Subtopic 1: Microplastics in the food chain: How harmful are they?

What are microplastics?

Microplastics are minuscule plastic particles measuring less than 5 millimeters that are present in a variety of products, including cosmetics, cleaning agents, and our food and water sources. Due to their small size, marine organisms can easily ingest them, resulting in severe ecological consequences. However, recent research indicates that microplastics may also pose a significant risk to human health. Evidence suggests that microplastics are widespread across land, sea, and air. Studies from 2019 have shown that humans consume thousands of plastic particles annually, while more recent research conducted in May 2022 discovered microplastics in human blood.

Source: Hincks (2022)

How do they get into the food chain?

Microplastics are small particles that can originate from various sources, such as industrial activities, plastic waste, and urban runoff. They can be found in everyday products like toothpaste, facial scrubs, and cleaning agents. Additionally, the breakdown of larger plastic debris, such as bottles and bags, can release microplastics into the environment, including waterways and even the atmosphere, spreading them to the farthest corners of the earth.

The presence of microplastics in water systems and oceans can have a severe impact on marine life, as they can be ingested by fish and shellfish, eventually finding their way into the human food chain. For example, as Klein et al. (2022) indicated, microplastics were found in blue mussels near the Australian coast, which highlights the potential risk of microplastic pollution to South Australia’s unique marine ecosystems and the local human food chain.

Furthermore, microplastics have been detected in a variety of foodstuffs, such as tea, sugar, honey, and even salt, raising concerns about their impact on human health. A recent study by Cardiff University has also found that the use of sewage sludge as fertilizer on farmland could be introducing microplastics to agricultural soil, which may then end up in waterways due to runoff. Overall, microplastic pollution is a widespread and growing issue that requires urgent attention to prevent further harm to the environment and human health.

Source: Al Mamun, A., Prasetya, T. A. E., Dewi, I. R., & Ahmad, M. (2023)

Ingestion of Microplastics

Ingesting contaminated seafood can lead to exposure to microplastics, with an average of 11,000 microplastic particles consumed per year according to the University of Ghent’s study. Inhaling, ingesting, and having skin contact with microplastics can all put humans at risk of health complications. Through the digestive system, microplastics can enter the body and accumulate in it, creating potential health problems.

Source: Wright & Kelly (2017)

Are microplastics harmful to human health?

The long-term health effects of microplastics on humans are still largely unknown. However, recent studies suggest that microplastics can cause a range of health problems, including:

1. Inflammation: In human cells, microplastics have been found to induce inflammation, leading to various diseases, including cancer.
2. Endocrine disruption: The endocrine system can be disrupted by microplastics, which can mimic the actions of hormones in the body. This can lead to reproductive problems and other health issues by altering hormone levels.
3. Neurological damage: Microplastics have been discovered to be capable of crossing the blood-brain barrier, potentially causing neurological damage.
4. Immunotoxicity: The immune system can be affected by microplastics, making individuals more vulnerable to infections and other illnesses.
5. Genotoxicity: Microplastics have been shown to induce DNA damage, which can increase the risk of cancer and other diseases by causing genotoxicity.