Endocrine disruptors in question

Many chemicals found in the environment disrupt the hormonal system of living beings, including our own. How and with what consequences? Our researchers are tracking down the offending substances and studying their impact. With what results?

You have probably heard of endocrine disruptors. And probably nothing good. And for good reason, they are chemical substances that alter the health and even the survival of living beings, without mercy. And it is impossible to avoid them. They are used in the composition of plastics, cosmetics, furniture, textiles... and then end up in the air we breathe, the food we eat, the water we drink.

To understand these risks, we must go back to the 70s. Scientists then discovered that vertebrates have a hormonal functioning that has been very much preserved throughout evolution. The Museum, a pioneer in this research, showed, for example, that the thyroid hormone that prevents the disease called cretinism in young children is also responsible for the metamorphosis of amphibians. At the same time, researchers are noticing problems with the reproduction of animal species in the wild and are realizing that certain molecules released into the environment are the cause. The first disruptions of hormonal systems were identified in the early 90s.

Têtard de Xenopus laevis rendu doublement transgénique par le méthode REMI. Les neurones sont visibles en rouge tandis que les oligodendrocytes sont visibles en vert. Son nom est Tg(Mmu Mbp-GFP::NTR; Nbeta DsREd).

© S. Le Mével

In our laboratories, the major role of thyroid hormones continues to be studied, as well as its dysfunctions, in the development of vertebrates. To discover the substances that interfere with these processes, one of our researchers and her team have designed a specific test. It is based on the use of genetically modified xenopus larvae. Depending on the amount of thyroid hormone present in these organisms, a fluorescent signal of varying intensity is emitted. Exposure to chemical molecules or mixtures makes it possible to verify whether their production is normal or altered. Today, it is part of the range of tests available to public or private laboratories and is widely used by our teams as part of collaborative projects.

At the same time, our scientists are making progress in their knowledge of the impact of these substances on human health. In particular, they have shown that 15 substances frequently found in the amniotic fluid of pregnant women (triclosan, pesticides, bisphenol A, perchlorate, heavy metals, etc.) impact the normal functioning of thyroid hormones and prevent the normal cerebral development of amphibians, causing mobility problems... This is enough to get alarm bells ringing. The European project EDC mix risk, in which the Museum has taken an active part, has made it possible to study the effects of such mixtures on humans. A link has indeed been demonstrated between certain molecules found in mothers during pregnancy and language delays in children at the age of three (bisphenol and phthalates in particular). This work has earned our researchers international recognition. They issue recommendations for the European Parliament, the French and European health safety agencies, that have already led to certain harmful products being banned. An intervention for our protection.

Today, the research continues and goes far beyond brain development. In one or two decades, the number of cases of several disorders or diseases has exploded: obesity, diabetes, infertility. The cocktail of chemicals in which we are immersed from the moment we are conceived is therefore more questionable than ever. Our scientists are constantly exploring the links between exposure to these substances and our health, in connection with the environment.

When science and vigilance are in tune...

Research team

The UMR PhyMA scientists, directed by Dr Laurent Sachs, who work on the study of endocrine disruptors are united in the group of Prof. Jean-Baptiste Fini.

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