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Definitions to help you understand the impact of endocrine disruptors
Hormones and the endocrine system
Hormones are molecules produced by organs called endocrine glands and released into the bloodstream. They act as chemical messengers that regulate physiological constants such as body temperature, blood sugar levels, and blood pressure. Hormones, therefore, play a fundamental role in the smooth running of the body. They ensure communication between all the organs. Hormones regulate numerous functions such as metabolism, nutrition, sleep, growth, sexual development, reproduction, etc...
The endocrine system is made up of seven main glands
How do hormones work?
Once released into the bloodstream, hormones act on the cells of their target organs by attaching themselves to specific receptors. The hormone acts here like a key that unlocks a lock, its receptor.
Following the formation of the hormone/receptor complex, the hormonal signal is transmitted inside the cell. This triggers the activation of certain enzymes within the cell, which can regulate gene expression and modulate the production of numerous proteins. These proteins are the ultimate regulators of all vital functions. It is through this mechanism that hormones regulate all the body's physiological functions.
What is an endocrine disruptor?
According to the World Health Organisation (WHO), an endocrine disruptor "is a chemical substance that alters the functioning of the endocrine system. It can thus induce harmful effects on an organism or its descendants". At present, more than 550 chemical compounds are known or suspected endocrine disruptors. They are found in a large number of products on the market.
How do endocrine disruptors work?
Endocrine disruptors can enter the body through ingestion, inhalation, or simple contact. They can then interfere with the endocrine system through three mechanisms of action.
What are the effects of endocrine disruptors?
Endocrine disruptors modify the natural hormonal signal at a cellular level and are thus responsible for altering physiological functions.
This is why these chemical molecules can have numerous consequences on the body and be responsible for pathologies such as obesity, hormone-dependent cancers, type 2 diabetes, autism, cognitive disorders, thyroid problems, behavioural disorders, etc. Although exposure to endocrine disruptors is dangerous throughout a person's life, windows of vulnerability have been defined. These correspond to periods during which organs are still developing.
Endocrine disruptors: impact on male fertility
In recent decades, there has been an increase in the number of men suffering from Testicular Dysgenesis Syndrome (TDS). This syndrome includes various alterations to the male genital tract that can lead to male fertility problems.
Numerous studies carried out in various countries around the world link the increase in the number of these alterations to the male genital tract with growing exposure to endocrine disruptors. More specifically, the appearance of Testicular Dysgenesis Syndrome is thought to be associated with the effect of chemical molecules that mimic the action of oestrogens (female hormones) and/or block the action of androgens (male hormones).
Endocrine disruptors: impact on female fertility
In women, endocrine disruptors are implicated in a range of gynaecological pathologies. They are chemical molecules that mimic the action of oestrogens (female hormones) or androgens (male hormones).
How can we protect ourselves from endocrine disruptors?
In order to limit contact with endocrine disruptors, a few precautions need to be taken. Avoiding plastics in food, favouring pesticide- and herbicide-free farming, reducing the use of detergents, paying attention to the composition of cosmetics and household products... Contact with harmful substances in general, and endocrine disrupters in particular, cannot be totally eliminated. However, we can at least reduce their impact by adopting a healthier lifestyle.
Fabien Duval, Ph.D. Reproductive and developmental biology