"Mice exposed to BPA in the womb and during nursing subsequently had fewer successful pregnancies and delivered fewer pups over the course of the study," reported one of the study's co-senior authors, Ana M. Soto, MD, professor of anatomy and cellular biology at Tufts University School of Medicine (TUSM) and member of the cell, molecular and developmental biology program faculty at the Sackler School of Graduate Biomedical Sciences.
At the highest of three doses tested, only 60% of the BPA-exposed mice had four or more deliveries over a 32-week period, compared with 95% in the unexposed control group. Decline of the reproductive capacity of the female mice in this study was not obvious at first pregnancy, when the animals were very young, but manifested later in life with a decline in number of pups born per delivery.
"This finding is important because standard tests of reproductive toxicology currently consist of assessing the success of a first pregnancy in young animals. If subsequent pregnancies are not examined, relevant effects may be missed," said co-senior author Beverly S. Rubin, PhD, associate professor of anatomy and cellular biology at TUSM and member of the cell, molecular and developmental biology and neuroscience program faculties at the Sackler School.
"In addition, the infertility effect of BPA was dose-specific in our study. The lowest and highest doses we tested both impaired fertility, while the intermediate dose did not. This phenomenon, called non-monotonicity, is a common characteristic of hormone action. In other words, chemicals have to be tested at a variety of doses in order to avoid false "no effect" results," added co-senior author Carlos Sonnenschein, MD, professor of anatomy and cellular biology at TUSM and member of the cell, molecular and developmental biology program faculty at the Sackler School.
"BPA has effects that mimic those of estrogen, a natural hormone. Fetal and neonatal exposure to BPA has been shown to have other hormone-related effects in rodents, including increased risk of mammary and prostate cancers, altered behavior, and obesity. BPA has been found in the urine of over 92% of Americans tested, with higher levels in children and adolescents relative to adults. It has also been detected in human maternal and fetal plasma," said co-first author Perinaaz R. Wadia, PhD, a research associate in the Soto/Sonnenschein laboratory at TUSM.
"Our findings are potentially of great relevance to humans because BPA is used in the production of materials people are exposed to every day, such as polycarbonate plastics and the resins used to coat the inside of food and beverage cans," said co-first author Nicolas J. Cabaton, PhD, formerly a post-doctoral fellow in the Soto/Sonnenschein laboratory at TUSM and now at the French National Institute for Agricultural Research (INRA).
The authors compared the effects of BPA to those of diethylstilbestrol (DES), a hormonally active chemical that is known to have caused reproductive impairment in women exposed during fetal life, and concluded that the effects of these two chemicals on fertility were comparable. Similar to BPA, low doses of DES had failed to cause obvious reproductive problems when evaluated only at first pregnancy as in the standard tests used by regulatory agencies to determine toxicity.
The three doses of BPA tested are within the range of human exposure and below the Environmental Protection Agency (EPA) reference dose (i.e., the maximal acceptable daily dose). "Our results suggest that a more sensitive test, like the one used in this report should be adopted by regulatory agencies in order to uncover the true risk and possible epigenetic effects of suspected endocrine disruptors," said Soto.
Additional authors include Daniel Zalko, DVM, PhD, French National Institute for Agricultural Research (INRA), Cheryl M. Schaeberle, BS, laboratory coordinator in the Soto/Sonnenschein lab; Michael H. Askenase, BS, formerly a research technician in the Soto/Sonnenschein lab; Jennifer L. Gadbois, RN, Andrew P. Tharp, BS, and Gregory S. Whitt, BS, all research technicians in the Soto/Sonnenschein lab in the department of anatomy and cellular biology at TUSM.
This study was supported by the National Institute of Environmental Health Sciences, part of the National Institutes of Health.
Cabaton NJ, Wadia PR, Rubin BS, Zalko D, Schaeberle CM, Askenase MH, Gadbois JL, Tharp AP, Whitt GS, Sonnenschein C, Soto AM. Environmental Health Perspectives. 2010. "Perinatal exposure to environmentally relevant levels of bisphenol-A decreases fertility and fecundity in CD-1 mice." http://ehponline.org/article/info:doi/10.1289/ehp.1002559
About Tufts University School of Medicine and the Sackler School of Graduate Biomedical Sciences
Tufts University School of Medicine and the Sackler School of Graduate Biomedical Sciences at Tufts University are international leaders in innovative medical education and advanced research. The School of Medicine and the Sackler School are renowned for excellence in education in general medicine, biomedical sciences, special combined degree programs in business, health management, public health, bioengineering and international relations, as well as basic and clinical research at the cellular and molecular level. Ranked among the top in the nation, the School of Medicine is affiliated with six major teaching hospitals and more than 30 health care facilities. Tufts University School of Medicine and the Sackler School undertake research that is consistently rated among the highest in the nation for its effect on the advancement of medical science.
If you are a member of the media interested in learning more about this topic, or speaking with a faculty member at the Tufts University School of Medicine, the Sackler School of Graduate Biomedical Sciences, or another Tufts health sciences researcher, please contact Siobhan Gallagher at 617-636-6586.
Siobhan Gallagher | EurekAlert!
Neutrons produce first direct 3D maps of water during cell membrane fusion
21.09.2018 | DOE/Oak Ridge National Laboratory
Narcolepsy, scientists unmask the culprit of an enigmatic disease
20.09.2018 | Universitätsspital Bern
The building blocks of matter in our universe were formed in the first 10 microseconds of its existence, according to the currently accepted scientific picture. After the Big Bang about 13.7 billion years ago, matter consisted mainly of quarks and gluons, two types of elementary particles whose interactions are governed by quantum chromodynamics (QCD), the theory of strong interaction. In the early universe, these particles moved (nearly) freely in a quark-gluon plasma.
This is a joint press release of University Muenster and Heidelberg as well as the GSI Helmholtzzentrum für Schwerionenforschung in Darmstadt.
Then, in a phase transition, they combined and formed hadrons, among them the building blocks of atomic nuclei, protons and neutrons. In the current issue of...
Thin-film solar cells made of crystalline silicon are inexpensive and achieve efficiencies of a good 14 percent. However, they could do even better if their shiny surfaces reflected less light. A team led by Prof. Christiane Becker from the Helmholtz-Zentrum Berlin (HZB) has now patented a sophisticated new solution to this problem.
"It is not enough simply to bring more light into the cell," says Christiane Becker. Such surface structures can even ultimately reduce the efficiency by...
A study in the journal Bulletin of Marine Science describes a new, blood-red species of octocoral found in Panama. The species in the genus Thesea was discovered in the threatened low-light reef environment on Hannibal Bank, 60 kilometers off mainland Pacific Panama, by researchers at the Smithsonian Tropical Research Institute in Panama (STRI) and the Centro de Investigación en Ciencias del Mar y Limnología (CIMAR) at the University of Costa Rica.
Scientists established the new species, Thesea dalioi, by comparing its physical traits, such as branch thickness and the bright red colony color, with the...
Scientists have succeeded in observing the first long-distance transfer of information in a magnetic group of materials known as antiferromagnets.
An international team of researchers has mapped Nemo's genome, providing the research community with an invaluable resource to decode the response of fish to...
21.09.2018 | Event News
03.09.2018 | Event News
27.08.2018 | Event News
21.09.2018 | Physics and Astronomy
21.09.2018 | Life Sciences
21.09.2018 | Event News