro, G. T.; Blanco, S. E.; Giordano, O. S. (2000). "UV Spectral Properties of Benzophenone. Influence of Solvents and Substituents". Molecules. 5 (3): 424. doi:10.3390/50300424.
  5. ↑ Lago, A. F.; Jimenez, P.; Herrero, R.; Dávalos, J. Z.; Abboud, J.-L. M. (2008). "Thermochemistry and Gas-Phase Ion Energetics of 2-Hydroxy-4-methoxy-benzophenone (Oxybenzone)". The Journal of Physical Chemistry A. 112 (14): 3201–8. doi:10.1021/jp7111999. PMID 18341312.
  6. ↑ ChréTien, Michelle N.; Heafey, Eve; Scaiano, Juan C. (2010). "Reducing Adverse Effects from UV Sunscreens by Zeolite Encapsulation: Comparison of Oxybenzone in Solution and in Zeolites". Photochemistry and Photobiology. 86 (1): 153–61. doi:10.1111/j.1751-1097.2009.00644.x. PMID 19930122.
  7. 1 2 3 4 5 "Hazardous Substances Data Bank". 2-HYDROXY-4-METHOXYBENZOPHENONE. National Library of Medicine (US), Division of Specialized Information Services. Retrieved 9 March 2014.
  8. ↑ Koivikko, R; Pastorelli, S; Rodríguez-Bernaldo de Quirós, A; Paseiro-Cerrato, R; Paseiro-Losada, P; Simoneau, C (2010). “Rapid multi-analye quantification of benzophenone, 4-methylbenzophenone and related derivatives form paperboard food packaging”. Food Addit Contam Part A Chem Anal Control Expo Risk Assess. 2010 Oct;27(10):1478-86. doi: 10.1080/19440049.2010.502130. Retrieved 8 February 2015. PMID 20640959.
  9. 1 2 3 Burnett, M. E.; Wang, S. Q. (2011). "Current sunscreen controversies: A critical review". Photodermatology, Photoimmunology & Photomedicine. 27 (2): 58–67. doi:10.1111/j.1600-0781.2011.00557.x. PMID 21392107.
  10. ↑ Centers for Disease Control. CDC: Americans Carry Body Burden of Toxic Sunscreen Chemical. Environmental Working Group. EWG, 25 March 2008. Web. 14 March 2014.
  11. ↑ "The Trouble With Sunscreen Chemicals". Environmental Working Group, Washington. Retrieved 27 April 2014.
  12. ↑ Rietschel, Robert L.; Fowler, Joseph F. (2008). Fisher's Contact Dermatitis (6th ed.). Hamilton: PMPH-USA. p. 460. ISBN 9781550093780. Retrieved 8 February 2015.
  13. ↑ DeLeo, Vincent A.; Suarez, Sylvia M.; Maso, Martha J. (1992). "Photoallergic contact dermatitis; results of photo patch testing in New York, 1985-1990". Arch Dermatol. 128 (11): 1513–1518. doi:10.1001/archderm.1992.01680210091015. Retrieved 8 February 2015.
  14. ↑ Scheuer, Elyse; Warshaw, Erin (March 2006). "Sunscreen Allergy: A Review of Epidemiology, Clinical Characteristics, and Responsible Allergens". Dermatitis. 17 (1): 3–11. doi:10.2310/6620.2006.05017. Retrieved 8 February 2015.
  15. ↑ Zhang, Xiao-Min; Nakagawa, Mikio; Kawai, Keiichi; Kawai, Kyozo (January 1998). "Erythema-multiforme-like eruption following photoallergic contact dermatitis from oxybenzone". Contact Dermatitis. 38 (1): 43–44. doi:10.1111/j.1600-0536.1998.tb05637.x. Retrieved 8 February 2015.
  16. ↑ Rodríguez, E; Valbuena, M. C.; Rey, M; Porras De Quintana, L (2006). "Causal agents of photoallergic contact dermatitis diagnosed in the national institute of dermatology of Colombia". Photodermatology, Photoimmunology & Photomedicine. 22 (4): 189–92. doi:10.1111/j.1600-0781.2006.00212.x. PMID 16869867.
  17. ↑ Calafat, A. M.; Wong, L. Y.; Ye, X.; Reidy, J. A.; Needham, L. L. (2008). "Concentrations of the Sunscreen Agent Benzophenone-3 in Residents of the United States: National Health and Nutrition Examination Survey 2003–2004". Environmental Health Perspectives. 116 (7): 893–7. doi:10.1289/ehp.11269. PMC 2453157Freely accessible. PMID 18629311.
  18. ↑ Gonzalez, H.; Farbrot, A.; Larko, O.; Wennberg, A. M. (2006). "Percutaneous absorption of the sunscreen benzophenone-3 after repeated whole-body applications, with and without ultraviolet irradiation". British Journal of Dermatology. 154 (2): 337–40. doi:10.1111/j.1365-2133.2005.07007.x. PMID 16433806.
  19. ↑ Hanson, K. M.; Gratton, E; Bardeen, C. J. (2006). "Sunscreen enhancement of UV-induced reactive oxygen species in the skin". Free Radical Biology and Medicine. 41 (8): 1205–12. doi:10.1016/j.freeradbiomed.2006.06.011. PMID 17015167.
  20. 1 2 3 Chisvert, A; León-González, Z; Tarazona, I; Salvador, A; Giokas, D (2012). "An overview of the analytical methods for the determination of organic ultraviolet filters in biological fluids and tissues". Analytica Chimica Acta. 752: 11–29. doi:10.1016/j.aca.2012.08.051. PMID 23101648.
  21. ↑ Okereke, C. S.; Kadry, A. M.; Abdel-Rahman, M. S.; Davis, R. A.; Friedman, M. A. (1993). "Metabolism of benzophenone-3 in rats". Drug metabolism and disposition: the biological fate of chemicals. 21 (5): 788–91. PMID 7902237.
  22. ↑ Okereke, C. S.; Abdel-Rhaman, M. S.; Friedman, M. A. (1994). "Disposition of benzophenone-3 after dermal administration in male rats". Toxicology letters. 73 (2): 113–22. doi:10.1016/0378-4274(94)90101-5. PMID 8048080.
  23. 1 2 Sarveiya, V; Risk, S; Benson, H. A. (2004). "Liquid chromatographic assay for common sunscreen agents: Application to in vivo assessment of skin penetration and systemic absorption in human volunteers". Journal of Chromatography B. 803 (2): 225–31. doi:10.1016/j.jchromb.2003.12.022. PMID 15063329.
  24. ↑ "Hazardous Substances Data Bank". 2,4-Dihydroxybenzophenone. National Library of Medicine (US), Division of Specialized Information Services. Retrieved 19 April 2014.
  25. ↑ "Protect Yourself, Protect The Reef! The impacts of sunscreens on our coral reefs" (PDF). U.S. National Park Service. Retrieved 1 July 2013.
  26. ↑ Than, Ker. "Swimmers' Sunscreen Killing Off Coral". National Geographic News. National Geographic News. Retrieved January 29, 2008.
  27. ↑ http://www.badgerbalm.com/s-35-coral-reef-safe-sunscreen.aspx
  28. ↑ Dowd, Katie (21 October 2015). "Study shows sunscreen is killing coral reefs in tourist areas". San Francisco Chronicle.
  29. ↑ "NICNAS COSMETICS GUIDELINES". Australian Government Department of Health. Retrieved 9 March 2014.
  30. ↑ "Guidance Document Sunscreen Monograph". Health Canada. Retrieved 9 March 2014.
  31. ↑ Aguirre, Claudia. "Shedding Light on Sun Safety – Part Two". The International Dermal Institute. Retrieved 9 March 2014.
  32. ↑ "Standards for Cosmetics" (PDF). Ministry of Health and Welfare Notification No.331 of 2000. Japanese Government. Retrieved 9 March 2014.
  33. ↑ "Suncreen Drug Products for Over-the-Counter Human Use". Code of Federal Regulations Title 21. FDA. Retrieved 9 March 2014.
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