What Are Endocrine Disruptors and How Do They Affect Fertility?


Introduction

Endocrine disrupting chemicals (EDCs) are substances from outside the body that upset how our hormones work. They can act like, block, or change the production and action of natural hormones. Because hormones control everything from egg and sperm development to implantation, it’s important for fertility specialists to know how EDCs interfere. You’ll find EDCs in many everyday items—food wrappers, cosmetics, cleaning products, clothes and even farm sprays. Below, we explain how they work, how we come into contact with them and what they do to fertility in individuals.

What Are Endocrine Disruptors?

EDCs come from both man-made and natural sources. Even at very low levels, they can affect the body. Main types include:

• Industrial chemicals like bisphenol A (BPA), bisphenol S (BPS) and phthalates
• Pesticides such as DDT, atrazine and glyphosate
• Heavy metals like lead, mercury and cadmium
• Cosmetic additives including parabens, triclosan and certain UV filters

How EDCs Work

1. Mimicking or blocking hormone receptors

• Some EDCs fit into hormone receptors on cells, like a key in a lock.
• If they act like a hormone (agonism), they trigger the cell to respond even when the real hormone isn’t there.
• If they block the receptor (antagonism), they stop the real hormone from working.
• This can upset processes such as egg development in the ovary or support of sperm cells in the testes.

2. Changing hormone production

1. Hormones are made by enzymes in the ovaries, testes and adrenal glands.
2. EDCs can reduce or boost these enzymes, shifting the balance of oestrogen, testosterone and other hormones.
3. In women, this can lead to cycles without ovulation or a weak luteal phase. In men, it can lower sperm production and quality.

3. Altering gene activity (epigenetics)

1. EDCs can change how genes turn on or off without altering the DNA itself.
2. They may add or remove chemical tags on DNA or affect small RNA molecules that control gene messages.
3. These changes can be passed down to children and even grandchildren.

4. Disrupting hormone feedback loops

1. The brain and glands use feedback loops to keep hormone levels steady.
2. EDCs can confuse these signals, for example by making the brain think there’s too much or too little hormone.
3. This can lead to early puberty, missed ovulation, irregular cycles or poor sperm development.

How We Are Exposed

• Eating and drinking: Plastics can leach chemicals into food, pesticides remain on fruit and veg, and “forever chemicals” (PFAS) turn up in water.
• Breathing: Household dust and cleaning sprays can carry EDCs into the lungs.
• Through the skin: Lotions, makeup and fragranced products often contain EDCs that soak in.

Many EDCs are fat-loving and stay in our body fat for years, so even small exposures add up over time.

Effects on Female Fertility

1. Ovary problems and no ovulation
   • EDCs can stop egg-supporting cells in the ovary from growing and making the right hormones, so eggs don’t mature or ovulate.
2. Polycystic ovary syndrome (PCOS)
3. Some EDCs boost male hormone activity and cause insulin resistance, both key features of PCOS.
4. Lower egg quality
5. Chemicals like BPA and cadmium raise oxidative stress in eggs, leading to DNA and structural damage.
6. Smaller egg reserve
7. EDCs can reduce levels of AMH, a hormone that tells us how many eggs a woman has left.
8. Higher miscarriage risk
9. Pesticides may weaken progesterone production or harm the lining of the womb, making implantation harder.
10. Irregular or missing periods
11. By upsetting the brain–ovary hormone signals, EDCs can cause unpredictable or absent menstrual cycles.

Effects on Male Fertility

1. Sperm production and quality
   • EDCs harm the cells that make sperm and testosterone, breaking down protective barriers and upsetting energy supply. This leads to fewer, less mobile and misshapen sperm, with more DNA breaks.
2. Testicular dysgenesis
3. Exposure before birth can cause undescended testicles or misplaced urethra openings, conditions linked to low sperm counts later in life.
4. Hormone imbalances
5. Damaged testosterone production makes the body crank up LH levels. Over time, this stresses the hormone-making cells further.
6. Population declines
7. Large studies show that in areas with more EDC exposure, average sperm counts and motility have fallen over recent decades.

Worrying Long-Term Effects

Changes made to genes in early development can last for generations, affecting children and grandchildren who were never directly exposed.

Summary

EDCs are everywhere and can act like or block our natural hormones, upsetting everything from egg and sperm production to monthly cycles and implantation. Even tiny amounts can have big effects, especially at sensitive times such as before birth or puberty. Although more long-term human studies are needed, it makes sense to follow the “precautionary principle”: reduce exposure where we can, especially for anyone planning to start a family. Fertility professionals play a vital role in raising awareness, advising on safer choices, and supporting policies that limit these harmful chemicals.

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