Introduction

Microplastic can easily enter the bodies of humans and animals due to the distribution of plastic pollution in every space of our planet. When fish and other animals consume plastic particles, they make their way up to the food chain. Humans are at the top of the food chain, meaning these plastic particles will eventually end up in our plates when we eat and drink. Microplastics are found in human feces, which confirms that we are ingesting them regularly. Therefore, the health implications on our systems, especially in infertility caused by plastic are inevitable and concerning. 

Animal studies have shown that exposure to microplastics can directly harm male reproductive systems. In mice, polystyrene microplastics reduced sperm count and testosterone levels after just a few weeks of exposure. They also caused damage to testicular cells, triggered inflammation, and disrupted the blood-testis barrier, a natural defense that protects sperm from harmful substances. Thus this article will break down the science behind the issue of men' s fertility (Zhang et al., 2020).

The Decline in Male Fertility

In a study in 2015, it was estimated that approximately 15% of childbearing human couples worldwide suffer from infertility, while this incidence is increasing every year, nearly half of which are caused by male factors. Thus, the human semen has gradually and significantly decreased over the last 80 years. The sperm concentration has dropped to approximately one seventh of its original value. Meanwhile, this timing is aligned with the development and distribution of plastic worldwide. Since the 1940s, studies have shown a major drop in sperm count. Back then, men had around 113 million sperm per milliliter of semen. Today, that number has fallen to just 16 million or so. Other factors play a huge role in these outcomes like stress, diet, and other lifestyle choices, nonetheless the most persistent threat to our health is by far plastic pollution (Zhang et al., 2020). 

A basic sperm test usually looks at sperm count, shape, and movement. But it doesn’t show the condition of the sperm’s DNA, the material that carries the genetic code to offspring. Damaged DNA in sperm can reduce fertility and increase the chances of miscarriage. One important measure of this is called the DNA Fragmentation Index (DFI). When the DFI is high, it means the DNA in the sperm is broken or damaged.

Studies have shown that even when sperm looks normal under a microscope, the DNA can still be damaged especially in men who struggle with infertility or whose partners have had repeated miscarriages. Microplastics and nanoplastics (even smaller particles) have been found to increase DFI in lab animals, which could help explain the rising fertility problems in humans (Trifuoggi et al., 2019).

Conclusion

Microplastics may be invisible to the eye, but their impact on our health, especially male reproductive health, is becoming harder to ignore. From damaging sperm quality to disrupting DNA, these tiny plastic particles might be contributing to a global fertility decline. 

While more research is still needed, this evidence reminds us of the urgent need to reduce plastic pollution, limit our exposure, and support policies that protect both the environment and our health.