(Press-News.org) Bisphenol A (BPA) is a chemical compound that is included in the composition of plastics and resins. It is used, for example, in the manufacture of food containers such as bottles and babies' feeding bottles. It is also found in the protective films used inside food and drink cans and on till receipts where it used as a discloser. Significant levels of BPA have also been found in human blood, urine, amniotic fluid and placentas. Recent studies have shown that this industrial component has harmful effects on reproductive ability, development and the metabolism of laboratory animals. BPA is strongly suspected of having the same effects on humans.
As a precautionary measure, the manufacture and sale of babies' feeding bottles containing bisphenol A have been banned in Europe since January 2011. This ban will be extended in France to all food containers from July 2015. It will also be important to ensure that in the future, bisphenol A is not replaced by substitutes that have the same action.
In an article published in PLOS ONE, René Habert and his colleagues provide the first experimental proof that weak concentrations of bisphenol A are sufficient to produce a negative reaction on the human testicle. No experimental study has shown hitherto that bisphenol A has a deleterious effect on male human reproduction and the few epidemiological studies that exist remain contradictory.
In collaboration with the Antoine-Béclère Hospital, Clamart[1], researchers kept petri dishes of human fœtal testicles alive in the presence of bisphenol A or in the absence thereof, using an original procedure developed by this team. In 2009, this procedure made it possible to show for the first time, that phtalates (a different category of endocrine disruptors[2] that are found in PVC, plastics, synthetic materials, sprays, etc.) inhibit the development of future spermatozoa in the human fœtus.
In this new study, researchers observed that exposure of human fœtal testicles to bisphenol A reduces the production of testosterone, and of another testicular hormone that is necessary for the testicles to descend into the sacs in the course of fœtal development. A concentration equal to 2 micrograms per litre of bisphenol A in the culture medium was sufficient to produce these effects. This concentration is equal to the average concentration generally found in the blood, urine and amniotic fluid of the population.
Testosterone is known to be produced by the testicle during the life of the fœtus, imposing masculinisation of the internal and external genitals which, in the absence of testosterone, develops spontaneously in the female direction. Furthermore, it is likely that testosterone also plays a role in the development of the testicle itself. Consequently, the current exposure of pregnant women to bisphenol A may be one of the causes of congenital masculinisation defects (of the hypospadia and cryptorchidism types) the frequency of which has doubled overall in the past 40 years. According to René Habert, "it is also possible that bisphenol A contributes to a reduction in the production of sperm and the increase in the incidence of testicular cancer in adults that have been observed in recent decades".
Furthermore, researchers have compared the response to bisphenol A in human fœtal testicles to those in the fœtal testicles of rats and mice. "We have observed that the human species is far more sensitive to bisphenol A than the rat and the mouse. These results should encourage greater caution in regulatory toxicology in the extrapolation of data obtained on animals to define tolerable exposure thresholds in human health", explains René Habert.
Finally, the researchers show in this article that Bisphenol A acts through a mechanism that is non-standard and that remains unknown but that it is important to identify in order to better understand the action of endocrine disruptors.
###
1 Gynæcology, Obstetrics and Reproductive Medicine Department
2 Substance or mixture not produced by the body that alters the functioning of the hormonal system, thus introducing harmful effects on the health of an intact organism, its descendants or sub-populations
Sources
Differential Effects of Bisphenol A and Diethylstilbestrol on Human, Rat and Mouse Fetal Leydig Cell Function
Thierry N'Tumba-Byn, Delphine Moison, Marlène Lacroix, Charlotte Lecureuil, Laëtitia Lesage, Sophie M. Prud'homme, Stéphanie Pozzi-Gaudin,René Frydman, Alexandra Benachi, Gabriel Livera,Virginie Rouiller-Fabre equal contributor,René Habert equal contributor
PLOS ONE, decembre 2012
Contact chercheur
René Habert
rene.habert@cea.fr END
DURHAM, N.C. -- Hydraulically fractured natural gas wells are producing less wastewater per unit of gas recovered than conventional wells would. But the scale of fracking operations in the Marcellus shale region is so vast that the wastewater it produces threatens to overwhelm the region's wastewater disposal capacity, according to new analysis by researchers at Duke and Kent State universities.
Hydraulically fractured natural gas wells in the Marcellus shale region of Pennsylvania produce only about 35 percent as much wastewater per unit of gas recovered as conventional ...
Alexandria, VA – Throughout history, humanity has steadily increased its dependence upon technology. Although technology has vastly improved the quality of life for billions of people, it has also opened us up to new risks and vulnerabilities. Terrorism and natural disasters might be at the forefront of the minds of policymakers and the U.S. population, but a significant threat lurks over our heads: the sun. A massive solar storm, the size last seen a century and a half ago, could easily leave hundreds of millions of people in the dark for days, weeks or even months.
The ...
Glaciers in the tropical Andes have been retreating at increasing rate since the 1970s, scientists write in the most comprehensive review to date of Andean glacier observations. The researchers blame the melting on rising temperatures as the region has warmed about 0.7°C over the past 50 years (1950-1994). This unprecedented retreat could affect water supply to Andean populations in the near future. These conclusions are published today in The Cryosphere, an Open Access journal of the European Geosciences Union (EGU).
The international team of scientists – uniting researchers ...
Over 500 billion cells in our bodies will be replaced daily, yet natural selection has enabled us to develop defenses against the cellular mutations which could cause cancer. It is this relationship between evolution and the body's fight against cancer which is explored in a new special issue of the Open Access journal Evolutionary Applications.
"Cancer is far from a single well-defined disease which we can identify and eradicate," said Dr Athena Aktipis, Director, Human and Social Evolution, Center for Evolution and Cancer at the University of California, San Francisco. ...
Ann Arbor, Mich. — Egg allergic children, including those with a history of anaphylaxis to egg, can safely receive a single dose of the seasonal influenza vaccine, according to a new study from the University of Michigan.
Historically, the CDC recommended that the seasonal influenza vaccine not be administered to egg allergic children. Recent research conducted at the University of Michigan, and elsewhere, helped modify this recommendation in 2011 so that caution was warranted for only those with severe egg allergy.
The new study, published in the Annals of Allergy, ...
Women with hypertensive disorders in pregnancy are at higher risk of chronic kidney disease and end-stage renal disease compared with women without the disorders, according to a study in CMAJ (Canadian Medical Association Journal).
"We found that women with hypertensive disorders during pregnancy were at higher risk of end-stage renal disease than women without complicated pregnancies," writes Dr. I-Kuan Wang, Division of Nephrology, China Medical University Hospital, Taichung, Taiwan, with coauthors.
Hypertensive disorders such as gestational hypertension and preeclampsia ...
When people wash their hands with antibacterial soap, most don't think about where the chemicals contained in that soap end up. University of Minnesota engineering researchers do.
A new University of Minnesota study determined that the common antibacterial agent, called triclosan, used in soaps and many other products is found in increasing amounts in several Minnesota freshwater lakes. The findings are directly linked to increased triclosan use over the past few decades.
In addition, the researchers found an increasing amount of other chemical compounds, called chlorinated ...
NEW YORK (January 22, 2012) —Wildlife Conservation Society scientists have documented a thriving population of lowland tapirs – the strange forest and grassland-dwelling herbivore with the trunk-like snout – living in a network of remote national parks spanning the Peru-Bolivia border.
Using a combination of camera traps, along with interviews with park guards and subsistence hunters, WCS estimates at least 14,500 lowland tapirs in the region. The population bridges five connected national parks in northwest Bolivia and southeastern Peru.
The WCS findings were described ...
This press release is available in German.
Dendritic cells, or DCs for short, perform a vital role for the immune system: They engulf pathogens, break them down into their component parts, and then display the pieces on their surface. This in turn signals other immune cells capable of recognizing these pieces to help kick-start their own default program for fighting off the invaders. In order to do their job, the DCs are dependent upon the support from a class of immune system molecules, which have never before been associated with dendritic cells: antibodies, best ...
Philadelphia, Pa. (January 22, 2013) – Researchers are making new strides in understanding the health consequences and treatment and rehabilitation needs of combat veterans and other service members affected by traumatic brain injury (TBI). The January-February issue of The Journal of Head Trauma Rehabilitation, official journal of the Brain Injury Association of America, is a special issue devoted to new research in military TBI. The journal is published by Lippincott Williams & Wilkins, a part of Wolters Kluwer Health.
"For the second consecutive year, we've expedited ...
