Presentation on theme: "Bisphenol A By: Brittani Ehrhorn Bio 2B/Dr. Blumberg Wednesday April 26, 2005."— Presentation transcript:
Bisphenol A By: Brittani Ehrhorn Bio 2B/Dr. Blumberg Wednesday April 26, 2005
What is Bisphenol A? Bisphenol A, also known as BPA, is a commonly used chemical to make polycarbonate plastics. Before its known use as a chemical that makes plastic, it was discovered as a synthetic estrogen in the 1930’s.
Who discovered its uses? The first reported synthesis of BPA was done by Thomas Zincke at the University of Marburg, Germany. Dodds and Lawson first showed BPA to be oestrogenic in ovariectomized rats in 1938. Then in 1953 Dr. Herman Schnell of Bayer, Germany & Dr. Dan Fox of General Electric in the U.S. developed manufacturing processes for a new plastic, polycarbonate, that used BPA as a starting material. In the same century large-scale uses for polycarbonate plastics.
Where is it in the environment? There are many places where BPA is found: Baby bottles and water bottles Dental sealants and medical equipment As coatings on soda cans Automotive primers Household appliances CD’s & DVD’s many things made of plastic are made with BPA….
Why is BPA used so much? BPA is used so frequently because it is highly durable: it has a high heat- resistance, is shatter resistance and has high optical clarity
Why is there such a controversy? The plastic industry is stating that the amount of BPA that a normal person is exposed to is not toxic. Other scientists and researchers have found that their research proves that in causes cancer and premature puberty.
The industry side of the argument… The United States has declared that the “acceptable” dose of BPA is.05 mg/kg body weight/day and their estimated daily intake is.000118 mg/kg body weight/day. Studies done by Dr. Rochelle Tyl at the Research Triangle Institute contradict the“low-dose” hypothesis that small doses can be more harmful than high doses. The the European Commission’s Scientific on Food estimated the total dietary intake to be.00048 to.0016 mg/kg body weight/day.
What the Industry says… Avent America Inc., one of the baby bottle manufacturer in the U.S., has sent a statement stating that BPA is not harmful when a mother wrote asking about the harmfulness of Bisphenol A stating it is “totally harmless”.
The independent researcher’s opinion Dr. John Peterson Meyers, former director of the W. Alton Jones Foundation, Senior VP for Science at the National Audubon Society, and co-author of the book Our Stolen Future argues against the Avent Company’s claim and says that: “there is a significant body of scientific research that establishes, beyond any doubt, that bisphenol A is highly estrogenic… it binds with the estrogen receptor and has the capacity to stimulate estrogenic responses. This means that it is biologically active and therefore not "totally safe." Moreover, there are a series of animal studies in the last 5 years that show that bisphenol A actually does lead to developmental abnormalities in laboratory animals at low levels of exposure. This also directly contradicts their assertion that it is totally safe.” Research has been done on mice and other animals. The process: ---a female mouse was exposed to BPA in their drinking water between day six of her pregnancy and her lactating period. ---some experimental mice received a low-dose of.1 mg BPA/mg body weight/day while others received a high dose of 1.2 mg BPA/mg body weight/day.
Their results… The offspring was found to be affected by this exposure to BPA, and female offspring were the most affected. ---compared to controlled females, female offspring had higher body weights. ---within the group of exposed offspring, low-dose females had higher body weights than high- dose exposed offspring.
Results continued… The male offspring of mice who were exposed to BPA also had higher body weights compared with those which were not exposed, but overall female offspring had a more dramatic weight difference.
More results… This is a specific graph of the male and female offspring. This graph displays mean body weights of female mice exposed and unexposed to BPA (A & B) and males exposed and unexposed to BPA (C & D). This is between days 22 to 110 days old.
The Estrous Cycle in Female Mice In addition the weight differences, female mice also differed in estrous cycles. The female mice not exposed to BPA had a more regular cycle (60% more mice had regular cycles than exposed mice). And within the group of exposed mice, low-dose BPA exposed mice witnessed a more regular cycle and more estrous cycles than high-dose BPA mice.
Plasma Luteinizing Hormone The plasma luteinizing hormone (LH) is also known as progesterone and testosterone. The amounts of LH found in females with exposure to BPA are lower than those females that were not exposed to BPA. In addition, after 16 months of age, only 10% of the controlled females developed mammary tumors while 20% of low-dose BPA females developed tumors and 28% of high-dose BPA female mice developed mammary tumors. Plasma LH levels (mean ± SEM) in ovariectomized females. GroupNo. of ratsLH levels (ng/mL) Control females714.97 ± 0.51 Low-dose females612.17 ± 1.54 High-dose females812.14 ± 0.46* *p < 0.001, high-dose vs. control females.
What to believe? It is very difficult to measure the exact amount of BPA that a human would be exposed to and how they become exposed to it (for example, if there is any BPA in running streams or such). Many investigations of this have been minimal. It is known though that “fertility pills” provide a woman with extra estrogen and it has been known to cause cancer. And Bisphenol A is also known as a synthetic estrogen.
What we can do to minimize exposure … Use filter systems instead of bottled water Buy fresh produces instead of canned food Choose baby bottles and cups made of glass or polyethylene (#1,#2,#4 recycling symbols), or polypropylene (#5) Store food in glass, ceramic or metal containers. Instead of having young children get dental sealants for teeth that will fall out within a few years, and have them increase their practice of at home dental care.