Polyester Underwear Could Be Causing Widespread Infertility In Men

A 2003 study found that, since World War II, the average sperm count has dropped 50%. Other research points to decreased sperm count as being responsible for one-half of couples experiencing infertility or fertility-related issues. Put two and two together and this spells bad news, not only for couples trying to conceive but for male fertility as a whole.

By Gwen Farrell3 min read
Polyester Underwear Could Be Causing Widespread Infertility In Men shutterstock

Male fertility issues, which usually connect back to low sperm count or low motility, are given a whole host of culprits, like the individual’s lifestyle choices, living environment, even the textiles and fibers he chooses to wear. Knowing what we know now, there’s an overwhelming amount of evidence concluding that polyester underwear could be causing widespread infertility in men.

Bad for the Earth and Bad for You

Polyester might technically be considered a (man-made) textile, fabric, or fiber, but in actuality, it’s a plastic. Like many other plastics, it’s composed of ingredients like dimethyl ester dimethyl terephthalate (DMT), monoethylene glycol (MEG), and purified terephthalic acid (PTS). Polyester is produced using components like coal and petroleum which have been subjected to high temperatures. The resulting product is one that manufacturers love to use, since it’s relatively strong and extremely cheap.

As you might have already guessed, it’s also terrible for the environment. Because, like many other plastics, it’s mass-produced and used in many products, so it’ll eventually wind up in a landfill. Polyester isn’t biodegradable and can only break down into microplastics which then end up in our waterways and natural habitats (and our babies). Making polyester specifically for textile purposes requires around seventy million barrels of oil.

Polyester is not ideal for sensitive skin and can result in rashes, eczema, and dermatitis.

And it isn’t ideal for human use, especially when it comes to clothing. Most of us want a fabric that’s breathable, but pure polyester can be very uncomfortable, which is why it’s often synthesized with other textile blends. It’s also not ideal for sensitive skin and can result in rashes, eczema, and dermatitis. The best alternative is products made with pure or organic materials like cotton, silk, linen, and wool, which feel better on us and are usually more sustainably made.

“Effective Contraception”

The idea that polyester could be potentially related to male infertility may seem far-fetched. But, in actuality, the results are overwhelming. In fact, one study which investigated a sling made of polyester worn by 14 men found that it had an extremely effective “contraceptive” effect. The slings were worn by the men for an entire year and rendered all 14 of them effectively sterile.

A 1993 investigation researched cotton versus polyester underwear (and additionally a control group with no underwear) on a group of male dogs over a two-year period. Researchers looked at factors like hormones, testicular temperature, semen quality, and even took testicular biopsies from the dogs to see how each textile was affecting those factors. While the dogs with the cotton underwear experienced no reproductive side effects or negative consequences, the dogs with the polyester underwear saw a sharp decrease in their sperm count. Researchers concluded that the electrostatic charge generated by the polyester material was responsible for the significant decline. 

The electrostatic charge generated by polyester was responsible for the significant decline in sperm count.

Given that the fabric isn’t breathable and has an electrostatic charge, we know that this isn’t great for sperm count. But what about other reproductive necessities – for example, a healthy sex drive?

A study conducted three years later and published in a urological medical journal observed 50 men, divided into four groups. Each group wore underwear made of different textiles, and their sexual desire and frequency of intercourse were studied, both before the study began and after six and 12 month periods. Out of the four groups, one wore 100% polyester underwear and another wore 50% polyester/50% cotton blend (the other two wore 100% cotton and 100% wool respectively). Once again, the researchers found that the 100% polyester and the blend underwear conducted electrostatic charges, resulting in “injurious [effects] on sexual activity.” Researchers also discovered that the sexual desire and amount of activity in the same subjects were “significantly reduced.”

Play It Cool

The findings are clear: keep petroleum by-products as far away as possible from the family jewels. But is that enough to combat male infertility?

Many experts agree that overall, natural fibers like cotton are the best choice when it comes to underwear. When it comes to bettering sperm quality and increasing motility, we might as well try anything. Some argue that polyester bedding is responsible for headaches, fatigue, and insomnia. Another source on an online forum points to a specific study where polyester underwear was been linked to miscarriage, in an investigation that researched different textiles and their positive or negative effects on pregnancy.

Natural fibers like cotton are the best choice when it comes to underwear.

Experts agree though that keeping things cool is what’s best for healthy sperm and motility. This means wearing boxers (and staying away from briefs), avoiding tight pants, and staying out of saunas and hot tubs. Testicles should ideally be kept away from the body – the closer they are, the higher the core temperature rises, which isn’t good for sperm. In fact, evidence points to lower motility and sperm count when the temperature of the scrotum rises just 2 to 4 degrees.

Closing Thoughts

Most of us are aware of how bad plastic is for us, and that it should be kept out of our homes (especially our bedrooms) and as far away as possible. 

Not all of us can afford to go out and buy silk underwear or pure linen bedding, but with more awareness comes better alternatives to plastic-filled products, and that includes our underwear.

When it comes to conception and optimizing fertility, each individual has to play their part. For centuries, the burden was on the woman and her fertility, but as we now know, the male reproductive system is just as crucial – and susceptible to infertility. Starting with what we put on under our clothes could be the key.

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