New research is suggesting that microplastics may be playing a role in the declining fertility rates that are being observed in nearly every corner of the globe.
According to a study published in Toxicological Sciences on May 15, twelve different types of microplastics were identified in testicle samples from both humans and canines.
The study was limited, involving samples from just 47 dogs and 23 men. However, microplastics were found in every sample.
Researchers say that the most common type of polymer found was polyethylene (PE), and the second most common was polyvinyl chloride (PCV).
“PE is commonly used in packaging, water supply systems, and agricultural films. PVC is also very common, used in construction, medical equipment, packaging, and insulation for electronics,” Medical News Today (MNT) reported.
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A professor and director of Environmental Research and Translation for Health (EaRTH) , at the University of California, Tracey Woodruff, PhD, who was not involved in the study told MNT, “This study evaluates the types of plastics found in the testis, and it is not surprising that PE is the most common – because PE is the most commonly produced plastic – it is used in plastic bags, bottles, food containers, carpet films, etc.,” adding that, “Bottom line – if it is being produced then there is a good chance some of it is ending up in us and our pets. As for health effects – this adds further evidence to our work showing that MPs [microplastics] are suspected to adversely affect the male reproductive system.”
Microplastics influence on fertility
However, it remains unclear exactly what kind of effect microplastics are having on male fertility.
Researchers found that certain types of microplastics were associated with a decrease in sperm count and declines in testis weight. The study says these findings reached a level of “statistical significance.”
However, one microplastic type was associated with an increase in sperm count, and two others were associated with an increase in testis weight. The researchers determined however that these results were not statistically significant.
James Kashanian, MD, who was also not part of the study, told MNT that the current study highlights how man-made environmental factors can impact men’s reproductive health.
“Higher levels of these microplastics can potentially cause deleterious effects on testicular function, i.e. testosterone production and sperm production. Unfortunately, many environmental factors, like those studied in this article, accumulate over decades and are not easily reversed,” Kashanian said.
While alarming, the findings are far from conclusive as there were a number of limitations on the study.
First, it examined a small number of samples, samples that were gathered from one area of the United States and secondly the samples were from 2016, a factor that could have impacted the results.
“Researchers also acknowledge that the humans from which samples came typically did not experience natural deaths, so experts cannot broaden the results to an entire population,” MNT noted.
The researchers also concluded that the results cannot establish causality.
They noted that their research “highlights the need to determine the dose-response effects of these microplastics and to conduct mechanistic studies on the reproductive system.”
Fertility rates dropping globally
According to a study published in The Lancet on March 20 this year governments around the world need to prepare for massive changes over the coming decades as global population patterns change.
The study concluded that by 2050, people living in 155 out of the 204 countries and territories studied will have fewer babies than it would take to maintain a stable population.
“These future trends in fertility rates and live births will completely reconfigure the global economy and the international balance of power and will necessitate reorganizing societies,” Natalia Bhattacharjee, a population statistician with the Institute for Health Metrics and Evaluation (IHME) in the United States told Science Alert.
The study noted that in the 1950s there were just under five children born to each female on the planet, a number that has plummeted to just over two children to each female in 2021.
The study also notes that the findings are not entirely bad.
“In many ways, tumbling fertility rates are a success story, reflecting not only better, easily available contraception but also many women choosing to delay or have fewer children, as well as more opportunities for education and employment,” Stein Emil Vollset, a member of the Future Health Scenarios forecasting team told Science Alert.
Researchers believe that should these trends continue, the number of people on the planet will peak at around 9.7 billion in 2064, before falling to 8.8 billion by the end of this century.
In the United States, declining fertility rates are not being blamed on health or environmental factors, but rather social and economic issues.