Featured Research

from universities, journals, and other organizations

Unexpected action of bisphenol A on the inner ear of certain vertebrates

Date:
March 25, 2011
Source:
CNRS (Délégation Paris Michel-Ange)
Summary:
Bisphenol A, whose impact on reproduction and development is the subject of numerous studies, induces anomalies in the inner ear of embryos of certain vertebrates. This new, completely unsuspected effect has been demonstrated on zebrafish and Xenopus, a type of frog. These results illustrate, for the first time, the sensitivity of the inner ear in vertebrates to bisphenol A. The study demonstrates that the effects of this chemical compound on the embryonic development of animals, including mammals, now needs to be explored in greater depth.

Close-up side view of a 4-day-old zebrafish embryo. The otic vesicle, the future inner ear of the fish, can be seen with a properly formed otolith, colored yellow, in the center.
Credit: Copyright Florent Campo-Paysaa

Bisphenol A, whose impact on reproduction and development is the subject of numerous studies, induces anomalies in the inner ear of embryos of certain vertebrates. This new, completely unsuspected effect has been demonstrated on zebrafish and Xenopus, a type of frog, by a team headed by Vincent Laudet of the Institut de Génomique Fonctionnelle (CNRS/ENS de Lyon/Université Lyon 1) in collaboration with researchers from Inserm, the Muséum National d'Histoire Naturelle and INRA.

Published in the journal BMC Developmental Biology, these results illustrate, for the first time, the sensitivity of the inner ear in vertebrates to bisphenol A. The study demonstrates that the effects of this chemical compound on the embryonic development of animals, including mammals, now needs to be explored in greater depth.

Bisphenol A (BPA) is a synthetic chemical compound widely used in the industrial manufacture of polycarbonate type plastic containers and other everyday items such as CDs, spectacles, certain plastic bottles and some baby bottles. It is also employed in epoxy resins used in the internal linings of tin and drink cans, and in dental amalgams. However, BPA can modify the hormonal balance of vertebrates by directly interacting with hormonal receptors or with the enzymes that ensure the metabolism of these hormones: it is an endocrine disruptor. In fact, BPA is capable of binding to estrogen receptors, female sexual hormones, and mimicking their action in the body. For this reason, it is now classified as a "category 3 reprotoxin," in other words, as a "substance which causes concern for human fertility" due to "possible" (albeit not conclusively demonstrated) "toxic effects" on reproduction.

Risk assessments have led to the definition of a tolerable daily intake (TDI) of 50 µg of BPA per kg body weight per day, i.e. 2.5 mg per day for a person who weighs 50 kg. Until now, most of the studies carried out to characterize and evaluate its effects on the human body have focused on the reproductive function and the development of the brain.

The researchers focused on the effect of this compound on embryonic development by exposing zebrafish (Danio rerio) eggs to increasing concentrations of BPA (from 1 mg/L to 20 mg/L). The results were surprising, to say the least: following exposure to BPA, most of the zebrafish embryos developed abnormalities of the otoliths, the small structures of the inner ear that control balance and play a role in hearing. Otolith aggregates formed in 60% of the embryos. Other, less frequent abnormalities of the inner ear were also observed. Above a concentration of 15 mg/L, all of the zebrafish developed abnormalities. However, this dose corresponds to a very acute exposure, much higher than the possible range of exposure levels in humans.

Going further, the scientists repeated their experiment on another vertebrate of the amphibian family, Xenopus. Once again, they observed the development of abnormalities in the inner ear, suggesting that this effect could exist in other vertebrates. The team has thus brought to light an unexpected and hitherto unobserved effect of BPA. Obviously, no conclusion can be reached for humans as long as the action mechanisms have not been completely elucidated and in-depth research has been carried out on mammals and on humans in particular.

In addition, the researchers observed that these anomalies persisted even when estrogen receptors -- the conventional targets of bisphenol A -- were blocked, implying that BPA could attach to another receptor. This newly discovered effect could therefore be completely independent of estrogen receptors.

This work clearly demonstrates that, apart from its reprotoxic effects, bisphenol A at quite high doses also has an effect on embryonic development. It also shows that this compound has more target sites than previously thought. Finally, it opens new research avenues to characterize the way in which bisphenol A functions, and to correctly evaluate its effects.

This work benefited in particular from support from ANR and the European Commission.


Story Source:

The above story is based on materials provided by CNRS (Délégation Paris Michel-Ange). Note: Materials may be edited for content and length.


Journal Reference:

  1. Yann Gibert, Sana Sassi-Messai, Jean-Baptiste Fini, Laure Bernard, Daniel Zalko, Jean-Pierre Cravedi, Patrick Balaguer, Monika Andersson-Lendahl, Barbara Demeneix, Vincent Laudet. Bisphenol A induces otolith malformations during vertebrate embryogenesis. BMC Developmental Biology, 2011; 11 (1): 4 DOI: 10.1186/1471-213X-11-4

Cite This Page:

CNRS (Délégation Paris Michel-Ange). "Unexpected action of bisphenol A on the inner ear of certain vertebrates." ScienceDaily. ScienceDaily, 25 March 2011. <www.sciencedaily.com/releases/2011/03/110324104416.htm>.
CNRS (Délégation Paris Michel-Ange). (2011, March 25). Unexpected action of bisphenol A on the inner ear of certain vertebrates. ScienceDaily. Retrieved August 28, 2014 from www.sciencedaily.com/releases/2011/03/110324104416.htm
CNRS (Délégation Paris Michel-Ange). "Unexpected action of bisphenol A on the inner ear of certain vertebrates." ScienceDaily. www.sciencedaily.com/releases/2011/03/110324104416.htm (accessed August 28, 2014).

Share This




More Health & Medicine News

Thursday, August 28, 2014

Featured Research

from universities, journals, and other organizations


Featured Videos

from AP, Reuters, AFP, and other news services

CDC Director On Ebola Outbreak: 'It's Worse Than I Feared'

CDC Director On Ebola Outbreak: 'It's Worse Than I Feared'

Newsy (Aug. 28, 2014) — CDC director Tom Frieden says the Ebola outbreak is even worse than he feared. But he also said there's still hope to contain it. Video provided by Newsy
Powered by NewsLook.com
Treadmill 'trips' May Reduce Falls for Elderly

Treadmill 'trips' May Reduce Falls for Elderly

AP (Aug. 28, 2014) — Scientists are tripping the elderly on purpose in a Chicago lab in an effort to better prevent seniors from falling and injuring themselves in real life. (Aug.28) Video provided by AP
Powered by NewsLook.com
Japan's Golden Generation Shows No Sign of Slowing Down

Japan's Golden Generation Shows No Sign of Slowing Down

AFP (Aug. 27, 2014) — For many people in the autumn of their lives, walking up stairs is the biggest physical challenge they face. But in Japan, race tracks, hammer or pole vault await competitors at the Kyoto Masters, some of them more than 100 years old. Duration: 02:32 Video provided by AFP
Powered by NewsLook.com
Mini Pacemaker Has No Wires

Mini Pacemaker Has No Wires

Ivanhoe (Aug. 27, 2014) — Cardiac experts are testing a new experimental device designed to eliminate major surgery and still keep the heart on track. Video provided by Ivanhoe
Powered by NewsLook.com

Search ScienceDaily

Number of stories in archives: 140,361

Find with keyword(s):
 
Enter a keyword or phrase to search ScienceDaily for related topics and research stories.

Save/Print:
Share:  

Breaking News:
from the past week

In Other News

... from NewsDaily.com

Science News

Health News

Environment News

Technology News



Save/Print:
Share:  

Free Subscriptions


Get the latest science news with ScienceDaily's free email newsletters, updated daily and weekly. Or view hourly updated newsfeeds in your RSS reader:

Get Social & Mobile


Keep up to date with the latest news from ScienceDaily via social networks and mobile apps:

Have Feedback?


Tell us what you think of ScienceDaily -- we welcome both positive and negative comments. Have any problems using the site? Questions?
Mobile iPhone Android Web
Follow Facebook Twitter Google+
Subscribe RSS Feeds Email Newsletters
Latest Headlines Health & Medicine Mind & Brain Space & Time Matter & Energy Computers & Math Plants & Animals Earth & Climate Fossils & Ruins