Bisphenol
verlaagt vruchtbaarheid man*
Uit
een studie, weliswaar met muizen blijkt dat bisphenol-A de vruchtbaarheid van
mannen duidelijk kan verlagen. Uit een andere studie blijkt dat bisphenol-A veel
beter opgenomen wordt in het lichaam dan zou kunnen blijken uit gebruikelijke
laboratorium proeven. Het inmiddels in Canada verboden BPA
is een chemische stof die wordt gebruikt voor de productie van polycarbonaat,
een transparante plastic die onder andere gebruikt wordt als drager van CD's en
DVD's en voor onbreekbare flessen voor (baby)voeding, voor tafelbestek, en
voorwerpen voor gebruik in microgolfovens. Het wordt ook gebruikt in epoxyharsen
die als beschermende coating aan de binnenkant van voedingsverpakkingen in blik
of karton worden aangebracht, of in leidingen en reservoirs voor drinkwater.
Bisfenol A wordt ook gebruikt in vlamvertragende middelen, ook in tandvullingen
en als oplosmiddel voor drukinkten. Het is bewezen dat BPA kan vrijkomen uit de
verpakking en in de voeding terechtkomt. Voeding is daardoor de grootste bron
van lichaamsvervuiling door BPA.Hier een brochure
om toxische stoffen te vermijden.
Bisphenol A (BPA) Accumulates More Rapidly Within the Body Than Previously Thought
A new University of Missouri study shows that the exposure to the controversial chemical Bisphenol A (BPA) through diet has been underestimated by previous lab tests. In the study, researchers compared BPA concentrations in mice that were given a steady diet supplemented with BPA throughout the day, compared to the more common lab method of single exposure, and found an increased absorption and accumulation of BPA in the blood of mice.
This is the first study to examine concentrations of BPA in any animal models after exposure through a regular, daily diet, which is a better method to mirror the chronic and continuous exposure to BPA that occurs in animals and humans. Cheryl Rosenfeld, associate professor in biomedical sciences and Bond Life Sciences investigator, is the corresponding lead author of the study published in Environmental Health Perspectives.
The authors continuously exposed the mice to BPA through their feed, which is considered the primary route of exposure to this chemical in animals and humans. In previous studies examining the effects of BPA, mice were exposed to BPA only through a one-time administration. Following the exposure through the diet, a significantly greater increase in the active form of BPA, which is the greatest threat as it is the form that can bind to sex steroid receptors and exert adverse effects, was absorbed and accumulated in the animals.
"People are primarily and unknowingly exposed to BPA through the diet because of the various plastic and paper containers used to store our food are formulated with BPA," Rosenfeld said. "We know that the active form of BPA binds to our steroid receptors, meaning it can affect estrogen, thyroid and testosterone function. It might also cause genetic mutations. Thus, this chemical can hinder our ability to reproduce and possibly cause behavioral abnormalities that we are just beginning to understand."
The study notes that more than 8 billion pounds of BPA are produced every year, and more than 90 percent of people in the United States have measurable amounts of BPA in their bodies.
"We believe that these mouse model studies where the BPA exposure is through the diet is a more accurate representation of what happens to BPA as the human body attempts to processes this toxic substance," said Rosenfeld. "When BPA is taken through the food, the active form may remain in the body for a longer period of time than when it is provided through a single treatment, which does not reflect the continuous exposure that occurs in animal and human populations. We need to study this further to determine where the ingested BPA becomes concentrated and subsequently released back into the bloodstream to be distributed throughout the body."
Funding from this study came from a National Institute of Environmental Health and Sciences challenge grant program that was established to investigate the biological effects of exposure to BPA
BPA Lowers Male Fertility, Mouse Study Finds
Daily exposure to a chemical that is prevalent in the human environment, bisphenol A (BPA), causes lowered fertility in male mice, according to the results of a new study that being presented at The Endocrine Society's 93rd Annual Meeting in Boston.
Mice that received daily BPA injections for two months had lower sperm counts and testosterone levels than those of mice that received saline injections without BPA, investigators from Banaras Hindu University in Varanasi, India, found. Compared with untreated controls, mice exposed to BPA produced litters that were 50 percent smaller.
"We are being exposed to BPA in our daily lives at a level much higher than the safe recommended exposure," said the study's principal author, Surya Singh, PhD, associate professor in the university's biochemistry department. "In this study, we are trying to explore what the outcome can be if we are continuously exposed to BPA in our routine life."
BPA-exposed mice received a dose that was twice the daily upper limit of safe exposure recommended by the U.S. Food and Drug Administration and the Environmental Protection Agency.
At a BPA dosage of 100 micrograms per kilogram of body weight daily, the mice also had structural defects in their testicles and were considered subfertile. If the same dose had been given longer than two months, Singh speculated that it might lead to infertility.
However, he said they saw lowered fertility in the mice as early as one month of BPA exposure.
"Even short-term exposure to BPA could be dangerous to fertility, but we are still investigating this possibility," Singh said.
These new research findings add to a growing body of scientific evidence that links exposure to BPA, an endocrine (hormone) disrupter, with numerous adverse health effects, including on reproductive function.
Human exposure to BPA comes from sources such as epoxy resin-lined food cans and hard polycarbonate plastics, which leach the chemical, especially when heated to high
temperatures. (Juli 2011)
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