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.

Related Articles


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 December 18, 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 December 18, 2014).

Share This


More From ScienceDaily



More Health & Medicine News

Thursday, December 18, 2014

Featured Research

from universities, journals, and other organizations


Featured Videos

from AP, Reuters, AFP, and other news services

Kids Die While Under Protective Services

Kids Die While Under Protective Services

AP (Dec. 18, 2014) — As part of a six-month investigation of child maltreatment deaths, the AP found that hundreds of deaths from horrific abuse and neglect could have been prevented. AP's Haven Daley reports. (Dec. 18) Video provided by AP
Powered by NewsLook.com
UN: Up to One Million Facing Hunger in Ebola-Hit Countries

UN: Up to One Million Facing Hunger in Ebola-Hit Countries

AFP (Dec. 17, 2014) — Border closures, quarantines and crop losses in West African nations battling the Ebola virus could lead to as many as one million people going hungry, UN food agencies said on Wednesday. Duration: 00:52 Video provided by AFP
Powered by NewsLook.com
When You Lose Weight, This Is Where The Fat Goes

When You Lose Weight, This Is Where The Fat Goes

Newsy (Dec. 17, 2014) — Can fat disappear into thin air? New research finds that during weight loss, over 80 percent of a person's fat molecules escape through the lungs. Video provided by Newsy
Powered by NewsLook.com
Why Your Boss Should Let You Sleep In

Why Your Boss Should Let You Sleep In

Newsy (Dec. 17, 2014) — According to research out of the University of Pennsylvania, waking up for work is the biggest factor that causes Americans to lose sleep. Video provided by Newsy
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:

Strange & Offbeat Stories

 

Health & Medicine

Mind & Brain

Living & Well

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