Plastic Venom: Bisphenol A and its Possible Health Risks
Take a look around you and you will find innumerable products containing the hazardous compound Bisphenol A. You wake up in the morning, squeeze toothpaste on the toothbrush that contains Bisphenol A, get ready for university wearing your favorite colored lenses or reading glasses containing Bisphenol A. You rush downstairs having just enough time to grab onto your canned food and eat out of the tin only, fill your plastic bottle, put some food in a plastic box and off to university. Sadly, the canned food, plastic bottle and the plastic box all have some amounts of Bisphenol A.
Bisphenol A is the main component of polycarbonate, the strong and stable plastic used in the manufacture of many products. Many medical and electrical devices, even baby milk bottles, baby toys and baby sipping cups are made from polycarbonate. When babies suck on toys or bottle nipples they are directly ingesting Bisphenol A. Another substance- epoxy resins used for making lacquers to coat water pipes and the inside of food cans also contain Bisphenol A. This causes it to leach into the canned food.
Research indicates that Bisphenol A alters the effects of estrogen: the hormone produced by the ovaries, brain and fat cells in both males and females and plays a variety of important functions including brain development, feminization in females, growth of the endometrium, release of FSH, etc. Estrogen also prevents various diseases such as osteoporosis, Alzheimer’s and atherosclerosis. Therefore, if Bisphenol A through the various plastics and lacquers is consumed, it can adversely affect bodily functions.
One of the effects of Bisphenol A is on development of the nervous system. Normally, estrogen binds to estrogen receptors in the cytoplasm of neurons. The hormone-receptor complex then goes into the nucleus and activates certain DNA sequences called estrogen response elements. Once activated, these DNA sequences result in the formation of specific proteins responsible for overall motor control, pain sensitivity, learning and memory of an individual. Furthermore, it is also seen that estrogen acts on endothelial cells of cerebral capillaries stimulating the release of:
1. Nitric oxide that causes vasodilation preventing the brain from ischemia and stroke.
2. Glucose 1 transporters to plasma membrane of endothelial cells so that glucose from the blood can be taken up by neurons and metabolized to produce energy.
Though the exact mechanism of action of Bisphenol A is yet not known, the following explains the potential mechanism by which Bisphenol A might alter the effects of estrogen.
Bisphenol A competitively binds to estrogen receptors (estrogen receptor alpha, estrogen receptor beta and estrogen related receptor gamma) in the cytoplasm of neurons and endothelial cells. The hormone-receptor complex then goes into the nucleus and acts on estrogen response elements modifying the histone proteins, changing nucleotide sequence and changing methylation sites. The resultant modified estrogen response elements cannot be translated into normal proteins. Furthermore, research also indicates that Bisphenol A-estrogen receptor complex can also modify genes of estrogen receptors thereby reducing the number of normal estrogen receptors.Due to this, estrogen effect on neurons and endothelial cells is made ineffective resulting in lack of development of the nervous system.
So far we have discussed only one of the numerous harmful effects associated with Bisphenol A consumption. Other possible effects include formation of breast cancer, prostate cancer, type 2 diabetes, male impotence, heart disease (in females only), reduced quality of female eggs, changes in male sex hormones, asthma and reduced effectiveness of chemotherapy. Studies are still being conducted to know more about the pharmacodynamics of Bisphenol A and whether the exposed levels are great enough to cause these hazardous conditions.
However, it is evident that the fetus and new born babies are greatly vulnerable to the effects of Bisphenol A mainly because their bodies are not strong enough to eliminate a foreign compound. Therefore, many countries are taking measures to eliminate the use of polycarbonate in the making of baby toys, milk bottles, sipping cups, etc.
In 2008, the use of polycarbonate in baby bottles was banned in Canada, while the same ban in Europe was put in 2011. In 2012, U.S. law makers banned the use of polycarbonate in all children products. However, in Pakistan no such step has been taken.
Though the elimination of Bisphenol A exposure is impossible, it can be reduced. Its main source is through the diet which means the use of canned foods and canned beverages should be avoided. Heating polycarbonate plastics overtime (or even washing them with acidic soaps) breaks down the polycarbonate releasing Bisphenol A. Therefore, polycarbonate plastics should not be heated, especially when heating food in the microwave oven, glass or porcelain dishes should be used as an alternative.
While shopping for plastic goods, look for Bisphenol A free products (such products are usually labeled BPA free) or shop through a reliable website that sells BPA free products.
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