Bisphenol_a

Bisphenol A
IUPAC name	4,4\'-dihydroxy-2,2-diphenylpropane
Other names	BPA, 4,4\'-(propan-2-ylidene)diphenol, p, p\'-isopropylidenebisphenol
Identifiers
CAS number	[80-05-7]
RTECS number	SL6300000
SMILES	CC(c2ccc(O)cc2)(C)c1ccc(O)cc1
Properties
Molecular formula	C15H16O2
Molar mass	228.29 g/mol
Appearance	White to light brown flakes or powder
Density	1.20 g/cm³, solid
Melting point	158 to 159 °C (430 K)
Boiling point	220 °C (493 K) / 4 mmHg
Solubility in water	120–300 ppm (at 21.5 °C)
Hazards
R/S statement	R: 36, 37, 38, 43 S: 24, 26, 37
Flash point	227 °C, autoignition: 600 °C
Related compounds
Related compounds	phenols
Except where noted otherwise, data are given for materials in their standard state (at 25 °C, 100 kPa) Infobox disclaimer and references

Bisphenol A (abbreviated BPA) is an organic compound with the formula (CH₃)₂C(C₆H₄OH)₂. Containing two phenol functional groups, it is a difunctional building block to several important polymers and polymer additives. Helmut Fiege, Heinz-Werner Voges, Toshikazu Hamamoto, Sumio Umemura, Tadao Iwata, Hisaya Miki, Yasuhiro Fujita, Hans-Josef Buysch, Dorothea Garbe, Wilfried Paulus "Phenol Derivatives" in Ullmann\'s Encyclopedia of Industrial Chemistry Wiley-VCH: Weinheim, 2002. DOI: 10.1002/14356007.a19_313. Bisphenol A has become controversial because it mimics estrogen and thus could induce hormonal responses.Hot liquids release potentially harmful chemicals in polycarbonate plastic bottlesLe HH, Carlson EM, Chua JP, Belcher SM (2008). "Bisphenol A is released from polycarbonate drinking bottles and mimics the neurotoxic actions of estrogen in developing cerebellar neurons". Toxicol. Lett. 176 (2): 149–56. doi:10.1016/j.toxlet.2007.11.001. PMID 18155859. 

Synthesis

Bisphenol A is prepared by the reaction of two equivalents of phenol with one equivalent of acetone. Hydrochloric acid (HCl) and or sulfonated polystyrene is used as a catalyst. Typically, a large excess of phenol is used to ensure full condensation:

(CH₃)₂CO + 2 C₆H₅OH → (CH₃)₂C(C₆H₄OH)₂ + H₂O

A large number of ketones undergo analogous condensation reactions. The methodology is an example of a "green chemical reaction" in the sense that the process is efficient and the only by-product is water.

History and use

Bisphenol A was first reported by A.P. Dianin in 1891.Dianin, Zhurnal russkogo fiziko-khimicheskogo obshchestva, 23 (1891), pp. 492 ff.Theodor Zincke (1905). "Ueber die Einwirkung von Brom und von Chlor auf Phenole: Substitutionsproducte, Pseudobromide und Pseudochloride". Justus Liebigs Annalen der Chemie (343): 75–99. doi:10.1002/jlac.19053430106.  Bisphenol A current uses are numerous. It is a key monomer in production of polycarbonate plastic and epoxy resins. Otherwise it is used in the following polymer types: polyesters, polysulfones, and polyether ketones. Bisphenol A is also used as an antioxidant in plasticizers and as a polymerization inhibitor in PVC.

It is a precursor to the flame retardant tetrabromobisphenol A.

Health effects

Bisphenol-A has a low acute toxicity and negligible skin permeability. Bisphenols have been widely used as antioxidants in cosmetics and foods.

Endocrine disruptor controversy

Main article: Endocrine disruptor

There is growing concern that exposure to bisphenol A may induce adverse effects in humans.vom Saal FS, Hughes C (2005). "An extensive new literature concerning low-dose effects of bisphenol A shows the need for a new risk assessment". Environ. Health Perspect. 113 (8): 926–33. PMID 16079060. 

Bisphenol A was investigated in the 1930s during the search for estrogen mimics. From this study the synthetic compound diethylstilbestrol was shown to be a better competitor with estrogen.^{[citation needed]} Bisphenol A, like many other compounds, is known to be an estrogen receptor agonist.Okada, H & et al. (2008), "Direct evidence revealing structural elements essential for the high binding ability of bisphenol A to human estrogen-related receptor-gamma.", Environ. Health Perspect. 116 (1): 32-38, PMID: 18197296, <http://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pubmed&pubmedid=18197296> Such agonists can activate estrogen receptors, leading to similar physiological effects as the body\'s own estrogens.O’Connor, Chapin (2003). "Critical evaluation of observed adverse effects of endocrine active substances on reproduction and development, the immune system, and the nervous system" (Full Article). Pure Appl. Chem 75 (11–12): 2099–2123. Retrieved on 2007-02-28.  The first evidence of the estrogenicity of bisphenol A came from experiments in the 1930s in which it was fed to ovariectomized rats.E. C. Dodds and Wilfrid Lawson, "Synthetic Œstrogenic Agents without the Phenanthrene Nucleus", Nature, 137 (1936), 996.E. C. Dodds and W. Lawson, Proceedings of the Royal Society of London, Series B, Biological Sciences, 125, #839 (27-IV-1938), pp. 222–232. Some hormone disrupting effects in studies on animals and human cancer cells have been shown to occur at levels as low as 2–5 ppb (parts per billion). It has been claimed that these effects lead to health problems such as, in men, lowered sperm count and infertile sperm. Recent studies have confirmed that bisphenol A exposure during development has carcinogenic effects and produce precursors of breast cancer.Murray TJ (2007). "Induction of mammary gland ductal hyperplasias and carcinoma in situ following fetal bisphenol A exposure." (Abstract). Reproductive Toxicology. Retrieved on 2007-02-28. Soto AM, Vandenberg LN, Maffini MV, Sonnenschein C (2008). "Does breast cancer start in the womb?". Basic Clin. Pharmacol. Toxicol. 102 (2): 125–33. doi:10.1111/j.1742-7843.2007.00165.x. PMID 18226065.  Bisphenol A has been shown to have developmental toxicity, carcinogenic effects, and possible neurotoxicity.Lee Ym, et al. (2007). "Estrogen receptor independent neurotoxic mechanism of bisphenol A, an environmental estrogen." (Abstract). J Vet Sci. 8 (1): 27–38. Retrieved on 2007-02-28. Zsarnovszky A, Le HH, Wang HS, Belcher SM. (2005). "Ontogeny of rapid estrogen-mediated extracellular signal-regulated kinase signaling in the rat cerebellar cortex: potent nongenomic agonist and endocrine disrupting activity of the xenoestrogen bisphenol A" (Abstract). Endocrinology. 146 (12): 5388–96. Retrieved on 2007-02-28.  Recent studies suggest it may also be linked to obesity by triggering fat-cell activity.Grossman, Elizabeth. (March 12, 2007). "Chemicals May Play Role in Rise in Obesity.". Washington Post..  Schizophrenia research indicates endocrine disruptors like BPA may be involved in schizophrenia pathogenesis.Brown JS (2008). "Effects of Bisphenol-A and Other Endocrine Disruptors Compared With Abnormalities of Schizophrenia: An Endocrine-Disruption Theory of Schizophrenia". Schizophrenia Bulletin. doi:10.1093/schbul/sbm147. PMID 18245062. 

A consensus statement by 38 BPA experts concluded that average levels in people are above those that cause harm to animals in laboratory experiments,vom Saal, Fred. (July 27, 2007). "Chapel Hill bisphenol A expert panel consensus statement: integration of mechanisms, effects in animals and potential to impact human health at current levels of exposure.". Reprod Toxicol..  and a NIH-sponsored panel in the U.S. determined that there was \'some concern\' about BPA\'s effect on fetal and infant brain and behavior."CERHR Expert Panel Report for Bisphenol A". Retrieved on 2007-12-07.  Peer reviewed publications have appeared pointing out flaws within the chemical industry funded studies that report bisphenol A safety.Frederick S. vom Saal (2006). "Large effects from small exposures. II. The importance of positive controls in low-dose research on bisphenol A." (Abstract). Environmental Research 100 (1): 50–76. Retrieved on 2007-02-28.  In 2006, Canadian regulators selected bisphenol A as one of 200 substances deserving of thorough safety assessments after preliminary studies found it to be \'inherently toxic\'; the chemical had not previously been studied by them in depth, having been accepted under grandfather clauses when stricter regulations were passed in the 1980s. The research will begin in May 2007, and take some time to complete.Mittelstaedt, Martin. "\'Inherently toxic\' chemical faces its future", Globe & Mail, 2007-04-07. Retrieved on 2007-04-07. 

Dr. Maida Galvez, a pediatrician studying BPA, recommends parents stay away from bottles containing the chemical and says, "We know the animal studies raise concerns, but there aren\'t human studies showing effects yet ... so, when we don\'t have the evidence, what we recommend is that parents try to err on the side of caution."Parents Concerned Over Potentially Toxic Baby Bottles ABC News, Feb. 7, 2008.

Bisphenol A has been known to leach from the plastic lining of canned foods and, to a lesser degree, polycarbonate plastics that are cleaned with harsh detergents or used to contain acidic or high-temperature liquids.Environmental Working Group. Retrieved on 2007-03-07. The chemical is found in almost everyone that lives in developed countries at low concentrations. Infants fed with liquid infant formula have among the highest exposures of anyone eating canned foods. Infants fed canned formula with polycarbonate bottles can consume quantities of bisphenol A up to 13 µg/kg/day,European Food Safety Authority Opinion (Abstract). Retrieved on 2007-02-28. while the most sensitive animal studies show effects at much lower concentrations. Debate continues on what is the safe limit of this compound. Within the United States, an exposure of up to 50 µg/kg/day (50 ppb/day) is considered safe by the United States Environmental Protection AgencyBisphenol A - United States Environmental Protection Agency - well above the levels found to have caused negative health effects in studies (see table below).

The city of San Francisco, California, banned the sale of baby bottles and other products for young children containing bisphenol A effective December 2006, and was, at the time, the only jurisdiction in the world to outright forbid the substance."Anxieties about toxics", San Francisco Chronicle, 2006-11-22.  The ban was never enforced, and in May 2007 the city repealed the ban. In January 2006, the German Federal Institute for Risk Assessment announced that polycarbonate baby bottles are safe, stating that published research is "difficult to interpret and [is] occasionally contradictory".Selected questions and answers relating to bisphenol A in baby bottles- Federal Institute for Risk Assessment A subsequent study by the European Union’s Food Safety Authority reached a similar conclusion, and sharply criticized the methodology used in many of the low-dose exposure studies on rodents. European Safety Review: No Risk from Bisphenol A Exposure Japan has also concluded that normal use of these products is safe.Why has bisphenol A not been banned? - Federal Institute for Risk Assessment Currently 9 U.S. states have legislation pending that would affect the use of BPA in containers.

Growing awareness of health concerns in the U.S. retail sector, particularly in chains promoting healthy food and lifestyles, has led to a number of classes of products containing Bisphenol A to be withdrawn. In 2005, Patagonia Inc., a retailer of outdoor gear, ceased selling polycarbonate bottles. In 2006, Whole Foods Markets ceased selling baby bottles. In 2007, Mountain Equipment Co-op ceased selling bottles containing BPA."Polycarbonate bottles raise questions", Associated Press, 2007-12-23. 

Environmental risk

As an environmental contaminant this compound interferes with nitrogen fixation at the roots of leguminous plants associated with the bacterial symbiont Sinorhizobium meliloti. Despite a half-life in the soil of only 1–10 days, its ubiquity makes it an important pollutant.Fox, J.E., J. Gulledge, E. Engelhaupt, M.E. Burrow & J.A. McLachlan (2007). "Pesticides reduce symbiotic efficiency of nitrogen-fixing rhizobia and host plants". Proc. Nat. Acad. Sci. 104: 10282–7. 

Identification in Plastics

Highlighted types in the table below are believed to not leach chemicals in any significant amount. Type 7 is the highest risk for BPA (Bisphenol A) leaching.Gurd, Vreni (2007). Which plastic water bottles don\'t leach chemicals?.

There are seven groups of plastic polymers,Safe Use Of Plastic Food Packaging And Containers. each with specific properties that are used worldwide for many packaging applications (see table below). Each group of plastic polymer can be identified by its Plastic Identification code (PIC) - usually a number or a letter abbreviation. For instance, Low-Density Polyethylene can be identified by the number "4" and/or the letters "LDPE". The PIC appears inside a three-chasing arrow recycling symbol. The symbol is used to indicate whether the plastic can be recycled into new products.

References

External links

• Plastics chemical alters female brains
• Frontline Fooling With Nature, interview Fredrick Vom Saal, Ph.D.
• News report on effect through plastic bottles
• Bisphenol A. A Known Endocrine Disruptor WWF publication
• Plastics Industry Bisphenol A information site
• United States Environmental Protection Agency page on Bisphenol A
• An Endocrine/Estrogen Letter special Report on BPA
• News coverage of bisphenol A from EnvironmentalHealthNews.org
• EWG testing of Bisphenol A in canned food and formula
• The Toxic Origins of Disease, Liza Gross, PLoS Biology - an essay examining some of the evidence and effects.
• CHEMICAL FALLOUT: JOURNAL SENTINEL WATCHDOG REPORT, Milwaukee Journal Star newspaper article examining effects of Bisphenol A on lab animals and humans.
• Safe Use Of Plastic Food Packaging And Containers, Agri-Food & Veterinary, Authority of Singapore
• Which plastic water bottles don\'t leach chemicals?, Vreni Gurd, 03/29/2007

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