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| Bisphenol A | |
|---|---|
| |
| General | |
| Systematic name | 4,4'-dihydroxy-2,2-diphenylpropane |
| Other names | BPA, 4,4'-(propan-2-ylidene)diphenol, p,p'-isopropylidenebisphenol |
| Molecular formula | C15H16O2 |
| Molar mass | 228.29 g/mol |
| SMILES | CC(c2ccc(O)cc2)(C)c1ccc(O)cc1 |
| Appearance | free-flowing prills |
| CAS number | |
| Properties | |
| Density and phase | 1.20 g/cm, solid |
| Solubility in water | ? g/100 ml (? °C) |
| Melting point | 157 °C (? K) |
| Boiling point | 220 °C (? K) |
| Viscosity | ? cP at ? °C |
| Structure | |
| Molecular shape | ? |
| Crystal structure | ? |
| Dipole moment | ? D |
| Hazards | |
| MSDS | External MSDS |
| Main hazards | ? |
| Flash point | 207 °C, autoignition: 600 °C |
| R/S statement | R: 36, 37, 38, 43 S: 24, 26, 37 |
| RTECS number | ? |
| Supplementary data page | |
| Structure & properties | n, εr, etc. |
| Thermodynamic data | Phase behaviour Solid, liquid, gas |
| Spectral data | UV, IR, NMR, MS |
| Related compounds | |
| Related ? | ? |
| 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 is a chemical compound that is prepared by reaction of two equivalents of phenol with one equivalent of acetone. Bisphenol A belongs to the phenol class of aromatic organic compounds; it has two phenol functional groups in its molecule.
History and use
Bisphenol A was first synthesized by Dianin in 1891,. Bisphenol A was investigated in the 1930s during the search for synthetic estrogens. At that time, another synthesized compound, diethylstilbestrol, turned out to be more powerful an estrogen, so bisphenol A was not used as a synthetic estrogen. Its current main uses are as a monomer in the manufacture of polycarbonate plastic and in the manufacture of epoxy resins. Bisphenol A is also used as an antioxidant in plasticizers and in PVC, and as a polymerization inhibitor in PVC.
Polycarbonates are widely used in many consumer products, from sunglasses and CDs to water and food containers and shatter-resistant baby bottles. Some polymers used in dental fillings also contain bisphenol A, while epoxy resins containing bisphenol A are popular coatings for the inside of cans used for canning food.
Possible health risks
BPA has been known to leach from plastics which are cleaned with harsh detergents or used to contain acidic or high temperature liquids. The chemical has been found in nearly every human tested in the United States.
BPA can activate estrogen receptors leading to similar physiological effects as the body's own estrogens. The first evidence of BPA's estrogenicity came from experiments in the 1930s in which it was fed to ovariectomised rats,. 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.
The plastics industry has long claimed that bisphenol A is safe at typical levels of human exposure, minimizing or discounting all tests to the contrary. Eleven industry-funded studies found no risk from bisphenol A, while 90% of 104 independent studies showed possible risks, says a December 2004 report from scientists F.vom Saal and Claude Hughes . A previous report, released by the Harvard Center for Risk Analysis and funded by the American Plastics Council, called the evidence for risks "weak" and "inconsistent". Claude Hughes, who co-authored the 2004 paper with vom Saal, had served on the Harvard Center for Risk Analysis panel. As indicated in his publication with vom Saal, he regards that assessment as out-of-date because it considered so few of the many papers published on low-dose BPA since 2001.
In 2006, vom Saal and Welshons published a detailed analysis of why a small number of studies, mostly conducted in industry-funded laboratories, failed to replicate findings on low-level effects of BPA. Independent review by a scientific panel convened by a US government agency found through reanalysis of the data in one of those papers that it in fact had found an effect, even though its conclusions stated otherwise. Several of the studies failed to use positive controls, and comparisons with other studies suggest that the negative controls were contaminated. Finally, several use a variety of rat that is known to be extremely insensitive to estrogens.
Belcher and coworkers demonstrated that even very low levels of BPA can disrupt neural development in the fetus (rat). While a "low-dose hypothesis" has been debated for years , this study questions the assumption that a simple "dose-equals-effect" model is adequate to assess endocrine disruptor activity.
References
- 1: Dianin, Zhurnal russkogo fiziko-khimicheskogo obshchestva, 23 (1891), pp. 492 ff.
- 2: Th. Zincke, Mittheilungen aus dem chemischen Laboratorium der Universität Marburg, Justus Liebigs Annalen der Chemie, 343 (1905), pp. 75-131.
- 3: Handbook of Chemistry and Physics, CRC Press, 76th edition (1995-1996).
- 4: E. C. Dodds and Wilfrid Lawson, Nature, 137 (1936), 996.
- 5: 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.
- 6: vom Saal FS, Hughes C. Environ Health Perspect. 2005 Aug;113(8):926-33 PMID 16079060
- 7: Zsarnovszky A, Le HH, Wang HS, Belcher SM. Endocrinology, 2005 Dec;146(12):5388-96. PMID 16123166
- 8: vom Saal FS, Welshons W. Environmental Research 100: 50-76. doi:10.1016/j.envres.2005.09.001
External links
- An Endocrine/Estrogen Letter special Report on BPA
- News coverage of bisphenol A from EnvironmentalHealthNews.org