Bisphenol A (BPA) . It is a chemical product that has been used for many years as a component for the manufacture of polycarbonate and epoxy-phenolic resins. This substance is currently authorized for the manufacture of plastic materials by Regulation (EU) 10/2011 of the Commission of 14 January of 2011 , on plastic materials and articles intended to come into contact with food.
Polycarbonate is a type of transparent rigid plastic that is used both to make food containers and many other non-food-related objects with which we are in daily contact, such as cash register receipts made of thermal paper, CDs or DVDs , toys, cosmetics, etc.
For their part, epoxy-phenolic resins are used in coatings and linings for preserves and food and beverage tanks.
Summary
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- 1 Synthesis
- 2 uses
- 3 Identification in plastics
- 1 Plastics type 1, 2, 4 and 5
- 2 Type 3 plastics
- 3 Type 7 plastics
- 4 Type 6 plastics
- 4 Affected
- 5 Toxicity
- 6 Toxic effects
- 1 Effects on the male reproductive system
- 2 Effects on the female reproductive system
- 3 Effects on the brain and behavior
- 4 Effects on metabolism and cardiovascular system
- 5 Effects on thyroid
- 6 Effects on the immune system
- 7 Effects on the intestine
- 8 Carcinogenic Effects
- 7 Source
Synthesis
Bisphenol-A was first synthesized by the Russian chemist Aleksandr Dianin in 1891 . It is prepared by condensing acetone (hence the suffix ‘-A’) 5 with two equivalents of phenol. The reaction is catalyzed by an acid, such as hydrochloric acid (HCl) or a sulfonated polystyrene resin. A large amount of phenol is normally used to ensure its complete condensation. A large number of ketones undergo similar condensation reactions. This method is efficient and the only derived product is water.
Applications
Bisphenol-A is mainly used to make plastics. Products containing bisphenol-A have been on the market for more than fifty years. It is a key monomer in the production of epoxy resin and in the most common form of plastic polycarbonate. Plastic polycarbonate, which is transparent and almost shatterproof, is used to make a wide variety of common products, including baby bottles and water bottles , sports equipment, dental and medical devices, dental composites and sealants, organic glasses, CDs and DVDs, and various appliances.
It is also used in the synthesis of polysulfones, polyether ketones, as an antioxidant in some plasticizers and as a polymerization inhibitor in PVC. Bisphenol-A containing epoxy resins are used as a coating on almost all food and beverage cans, 12 however, due to health problems, in Japan the epoxy coating was replaced by a polyester film. BPA is also a precursor to a flame retardant, tetrabromobisphenol A, and is used as a fungicide. In addition, BPA is a color developer for thermal paper15 and NCR paper. Past products in BPA are used in casting molds and as a coating for water pipes.
Identification in plastics
There are 7 types of plastic used in packaging. Type 7 contains all the “others”, and some of these, such as polycarbonate (sometimes identified by the letters ‘PC’ next to the recycling symbol) and epoxy resins, these are made from the bisphenol-A monomer.
Type 1, 2, 4 and 5 plastics
Type 1 (PET), 2 (HDPE), 4 (LDPE) and 5 (Polypropylene) plastics do not use bisphenol-A during their polymerization or packaging formation.
Type 3 plastics
Type 3 plastics (PVC) may also contain bisphenol-A as an antioxidant in plasticizers.
Type 7 plastics
ABS (Acrylonitrile-Butadienestyrene) is a hard plastic used in pipes, car fenders, and toys. Its production uses butadiene and styrene in addition to acrylonitrile, a highly toxic product. Given its very complex chemical composition, ABS is extremely difficult to recycle. Compact discs and 19-liter water jugs are typically made of polycarbonate (PC). PC does not require additives, but phosgene and solvents such as chloroethane and chlorobenzene are used in its production in addition to bisphenol-A, a frequently used endocrine disruptor. Processes to produce PC without such compounds are currently being explored . Some PC recovery processes have been designed for the production of lower quality products.
Type 6 plastics
Polystyrene (PS). Plastic foam (better known by the brand “Styrofoam”). Includes cups for hot drinks, clam shell container for quick meals, egg cartons and meat trays. PS represents approximately 11% of all plastics. All other plastic resins or mixtures of those indicated above in the same product. These plastics represent approximately 4 % of all plastics .
Affected
The main affected are mostly babies, both in their embryonic and lactation stages, since it is then that hormones play a fundamental role. It is in these moments of her life, when her mother transfers to her, either through the umbilical cord or milk, all these hormones that have accumulated in her body.
Toxicity
Bisphenol A is an endocrine disruptor. It is capable of causing imbalances in the hormonal system at very low concentrations with possible repercussions on health. Its toxic effects are due to the consumption of foods that have been contaminated by contact with materials containing this substance, such as very different kinds of containers, cans or containers. The wide distribution of bisphenol A products, especially in developed countries, causes continuous exposure of the population, affecting all ages (from fetuses to the elderly). The continuous presence of this disruptor in the body has been linked to an increased risk of suffering from various organic disorders.
Toxic effects
Numerous alterations caused by bisphenol A have been associated in living beings, based on a dysregulation of the endocrine system and the corresponding production of hormones:
Effects on the male reproductive system
Numerous works refer to an alteration of spermatogenesis that conditions a decrease in sperm levels, testosterone and, in general, male fertility. Furthermore, other studies suggest a change in sexual behavior.
Effects on the female reproductive system
In women, changes occur in the maturation of oocytes, decreasing their number and quality. There is also a study that relates exposure to bisphenol A with negative effects on the endometrium, appearance of polycystic ovaries , abortions and premature deliveries. On the other hand, in animals there is evidence of ovarian cysts , endometriosis , early puberty and involvement of the hypothalamic-pituitary-gonadal axis. Bisphenol A can modify the activity of maternal steroids in vertebrate animal embryos.
Effects on the brain and behavior
Various animal tests have confirmed the effect of bisphenol A on the differentiation of neurons, alteration of the systems mediated by glutamine and dopamine and changes in the expression of estrogenic receptors. It has also been associated with possible changes in maternal behavior (less attention to offspring), anxiety, reduced exploratory behavior and a feminization of males. In humans, changes have been established that include hyperactivity, increased aggressiveness, increased susceptibility of addictive substances, and problems in both learning and memory.
Effects on metabolism and cardiovascular system
Associations of a higher bisphenol A concentration have been established with cases of various heart diseases and hypertension. Furthermore, exposure to bisphenol A leads to an increase in blood lipids, an increase in weight and an increase in lipogenesis. It can also affect the appearance of type II diabetes mellitus by increasing insulin resistance and the number of fat cells.
Effects on thyroid
Animal studies conclude that bisphenol A is capable of affecting thyroid function by acting as an antagonist of thyroid hormone. In amphibians, this effect results in an inhibition of their metamorphosis. Thyroid involvement also affects rodents. In the case of humans, not enough studies have been carried out to draw conclusive results.
Effects on the immune system
An induction of T lymphocytes and an increase in the production of cytokines have been demonstrated in experimental animals, thus favoring allergic processes.
Effects on the intestine
Possible inflammation and alteration of intestinal permeability in animals.
Carcinogenic effects
When bisphenol A is metabolized by hydroxylation and subsequent oxidation, it forms an orthoquinone that can establish covalent bonds with DNA and develop mutagenic and teratogenic effects. The mutagenic effects could be the initiators of various carcinogenic processes associated with bisphenol A:
- Prostate cancer
The estrogenic activity of the substance can lead to an increase in the size of the prostate and a decrease in the size of the epididymis.
- Breast cancer
Increased mutagenic and carcinogenic susceptibility has been detected at the level of mammary cells in women due to estrogenic stimulation of the development and division of the mammary glands.