Microplastics: Exploring the Environmental and Human Health Impacts
By Clara Martín Fernández
Microplastics represent one of the most significant anthropogenic disasters of our era. These tiny particles are everywhere, from the most isolated regions devoid of human presence for hundreds of kilometers, to the very food we consume and the water we drink.1
They are plastic particles smaller than 5 mm in diameter and are the result of plastic pollution. In Europe, almost 26 million tons of plastic waste is generated every year.2 Microplastics possess a remarkable level of persistence, mobility, and resistance to removal from natural ecosystems. Once introduced into the environment, these minuscule particles do not undergo biodegradation and tend to accumulate, unless they are intentionally engineered to biodegrade within the open environment.3
Microplastics can be classified into two main categories: primary and secondary. Primary microplastics encompass minuscule particles intentionally manufactured for commercial purposes. These particles can be present in various items such as cosmetics, synthetic clothing, plastic bags, and bottles. An example of primary microplastics is microbeads, which are commonly incorporated into numerous health and beauty products.
On the contrary, secondary microplastics emerge as a consequence of the gradual degradation of larger plastic objects over time, caused by exposure to environmental factors. This degradation process can be influenced by various conditions like sunlight and wave action. It is important to note that single-use plastics constitute the primary contributor to the presence of secondary microplastics in the environment.
The presence of microplastics in the environment, ranging from sea and soil to food and drinking water, is steadily on the rise. This escalating occurrence has raised significant concerns regarding the impact of microplastics on the environment, biodiversity, and potentially human health. It is crucial to address these concerns and understand the implications associated with the prevalence of microplastics across various environmental compartments, particularly water sources.3
Impact on Aquatic Ecosystems
Microplastics have a significant environmental impact, particularly in aquatic ecosystems, where they tend to accumulate. These tiny particles are frequently found in rivers, lakes, and oceans, posing a risk to marine organisms like fish, turtles, and seabirds that may ingest them. The ingestion of microplastics can have various adverse effects, including physical damage to the digestive system, hindering nutrient absorption, and potentially leading to starvation or suffocation. Moreover, the accumulation of microplastics in marine organisms can contribute to the bioaccumulation and biomagnification of toxic chemicals present in the plastics, further exacerbating the ecological consequences.4
A recent study5 has investigated the effects of microplastics on red coral, which is present at almost all latitudes from shallow water to deep-sea habitats. This study concludes that microplastics had multiple detrimental effects on Corallium rubrum, including impaired feeding and increased mortality at high contamination levels. They were found to accumulate through direct ingestion and trophic transfer via contaminated prey. Microplastic exposure led to tissue damage, increased mucus production, oxidative DNA damage, altered gene expression, and shifts in the coral microbiome. These findings suggest that the negative impacts of microplastics extend to other marine organisms, and if microplastic pollution persists, it could result in higher mortality rates in the future.
Freshwater ecosystems are at risk from the effects of microplastics as well. Microplastics can infiltrate rivers, lakes, and streams through multiple avenues, including urban runoff and wastewater treatment plants. Once introduced into freshwater environments, microplastics can be consumed by aquatic organisms like fish, insects, and crustaceans, leading to negative consequences comparable to those observed in marine ecosystems. The presence of microplastics in freshwater systems has the potential to disrupt food chains, modify aquatic habitats, and potentially compromise water quality.6
When fish consume microplastics, it can lead to various negative effects. The ingestion of these particles can inflict physical harm on the fish’s digestive system, impairing nutrient absorption and growth. Moreover, the quantity of microplastics within the fish’s tissues can progressively accumulate, posing potential threats to their overall well-being and reproductive capacities. This disruption within the fish population can trigger a domino effect throughout the freshwater ecosystem, influencing predator-prey relationships and biodiversity.7
Impact on Soil and Terrestial Ecosystems
The accumulation of microplastics in soils causes a significant threat to terrestrial ecosystems and agriculture. Originating from agricultural soils, industrial activities, construction, transportation, and landfills, these microplastics can have a detrimental long-term impact. For instance, researchers in Germany estimate that terrestrial microplastic pollution is between 4 and 23 times greater than that in the oceans.8 This pollution can lead to soil degradation, decreased soil porosity, and compacted soil, affecting plant growth and nutrient absorption. Additionally, the presence of microplastics in the soil can disrupt the soil food web, potentially impacting the balance of the entire ecosystem.
The surfaces of tiny fragments of plastic have the potential to host disease-causing organisms and serve as a vehicle for transmitting diseases in the environment. Furthermore, microplastics can have an impact on soil-dwelling organisms, compromising their well-being and influencing the overall functionality of the soil. A notable example is earthworms, which exhibit altered burrowing behavior in the presence of microplastics, thereby affecting both their own fitness and the condition of the soil.8
The Royal Society published a pioneering field study in 2020, which examined the effects of microplastics on soil fauna for the first time.9 According to this paper, the presence of microplastic pollution in terrestrial environments has resulted in a decline in subterranean species, including mites, larvae, and other minuscule organisms that play a crucial role in preserving soil fertility.
Furthermore, the presence of chlorinated plastic can result in the release of harmful chemicals into the surrounding soil. These chemicals have the potential to infiltrate groundwater, other nearby water sources, and the broader ecosystem. As a result, the species that depend on these water sources for drinking may experience a range of detrimental effects.
Impact on Human Health
Microplastics present a potential threat to human health through three distinct avenues: physical harm, chemical exposure, and acting as a breeding ground for other microorganisms to congregate and proliferate. Evaluating the potential risks that they may pose to human health is a complex endeavor, primarily due to the unique combination of chemicals present in each plastic. Additionally, the diverse range of shapes, sizes, and textures exhibited by plastics further complicates the assessment of their toxicity.
Multiple studies, conducted both in vitro and in vivo, have provided compelling evidence regarding the potential harmful effects of microplastics on human health. These studies have demonstrated that microplastics have the capacity to induce physical stress, cause cellular damage, trigger processes such as apoptosis and necrosis, promote inflammation and oxidative stress, and elicit immune responses. Furthermore, the presence of microplastics has been associated with serious health concerns, including an increased risk of heart attacks and strokes. A notable landmark study revealed that nearly 60 percent of individuals undergoing surgery had microplastics or nanoplastics detected within a major artery, resulting in a 4.5 times greater likelihood of experiencing cardiovascular issues.10
In a recent study, researchers examined the interaction between microplastics and macrophages, a type of immune cell responsible for engulfing foreign substances. Although the direct impact of chronic exposure to microplastics on human health remains uncertain, the fact that macrophages actively target and engulf these particles raises concerns about potential risks.11
While the current scientific evidence suggests that microplastics may have detrimental effects on human health, further research is necessary to fully comprehend the extent of their impact. Conducting long-term studies on human populations is crucial in order to assess the chronic effects of microplastic exposure. Additionally, research efforts should be directed towards identifying the precise mechanisms by which microplastics exert their toxic effects. This comprehensive understanding will contribute to better addressing the potential risks associated with microplastics and developing effective mitigation strategies.
A Call for Action
Microplastics present a significant environmental and health concern that requires our attention. These minuscule particles, resulting from anthropogenic plastic pollution, have unfortunately reached every corner of our planet, from remote areas to the very food and water we consume.
Nevertheless, it is important to note that researchers are actively studying the full extent of microplastics’ impact, which provides hope for finding effective solutions. By gaining a deeper understanding of the mechanisms through which microplastics exert their harmful effects, we can develop strategies to mitigate their presence and minimize their impact.
Addressing microplastic pollution is a critical issue for our era, and it is encouraging to see increasing efforts being made to tackle this problem. By focusing on research, education, and implementing sustainable practices, we can work towards a cleaner and healthier future for our planet and ourselves. Together, we can make a positive difference in combating microplastic pollution.
References
- Microplastics: what they are and how you can reduce them.
www.nhm.ac.uk/discover/what-are-microplastics.html - European Commission. Energy, climate change, environment: Plastics.
environment.ec.europa.eu/topics/plastics_en - European Commission. Energy, climate change, environment: Microplastics.
environment.ec.europa.eu/topics/plastics/microplastics_en - Sarma, H., Hazarika, R.P., Kumar, V. et al. Microplastics in marine and aquatic habitats: sources, impact, and sustainable remediation approaches. Environmental Sustainability 5, 39–49 (2022).
link.springer.com/article/10.1007/s42398-022-00219-8 - Corinaldesi, C., Canensi, S., Dell’Anno, A. et al. Multiple impacts of microplastics can threaten marine habitat-forming species. Commun Biol 4, 431 (2021).
www.nature.com/articles/s42003-021-01961-1 - Talbot, R., Chang, H. Microplastics in freshwater: A global review of factors affecting spatial and temporal variations. Environmental Pollution 292, Part B (2022).
www.sciencedirect.com/science/article/pii/S0269749121019758 - Wang, Y., Liu, G., Wang, Y. et. al. The global trend of microplastic research in freshwater ecosystems. Toxics 11, 539 (2023).
www.mdpi.com/2305-6304/11/6/539 - An underestimated threat: land-based pollution with microplastics.
www.igb-berlin.de/en/news/underestimated-threat-land-based-pollution-microplastics - Lin, D., Yang, G., Dou, P. et al. Microplastics negatively affect soil fauna but stimulate microbial activity: insights from a field-based microplastic addition experiment. Proceedings of the Royal Society 287, 1934 (2020).
royalsocietypublishing.org/doi/10.1098/rspb.2020.1268 - Marfella, R., Prattichizzo, F., Sardu, C. et al. Microplastics and nanoplastics in atheromas and cardiovascular events. The New England Journal of Medicine 390, 10 (2024).
www.nejm.org/doi/full/10.1056/NEJMoa2309822 - Scientists shed light on how macrophages interact with microplastics.
phys.org/news/2023-03-scientists-macrophages-interact-microplastics.html
