Microplastics and Infertility: An Invisible Crisis

BY SAM OBIOMA

According to the International Union for Conservation of Nature (IUCN), over 430 million tons of plastic are produced every year. Via ultraviolet (UV) radiation, fragmentation, and even bacteria, plastic is broken down from everyday products into smaller fragments which, over time, have been found in our air, food, and water. Microplastics have been implicated in the physiological harm, reduced habitat, and overall destruction of marine wildlife in certain areas.¹ Nowadays, however, it has become increasingly clear that their effects are far more outreaching toward humans than previously thought. Specifically, emerging research suggests that these microplastics may be silently contributing to infertility worldwide. As the global birth rate steadily declines, we must question whether microplastics are simply an environmental issue or an active threat to human reproduction.

The evidence against the role of microplastics in reproductive health is mounting. Studies have already shown that microplastics are present in human ovarian follicular fluid and that higher concentrations of microplastics strongly correlate with lower levels of the fluid itself.² The hormone plays a major role in ovulation, so any disruptions to its levels and function in potentially impairing fertility is worrisome. It is also important to recognize that it is far from exclusive to one sex: microplastics have also been shown to interfere with spermatogenesis in male animal models, with polystyrene microplastics significantly reducing the number of viable epididymis sperm in male mouse models.³ Evidence like this is especially alarming given that global sperm counts have already dropped by over 50% in the past five decades.⁴ Lifestyle and environmental stressors have been considered the primary drivers of declining fertility for a long time, but the presence of microplastics in our reproductive process suggests that there is another lurking contaminant that may also be accelerating this crisis. 

Aside from hormone disruption, microplastic presence has been shown to have a direct effect on reproductive organs. In both animal studies and systematic reviews of humans, microplastics have been detected in the placenta, a crucial organ that supplies oxygen and nutrients from the mother to the fetus during pregnancy.⁵ Capable of reaching vital and transient structures, the presence of microplastics is concerning in the short term and potentially in the long term as we await its impact on further pregnancy outcomes. Even after birth, microplastics have also been found in human breast milk, further increasing concerns about early-life exposure and how that may affect reproduction across multiple generations as these harmful pollutants starts to accumulate.⁶ This build up and persistence in the environment is one of the most alarming things about microplastics and its effects on human fertility. Unlike many other toxins, microplastics can take hundreds of years to degrade, building up in our environment and bodies. As plastic production only continues to rise,⁷ there is no question that human exposure to subsequent microplastics will also rapidly increase as well.

The problem of microplastics is no longer one of sustainability, but of survival. Urgent, legislative action and awareness is by far the most effective avenue of intervention. To help mitigate our vulnerability, reducing the production of single-use plastics and improving water filtration systems are promising avenues to pursue. Given that advocating for permanent reductions of plastic production would likely be unsuccessful, legislative and advocacy efforts would benefit from focusing on constructing safer alternatives that limit the prevalence of microplastics. Besides prevention, medical research initiatives focusing on investigating microplastics and their long-term health risks must be financially supported, as these efforts can not only aid in prevention but also in devising future treatments. If left unchecked, microplastics will not only just threaten fertility but also redefine the future of human health. The invisible threat is already upon us, and ignoring it is no longer an option.

Sam Obioma is a sophomore in Benjamin Franklin College.

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References

1. Zolotova, N., Kosyreva, A., Dzhalilova, D., Fokichev, N. & Makarova, O. Harmful effects of the microplastic pollution on animal health: a literature review. PeerJ 10, e13503 (2022).
2. Montano, L. et al. First evidence of microplastics in human ovarian follicular fluid: an emerging threat to female fertility. medRxiv (Cold Spring Harbor Laboratory) (2024) doi:https://doi.org/10.1101/2024.04.04.24305264.
3. Hou, B., Wang, F., Liu, T. & Wang, Z. Reproductive toxicity of polystyrene microplastics: In vivo experimental study on testicular toxicity in mice. Journal of Hazardous Materials 124028 (2020) doi:https://doi.org/10.1016/j.jhazmat.2020.124028.
4. Levine, H. et al. Temporal trends in sperm count: a systematic review and meta-regression analysis. Human Reproduction Update 23, 646–659 (2017).
5. Hasti Balali, Morabbi, A. & Karimian, M. Concerning influences of micro/nano plastics on female reproductive health: focusing on cellular and molecular pathways from animal models to human studies. Reproductive Biology and Endocrinology 22, (2024).
6. Apisith Saraluck et al. Detection of Microplastics in Human Breast Milk and Its Association with Changes in Human Milk Bacterial Microbiota. Journal of Clinical Medicine 13, 4029–4029 (2024).
7. Walker, T. R. & Fequet, L. Current trends of unsustainable plastic production and micro(nano)plastic pollution. TrAC Trends in Analytical Chemistry 160, 116984 (2023).