The endocrine or hormone system consists of all the glands and organs that produce hormones. Around 50 different hormones act as chemical messengers, allowing organs to communicate. Hormones control our body’s growth, development, metabolism and reproduction.
Testosterone, produced by the testis, is responsible for developing the male reproductive organs and regulates sperm production.
The ovaries mainly produce oestrogen and progesterone. During puberty, oestrogen is responsible for the development of the female reproductive organs, as well as the breasts. Oestrogen regulates the menstrual cycle, while progesterone prepares the uterus for pregnancy. Progesterone is also produced by the placenta throughout pregnancy to support it and, alongside oestrogen, prepares the breast for breastfeeding.
When an individual goes through menopause, the amount of female hormones produced by the ovaries is greatly reduced, and the fat tissues become the primary site of oestrogen production.
High levels of oestrogen increase breast cancer risk in both men and women. In women, prolonged exposure to oestrogen throughout life, caused by early puberty or late menopause, may also increase breast cancer risk.
Testosterone has also been linked to an increased risk of breast cancer in women in some studies. However, more research is needed in this area, while the evidence of a possible link between progesterone and breast cancer is inconclusive.
Endocrine Disrupting Chemicals, or EDCs, are harmful chemicals that may interfere with the endocrine system by mimicking or blocking the action of hormones.
Most EDCs are manufactured and include:
EDCs may be present in many products, including cosmetics and beauty products, cookware, food packaging, toys, furniture, cleaning products and more.
EDCs may be released into the environment from products or during manufacturing, with some persisting for long periods.
EDCs may enter our body from contaminated food and water or be absorbed through our skin by cosmetics and other products.
They have been found in many body fluids and tissues, including blood, urine, amniotic fluid, breast milk and breast tissue.
EDCs may be linked with health issues, including diabetes, obesity, cardiovascular diseases, fertility, thyroid diseases, neurodevelopmental problems, and some cancers.
The harmful effects of EDCs depend on the dose and time of exposure. During certain life stages, we may be more susceptible to lower doses of EDCs, which may cause health issues later in life.
Some EDCs have been found to mimic oestrogen and affect the mammary gland in animals. This suggests that they may be involved in breast cancer.
Human studies have shown that some EDCs, such as DES, which is now banned, are linked to an increased breast cancer risk. However, for most EDCs, the possible link with breast cancer is still under investigation.
In our everyday lives, we may be exposed to mixtures of many different EDCs and not to one chemical at a time. The overall harmful effect of an EDC mixture may be given by adding together the effects of the different EDCs. This, known as the cocktail effect, means that mixtures may cause harmful effects even if each chemical is at levels considered safe.
Please see our Endocrine disrupting chemicals science review, for more details and references.
Use our A to Z Chemicals of Concern list to check if products contain harmful chemicals.
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