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Common Chemical Disrupts Young Brains |
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Since 1997, scientists have known that bisphenol A acts like the female hormone estrogen and disrupts estrogen dependent development in foetuses and children, as well as normal sexual development, and have recommended that it be banned. |
Since then, and in more than 100 peer-reviewed studies, Bisphenol A has been implicated in breast cancer, prostate cancer, and now, in brain development of foetuses and infants. Bisphenol A is everywhere and used in the manufacture of linings for food cans and lids, and is the main ingredient in polycarbonate plastics - such as food and drink packaging, and in soft plastics, such as bay bottles and toys .
Bisphenol A can imitate the female hormone estrogen, and low level exposures in developing female mice have been shown to advance their puberty [15]. Recent research has shown it can easily cross the placental barrier from mother to foetus in rats [16], and it has also been found to contaminate human blood serum [17]. It has been estimated that 80 - 85% of food cans have linings containing bisphenol A, though there is no way consumers can tell which ones contain it.
Recent Food Standards Agency research has shown that bisphenol A does migrate from can linings into food [18]. In January 2002, EU governments decided to classify bisphenol A as a “category 3” reproductive toxicant (causing concern) because of its possible effects on fertility, though the UK experts had proposed that it should be classified as category 2 (substances which “should be regarded as if they impair human fertility or cause developmental toxicity”.). [19].
Incredibly, nothing has been done, and bisphenol A is still allowed to wreak havoc with the normal brain and sexual development of foetues, of our infants and children - despite the fact that harmless chemical alternatives are readily available.
[References:
[15] Howdeshell, K.L., A.K. Hotchkiss, K.A. Thayer, J.G. Vandenbergh, and F.S. vom Saal (1999). Exposure to bisphenol A advances puberty. Nature 401, 763-764.
[16] Takashi, O. and S. Oishi (2000). Disposition of orally administered 2,2-bis(4-hydroxyphenyl)propane (bisphenol a) in pregnant rats and the placental transfer to fetuses. Environmental Health Perspectives 108, 931-935.
[17] Inoue, K., K. Kato, Y. Yoshimura, T. Makino, and H. Nakazawa (2000). Determination of bisphenol A in human serum by high-performance liquid chromatography with multi-electrode electrochemical detection. J Chromatogr B Biomed Sci Appl 749, 17-23.
[18] FSA (2001). Food Surveillance Information Sheet 13/01: Survey of Bisphenols in Canned Food. Food Standards Agency, London. www.foodstandards.gov.uk/science/surveillance/fsis-2001/bisphenols
[contributed by Ashley Hotz] |
Original Article:
Bisphenol A Disrupts Young Brains, Scientists report
Low doses of Bisphenol A (BPA), a packaging chemical, can damage the development of young brains, according to new scientific study.
The research from a University of Cincinnati scientific team on the packaging chemical adds to the growing body of scientific evidence indicating that it should not be used for food contact materials. BPA works by disrupting the important effects of estrogen in the developing brain, the University of Cincinnati team, headed by Scott Belcher, reported.
BPA shows negative effects in brain tissue "at surprisingly low doses", they say in two articles in the December 2005 edition of the journal Endocrinology. "In the face of more than 100 studies published in peer-reviewed journals showing the detrimental effects of BPA, the chemical industry and federal regulatory agencies have resisted banning BPA from plastics used as food and beverage containers, despite the fact that plastics free of BPA and other toxic chemicals are available," Belcher stated.
BPA is used in the production of epoxy resins and polycarbonate plastics. The plastics are used in many food and drink packaging applications. Resins are commonly used as lacquers to coat metal products such as food cans, milk container linings, bottle tops, water supply pipes and dental sealants. "While plastics are typically thought of as being stable, scientists have known for many years that the chemical linkage between BPA molecules was unstable, and that BPA leaches into food or beverages in contact with the plastics," he stated.
Scientific research has often implicated BPA in disease or developmental problems. The chemical has long been known to act as an artificial estrogen, the primary hormone involved in female sexual development. BPA has already been shown to increase breast cancer cell growth. In the January 2005 edition of the journal Cancer Research, another University of Cincinnati research team reported that it increased the growth of some prostate cancer cells as well.
Warnings about other possible long-term health risks associated with fetal exposures to BPA have also been discussed in recent scientific literature. Belcher and his colleagues worked with rats at a period in their development equivalent to the third trimester of human fetal development through to the first few years of childhood.
Although best known for its function as a female sex hormone, Dr. Belcher explained, estrogen also has very important roles in the developing brain of both males and females. In the absence of estrogen, Dr. Belcher said, BPA alone was found to mimic the actions of estrogen in developing neurons. Very low doses of BPA completely inhibited the activity of estrogen. Because estrogen normally increases the growth and regulates viability of developing neurons, he said, these results support the idea that BPA may harm developing brain cells.
While high doses cause little effect, analysis of cellular and molecular markers of estrogen signaling revealed that near-maximal effects of BPA on rat brain neurons not only occurred "at surprisingly low" doses of 0.23 parts per trillion, they also happened in a matter of minutes, Belcher stated.
"From other studies it's clear that these low concentrations are in line with human fetal exposures, and at levels one might even see in the water supply," he stated.
This "low-dose" effect of BPA is troubling, since its maximum effects occur at the level typical of human exposure. This means that the harmful effects of BPA could easily be missed using standard approaches for determining the risks of chemical exposure, he stated. "These are important considerations in view of the widespread presence of low concentrations of BPA in the environment," he stated.
Earlier research, which showed estrogens could control the survival of maturing neurons in the brain region involved in movement and coordination. Belcher and his co-workers found the effects of estrogen were the same in both males and females. "Estrogen's actions on these neurons appear to be a double-edged sword," he stated. "During certain periods of development estrogen can kill specific subsets of neurons, but at a later developmental stage it actually appears to increase their viability." Disruption of either of these actions of estrogen could be considered potentially harmful, he added.
"We have now shown that environmental estrogens like BPA appear to alter, in a very complicated fashion, the normal way estrogen communicates with immature nerve cells," Belcher stated. "The developmental effects that we studied are known to be important for brain development and also for normal function of the adult brain." What remains unclear is how the inappropriate hormone signaling, or blocking the normal signaling at a critical time during development, will influence humans in later life.
"These new studies are also the first to show that estrogen's rapid signaling mechanisms are active in the developing and maturing brain in regions not thought to be involved with sexual differences or reproductive functions," Belcher stated.
As reported earlier in FoodProductionDaily.com, US scientists from Tufts University School of Medicine in the US reported during the summer that low doses of BPAcould be a contributing factor to the development of breast cancer in women. BPA was first shown to be oestrogenic in 1938, in a study using rats. In a 1993 study BPA was found to be oestrogenic in the human breast cancer cell, the scientists state. Another 1995 study found that the liquid in some cans of tinned vegetables have been found to contain both BPA and the related chemical dimethyl bisphenol-A. The highest levels of BPA were found in cans of peas. BPA was also found in the liquid from cans of artichokes, beans, mixed vegetables, corn and mushrooms. All liquids which contained BPA were found to be oestrogenic to a human breast cancer cell, the scientists reported.
In 1997 researchers Fred vom Saal and others at the University of Missouri-Columbia concluded that BPA was harmful to humans and that its use should be banned. They noted that BPA is also used in the manufacture of bottles, from which it leaches at an increasing rate as the bottle ages.
BPA was first identified in the 1930's. In the 1950's, chemists linked BPA together to create polycarbonates and companies began using the chemical in plastics production. BPA is now one of the top 50 chemicals being produced in the US.
[ Source: FoodNavigator.com Europe - 05/12/2005 - http://www.foodnavigator.com/news/ng.asp?n=64328-bisphenol-chemical-bpa ]
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