This article could help you with choices that may come up as it
addresses the problem of the use of plastics in water storage or
filtration.
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Lexan, Bisphenol-A And The Big Berky Water Filter
First, it's important to note that the Big Berky water filter concept is the ideal way to filter water. No electricity is required, no batteries, and reliability is excellent because of pure simplicity. And it provides drinking water with everything harmful removed. I do not sell these units, and this is only my opinion.
Lexan[r] is made by General Electric and is one of "wonder plastics," first touted decades ago in television commercials as the toughest plastic equivalent of bullet-proof glass. It has been used for dishwashers, helmets and windshields (or, windscreens as our UK friends call them.) It has also quickly become a replacement for glass and metal in numerous applications. Hit with a hammer and it bounces right off. I have used it myself for numerous designs when ruggedness and machining was required. Though more expensive than Plexiglas(r), it can also be easily drilled and machined without cracking like Plexiglas.
Lexan has just the right amount of flexibility to take a hammer blow and dissipate the shockwave, but isn't so rigid that it shatters like Plexiglas which is commonly used for windows in storm doors. In fact, Lexan is the ideal solution for storm doors where children are considered. When broken, Plexiglas can have very sharp edges. In non-human consumption related products Lexan will be an excellent material for years to come, as it solves many engineering issues related to product performance. However, many hardware stores today still do not carry Lexan.
Bisphenol-A is a component of Lexan. In recent years, the chemical compound Bisphenol-A has made news as harmful to humans over a long term period. It creates an estrogen-like compound which affects human biology. Newer versions of the Big Berky(r) water purifier are injection or blow molded from this Lexan - which contains Bisphenol-A.
It's also worthy to note here, that common water bottles everyone buys in a store have the compound Bisphenol-A. Drinking such water may be contradictory to one's health. And glass bottles are vanishing from store shelves faster than ever.
But the answer to whether or not Bisphenol-A in Lexan in newer Big Berky water filters is harmful to humans or whether the chemical is absorbed by water is not as simple as it would appear. It may be that laboratory studies for Lexan toxicity are like cell-phone radiation studies, whereas the outcome is directly related to which company funds the study.
Plastic out-gassing is a phenomenon which everyone who has bought a new car is familiar with. It isn't just the source of that "new car smell." It also deposits that cloudy film on the inside of the glass for months on end. Invisible chemical gasses from the numerous plastics from which car interiors are made of condense on cooler window glass surfaces. Most plastics have a very long out-gassing period. You can open up an old transistor radio, place it near your nose and STILL smell the plastic 30 years later.
When plastics are in contact with liquids molecular compounds may be released. But just as Sugar doesn't dissolve in certain chemicals, significant amounts of Bisphenol-A may or may not be absorbed into the surrounding water while inside a Big Berky. How can this be? Bottled water can sit on a store or warehouse shelf from six months to a year or more. Water inside a Big Berky is probably used within hours or a few days. This can make a difference as to the level of Bisphenol-A in the water measured in parts per million. Logically, the amount of the chemical released must reduce over a period of time. Whether or not this is a linear function is not known, as many factors contribute to this such as time, temperature, local water composition which might have chemicals that attack the plastic, etc
So what's the possible solution? Remove filtered water from a plastic Big Berky as soon as possible, and store it in a stainless steel or glass container. This will eliminate any further infiltration into the water by chemical compounds. If you are buying a Big Berky, the logical solution is to purchase the original stainless steel model. If properly cared for, this model may last longer than the plastic version, too.
Ted Twietmeyer
essay source~~
http://data4science.net/essays.php?EssayID=766
blessings,
Zoe
-_-