Microplastics in testicles are giving men a hard time having kids

The placenta is the first and largest organ to develop for a growing embryo, not just “afterbirth” meant to be tossed into the trash bin — assuming your parent didn’t eat it under the belief that it would do them any good.

It’s a pancake-shaped organ about ten inches long, an inch at its center, and about five hundred grams in mass, with a dull maternal side and a shiny fetal side. During the early development of the fetus, the placenta is the most important organ: It has to do the jobs of organs that have not yet developed — metabolizing nutrients, excreting waste, and facilitating gaseous exchange. Over the course of the pregnancy, the placenta must adapt to variable nutrient supplies; to alterations in maternal physiology; to the dynamically changing fetal growth rates. But its most important feature is to serve as the gatekeeper between the mother and the fetus.

The placenta acts as a selective barrier — keeping unwelcomed stowaways out of the womb, be they pollutants or pathogens. It was surprising, therefore, when a team of researchers from Italy announced that they found microplastics in multiple human placentas. Just a few months later, researchers from Germany and Austria announced that they’d found these microplastics in meconium — medical nomenclature for a newborn’s first poop. It was apparent, then, that children had been feeding on microplastics far before they could even eat.

These plastic particles — no more than five millimeters in size — have also been found in seminal fluid, adult stool, breast milk, and blood; in livers, lungs, and the heart. It’s almost overwhelming that there hasn’t been a body part that people have looked at but haven’t found microplastics in.

Another such report took over the news last week: Researchers at the University of Mexico recently tested 70 samples of testicular tissue — 47 from dogs and 23 from humans. What they reported was a “pervasive presence” of microplastics in the male reproductive system, implicating consequences on male fertility.

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This study isn’t the first to identify microplastics in the male reproductive system; that came last year when a small-scale analysis out of China identified microplastics in 6 testes and 30 semen samples (all the samples they tested). The new paper built on that research and found alarmingly more microplastic in human samples than the previous study — finding polythene (commonly used in plastic bags) to be the most dominant polymer in the samples. But how are microplastics getting in so deep, and what does this implicate?

It’s almost overwhelming that there hasn’t been a body part that people have looked at but haven’t found microplastics in.

In the form of ragged food packaging, chewed-up straws, empty water bottles, and used plastic bags, plastic waste turns up pretty much everywhere — around 350 million tonnes of it is disposed of every year, after all. It has been found at the bottom of the Mariana Trench, over nine-thousand feet below sea level; in the snow samples near the summit of Mt. Everest, around eighty-five hundred meters above sea level.

The problem is that all this plastic has a tendency to devolve, lofting up as far as the skies. Tires today contain a wide variety of plastics, and as friction erodes them, they release a large number of microplastics into the air (although they might not be responsible for seventy-eight percent of all ocean microplastics). Plastic waste that enters the oceans continues to be tossed around by waves and bombarded by UV radiation, disintegrating into smaller particles. Most clothes, furniture upholstery, and other textiles all contain plastics, and are constantly shedding fibers, which are carried through the dust to distant locations.

Researchers point to two main pathways by which microplastics enter our bodies: We swallow them, and we inhale them. Travelling through contaminated water and soil, microplastics can enter into everyday fruits and vegetables, as well as the animals we consume.

Shouldn’t it be unsurprising, then, that microplastics have invaded our biology and reached the farthest corners of our bodies? Research published earlier this year estimated that, on average, a liter of bottled water included about 240,000 tiny pieces of plastic — 90 percent of which were nanoplastics. Another study estimates that people could be inhaling more than 48,000 microplastic particles every day.

Since these particles have been shown to be absorbed by the bloodstream, they have a convenient cross-organ highway. This allows the microplastics to get across, say, the “blood-testes barrier” and get lodged in there. But the manner in which they’re affecting these organs remains largely a mystery.

The manner in which they’re affecting these organs remains largely a mystery.

Since the late 1930s, sperm counts around the world appear to have dropped significantly — an observed decline in both the “quality of human semen” and “normal value for semen concentration.”

In 2011, statistician-turned-epidemiologist Shanna Swan and her team of andrologists, epidemiologists, statisticians, and a reference librarian began working on the most comprehensive analysis of falling sperm counts to date. The report they published six years later concluded that there had been declines of 52.4 percent in sperm concentration and 59.3 percent in total sperm count among men in Europe, North America, Australia, and New Zealand.

The results eventually led to her publishing “Count Down,” a book aimed at a wider audience. Swan’s conclusion, one that pervades the book, is that endocrine-disrupting chemicals (EDCs) — which can interfere with the body’s natural hormones — are the primary culprit behind these lowering sperm counts. Her work mainly revolves around pesticides and phthalates (which are released by microplastics), traces of which have been found in breast milk, placental tissue, urine, blood, and seminal fluid.

According to Swan, these EDCs could be affecting the reproductive systems not only of adults, but of unborn children as well. She pointed to her discoveries regarding the “ass-ball connector,” also known as “the taint,” as proof: She found that the anogenital distance (AGD), as it is known among professionals, can act as a predictor of a man’s ability to, years later, conceive a child. There’s compelling data that supports Swan’s hypothesis — in utero phthalate exposure is linked to a decrease in AGD in male babies, and a shorter AGD in men has been associated with less testosterone, poorer semen quality, and a higher risk of fertility. And she suggests that these alterations happening in utero can result in non-correctable, lifelong changes.

Research has shown how microplastics are a long-term source of these plasticizing chemicals, these phthalates. By extension of these ideas, it may be the microplastics lodged in fetuses and male testicles that are making it harder for men to have children.

But there could also be other factors accounting for increasing infertility rates. For example, couples are waiting longer than ever to get pregnant, and older age is associated with a greater likelihood of infertility. A paper published in August 2022 in Nature Reviews Urology even states that “available data do not enable us to conclude that human semen quality is deteriorating worldwide or in the Western world, but that a trend is observed in some specific areas.”

But the fact that microplastics are negatively impacting our health in some ways cannot be refuted. They don’t just leach chemicals; they attract toxic substances from the environment into our bodies — essentially acting “like magnets for PBTs”, or “persistent bioaccumulation and toxic substances,” as the Environmental Protection Agency puts it.

So how do you keep microplastics out of your testicles? Out of your system, in fact.

A small study from Australia found that donating blood or plasma seems to reduce the level of perfluoroalkyl and poly-fluoroalkyl substances — or “forever chemicals” to use a more fashionable term — from the bodies of firefighters who were exposed to them. But the best that can be done for now (at least on a more personal level) is to limit your exposure to microplastics.

Don’t microwave food in plastic. Reduce your use of plastic water bottles and other types of plastic containers. Shift away from highly processed foods, which may have more microplastic contamination than unprocessed ones. Also, wash your hands before you eat — microplastics released from synthetic clothing, furniture upholstery, and other textiles can migrate through dust onto your hands and down your gullet.