(Press-News.org) Polybrominated diphenyl ethers (PBDEs) are chemicals that have been widely used as flame retardants and are now classified as persistent organic pollutants. Health concerns in humans have arisen based primarily on studies with laboratory animals exposed to high levels of PBDEs. Three commercial mixtures of PBDEs have been manufactured in or imported into the United States which include penta-, octa-, and deca-brominated diphenyl ethers (BDEs). Of particular concern has been the penta-BDEs used primarily in foams in computers, televisions, mattresses, pillows, carpets, and furniture. The components of penta-BDEs mixtures are present in water, soil, animal products and air, and people are exposed primarily through ingestion of food or inhalation. Penta-BDEs have been measured in human blood, fat, breast milk, and umbilical cord blood. Since 2004, the penta- and octa-BDEs are no longer being manufactured in the USA and deca-BDE manufacture in the USA will be phased out by the end of 2013. Even so, due to their chemical nature, PBDEs will persist in the environment long after their use in manufacturing has ended. It is unclear what impact PBDEs have on human health as people are typically not exposed to the high concentrations of PBDE compounds that have detrimental neurological and endocrine effects in laboratory animals. There is a need to determine the impact of low doses of PBDEs in laboratory animals which approach the levels that humans are exposed to in daily life, and in addition to determine the effects of these compounds in offspring exposed during critical developmental periods.
In the work published in the April issue of Experimental Biology and Medicine, Blake, LaVoie, and co-investigators set out to determine the effects of a relatively low dose of the commercial penta-BDE mixture, DE-71, on reproductive and endocrine function in a laboratory rat model. Female rats were orally administered 60 micrograms/kilogram body weight/day during pregnancy and lactation to expose them and their developing offspring to DE-71. The offspring were followed to adulthood and mated to evaluate their reproductive outcomes, thyroid hormone concentrations, body and organ weights, and gene expression in selected organs. The work was carried out jointly by the laboratories of Charles A. Blake and Holly A. LaVoie at the University of South Carolina School of Medicine in Columbia, South Carolina.
Dr. LaVoie, who led the research team, stated "we were happy to see that low doses of DE-71 did not overtly affect reproductive outcome of pregnancy in terms of resorbed embryos and number of viable offspring of either the mothers receiving DE-71 or their first generation offspring. However, gene profiling of reproductive organs of offspring identified a single gene spp1 that encodes osteopontin, which exhibited 3-fold or higher expression in both the immature testes of male offspring and adult ovaries of female offspring that were exposed to low dose DE-71 in utero and via their mother's milk. This shows that molecular changes are occurring in reproductive organs and that some of these molecular changes appear even after the penta-BDE delivery was ceased."
Additional cell culture studies further confirmed that the osteopontin gene promoter is a novel target of PBDEs. Osteopontin is a multi-functional extracellular matrix protein. The long-term implications of elevated osteopontin gene expression in gonads is unclear at this time, however, osteopontin protein is known to be elevated in ovarian and other cancers. PBDEs are formed by adding 1-10 bromine groups to a double ring structure to form different congeners. Different PBDE congeners can mimic or inhibit thyroid hormone, estrogen, and androgen function. The mechanism of how PBDEs regulate the osteopontin gene will require further study. Also in need of further study are the long-term implications of altered osteopontin in ovaries and testes.
In contrast to prior studies with much higher concentrations of penta-BDEs that demonstrated reduced serum thyroid hormone concentrations, the study showed that first generation females during their own pregnancies had elevated serum thyroid hormones. Furthermore, the DE-71 exposed female offspring sacrificed two months after their own pregnancies, had enlarged thyroids without altered serum thyroid hormones.
Dr. Blake, who led the endocrine studies remarked, "Our thyroid findings, taken together with previous work with high doses of penta-BDEs, indicate that these compounds may have biphasic effects depending on exposure levels where low dose exposures may increase thyroid hormone concentrations and higher PBDE doses may decrease them. In addition, the physiological status of the animal (i.e., pregnant versus non-pregnant) may determine if the thyroid hormone levels are affected. These studies could potentially be critical to understanding the effects of PBDE accumulation in the tissues of pregnant women. They also emphasize the potential importance of reducing exposure to PBDEs in homes and the environment and regulating the import of manufactured items that contain PBDEs."
The first generation offspring in the study received DE-71 via maternal exposure to a low dose, showing that in utero and lactational exposure of offspring can have effects lasting into adulthood. Moreover, most differences were observed in female rat offspring, suggesting sex differences in the physiological responses to PBDEs. This study sets the stage for future investigations of long-term effects of low level PBDE ingestion.
Dr. Steven R. Goodman, Editor-in-Chief of Experimental Biology and Medicine, said "This important environmental health study by Holly Lavoie, Charles Blake and colleagues has looked at the effect of low doses of polybrominated diphenyl ethers (PBDEs) on laboratory animals. Their findings indicate these organic pollutants, found in flame retardents, caused pregnant and lactating rats to have increased levels of thyroid hormone in female offspring and increased gonadal osteopontin gene expression. It is clear that this sets the stage for future studies aimed at understanding the long term consequences of PBDE exposure."
###
Experimental Biology and Medicine is a journal dedicated to the publication of multidisciplinary and interdisciplinary research in the biomedical sciences. The journal was first established in 1903.
Experimental Biology and Medicine is the journal of the Society of Experimental Biology and Medicine. To learn about the benefits of society membership visit www.sebm.org. If you are interested in publishing in the journal please visit http://ebm.rsmjournals.com.
Low doses of penta-brominated diphenyl ether flame retardants alter gene expression
2011-04-14
ELSE PRESS RELEASES FROM THIS DATE:
HIV rate in SF could be cut sharply with expanded treatment, study predicts
2011-04-14
If HIV-infected adults in San Francisco began taking antiretroviral treatments as soon as they were diagnosed, the rate of new HIV infections among men who have sex with men would be cut by almost 6o percent over five years, according to a new study by scientists at the University of California, San Francisco.
In San Francisco, men who have sex with men comprise more than three quarters of the population of people living with HIV and more than three quarters of new HIV infections occur in this group. The study looked specifically at the impact of treatment upon rates ...
Bankruptcy Filings Rise As Stigma Falls
2011-04-14
The statistic is breathtaking: "More Americans filed for bankruptcy last year in the United States than in the entire decade of the 1960s," reports an article on MSN Money. The slowness of the recovery combined with the mountain of debt has put more people in the position of filing for bankruptcy than ever.
With the recession, more people have had problems paying their bills, in part, due to the fact they have more debt. From 1990 to 2003, credit card lending increased from $173 to $683 billion. Much of the lending was for subprime credit cards, which grew even faster ...
Children victims of most eye injuries from aerosols
2011-04-14
PROVIDENCE, R.I. [Brown University] — Children were the victims in more than half of the emergency room visits for eye injuries related to aerosol cans between 1997 and 2009, according to a new study by researchers at Brown University. More could be done, they said, to prevent injury from the pressurized and often harsh chemical contents of the common products.
The youngest children, ages 0 to 4, were the most likely to be hurt with an estimated 2,830 emergency room visits during the study timeframe, according to the study published in advance online March 30 in the American ...
Coffee in capsules contains more furan than the rest
2011-04-14
"Preparing a coffee in a drip coffee maker is not the same as making one in an espresso machine or from capsules, because these give rise to differing levels of furan", Javier Santos, a professor at the Department of Analytical Chemistry at the University of Barcelona and lead author of the study, tells SINC.
Concern has risen over recent years about the presence of this compound in foods, because of its toxic and carcinogenic effects in animals, as well as the fact that the International Agency for Research on Cancer has listed it as a possible carcinogen in humans.
Against ...
Texas Debating Sex Offender Registration Changes
2011-04-14
The stigma of a sex crime is something that can follow someone around for years, if not a lifetime. If a conviction results, many different punishments may be handed down. Not only may there be extensive prison time, but offenders will also be required to demonstrate that they have been rehabilitated. Additionally, those convicted will also need to register as a sex offender. Once someone is on this list it becomes very difficult to be removed. Some sexual offenses require lifetime registration.
All of this costs a lot of money for states. Many jurisdictions have embraced ...
Researchers create privacy mode to help secure Android smartphones
2011-04-14
Researchers at North Carolina State University have developed software that helps Android smartphone users prevent their personal information from being stolen by hackers.
"There are a lot of concerns about potential leaks of personal information from smartphones," says Dr. Xuxian Jiang, an assistant professor of computer science at NC State and co-author of a paper describing the research. "We have developed software that creates a privacy mode for Android systems, giving users flexible control over what personal information is available to various applications." The ...
Trial Court Upholds $4.2 Million Verdict Obtained by Greene Broillet & Wheeler, LLP in Lawsuit Against Paul Revere Life Insurance Company and UNUM Group
2011-04-14
A Los Angeles Superior Court trial judge has rejected a motion for a new trial in a case against defendants Paul Revere Life Insurance Company and UNUM Group involving a disability insurance policy. The jury had previously found the defendants liable for bad faith and breach of an insurance disability contract before awarding $4.2 million in damages to the insured.
The plaintiff, a dental hygienist, first purchased an individual disability insurance policy from Paul Revere in 1988. After she began to suffer from several disabling medical conditions in 1996, including ...
U.S. Justice Department Sues HSBC India for Disclosure of Accounts Held by United States Taxpayers
2011-04-14
The United States Department of Justice continues its vigorous efforts to open up foreign secret bank accounts. In its latest move, the United States Department of Justice, on behalf of the Internal Revenue Service has filed suit in San Francisco, California against HSBC India to require the disclosure of United States tax payers accounts. The Justice Department is committed to ensuring that all US tax payers meet their obligations to declare and pay taxes on foreign bank accounts. The IRS has announced that it is continuing to focus its attention on international tax evasion.
The ...
Programming regret for Google
2011-04-14
Tel Aviv — Human beings are well aware that hindsight is 20/20 — and the product of this awareness is often what we call "regret." Could this hindsight be programmed into a computer to more accurately predict the future? Tel Aviv University computer researchers think so — and the Internet giant Google is anxious to know the answer, too.
Prof. Yishay Mansour of Tel Aviv University's Blavatnik School of Computer Science launched his new project at the International Conference on Learning Theory in Haifa, Israel, earlier this year. His research will help computers minimize ...
Preparing for a cool life -- seasonal changes in lipid composition
2011-04-14
Animal cell membranes are a bilayer of phospholipids (charged fat molecules) made up to various degrees of fatty acids that must be acquired from the diet. The essential polyunsaturated fatty acids have been shown to be important in resistance to a variety of diseases and in coping with changes in body temperature. It is generally believed that mammals are unable to alter the proportions of essential fatty acids in their cell membranes except by changing their diets. Furthermore, mammals are unlikely candidates for extensive temperature-induced alteration, known to occur ...