(organic chemistry) (CH3)2C(C6H5OH)2 Brown crystals that are insoluble in water; used in the production of phenolic and epoxy resins.
| Sci-Tech Dictionary: bisphenol A |
(organic chemistry) (CH3)2C(C6H5OH)2 Brown crystals that are insoluble in water; used in the production of phenolic and epoxy resins.
| Wikipedia: Bisphenol A |
| Bisphenol A | |
|---|---|
| IUPAC name |
|
| Other names | BPA, 4,4'-(propan-2-ylidene)diphenol, p, p'-isopropylidenebisphenol, 4,4´-isopropylidenediphenol. |
| Identifiers | |
| CAS number | [] |
| RTECS number | SL6300000 |
| SMILES |
|
| ChemSpider ID | |
| Properties | |
| Molecular formula | C15H16O2 |
| Molar mass | 228.29 g mol−1 |
| 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 |
| NFPA 704 | |
| Flash point | 227 °C, autoignition: 600 °C |
| Related compounds | |
| Related compounds | phenols Bisphenol S |
| Except where noted otherwise, data are given for materials in their standard state (at 25 °C, 100 kPa) Infobox references |
|
Bisphenol A, commonly abbreviated as BPA, is an organic compound with two phenol functional groups. It is a difunctional building block of several important plastics and plastic additives. With an annual production of 2–3 million metric tonnes, it is an important monomer in the production of polycarbonate.
Suspected of being hazardous to humans since the 1930s, concerns about the use of bisphenol A in consumer products were regularly reported in the news media in 2008 after several governments issued reports questioning its safety, and some retailers removed products made of it from their shelves.
Contents |
Bisphenol A was first reported by A.P. Dianin in 1891.[1][2]
It is prepared by the condensation of acetone (hence the suffix A in the name)[3] with two equivalents of phenol. The reaction is catalyzed by an acid, such as hydrochloric acid (HCl) or a sulfonated polystyrene resin. Typically, a large excess of phenol is used to ensure full condensation:
A large number of ketones undergo analogous condensation reactions. The method is efficient and the only by-product is water.[4]
Bisphenol A is used primarily to make plastics, and products containing bisphenol A-based plastics have been in commerce for more than 50 years. It is used in the synthesis of polyesters, polysulfones, and polyether ketones, as an antioxidant in some plasticizers, and as a polymerization inhibitor in PVC. It is a key monomer in production of polycarbonate plastic and epoxy resins.[4] Polycarbonate plastic, which is clear and nearly shatter-proof, is used to make a variety of common products including baby and water bottles, sports equipment, medical and dental devices, dental fillings and sealants, eyeglass lenses, CDs and DVDs, and household electronics.[5] Epoxy resins containing bisphenol A are used as coatings on the inside of almost all food and beverage cans.[6] Bisphenol A is also a precursor to the flame retardant, tetrabromobisphenol A, and was formerly used as a fungicide.[7]
Global production of bisphenol A in 2003 was estimated to be over 2 million metric tonnes (t).[8] In the U.S., it is manufactured by Bayer MaterialScience, Dow Chemical Company, SABIC Innovative Plastics (formerly GE Plastics), Hexion Specialty Chemicals, and Sunoco Chemicals. In 2004, these companies produced just over 1 million t of bisphenol A, up from just 7,260 t in 1991. In 2003, annual U.S. consumption was 856,000 t, 72% of which was used to make polycarbonate plastic and 21% going into epoxy resins.[5]
Bisphenol A has low acute toxicity, with an oral LD50 of 3250 mg/kg in rats,[9] but it is an endocrine disruptor.[10][11] Low doses of bisphenol A can mimic the body's own hormones, possibly causing negative health effects.[12] There is thus concern that long term low dose exposure to bisphenol A may induce chronic toxicity in humans.[13][14][15]
The first evidence of the estrogenicity of bisphenol A came from experiments on rats conducted in the 1930s,[16][17] but it was not until 1997 that adverse effects of low-dose exposure on laboratory animals were first reported.[6] Since then, its endocrine disrupting properties have been extensively investigated, and more than 100 studies have been published "rais[ing] health concerns" about the chemical.[18]
Early development appears to be the period of greatest sensitivity to its effects,[19] and studies have demonstrated developmental toxicity, carcinogenic effects, and possible neurotoxicity at low doses in animal models (see table below).[20][21] Recent studies suggest it may also be linked to obesity[22] by triggering fat-cell activity[23] and have confirmed that bisphenol A exposure during development has carcinogenic effects and produce precursors of breast cancer.[24][25] However, neither the U.S. Environmental Protection Agency[26] nor the International Agency for Research on Cancer[27] have evaluated bisphenol A for possible carcinogenic activity.
In 2007, a consensus statement by 38 experts on bisphenol A concluded that average levels in people are above those that cause harm to animals in laboratory experiments,[28] and a panel convened by the U.S. National Institutes of Health determined that there was "some concern" about BPA's effects on fetal and infant brain development and behavior.[5] A 2008 report by the U.S. National Toxicology Program (NTP) agreed with the panel, expressing "some concern for effects on the brain, behavior, and prostate gland in fetuses, infants, and children at current human exposures to bisphenol A," and "minimal concern for effects on the mammary gland and an earlier age for puberty for females in fetuses, infants, and children at current human exposures to bisphenol A." The NTP had "negligible concern that exposure of pregnant women to bisphenol A will result in fetal or neonatal mortality, birth defects, or reduced birth weight and growth in their offspring."[29]
In April 2008, Health Canada released its Draft Screening Assessment for bisphenol A, which concluded that the chemical may pose some risk to infants[30] and proposed classifying the chemical as "'toxic' to human health and the environment."[31] This action follows Canadian regulators selection of bisphenol A in 2006 as one of 200 substances deserving of thorough safety assessments because preliminary studies had 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.[32]
A study from 2008 concluded that blood levels of bisphenol A in neonatal mice are the same whether it is injected or ingested.[33]
A study by the Yale School of Medicine demonstrated that adverse neurological effects occur in non-human primates regularly exposed to bisphenol A at levels equal to the United States Environmental Protection Agency's (EPA) maximum safe dose of 50 µg/kg/day.[34][35] This research found a connection between BPA and interference with brain cell connections vital to memory, learning and mood.
At an Endocrine Society meeting new research reported troubling data from animals experimentally treated with BPA.[36] Studies presented at the group's annual meeting show BPA can affect the hearts of women, can permanently damage the DNA of mice, and appear to be pouring into the human body from a variety of unknown sources.[37] The same Endocrine Society released a scientific statement expressing concern over current human exposure to BPA.[38]
A 2009 study in mice suggested that 1µg/kg BPA exposure causes long-term adverse reproductive and carcinogenic effects if exposure occurs during prenatal critical periods of differentiation.[39] Another study suggested that neonatal exposure of as low as 50µg/kg disrupts ovarian development in mice.[40][41]
| Dose (µg/kg/day) | Effects (measured in studies of mice or rats, descriptions (in quotes) are from Environmental Working Group)[32][42] |
Study Year |
|---|---|---|
| 0.025 | "Permanent changes to genital tract" | 2005[43] |
| 0.025 | "Changes in breast tissue that predispose cells to hormones and carcinogens" | 2005[44] |
| 2 | "increased prostate weight 30%" | 1997[45] |
| 2 | "lower bodyweight, increase of anogenital distance in both genders, signs of early puberty and longer estrus." | 2002[46] |
| 2.4 | "Decline in testicular testosterone" | 2004[47] |
| 2.5 | "Breast cells predisposed to cancer" | 2007[48] |
| 10 | "Prostate cells more sensitive to hormones and cancer" | 2006[49] |
| 10 | "Decreased maternal behaviors" | 2002[50] |
| 30 | "Reversed the normal sex differences in brain structure and behavior" | 2003[51] |
| 50 | U.S. human exposure limit (not a result from an animal study, but a guideline set by EPA) | 1998[52] |
The first study of bisphenol A's effects on humans was published in September 2008 by Iain Lang and colleagues in the Journal of the American Medical Association.[8][53] The cross-sectional study of almost 1,500 people assessed exposure to bisphenol A by looking at levels of the chemical in urine. The authors found that high bisphenol A levels were significantly associated with heart disease, diabetes, and abnormally high levels of certain liver enzymes. An editorial in the same issue notes that while this preliminary study needs to be confirmed and cannot prove causality, there is precedent for analogous effects in animal studies, which "add[s] biological plausibility to the results reported by Lang et al."[11]
However, both German Federal Institute for Risk Assessment (Bundesinstitut für Risikobewertung, BfR) and the European Food Safety Authority (EFSA) issued statements in which they concluded that the Lang Study provided no grounds to revise the current TDI (Tolerable Daily Intake) level for BPA.[54][55] However the Lang Study measured "urinary BPA" rather than "daily intake".
Bisphenol A has been known to leach from the plastic lining of canned foods[56] and, to a lesser degree, polycarbonate plastics that are cleaned with harsh detergents or used to contain acidic or high-temperature liquids. A recent Health Canada study found that the majority of canned soft drinks it tested had low, but measurable levels of bisphenol A.[57] While most exposure is through diet, exposure can also occur through air and through skin absorption.[58]
Studies by the CDC found bisphenol A in the urine of 95% of adults sampled in 1988–1994[59] and in 93% of children and adults tested in 2003–04.[60] Infants fed with liquid formula are among the most exposed, and those fed formula from polycarbonate bottles can consume up to 13 micrograms of bisphenol A per kg of body weight per day (μg/kg/day; see table below).[61] The most sensitive animal studies show effects at much lower doses, while the EPA considers exposures up to 50 µg/kg/day to be safe.[32][62] In 2009, a study found that drinking from polycarbonate bottles increased urinary bisphenol A levels by two thirds, from 1.2 micrograms/gram creatinine to 2 micrograms/gram creatinine.[63]
Consumer groups recommend that people wishing to lower their exposure to bisphenol A avoid canned food and polycarbonate plastic containers (which shares resin identification code 7 with many other plastics) unless the packaging indicates the plastic is bisphenol A-free.[64] The National Toxicology Panel recommends avoiding microwaving food in plastic containers, putting plastics in the dishwasher, or using harsh detergents, to avoid leaching.[65]
| Population | Estimated daily bisphenol A intake, μg/kg/day. Table adapted from the National Toxicology Program Expert Panel Report.[5] |
|---|---|
| Infant (0–6 months) formula-fed |
|
| Infant (0–6 months) breast-fed |
|
| Infant (6–12 months) |
|
| Child (1.5–6 years) |
|
| Adult |
|
| The examples and perspective in this article may not represent a worldwide view of the subject. Please improve this article or discuss the issue on the talk page. |
The Australia and New Zealand Food Safety Authority (Food Standards Australia New Zealand) does not see any health risk with bisphenol A baby bottles if the manufacturers instructions are followed. Levels of exposure are very low and do not pose a significant health risk. It added that “the move by overseas manufacturers to stop using BPA in baby bottles is a voluntary action and not the result of a specific action by regulators.”[4]It suggests the use of glass baby bottles if parents have any concerns.[66]
After the release of the Health Canada assessment in April 2008, Canadian Health Minister Tony Clement announced Canada's intent to ban the import, sale, and advertisement of polycarbonate baby bottles containing bisphenol A due to safety concerns, and investigate ways to reduce BPA contamination of baby formula packaged in metal cans. While the agency concluded that human exposures were less than levels believed to be unsafe, the margin of safety was not high enough for formula-fed infants.[19][67] Around the same time, Wal-Mart announced that it was immediately ceasing sales in all its Canadian stores of food containers, water and baby bottles, sippy cups, and pacifiers containing bisphenol A, and that it would phase out baby bottles made with it in U.S. stores by early 2009.[68] Nalgene also announced it will stop using the chemical in its products,[69] and
The federal government has formally declared bisphenol A a hazardous substance as of October 2008 and is now placed on its list of toxic substances. Health officials wrote in Canada Gazette that "It is concluded that bisphenol A be considered as a substance that may be entering the environment in a quantity or concentration or under conditions that constitute or may constitute a danger in Canada to human life or health."[72] The federal ministries of health and the environment announced they would seek to restrict imports, sales and advertising of polycarbonate baby bottles containing BPA.[73]
In its statement [5] released on 18 October 2008, Health Canada noted that “bisphenol A exposure to newborns and infants is below levels that cause effects” and that the “general public need not be concerned”.
In the updated 2008 European Union Risk Assessment Report [6] on bisphenol A, published in June 2008, the European Commission concluded that bisphenol A-based products, such as polycarbonate plastic and epoxy resins, are safe for consumers and the environment when used as intended.
On 23 July 2008, the European Food Safety Authority (EFSA), published an updated opinion [7] on the use of bisphenol A-based food contact materials. EFSA concluded that the current permanent Tolerable Daily Intake (TDI) of 0,05 mg/kg bodyweight (as set in EFSA’s 2006 opinion) [8] provides a sufficient margin of safety for the protection of the consumer, including sensitive subgroups such as foetuses and newborns. On 24 October 2008, EFSA issued a statement [9] following the study published in the Journal of the American Medical Association (JAMA) on 16 September (Lang et al., 2008). EFSA concluded that the study provided no grounds to revise the current TDI (Tolerable Daily Intake) level for BPA as derived by EFSA in 2006 [10].
On 6 November 2008, the Dutch Food and Consumer Product Safety Authority (VWA), released a newsletter [11] stating that baby bottles made from polycarbonate plastic do not release measurable concentrations of bisphenol A and therefore are safe to be used by babies and small children.
On 13 November 2008, the French Food Safety Agency (AFSSA) released a scientific opinion [12] on the heating of polycarbonate baby bottles in microwaves. AFSSA concluded that such use does not justify any precautionary measures against bisphenol A.
When asked, in March 2009, the French health minister Mrs. Roselyne Bachelot-Narquin declared that the French government does not consider BPA products to represent a health risk, following testing by the Agence Française de Sécurité Sanitaire des Aliments (AFSSA).[74] She evaluated, with regard to the Canadian situation, that “The Canadian authorities decided on the ban on BPA as a result of public pressure not on the basis of valid scientific studies.” [75]
On 19 September 2008, the German Federal Institute for Risk Assessment (Bundesinstitut für Risikobewertung, BfR) issued a statement[13] on the study published in the Journal of the American Medical Association (JAMA) on 16 September (Lang et al., 2008). The BfR concluded that there was no reason to change the current risk assessment for bisphenol A on the basis of the Study.
In February 2009 the Swiss Federal Office for Public Health (Bundesamt für Gesundheit, BAG), after evaluating the scientific reports of various food safety authorities, states its opinion that the intake of bisphenol A from food represents no risk to the consumer. This applies also to newborns and infants. [14]
As of the release of NTP and Health Canada reports in April, 10 U.S. states, including California,[76] Maryland,[18] and New Jersey,[77] already had legislation pending that would affect the use of BPA. In the wake of these reports, U.S. Senator Charles Schumer (D–N.Y.) introduced legislation that would ban bisphenol A nationally from products for infants.[18] In addition, the U.S. Congress is investigating the Weinberg Group, a chemical industry consulting firm, for its role in downplaying the health effects of bisphenol A and other chemicals,[78] and the Energy and Commerce Committee in the House of Representatives is investigating the use of BPA in baby products as well as the FDA's approval of the chemical. In asking the FDA to reassess its approval of bisphenol A, committee chairman Bart Stupak (D–Mich.) said "We would expect the FDA to make decisions based on the best available science…Yet the FDA relied on only two industry-funded studies, while other respected authorities used all available data to reach vastly different conclusions." The FDA maintained that bisphenol A is safe and did not recommend that people avoid using products made from it. The Consumer Product Safety Commission agreed, and its deputy director stressed that use of bisphenol A based plastics has many practical benefits and that "a ban could result in less effective protection of children from head, eye, or bodily injury."[6] FDA then announced it would set up a task force to address these concerns, and in August it released a draft finding[79] concurring with its initial position that the chemical is safe. The agency will make its final decision after an advisory panel on the issues is convened in September.[80]
In response to these events, an American Chemistry Council (ACC)/BPA Global Group (an industry trade association) spokesman said, “The weight of scientific evidence, as assessed by Health Canada and other agencies around the world, provides reassurance that consumers can continue to safely use products made from bisphenol A."[81] The Grocery Manufacturers Association also insisted that bisphenol A is safe, and argues that "Data purporting to demonstrate 'low' dose effects on the male reproductive system by BPA have not been successfully replicated and, therefore, are not credible to estimate human health risks and safety in light of the weight of a large body of evidence to the contrary."[82] A spokesman for the tin can industry said that without lining cans with bisphenol A based resins, E. coli and botulism poisoning would be "rampant."[6]
In September, the NTP finalized their report on bisphenol A, finding "some concern" that infants were at risk from exposure to the chemical.[29] At the same time, the FDA reassured consumers that it was safe, but convened an outside panel of experts to review the issue. The Lang study was also released that month, and David Melzer, a co-author of the study, presented the results of the study before the FDA panel.[83]
The editorial accompanying the Lang study's publication in JAMA criticized the FDA's assessment of bisphenol A: "A fundamental problem is that the current ADI [acceptable daily intake] for BPA is based on experiments conducted in the early 1980s using outdated methods (only very high doses were tested) and insensitive assays. More recent findings from independent scientists were rejected by the FDA, apparently because those investigators did not follow the outdated testing guidelines for environmental chemicals, whereas studies using the outdated, insensitive assays (predominantly involving studies funded by the chemical industry) are given more weight in arriving at the conclusion that BPA is not harmful at current exposure levels."[11]
The Union of Concerned Scientists similarly criticized the agency saying, "We're concerned that the FDA is basing its conclusion on two studies while downplaying the results of hundreds of other studies...This appears to be a case of cherry-picking data with potentially high cost to human health."[83] The chemical industry had earlier been criticized by Democrats and their allies. David Michaels, who served in the Clinton Administration, told the Washington Post that "Tobacco figured this out, and essentially it's the same model … If you fight the science, you're able to postpone regulation and victim compensation, as well. As in this case, eventually the science becomes overwhelming. But if you can get five or 10 years of avoiding pollution control or production of chemicals, you've greatly increased your product."[18] Diana Zuckerman, president of the National Research Center for Women and Families, also criticized the FDA stating "At the very least, the FDA should require a prominent warning on products made with BPA".[84]
In contrast, the American Chemistry Council, the manufacturing industry's lobby group, was skeptical of the latest study: "Due to inherent limitations in study design, this new study cannot support a conclusion that bisphenol A causes any disease...The weight of scientific evidence continues to support the conclusion of governments worldwide that bisphenol A is not a significant health concern at the trace levels present in some consumer products."[83]
Sunoco, a gas and chemical maker, is now refusing to sell the chemical to companies for use in food and water containers for children younger than 3, saying it can't be certain of the compound's safety. Sunoco plans to require its customers to guarantee that the chemical will not be used in children's food products.[85]
The six largest US companies which commercialize baby bottles decided to stop using bisphenol A in their products.[86] A NY County decided to ban baby bottles and toddler sippy cups made with bisphenol A.[87]
On March 13 leaders from the House and Senate proposed legislation to ban bisphenol A.[88]
In the same month, Rochelle Tyl, author of two studies used by FDA to assert BPA safety in August 2008, said those studies didn't claim that BPA is safe since they weren't designed to cover all aspects of the chemical's effects. [89]
In May 2009 the Washington Post accused the manufacturers of food and beverage containers and some of their biggest customers of trying to devise a public relations and lobbying strategy to block government BPA bans.[90]
In June 2009 the FDA announced the decision to reconsider the BPA safety levels.[91]
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.[92] According to Environment Canada, "initial assessment shows that at low levels, bisphenol A can harm fish and organisms over time. Studies also indicate that it can currently be found in municipal wastewater."[93]
There are seven classes of plastics used in packaging applications. Type 7 is the catch-all "other" class, and some type 7 plastics, such as polycarbonate (sometimes identified with the letters "PC" near the recycling symbol) and epoxy resins, are made from bisphenol A monomer.[4] When such plastics are exposed to hot liquids, bisphenol A leaches out 55 times faster than it does under normal conditions, at up to 32 ng/hour.[clarification needed][94] (in an 8 ounce glass, boiling for an hour will give concentrations of 29 parts per trillion) Type 3 (PVC) can also contain bisphenol A as antioxidant in plasticizers.[4] Types 1 (PET), 2 (HDPE), 4 (LDPE), 5 (polypropylene), and 6 (polystyrene) do not use bisphenol A during polymerization or package forming.[citation needed]
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